MOBILE SIGNAL JAMMER USING ARDUINO B.Tech. Project Report
A. Raja Gopal MD. Imthiyaz Ur Rahmaan P. Nischal Reddy Y. Siva Sai Krishna Kumar Reddy
DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING GOKARAJU RANGARAJU INSTITUTE OF ENGINEERING AND TECHNOLOGY (Affiliated to Jawaharlal Nehru Technological University)
HYDERABAD 500 090 2013
MOBILE SIGNAL JAMMER USING ARDUINO Project Report Submitted in Partial Fulfillment of the Requirements for the Degree of
Bachelor of Technology in Electronics and Communication Engineering by
A.Raja Gopal (09241A0458) MD.Imthiyaz Ur Rahmaan (09241A0482) P.Nischal Reddy (09241A0487) Y.Siva Sai Krishna Kumar Reddy(09241A04A5)
DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING GOKARAJU RANGARAJU INSTITUTE OF ENGINEERING AND TECHNOLOGY (Affiliated to Jawaharlal Nehru Technological University)
HYDERABAD 500 090 2013
Department of Electronics and Communication Engineering Gokaraju Rangaraju Institute of Engineering and Technology (Affiliated to Jawaharlal Nehru Technological University)
Hyderabad 500 090 2013
Certificate This is to certify that this project report entitled Mo b i l e S i gn a l Ja m me r U si n g A rd u ino by A. Ra j a G o p a l (Roll No.09241A0458), M D . Im t h i ya z Ur R a hm a a n (Roll No.09241A0482) , P . Ni s c ha l Red d y (Roll No.09241A0487) and Y.Siva Sai Krishna Kumar Reddy(Roll No.09241A04A5), submitted in partial fulfillment of the requirements for the degree of Bachelor of Technology in Electronics and Communication Engineering of the Jawaharlal Nehru Technological University, Hyderabad, during the academic year 2012-13, is a bonafide record of work carried out under our guidance and supervision. The results embodied in this report have not been submitted to any other University or Institution for the award of any degree or diploma.
(Guide) N.Madhu Sudhana Rao Assistant Professor
(External Examiner)
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(Head of Department) Dr.Ravi Billa
ACKNOWLEDGMENT
It is a pleasure to express thanks to Prof. N.Madhu Sudhana Rao for the encouragement and guidance throughout the course of this project.
It is a pleasure to express thanks to 1.Prof. K.N.Balajikumar 2. Prof. V.H.Raju 3.Prof. A.Radhanand
A. Raja Gopal
___________________________
MD. Imthiyaz Ur Rahmaan
___________________________
P. Nischal Reddy
___________________________
Y. Siva Sai Krishna Kumar Reddy ___________________________
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ABSTRACT
Mobile jammer is used to prevent mobile phones from receiving or transmitting signals with the base stations. Mobile jammer effectively disable mobile phones within the defined regulated zones without causing any interference to other communication means Mobile jammer can be used in practically any location, but are used in places where a phone call would be particularly disruptive like Temples, Libraries, Hospitals etc. As with other radio jamming, mobile jammer block mobile phone use by sending out radio waves along the same frequencies that mobile phones use. This causes enough interference with the communication between mobile phones and communicating towers to render the phones unusable. Upon activating mobile jammer, all mobile phones will indicate "NO NETWORK”. Incoming calls are blocked as if the mobile phone were off. When the Mobile jammers are turned off, all mobile phones will automatically reestablish communications and provide full service. Mobile jammer’s effect can vary widely based on factors such as proximity to towers, indoor and outdoor settings, presence of buildings and landscape, even temperature and humidity play a role.
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CONTENTS Chapter 1: Introduction
01
Chapter 2: Hardware Equipment
02
2.1 Arduino
02
2.1.1 Features of Arduino
02
2.1.2 Power Supply to Arduino
02
2.1.3 ATmega 328 Microcontroller
06
2.2 Real time Clock
10
2.2.1 DS 1307 IC
10
2.3 Liquid Crystal Display
17
2.4 Relay
20
2.5 Signal Isolator
23
Chapter3 : I2C Communication
40
3.1 Introduction
40
3.2 Design
40
3.3 Reference design
41
3.4 Timing Diagram
43
3.5 Limitations
43
3.6 I²C (wire) library
43
Chapter 4: Block Diagram and working
48
Chapter 5: Flow chart
49
Chapter 6: Program code
51
Chapter 7 : Applications and Advantages
58
Chapter 8 : Conclusion
59
List of figures Pin diagram of Atmega328
08
Pin diagram of DS1307
10
Block diagram of DS1307
11
Data transfer of I2C bus
12
Data write-slave receive mode
16
Data read- slave receive mode
16
Liquid Crystal Display
20
Circuit symbol of relay
21
Relay operation and use of protection diodes
21
Block diagram of transistor driver circuit
22
Relay interfacing with microcontroller
23
Block diagram of mobile jammer
29
White noise generator output spectrum
33
Block diagram of IF section
35
Pin diagram of MAXIM 2623
35
MAXIM 2623 pin connection
36
Circuit diagram of RF section
38
Block diagram of project
48
List of tables Features of Arduino board
02
Oscillator Circuit
11
Timekeeping registers
13
Pins Functions LCD
18
GSM Frequency Bands
28
Chapter 1 INTRODUCTION Communication jamming devices were first developed and used by military. Where tactical commanders use RF communications to exercise control of their forces, an enemy has interest in those communications. This interest comes from the fundamental area of denying the successful transport of the information from the sender to the receiver. Nowadays the mobile jammer devices are becoming civilian products rather than electronic warfare devices, since with the increasing number of the mobile phone users the need to disable mobile phones in specific places where the ringing of cell phone would be disruptive has increased. These places include worship places, university lecture rooms, libraries, concert halls, meeting rooms, and other places where silence is appreciated. Mobile jammer is used to prevent mobile phones from receiving or transmitting signals with the base stations. Mobile jammer effectively disable mobile phones within the defined regulated zones without causing any interference to other communication means Mobile jammer can be used in practically any location, but are used in places where a phone call would be particularly disruptive like Temples, Libraries, Hospitals etc. Mobile jammers were originally developed for law enforcement and the military to interrupt communications by criminals and terrorists to foil the use of certain remotely detonated explosives. The civilian applications were apparent with growing public resentment over usage of mobile phones in public areas on the rise & reckless invasion of privacy. Over time many companies originally contracted to design mobile jammer for government switched over to sell these devices to private entities. As with other radio jamming, mobile jammer block mobile phone use by sending out radio waves along the same frequencies that mobile phones use. This causes enough interference with the communication between mobile phones and communicating towers to render the phones unusable. Upon activating mobile jammer, all mobile phones will indicate "NO NETWORK”. Incoming calls are blocked as if the mobile phone were off. When the Mobile jammers are turned off, all mobile phones will automatically reestablish communications and provide full service. Mobile jammer’s effect can vary widely based on factors such as proximity to towers, indoor and outdoor settings, presence of buildings and landscape, even temperature and humidity play a role. The choice of mobile jammers are based on the required range starting with the personal pocket mobile jammer that can be carried along with you to ensure undisrupted meeting with your client or a personal portable mobile jammer for your room or medium power mobile jammer or high power mobile jammer for your organization to very high power military jammers to jam a large campuses.
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Chapter 2 Hardware equipment 2.1 Arduino The Arduino Uno is a microcontroller board based on the ATmega328. It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz ceramic resonator, a USB connection, a power jack, an ICSP header, and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started. 2.1.1 Features of Arduino board Microcontroller
ATmega328
Operating Voltage
5V
Input Voltage (recommended) 7-12V Input Voltage (limits)
6-20V
Digital I/O Pins
14 (of which 6 provide PWM output)
Analog Input Pins
6
DC Current per I/O Pin
40 Ma
DC Current for 3.3V Pin
50 mA
Flash Memory
32 KB (ATmega328) of which 0.5 KB used by boot loader
SRAM
2 KB (ATmega328)
EEPROM
1 KB (ATmega328)
Clock Speed
16 MHz
2.1.2 Power To Arduino The Arduino Uno can be powered via the USB connection or with an external power supply. The power source is selected automatically.
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External (non-USB) power can come either from an AC-to-DC adapter (wall-wart) or battery. The adapter can be connected by plugging a 2.1mm center-positive plug into the board's power jack. Leads from a battery can be inserted in the Ground and Vin pin headers of the POWER connector. The board can operate on an external supply of 6 to 20 volts. If supplied with less than 7V, however, the 5V pin may supply less than five volts and the board may be unstable. If using more than 12V, the voltage regulator may overheat and damage the board. The recommended range is 7 to 12 volts. The power pins are as follows: •
•
• •
VIN. The input voltage to the Arduino board when it's using an external power source (as opposed to 5 volts from the USB connection or other regulated power source). You can supply voltage through this pin, or, if supplying voltage via the power jack, access it through this pin. 5V.This pin outputs a regulated 5V from the regulator on the board. The board can be supplied with power either from the DC power jack (7 - 12V), the USB connector (5V), or the VIN pin of the board (7-12V). 3V3. A 3.3 volt supply generated by the on-board regulator. Maximum current draw is 50 mA. GND. Ground pins.
Each of the 14 digital pins (pins 0 to 13) on the Uno can be used as an input or output, using pinMode(), digitalWrite(), and digitalRead() functions. They operate at 5 volts. Each pin can provide or receive a maximum of 40 mA and has an internal pull-up resistor (disconnected by default) of 20-50 kΩ. In addition, some pins have specialized functions: Serial: 0 (RX) and 1 (TX). Used to receive (RX) and transmit (TX) TTL serial data. These pins are connected to the corresponding pins of the ATmega8U2 USB-to-TTL Serial chip. External Interrupts: 2 and 3. These pins can be configured to trigger an interrupt on a low value, a rising or falling edge, or a change in value. PWM: 3, 5, 6, 9, 10, and 11. Provide 8-bit PWM output with the analogWrite() function. SPI: 10 (SS), 11 (MOSI), 12 (MISO), 13 (SCK). These pins support SPI communication using the SPI library. LED: 13. There is a built-in LED connected to digital pin 13. When the pin is HIGH value, the LED is on, when the pin is LOW, it's off. The Uno has 6 analog inputs, labeled A0 through A5, each of which provide 10 bits of resolution (i.e. 1024 different values). By default they measure from ground to 5 volts, though is it possible to change the upper end of their range using the AREF pin and the analogReference() function. 3
The programs written for Arduino are called sketches. For the sketch to work on your Arduino Uno, there are two hardware related settings you need to make in the Arduino IDE – • •
Board Serial Port
The basic structure of the Arduino sketch is fairly simple and has two required functions: void setup() { statements; } void loop() { statements; } Where setup() is the preparation, loop() is the execution. Both functions are required for the program to work. The setup function should follow the declaration of any variables at the very beginning of the program. It is the first function to run in the program, is run only once, and is used to set pinMode or initialize serial communication. The loop function follows next and includes the code to be executed continuously – reading inputs, triggering outputs, etc. This function is the core of all Arduino programs and does the bulk of the work. setup() The setup() function is called once when your program starts. Use it to initialize pin modes, or begin serial. It must be included in a program even if there are no statements to run. void setup() { pinMode(pin, OUTPUT); // sets the 'pin' as output } loop() After calling the setup() function, the loop() function does precisely what its name suggests, and loops consecutively, allowing the program to change, respond, and control the Arduino board. void loop() { digitalWrite(pin, HIGH); // turns 'pin' on delay(1000); // pauses for one second digitalWrite(pin, LOW); // turns 'pin' off delay(1000); // pauses for one second }
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pinMode(pin, mode) Used in void setup() to configure a specified pin to behave either as an INPUT or an OUTPUT. pinMode(pin, OUTPUT); // sets ‘pin’ to output There are also convenient pullup resistors built into the Atmega chip that can be accessed from software. These built-in pullup resistors are accessed in the following manner: pinMode(pin, INPUT); // set ‘pin’ to input digitalWrite(pin, HIGH); // turn on pullup resistors Pull-up resistors would normally be used for connecting inputs like switches. Notice in the above example it does not convert pin to an output, it is merely a method for activating the internal pull-ups. Pins configured as OUTPUT can provide 40 mA (milliamps) of current to other devices/circuits. This is enough current to brightly light up an LED (don't forget the series resistor), but not enough current to run most relays, solenoids, or motors. Short circuits on Arduino pins and excessive current can damage or destroy the output pin, or damage the entire AT mega chip. It is often a good idea to connect an OUTPUT pin to an external device in series with a 470Ω or 1KΩ resistor. digitalRead(pin) Reads the value from a specified digital pin with the result either HIGH or LOW. The pin can be specified as either a variable or constant (0-13). value = digitalRead(Pin); // sets 'value' equal to // the input pin digitalWrite(pin, value) Outputs either logic level HIGH or LOW at (turns on or off) a specified digital pin. The pin can be specified as either a variable or constant (0-13). digitalWrite(pin, HIGH); // sets 'pin' to high analogRead(pin) Reads the value from a specified analog pin with a 10-bit resolution. This function only works on the analog in pins (0-5). The resulting integer values range from 0 to 1023. value = analogRead(pin); // sets 'value' equal to 'pin' Note: Analog pins unlike digital ones, do not need to be first declared as INPUT nor OUTPUT. analogWrite(pin, value) Writes a pseudo-analog value using hardware enabled pulse width modulation (PWM) to an output pin marked PWM. On Uno, this function works on pins 3, 5, 6, 9, 10, and 11. The value can be specified as a variable or constant with a value from 0-255. analogWrite(pin, value); // writes 'value' to analog 'pin' A value of 0 generates a steady 0 volts output at the specified pin; a value of 255 generates a steady 5 volts output at the specified pin. For values in between 0 and 255, the pin rapidly alternates between 0 and 5 volts - the higher the value, the more often the pin is HIGH (5 volts). For example, a value of 64 will be 0 volts three-quarters of the 5
time, and 5 volts one quarter of the time; a value of 128 will be at 0 half the time and 255 half the time; and a value of 192 will be 0 volts one quarter of the time and 5 volts threequarters of the time. Because this is a hardware function, the pin will generate a steady wave after a call to analogWrite in the background until the next call to analogWrite (or a call to digitalRead or digitalWrite on the same pin). Note: Analog pins unlike digital ones, do not need to be first declared as INPUT nor OUTPUT. delay(ms) Pauses a program for the amount of time as specified in milliseconds, where 1000 equals 1 second. delay(1000); // waits for one second millis() Returns the number of milliseconds since the Arduino board began running the current program as an unsigned long value. value = millis(); // sets ‘value’ equal to millis() Note: This number will overflow (reset back to zero), after approximately 9 hours. Serial.begin(rate) Opens serial port and sets the baud rate for serial data transmission. The typical baud rate for communicating with the computer is 9600 although other speeds are supported. void setup() { Serial.begin(9600); // opens serial port } // sets data rate to 9600 bps Note: When using serial communication, digital pins 0 (RX) and 1 (TX) cannot be used at the same time.
2.1.3 ATMEGA 328 Features High Performance, Low Power AVR® 8-Bit Microcontroller Advanced RISC Architecture – 131 Powerful Instructions – Most Single Clock Cycle Execution – 32 x 8 General Purpose Working Registers – Fully Static Operation – Up to 20 MIPS Throughput at 20 MHz – On-chip 2-cycle Multiplier High Endurance Non-volatile Memory Segments – 4/8/16/32K Bytes of In-System Self-Programmable Flash progam memory – 256/512/512/1K Bytes EEPROM (ATmega48P/88P/168P/328P) – 512/1K/1K/2K Bytes Internal SRAM (ATmega48P/88P/168P/328P) – Write/Erase Cycles: 10,000 Flash/100,000 EEPROM – Data retention: 20 years at 85°C/100 years at 25°C(1) – Optional Boot Code Section with Independent Lock Bits – Programming Lock for Software Security 6
Peripheral Features – Two 8-bit Timer/Counters with Separate Prescaler and Compare Mode – One 16-bit Timer/Counter with Separate Prescaler, Compare Mode, and CaptureMode – Real Time Counter with Separate Oscillator – Six PWM Channels – 8-channel 10-bit ADC in TQFP and QFN/MLF package – 6-channel 10-bit ADC in PDIP Package – Programmable Serial USART – Master/Slave SPI Serial Interface – Byte-oriented 2-wire Serial Interface (Philips I2C compatible) – Programmable Watchdog Timer with Separate On-chip Oscillator – On-chip Analog Comparator – Interrupt and Wake-up on Pin Change Special Microcontroller Features: – Power-on Reset and Programmable Brown-out Detection – Internal Calibrated Oscillator – External and Internal Interrupt Sources – Six Sleep Modes: Idle, ADC Noise Reduction, Power-save, Power-down, Standby, and Extended Standby I/O and Packages: – 23 Programmable I/O Lines – 28-pin PDIP, 32-lead TQFP, 28-pad QFN/MLF and 32-pad QFN/MLF Operating Voltage: – 1.8 - 5.5V for ATmega48P/88P/168PV – 2.7 - 5.5V for ATmega48P/88P/168P – 1.8 - 5.5V for ATmega328P Temperature Range: – -40°C to 85°C Speed Grade: – ATmega48P/88P/168PV: 0 - 4 MHz @ 1.8 - 5.5V, 0 - 10 MHz @ 2.7 - 5.5V – ATmega48P/88P/168P: 0 - 10 MHz @ 2.7 - 5.5V, 0 - 20 MHz @ 4.5 - 5.5V – ATmega328P: 0 - 4 MHz @ 1.8 - 5.5V, 0 - 10 MHz @ 2.7 - 5.5V, 0 - 20 MHz @ 4.5 5.5V Low Power Consumption at 1 MHz, 1.8V, 25°C for ATmega48P/88P/168P: – Active Mode: 0.3 mA – Power-down Mode: 0.1 µA – Power-save Mode: 0.8 µA (Including 32 kHz RTC) 7
Pin diagram:
Pin Description : VCC Digital supply voltage. GND Ground. Port B (PB7:0) XTAL1/XTAL2/TOSC1/TOSC2 Port B is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The Port B output buffers have symmetrical drive characteristics with both high sink and source Capability. As inputs, Port B pins that are externally pulled low will source current if the pull-up resistors are activated. The Port B pins are tri-stated when a reset condition becomes active, even if the clock is not running. Depending on the clock selection fuse settings, PB6 can be used as input to the inverting Oscillator amplifier and input to the internal clock operating circuit. Depending on the clock selection fuse settings, PB7 can be used as output from the inverting Oscillator amplifier. Port C (PC5:0) Port C is a 7-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The 8
PC5.0 output buffers have symmetrical drive characteristics with both high sink and source capability. As inputs, Port C pins that are externally pulled low will source current if the pull-up resistors are activated. The Port C pins are tri-stated when a reset condition becomes active, even if the clock is not running. PC6/RESET If the RSTDISBL Fuse is programmed, PC6 is used as an I/O pin. Note that the electrical characteristics of PC6 differ from those of the other pins of Port C. If the RSTDISBL Fuse is unprogrammed, PC6 is used as a Reset input. A low level on this pin for longer than the minimum pulse length will generate a Reset, even if the clock is not running. Shorter pulses are not guaranteed to generate a Reset. Port D (PD7:0) Port D is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The Port D output buffers have symmetrical drive characteristics with both high sink and source capability. As inputs, Port D pins that are externally pulled low will source current if the pull-up resistors are activated. The Port D pins are tri-stated when a reset condition becomes active,even if the clock is not running. AVCC AVCC is the supply voltage pin for the A/D Converter, PC3:0, and ADC7:6. It should be externally connected to VCC, even if the ADC is not used. If the ADC is used, it should be connected to VCC through a low-pass filter. Note that PC6..4 use digital supply voltage, VCC. AREF AREF is the analog reference pin for the A/D Converter.
ADC7:6 (TQFP and QFN/MLF Package Only) In the TQFP and QFN/MLF package, ADC7:6 serve as analog inputs to the A/D converter. These pins are powered from the analog supply and serve as 10-bit ADC channels.
2.2 Real time clock Introduction The real time clock (RTC) is a widely used device that provides accurate time and date for many applications. The RTC chip present in the PC provides time components of hour, minute and second in addition to the date/calendar components of year, month and day. 9
The RTC chip uses an internal battery that keeps the time and date even when the power is off. One of the most widely used RTC chips is the DS1307 from Dallas semiconductor. Description The DS1307 serial real-time clock (RTC) is a low power, full binary-coded decimal (BCD) clock/calendar plus 56 bytes of NV SRAM. Address and data are transferred serially through an I2C, bidirectional bus. The clock/calendar provides seconds, minutes, hours, day, date, month, and year information. The end of the month date is automatically adjusted for months with fewer than 31 days, including corrections for leap year. The clock operates in either the 24-hour or 12-hour format with AM/PM indicator. The DS1307 has a built-in power-sense circuit that detects power failures and automatically switches to the backup supply. Timekeeping operation continues while the part operates from the backup supply.
Fig: Pin configurations Features: Real-Time Clock (RTC) Counts seconds, minutes, hours, date of the month, month, day of the week, and year with Leap-Year Compensation valid up to 2100. • 56-Byte, Battery-Backed, Nonvolatile (NV) RAM for Data Storage. • I2C Serial Interface. • Programmable Square-Wave Output Signal. • Automatic Power-Fail Detect and Switch Circuitry. • Consumes Less than 500nA in Battery-Backup Mode with Oscillator Running. • Optional Industrial Temperature Range:-40°C to +85°C. • Available in 8-Pin Plastic DIP or SO. The DS1307 is a low-power clock/calendar with 56 bytes of battery-backed SRAM. The clock/calendar provides seconds, minutes, hours, day, date, month, and year information. The date at the end of the month is automatically adjusted for months with fewer than 31 days, including corrections for leap year. •
The DS1307 operates as a slave device on the I2C bus. Access is obtained by implementing a START condition and providing a device identification code followed by a register address. Subsequent registers can be accessed sequentially until a STOP condition is executed. When VCC falls below 1.25 x VBAT, the device terminates an 10
access in progress and resets the device address counter. Inputs to the device will not be recognized at this time to prevent erroneous data from being written to the device from an out-of tolerance system. When VCC falls below VBAT, the device switches into a lowcurrent battery-backup mode. Upon power-up, the device switches from battery to VCC when VCC is greater than VBAT +0.2V and recognizes inputs when VCC is greater than 1.25 x VBAT.
Fig: Block diagram Oscillator Circuit: The DS1307 uses an external 32.768 kHz crystal. The oscillator circuit does not require any external resistors or capacitors to operate. The below table specifies several crystal parameters for the external crystal. If using a crystal with the specified characteristics, the startup time is usually less than one second. Parameter Nominal frequency Series Resistance Load Capacitance
Symbol Fo ESR CL
Min Typ Max 32.768 KHz 45 KΩ 12.5 pF
Units
Clock Accuracy: The accuracy of the clock depends upon the accuracy of the crystal and the accuracy of the match between the capacitive load of the oscillator circuit and the capacitive load for which the crystal was trimmed. Additional error will be added by crystal frequency drift caused by temperature shifts. External circuit noise coupled into the oscillator circuit may result in the clock running fast.
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RTC and RAM Address map: The table below shows the address map for the DS1307 RTC and RAM registers. The RTC registers are located in address locations 00h to 07h. The RAM registers are located in address locations 08h to 3Fh. During a multibyte access, when the address pointer reaches 3Fh, the end of RAM space, it wraps around to location 00h, the beginning of the clock space. Clock and Calendar: The time and calendar information is obtained by reading the appropriate register bytes. Table 2 shows the RTC registers. The time and calendar are set or initialized by writing the appropriate register bytes. The contents of the time and calendar registers are in the BCD format. The day-of-week register increments at midnight. Values that correspond to the day of week are user-defined but must be sequential (i.e., if 1 equals Sunday, then 2 equals Monday, and so on.) Illogical time and date entries result in undefined operation. Bit 7 of Register 0 is the clock halt (CH) bit. When this bit is set to 1, the oscillator is disabled. When cleared to 0, the oscillator is enabled. It should be noted that the initial power-on state of all registers is not defined. Therefore, it is important to enable the oscillator (CH bit = 0) during initial configuration. The DS1307 can be run in either 12-hour or 24-hour mode. Bit 6 of the hours register is defined as the 12-hour or 24-hour mode-select bit. When high, the 12-hour mode is selected. In the 12-hour mode, bit 5 is the AM/PM bit with logic high being PM. In the 24-hour mode, bit 5 is the second 10-hour bit (20 to 23 hours). The hour’s value must be re-entered whenever the 12/24-hour mode bit is changed. When reading or writing the time and date registers, secondary (user) buffers are used to prevent errors when the internal registers update. When reading the time and date registers, the user buffers are synchronized to the internal registers on any I2C START. The time information is read from these secondary registers while the clock continues to run. This eliminates the need to re-read the registers in case the internal registers update during a read. The divider chain is reset whenever the seconds register is written. Write transfers occur on the I2C acknowledgement from the DS1307. Once the divider chain is reset, to avoid rollover issues, the remaining time and date registers must be written within one second.
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Table: Timekeeping registers Control Register The DS1307 control register is used to control the operation of the SQW/OUT pin.
Bit 7: Output Control (OUT) This bit controls the output level of the SQW/OUT pin when the square wave output is disabled. If SQWE = 0, the logic level on the SQW/OUT pin is1 if OUT = 1 and is 0 if OUT = 0. Bit 4: Square-Wave Enable (SQWE). This bit, when set to logic 1, enables the oscillator output. The frequency of the square-wave output depends upon the value of the RS0 and RS1 bits. With the square wave output set to 1Hz, the clock registers update on the falling edge of the square wave. Bits 1, 0: Rate Select (RS1, RS0). These bits control the frequency of the square-wave output when the square-wave output has been enabled. The following table lists the square-wave frequencies that can be selected with the RS bits.
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I2C DATA BUS The DS1307 supports the I2C protocol. A device that sends data onto the bus is defined as a transmitter and a device receiving data as a receiver. The device that controls the message is called a master. The devices that are controlled by the master are referred to as slaves. The bus must be controlled by a master device that generates the serial clock (SCL), controls the bus access, and generates the START and STOP conditions. The DS1307 operates as a slave on the I2C bus.
Fig: Data transfer on I2C Bus • •
Data transfer may be initiated only when the bus is not busy. During data transfer, the data line must remain stable whenever the clock line is HIGH. Changes in the data line while the clock line is high will be interpreted as control signals. Accordingly, the following bus conditions have been defined:
Bus not busy: Both data and clock lines remain HIGH. Start data transfer: A change in the state of the data line, from HIGH to LOW, while the clock is HIGH, defines a START condition. Stop data transfer: A change in the state of the data line, from LOW to HIGH, while the clock line is HIGH, defines the STOP condition. Data valid: The state of the data line represents valid data when, after a START condition, the dataline is stable for the duration of the HIGH period of the clock signal. The data on the line must be changed during the LOW period of the clock signal. There is one clock pulse per bit of data. Each data transfer is initiated with a START condition and terminated 14
with a STOP condition. The number of data bytes transferred between START and STOP conditions is not limited, and is determined by the master device. The information is transferred byte-wise and each receiver acknowledges with a ninth bit. Within the I2C bus specifications a standard mode (100 kHz clock rate) and a fast mode (400 kHz clock rate) are defined. The DS1307 operates in the standard mode (100 kHz) only. Acknowledge: Each receiving device, when addressed, is obliged to generate an acknowledgement after the reception of each byte. The master device must generate an extra clock pulse which is associated with this acknowledge bit. A device that acknowledges must pull down the SDA line during the acknowledge clock pulse in such a way that the SDA line is stable LOW during the HIGH period of the acknowledge related clock pulse. Of course, setup and hold times must be taken into account. A master must signal an end of data to the slave by not generating an acknowledge bit on the last byte that has been clocked out of the slave. In this case, the slave must leave the data line HIGH to enable the master to generate the STOP condition. Depending upon the state of the R/W bit, two types of data transfer are possible: 1. Data transfer from a master transmitter to a slave receiver: The first byte transmitted by the master is the slave address. Next follows a number of data bytes. The slave returns an acknowledge bit after each received byte. Data is transferred with the most significant bit (MSB) first. 2. Data transfer from a slave transmitter to a master receiver. The first byte (the slave address) is transmitted by the master. The slave then returns an acknowledge bit. This is followed by the slave transmitting a number of data bytes. The master returns an acknowledge bit after all received bytes other than the last byte. At the end of the last received byte, a “not acknowledge” is returned. The master device generates all the serial clock pulses and the START and STOP conditions. A transfer is ended with a STOP condition or with a repeated START condition. Since a repeated a START condition is also the beginning of the next serial transfer, the bus will not be released. Data is transferred with the most significant bit (MSB) first. The DS1307 may operate in the following two modes: 1. Slave Receiver Mode (Write Mode): Serial data and clock are received through SDA (Serial data) and SCL (Serial clock). After each byte is received, an acknowledge bit is transmitted. START and STOP conditions are recognized as the beginning and end of a serial transfer. Hardware performs address recognition after reception of the slave address and direction bit. The slave address byte is the first byte received after the master generates the START condition. The slave address byte contains the 7-bit DS1307 address, which is 1101000, followed by the direction bit (R/W), which for a write is 0. After receiving and decoding the slave address byte, the DS1307 outputs an acknowledgement on SDA. After the DS1307 acknowledges the slave address + write bit, the master transmits a word address to the DS1307. This sets the register pointer on the DS1307, with the DS1307 acknowledging the transfer. The master can then transmit zero or more bytes of data with the DS1307 acknowledging each byte received. The register pointer automatically 15
increments after each data byte are written. The master will generate a STOP condition to terminate the data write. 2. Slave Transmitter Mode (Read Mode): The first byte is received and handled as in the slave receiver mode. However, in this mode, the direction bit will indicate that the transfer direction is reversed. The DS1307 transmits serial data on SDA while the serial clock is input on SCL. START and STOP conditions are recognized as the beginning and end of a serial transfer (see Figure 5). The slave address byte is the first byte received after the START condition is generated by the master. The slave address byte contains the 7-bit DS1307 address, which is 1101000, followed by the direction bit (R/W), which is 1 for a read. After receiving and decoding the slave address the DS1307 outputs an acknowledgement on SDA. The DS1307 then begins to transmit data starting with the register address pointed to by the register pointer. If the register pointer is not written to before the initiation of a read mode the first address that is read is the last one stored in the register pointer. The register pointer automatically increments after each byte are read. The DS1307 must receive a Not Acknowledge to end a read.
Fig: Data Write- Slave Receive mode
Fig: Data Read- Slave Transmit mode
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Fig: Data Read (Write Pointer, Then Read)—Slave Receive and Transmit
2.3 Liquid crystal display LCD stands for Liquid Crystal Display. LCD is finding wide spread use replacing LEDs (seven segment LEDs or other multi segment LEDs) because of the following reasons: • • •
•
The declining prices of LCDs. The ability to display numbers, characters and graphics. This is in contrast to LEDs, which are limited to numbers and a few characters. Incorporation of a refreshing controller into the LCD, thereby relieving the CPU of the task of refreshing the LCD. In contrast, the LED must be refreshed by the CPU to keep displaying the data. Ease of programming for characters and graphics. 17
•
These components are “specialized” for being used with the microcontrollers, which means that they cannot be activated by standard IC circuits. They are used for writing different messages on a miniature LCD. A model described here is for its low price and great possibilities most frequently used in practice. It is based on the HD44780 microcontroller (Hitachi) and can display messages in two lines with 16 characters each . It displays all the alphabets, Greek letters, punctuation marks, mathematical symbols etc. In addition, it is possible to display symbols that user makes up on its own. Automatic shifting message on display (shift left and right), appearance of the pointer, backlight etc. are considered as useful characteristics. Pins Functions There are pins along one side of the small printed board used for connection to the microcontroller. There are total of 14 pins marked with numbers (16 in case the background light is built in). Their function is described in the table below:
Function
Pin Number
Name
Logic State
Description
Ground
1
Vss
-
0V
Power supply
2
Vdd
-
+5V
Contrast
3
Vee
-
0 – Vdd
Control of operating
4
RS
0 1
D0 – D7 are interpreted as commands
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D0 – D7 are interpreted as data
5
Data / commands
0 1
R/W
Write data (from controller to LCD) Read data (from LCD to controller)
0 Access to LCD disabled 1 Normal operating From 1 to Data/commands are transferred 0 to LCD
6
E
7
D0
0/1
Bit 0 LSB
8
D1
0/1
Bit 1
9
D2
0/1
Bit 2
10
D3
0/1
Bit 3
11
D4
0/1
Bit 4
12
D5
0/1
Bit 5
13
D6
0/1
Bit 6
14
D7
0/1
Bit 7 MSB
LCD screen: LCD screen consists of two lines with 16 characters each. Each character consists of 5x7 dot matrix. Contrast on display depends on the power supply voltage and whether messages are displayed in one or two lines. For that reason, variable voltage 0-Vdd is applied on pin marked as Vee. Trimmer potentiometer is usually used for that purpose. Some versions of displays have built in backlight (blue or green diodes). When used during operating, a resistor for current limitation should be used (like with anyLE diode).
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LCD initialization The initialization of LCD in Arduino programming is done by including LiquidCrystal.h header file. The statements for the LCD programming are as following. Description The GRIET LCD shield has the following resources • • • •
2x16 LCD LM35 temperature sensor LDR(Light Dependent Resistor) 2 LEDs
The 2x16 LCD uses the 4-bit interface. The RD/WR pin of the LCD is grounded so that write is permanently enabled. There is a potentiometer the contrast. Adjust the pot till you see a strip of dark blocks in the first line of the LCD. The LM35 is connected to the A5 analog input pin of Uno. The LDR forms part of a potential divider circuit whose output is given to A4 analog input pin of Uno.
2.4 Relay A relay is an electrically controllable switch widely used in industrial controls, automobiles and appliances. The relay allows the isolation of two separate sections of a system with two different voltage sources i.e., a small amount of voltage/current on one side can handle a large amount of voltage/current on the other side but there is no chance that these two voltages mix up.
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Fig: Circuit symbol of a relay Operation: When a current flow through the coil, a magnetic field is created around the coil i.e., the coil is energized. This causes the armature to be attracted to the coil. The armature’s contact acts like a switch and closes or opens the circuit. When the coil is not energized, a spring pulls the armature to its normal state of open or closed. There are all types of relays for all kinds of applications. Transistors and ICs must be protected from the brief high voltage 'spike' produced when the relay coil is switched off. The above diagram shows how a signal diode (eg 1N4148) is connected across the relay coil to provide this protection. The diode is connected 'backwards' so that it will normally not conduct. Conduction occurs only when the relay coil is switched off, at this moment the current tries to flow continuously through the coil and it is safely diverted through the diode. Without the diode no current could flow and the coil would produce a damaging high voltage 'spike' in its attempt to keep the current flowing.
Fig: Relay Operation and use of protection diodes In choosing a relay, the following characteristics need to be considered: 1. The contacts can be normally open (NO) or normally closed (NC). In the NC type, the contacts are closed when the coil is not energized. In the NO type, the contacts are closed when the coil is energized. 2. There can be one or more contacts. i.e., different types like SPST (single pole single throw), SPDT (single pole double throw) and DPDT (double pole double throw) relays. 21
3. The voltage and current required to energize the coil. The voltage can vary from a few volts to 50 volts, while the current can be from a few milliamps to 20milliamps. The relay has a minimum voltage, below which the coil will not be energized. This minimum voltage is called the “pull-in” voltage. 4. The minimum DC/AC voltage and current that can be handled by the contacts. This is in the range of a few volts to hundreds of volts, while the current can be from a few amps to 40A or more, depending on the relay. Transistor driver circuit: An SPDT relay consists of five pins, two for the magnetic coil, one as the common terminal and the last pins as normally connected pin and normally closed pin. When the current flows through this coil, the coil gets energized. Initially when the coil is not energized, there will be a connection between the common terminal and normally closed pin. But when the coil is energized, this connection breaks and a new connection between the common terminal and normally open pin will be established. Thus when there is an input from the microcontroller to the relay, the relay will be switched on. Thus when the relay is on, it can drive the loads connected between the common terminal and normally open pin. Therefore, the relay takes 5V from the microcontroller and drives the loads which consume high currents. Thus the relay acts as an isolation device. Digital systems and microcontroller pins lack sufficient current to drive the relay. While the relay’s coil needs around 10milli amps to be energized, the microcontroller’s pin can provide a maximum of 1-2milli amps current. For this reason, a driver such as a power transistor is placed in between the microcontroller and the relay. Vcc Arduino Uno Atmega328
Relay A3
Ground
Fig. Block diagram of transistor driver circuit 22
The operation of this circuit is as follows: The input to the base of the transistor is applied from the microcontroller port pin P1.0. The transistor will be switched on when the base to emitter voltage is greater than 0.7V (cut-in voltage). Thus when the voltage applied to the pin P1.0 is high i.e., P1.0=1 (>0.7V), the transistor will be switched on and thus the relay will be ON and the load will be operated. When the voltage at the pin P1.0 is low i.e., P1.0=0 (<0.7V) the transistor will be in off state and the relay will be OFF. Thus the transistor acts like a current driver to operate the relay accordingly. Relay interfacing with the microcontroller:
Arduino Uno Transistor driver
Relay
Load
circuit
2.5 Signal Isolator Communication jamming devices were first developed and used by military. Where tactical commanders use RF communications to exercise control of their forces, an enemy has interest in those communications. This interest comes from the fundamental area of denying the successful transport of the information from the sender to the receiver. Nowadays the mobile jammer devices are becoming civilian products rather than electronic warfare devices, since with the increasing number of the mobile phone users the need to disable mobile phones in specific places where the ringing of cell phone would be disruptive has increased. These places include worship places, university 23
lecture rooms, libraries, concert halls, meeting rooms, and other places where silence is appreciated. Mobile jammer is used to prevent mobile phones from receiving or transmitting signals with the base stations. Mobile jammers effectively disable mobile phones within the defined regulated zones without causing any interference to other communication means. Mobile jammers can be used in practically any location, but are used in places where a phone call would be particularly disruptive like Temples, Libraries, Hospitals, Cinema halls, schools & colleges etc. Mobile Jammers were originally developed for law enforcement and the military to interrupt communications by criminals and terrorists to foil the use of certain remotely detonated explosives. The civilian applications were apparent with growing public resentment over usage of mobile phones in public areas on the rise & reckless invasion of privacy. Over time many companies originally contracted to design mobile jammers for government switched over to sell these devices to private entities. As with other radio jamming, mobile jammers block mobile phone use by sending out radio waves along the same frequencies that mobile phones use. This causes enough interference with the communication between mobile phones and communicating towers to render the phones unusable. Upon activating mobile jammers , all mobile phones will indicate "NO NETWORK" . Incoming calls are blocked as if the mobile phone were off. When the mobile jammers are turned off, all mobile phones will automatically reestablish communications and provide full service. Mobile jammer 's effect can vary widely based on factors such as proximity to towers, indoor and outdoor settings, presence of buildings and landscape, even temperature and humidity play a role. The choice of mobile jammers are based on the required range starting with the personal pocket mobile jammer that can be carried along with you to ensure undisrupted meeting with your client or a personal portable mobile jammer for your room or medium power mobile jammer or high power mobile jammer for your organisation to very high power military jammers to jam a large campuses Types of jammers Pocket jammer
Portable jammer
Medium power jammer
High power jammer
Jamming devices overpower the cell phone by transmitting a signal on the same frequency as the cell phone and at a high enough power that the two signals collide and cancel each other out. Cell phones are designed to add power if they experience low-level 24
interference, so the jammer must recognize and match the power increase from the phone. Cell phones are full-duplex devices, which mean they use two separate frequencies, one for talking and one for listening simultaneously. Some jammers block only one of the frequencies used by cell phones, which has the effect of blocking both. The phone is tricked into thinking there is no service because it can receive only one of the frequencies. Less complex devices block only one group of frequencies, while sophisticated jammers can block several types of networks at once to head off dual-mode or tri-mode phones that automatically switch among different network types to find an open signal. Some of the high-end devices block all frequencies at once and others can be tuned to specific frequencies. To jam a cell phone, all you need is a device that broadcasts on the correct frequencies. Although different cellular systems process signals differently, all cell-phone networks use radio signals that can be interrupted. GSM, used in digital cellular and PCSbased systems, operates in the 900-MHz and 1800-MHz bands in Europe and Asia and in the 1900-MHz (some times referred to as 1.9-GHz) band in the United States. Jammers can broadcast on any frequency and are effective against AMPS, CDMA, TDMA, GSM, PCS, DCS, iDEN and Nextel systems. Old-fashioned analog cell phones and today's digital devices are equally susceptible to jamming. Disrupting a cell phone is the same as jamming any other type of radio communication. A cellphone works by communicating with its service network through a cell tower or base station. Cell towers divide a city into small areas, or cells. As a cell phone user drives down the street, the signal is handed from tower to tower. A portable cell phone jammer featured by universal and handheld design, could blocking worldwide cell phone networks within 0.5-10 meters, including GSM900MHz, GSM1800MHz, GSM850MHz/CDMA800MHz and also 3G networks (UMTS / WCDMA).
A mobile phone jammer is an instrument used to prevent cellular phones from receiving signals from or transmitting signals to base stations. When used, the jammer effectively disables cellular phones. These devices can be used in practically any location, but are 25
found primarily in places where a phone call would be particularly disruptive because silence is expected. Operation of jammer : As with other radio jamming, cell phone jammers block cell phone use by sending out radio waves along the same frequencies that cellular phones use. This causes enough interference with the communication between cell phones and towers to render the phones unusable. On most retail phones, the network would simply appear out of range. Most cell phones use different bands to send and receive communications from towers (called full duplexing). Jammers can work by either disrupting phone to tower frequencies or tower to phone frequencies. Smaller handheld models block all bands from 800MHz to 1900MHz within a 30-foot range (9 meters). Small devices tend to use the former method, while larger more expensive models may interfere directly with the tower. The radius of cell phone jammers can range from a dozen feet for pocket models to kilometers for more dedicated units. The TRJ-89 jammer can block cellular communications for a 5-mile (8 km) radius. Actually it needs less energy to disrupt signal from tower to mobile phone, than the signal from mobile phone to the tower (also called base station), because base station is located at larger distance from the jammer than the mobile phone and that is why the signal from the tower is not so strong.
Older jammers sometimes were limited to working on phones using only analog or older digital mobile phone standards. Newer models such as the double and triple band jammers can block all widely used systems (CDMA, iDEN, GSM, et al.) and are even very effective against newer phones which hop to different frequencies and systems when interfered with. As the dominant network technology and frequencies used for mobile phones vary worldwide, some work only in specific regions such as Europe or North America.
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The jammer's effect can vary widely based on factors such as proximity to towers, indoor and outdoor settings, presence of buildings and landscape, even temperature and humidity play a role.There are concerns that crudely designed jammers may disrupt the functioning of medical devices such as pacemakers. However, like cell phones, most of the devices in common use operate at low enough power output (<1W) to avoid causing any problems. Gsm-Mobile jamming requirements Jamming objective is to inject an interference signal into the communications frequency so that the actual signal is completely submerged by the interference. It is important to notice that transmission can never be totally jammed - jamming hinders the reception at the other end. The problem here for the jammer is that only transmitters can be found using direction finding and the location of the target must be a specific location, usually where the jammer is located and this is because the jamming power is never infinite. Jamming is successful when the jamming signal denies the usability of the communications transmission. In digital communications, the usability is denied when the error rate of the transmission cannot be compensated by error correction. Usually successful jamming attack requires that the jammer power is roughly equal to signal power at the receiver. The effects of jamming depend on the jamming-to-signal ratio (J/S), modulation scheme, channel coding and interleaving of the target system. Generally Jamming-to-Signal ratio can be measured according to the following Equation.
Pj= jammer power Pt= transmitter power Gjr= antenna gain from jammer to receiver Grj= antenna gain from receiver to Jammer Gtr= antenna gain from transmitter to receiver Grt= antenna gain from receiver to transmitter Br= communications receiver bandwidth Bj= jamming transmitter bandwidth Rtr= range between communications transmitter and receiver Rjt= range between jammer and communications receiver Lj= jammer signal loss (including polarization mismatch) Lr= communication signal loss The above Equation indicates that the jammer Effective Radiated Power, which is the product of antenna gain and output power, should be high if jamming efficiency is required. On the other hand, in order to pr event jamming, the antenna gain toward the communication partner should be as high as possible while the gain towards the jammer 27
should be as small as possible. As the equation shows, the antenna pattern, the relation between the azimuth and the gain, is a very important aspect in jamming. Also as we know from Microwave and shown in the equation distance has a strong influence on the signal loss. If the distance between jammer and receiver is doubled, the jammer has to quadruple its output in order for the jamming to have the same effect. It must also be noted here the jammer path loss is often different from the communications path loss; hence gives jammer an advantage over communication transmitters. In the GSM network, the Base Station Subsystem (BSS) takes care of the radio resources. In addition to Base Transceiver Station (BTS), the actual RF transceiver, BSS consists of three parts. These are the Base Station Controller (BSC), which is in charge of mobility management and signaling on the Air-interface between Mobile Station (MS), the BTS, and the Air-interface between BSS and Mobile Services Switching Center (MSC). The GSM Air-interface uses two different multiplexing schemes: TDMA (Time Division Multiple Access) and FDMA (Frequency Division Multiple Access). The spectrum is divided into 200 kHz channels (FDMA) and each channel is divided into 8 timeslots (TDMA).
Each 8 timeslot TDMA frame has duration of 4.6 ms (577 s/timeslot) [3]. The GSM transmission frequencies are presented in Table 1 Frequency Hopping in GSM is intended for the reduction of fast fading caused by movement of subscribers. The hopping sequence may use up to 64 different frequencies, which is a small number compared to military FH systems designed for avoiding jamming. Also, the speed of GSM hopping is approximately 200 hops /s; So GSM Frequency Hopping does not provide real protection against jamming attacks. Although FH doesn’t help in protection against jamming, interleaving and forward error correction scheme GSM Systems can protect GSM against pulsed jamming. For GSM it was shown that as the specified system SNR is 9 dB, a jammer min requires a 5 dB S/J in order to successfully jam a GSM channel. The optimum GSM SNR is 12 dB, after this point the system starts to degrade. GSM system is capable to withstand abrupt cuts in Traffic Channel (TCH) connections. These cuts are normally caused by propagation losses due to obstacles such as bridges. Usually another cell could be used to hold communication when the original BTS has disconnected. The GSM architecture provides two solutions for this: first handover when the connection is still available, second call reestablishment when the original connection 28
is totally lost. Handover decisions are made based on transmission quality and reception level measurements carried out by the MS and the BTS. In jamming situations call reestablishment is probably the procedure the network will take in order to re-connect the jammed TCH. It is obvious that downlink jamming (i.e. Jamming the mobile station’ handset'(receiver) is easier than uplink, as the base station antenna is usually located far a way from the MS on a tower or a high building. This makes it efficient for the jammer to overpower the signal fro m BS. But the Random Access Channel (RACH) control channels of all BTSs in the area need to be jammed in order to cut off transmission. To cut an existing connections, the jamming has to last at least until the call re-establishment timer at the MSC expires and the connection is released, which means that an existing call can be cut after a few seconds of effective jamming. The GSM RACH random access scheme is very simple: when a request is not answered, the mobile station will repeat it after a random interval. The maximum number of repetitions and the time between them is broadcast regularly. After a MS has tried to request service on RAC Hand has been rejected, it may try to request service from another cell. Therefore, the cells in the area should be jammed .In most cases, the efficiency of a cellular jamming is very difficult to determine, since it depends on many factors, which leaves the jammer confused.
Block diagram of Mobile Jammer
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Design and implementation of mobile jammer: The block diagram of mobile jammer consists of 4 main blocks. Those are •Power supply •IF section •RF section •Antennas Power Supply: The mobile Jammer was designed for fixed use, and to take its power from the regular 220V AC wall outlets. The IF & RF sections of the jammer require +5V, +9Vand -9V dc. So a dc-dual polarity power supply should be designed. The basic parts of power supply are rectifier, filter and regulator. The rectifier converts ac voltage to a pulsating dc voltage and can be either half wave rectifier and full wave rectifier, the one we use here is the full wave rectifier which has the advantage that it allows unidirectional current to the load during the entire cycle of the input voltage and the result of the full wave rectification is an output voltage with a frequency twice the input frequency that pulsated every half cycle of the input. The average value for a full wave rectifier for a sinusoidal input is given by
The full wave rectifier used in the project is a full wave bridge rectifier, which uses four diodes the peak output is given by the, Where Vpsec is the output voltage across the secondary winigng of the transformer .In the project the transformer used is 220/12,1.5A rating ,So Vavg=11V and Vp=15.88V.The second part of the power supply is the filter which eliminate the fluctuations in the output of the full wave rectifier so as to produce a constant dc voltage ,the filter is simply a capacitor and its chosen to be as large as possible to minimize voltage ripple in the output. The final part of the power supply is the
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regulator and it is used to provide the desire dconstant dc output that is basically independent of the input voltage. Single chip regulators were used to give +5V, +9V and -9V dc voltages.Fig: 9.3 Circuit Schematic of the power supply
Schematic Diagram Of Powersupply If Section
The function of IF section of jammer is to generate tuning signal for the VCO in the RFsection, which will sweep the VCO through the desired range of frequencies. This tuning signalis generated by a triangular wave generator along with noise generator, and then offset by proper amount so as to sweep the VCO output from the minimum desired frequency to a maximum. Triangular Wave Generator: To generator triangular wave we use 555 timer as a Astable Multivibrator
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The 555 timer consist basically of two comparators, a flip-flop, a discharge transistor, and a resistive voltage divider. The resistive divider is used to set the voltage comparator levels. A 555 timer connected to operate in the a stable mode as a free running non – sinusoidal oscillator, the threshold input is connected to the trigger input. The external components R1,R2 and Cex forms the timing circuit that sets the frequency of oscillation. The 0.01 uF capacitor connected to the control input is strictly for decoupling and has no effect on the operation, in some cases it can be left off. Initially when the power is turned on, the capacitor Cex is uncharged and thus the trigger voltage(pin2) is at 0V.This causes the output of the lower comparator to be high and the output of the upper comparator to be low, forcing the output of the flip-flop, and thus the base of Qd, low and keeping the transistor off. Now, Cex begin charging through R1 & R2 (to obtain 50% duty cycle, one can connect a diode parallel with R2 and choose R2=R1). When the capacitor voltage reaches 1/3Vcc,the lower comparator switcher to it slow output state, and when the capacitor voltage reaches 2/3Vcc the upper comparator switches to its high output state. This reset the flip flop causes the base of Qd to go high, and turns on the transistor. This sequence creates a charge path for the capacitor through R2 and the transistor, as indicated. The capacitor begins to discharge, causing the upper comparator to go low. At the point when capacitor discharge down to 1/3Vcc, the lower comparator switches high, setting the flip flop, which makes the base of Qd low and turns off the transistor. Another charging cycles begins and entire process repeats the result is a rectangular wave output whose duty cycle depends on the values of R1 and R2, The frequency of oscillator is given by the following formula. Using the above equation for frequency equal 110KHz, one found the values of R1, R2,and Cex. Then the output was taken from the voltage on the external capacitor which has triangular wave form. A simulation was done to verify the operation of circuit and the output is shown in figure.
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To avoid loading the timing circuit and changing the operation frequency, the triangular wave on the terminal of the external capacitor was buffered using op-amp
To achieve jamming a noise signal is mixed with the triangle wave signal to produce the tuning voltage for the VCO. The noise will help in masking the jamming transmission, making it look like random “noise” to an outside observer. Without the noise generator, the jamming signal is just a sweeping, unmodulated continuous wave RF carrier.
White noise generator output spectrum Signal mixer and DC-Offset circuits: The triangle wave and noise signals are mixed using OP-Amp configured as summer, then a dcvoltage is added to the resulted signal to obtain the required tuning voltage using Diode-clamper circuit. To gain good clamping the RC time constant selected so that it’s more than ten times the period of the input frequency, also a potentiometer was added to control the biasing voltage so as to get the desired tuning voltage.
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Op-Amp Summer Circuit
Rf Section The RF-section is the most important part of the mobile jammer it consist of the VoltageControlled oscillator(VCO),RF Power amplifier ,and the antenna.These compone nts wereselected according to the desired specification of the jammer such as the frequency range and the coverage range . Its important to note that all the components used has 50 ohm input/output impedance, so 50 ohm microstrip was needed for matching between the components. To obtain the desired output jamming power for coverage range of 20m first we found the jamming power required at the mobile receiver ”Jr”, knowing that SNRmin =9dB and Smax =-15dBm (i.e worst jamming case).[5] then from SNRmin=S/J, where S=the signal power Jr=-24dbm,then by invoking the free space path loss equationF=32.45+20log(f*D),where ”Ds” is distance in km and “f “ is frequency in MHz for 20 m the loss equals 58dB hence the jammer should transmit a jamming signal with power equals :58dBm-24dBm=34dBm,to sustain a 20m area.
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Block diagram of IF section Voltage controlled oscillator The VCO is responsible for generating the RF signal which will over power the mobile downlink signal. The selection of the VCO was influenced by two main factors, the frequency of the GSM system, which will be jammed and the availability of the chip. For the first factor which implies that the VCO should cover the frequencies from 935 MHz to 960 MHz , The MAX2623 VCO from MAXIM IC was found to be a good choice , and fortunately the second factor was met sequentially since MAXIM IC was willing to send two of the MAX2623 for free.
Pin diagram of MAXIM
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The MAX2623 VCO is implemented as an LS oscillator configuration,integrating all tank circuit of the tank circuit on-chip, this makes the VCO extremely easy-to-use , and the tuning input is internally connected to the varactor as shown in figure .The typical output power is -3dBm, and the output was best swept over the desired range when the input tuning voltage was around 120 KHz.
MAXIM 2623 Pin connection Features of VCO: •Fully Monolithic •Guaranteed Performance •On-Chip 50Ω Output Match •885MHz to 950MHz (MAX2623) •+2.7V to +3.3V Single-Supply Operation •Low Current Shutdown Mode •Smaller than Modules (8-pin µMAX package) Pin description of VCO: 1-NC- No Connection. Not internally connected. 2-TUNE- Oscillator Frequency Tuning Voltage Input. High-impedance input with a voltage input range of 0.4V (low frequency) to 2.4V (high frequency) adjustment.
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3-GND-Ground Connection for Oscillator and Biasing requires a low-inductance connection to the circuit board ground plane. 4- SHDN-Shutdown Logic Input. A high-impedance input logic level low disables the device and reduces supply current to 0.1µA. A logic level high enables the device 5- VCC-Output Buffer DC Supply Voltage Connection, bypass with a 220pF capacitor to GND for best high frequency performance 6 - VCC-Bias and Oscillator DC Supply Voltage Connection. Bypass with a 220pF capacitor to GND for low noise and low spurious content performance from the oscillator 7 -OUT Buffered Oscillator Output 8- GND-Ground Connection for Output Buffer. Requires a low-inductance connection to the circuit board ground plane. RF Power Amplifier: To achieve the desired output power a gain stage was needed, about searching for a suitable power amplifier it is cheaper to use power amplifier from an old Mobile phones.ThePF08103b hitachi power amplifier module from nokia mobile phone is sufficient to amplify an input signal in the range 800MHz to 1 GHz by 34 dB.But in the data sheet input should be1dBm.To meet this requirement we use another power amplifier stage after vco and before hitachi power amplifier .For this stage we use Mar4SM power amplifier. The MAR-4Sm has atypical gain of 8-dB for the frequencies range from dc to 1GHz,so the output at this stage is around 5dBm.A typical biasing configuration for MAR-4SM is shown in the figure
Now the power before the Hitachi RF power amplifier is 5dBm and since 1dBm is required; so here we used 4dBm T-Network attenuator as shown in the figure.
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For a 4-dB attenuation and symmetric Network S12=S21=0.631And for 50 ohms characteristic impedance we found the values of the resistor using the following equations, Where X= (R2+50))//R3.
Antenna: The most important part of any transmitter is the antenna. So a suitable antenna should be selected .The antenna used in the project is λ/4 wave monopole antenna and it has 50 Ohm impedance so that the antenna is matched to the transmission system .Also this antenna has low VSWR less than 1.7,and a bandwidth
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of 150MHz around 916MHz center frequency which cover the mobile jammer frequency range .The antenna gain is 2dBi.
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Chapter 3 I2C COMMUNICATION 3.1
Introduction
I²C ("eye-squared cee" or "eye-two-cee" Inter-Integrated Circuit, generically referred to as "two-wire interface") is a multimaster serial single-ended computer bus invented by Philips used for attaching low-speed peripherals to a motherboard, embedded system, cellphone, or other electronic device. SMBus, defined by Intel in 1995, is a subset of I²C that defines the protocols more strictly. One purpose of SMBus is to promote robustness and interoperability. Accordingly, modern I²C systems incorporate policies and rules from SMBus, sometimes supporting both I²C and SMBus with minimal reconfiguration required.
3.2
Design
I²C uses only two bidirectional open-drain lines, Serial Data Line (SDA) and Serial Clock (SCL), pulled up with resistors. Typical voltages used are +5 V or +3.3 V although systems with other voltages are permitted. The I²C reference design has a 7-bit or a 10-bit (depending on the device used) address space.[5] Common I²C bus speeds are the 100 kbit/s standard mode and the 10 kbit/s low-speed mode, but arbitrarily low clock frequencies are also allowed. Recent revisions of I²C can host more nodes and run at faster speeds (400 kbit/s Fast mode, 1 Mbit/s Fast mode plus or Fm+, and 3.4Mbit/s High Speed mode). These speeds are more widely used on embedded systems than on PCs. There are also other features, such as 16bit addressing. Note the bit rates are quoted for the transactions between master and slave without clock stretching or other hardware overhead. Protocol overheads include a slave address and perhaps a register address within the slave device as well as per-byte ACK/NACK bits. Thus the actual transfer rate of user data is lower than those peak bit rates alone would imply. For example, if each interaction with a slave inefficiently allows only 1 byte of data to be transferred, the data rate will be less than half the peak bit rate. The maximum number of nodes is limited by the address space, and also by the total bus capacitance of 400 pF, which restricts practical communication distances to a few meters.
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3.3
Reference design
Therefore mentioned reference design is a bus with a clock (SCL) and data (SDA) lines with 7-bit addressing. The bus has two roles for nodes: master and slave: • •
Master node — node that generates the clock and initiates communication with slaves Slave node — node that receives the clock and responds when addressed by the master
The bus is a multi-master bus which means any number of master nodes can be present. Additionally, master and slave roles may be changed between messages (after a STOP is sent). There are four potential modes of operation for a given bus device, although most devices only use a single role and its two modes: 1. 2. 3. 4.
master transmit — master node is sending data to a slave master receive — master node is receiving data from a slave slave transmit — slave node is sending data to the master slave receive — slave node is receiving data from the master
The master is initially in master transmit mode by sending a start bit followed by the 7-bit address of the slave it wishes to communicate with, which is finally followed by a single bit representing whether it wishes to write(0) to or read(1) from the slave. If the slave exists on the bus then it will respond with an ACK bit (active low for acknowledged) for that address. The master then continues in either transmit or receive mode (according to the read/write bit it sent), and the slave continues in its complementary mode (receive or transmit, respectively). The address and the data bytes are sent most significant bit first. The start bit is indicated by a high-to-low transition of SDA with SCL high; the stop bit is indicated by a low-to-high transition of SDA with SCL high. All other transitions of SDA take place with SCL low. If the master wishes to write to the slave then it repeatedly sends a byte with the slave sending an ACK bit. (In this situation, the master is in master transmit mode and the slave is in slave receive mode.) If the master wishes to read from the slave then it repeatedly receives a byte from the slave, the master sending an ACK bit after every byte but the last one. (In this situation, the master is in master receive mode and the slave is in slave transmit mode.) 41
The master then either ends transmission with a stop bit, or it may send another START bit if it wishes to retain control of the bus for another transfer (a "combined message"). I²C defines basic types of messages, each of which begins with a START and ends with a STOP: • • •
Single message where a master writes data to a slave; Single message where a master reads data from a slave; Combined messages, where a master issues at least two reads and/or writes to one or more slaves.
In a combined message, each read or write begins with a START and the slave address. After the first START, these are also called repeated START bits; repeated START bits are not preceded by STOP bits, which is how slaves know the next transfer is part of the same message. Any given slave will only respond to particular messages, as defined by its product documentation. Pure I²C systems support arbitrary message structures. SMBus is restricted to nine of those structures, such as read word N and write word N, involving a single slave. PMBus extends SMBus with a Group protocol, allowing multiple such SMBus transactions to be sent in one combined message. The terminating STOP indicates when those grouped actions should take effect. For example, one PMBus operation might reconfigure three power supplies (using three different I2C slave addresses), and their new configurations would take effect at the same time: when they receive that STOP. With only a few exceptions, neither I²C nor SMBus define message semantics, such as the meaning of data bytes in messages. Message semantics are otherwise productspecific. Those exceptions include messages addressed to the I²C general call address (0x00) or to the SMBus Alert Response Address; and messages involved in the SMBus Address Resolution Protocol(ARP) for dynamic address allocation and management. In practice, most slaves adopt request/response control models, where one or more bytes following a write command are treated as a command or address. Those bytes determine how subsequent written bytes are treated and/or how the slave responds on subsequent reads. Most SMBus operations involve single byte commands.
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3.4
Timing diagram
3.5
Limitations
•
The assignment of slave addresses is one weakness of I²C
•
Automatic bus configuration is a related issue. A given address may be used by a number of different protocol-incompatible devices in various systems, and hardly any device types can be detected at runtime.
•
I²C supports a limited range of speeds.
•
Devices are allowed to stretch clock cycles to suit their particular needs, which can starve bandwidth needed by faster devices and increase latencies when talking to other device addresses. Bus capacitance also places a limit on the transfer speed, especially when current sources are not used to decrease signal rise times.
•
Because I²C is a shared bus, there is the potential for any device to have a fault and hang the entire bus.
Because of these limits (address management, bus configuration, potential faults, speed), few I²C bus segments have even a dozen devices. It is common for systems to have several such segments. One might be dedicated to use with high speed devices, for low latency power management. Another might be used to control a few devices where latency and throughput are not important issues; yet another segment might be used only to read EEPROM chips describing add-on cards (such as the SPD standard used with DRAM sticks).
3.6
I²C (wire) library
This library allows you to communicate with I2C / TWI devices. On the Arduino boards with the R3 layout (1.0 pinout), the SDA (data line) and SCL (clock line) are on the pin headers close to the AREF pin. The Arduino Due has two I2C / TWI interfaces SDA1 and SCL1 are near to the AREF pin and the additional one is on pins 20 and 21.
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Wire.begin() Wire.begin(address) Desc ri p t i on Initiate the Wire library and join the I2C bus as a master or slave. This should normally be called only once. Pa ram et e rs address: the 7-bit slave address (optional); if not specified, join the bus as a master. Ret u rn s None
Wire.requestFrom() Desc ri p t i on Used by the master to request bytes from a slave device. The bytes may then be retrieved with the available() and read()functions. As of Arduino 1.0.1, requestFrom() accepts a boolean argument changing its behavior for compatibility with certain I2Cdevices. If true, requestFrom() sends a stop message after the request, releasing the I2C bus. If false, requestFrom() sends a restart message after the request. The bus will not be released, which prevents another master device from requesting between messages. This allows one master device to send multiple requests while in control. The default value is true. S y n t ax Wire.requestFrom(address, quantity) Wire.requestFrom(address, quantity, stop) Pa ram et e rs address: the 7-bit address of the device to request bytes from quantity: the number of bytes to request stop :boolean. true will send a stop message after the request, releasing the bus. false will continually send a restart after the request, keeping the connection active. Ret u rn s byte : the number of bytes returned from the slave device
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Wire.beginTransmission(address) Desc ri p t i on Begin a transmission to the I2C slave device with the given address. Subsequently, queue bytes for transmission with the write() function and transmit them by calling endTransmission(). Pa ram et e rs address: the 7-bit address of the device to transmit to Ret u rn s None
Wire.endTransmission() Desc ri p t i on Ends a transmission to a slave device that was begun by beginTransmission() and transmits the bytes that were queued by write(). As of Arduino 1.0.1, endTransmission() accepts a boolean argument changing its behavior for compatibility with certainI2C devices. If true, endTransmission() sends a stop message after transmission, releasing the I2C bus. If false, endTransmission() sends a restart message after transmission. The bus will not be released, which prevents another master device from transmitting between messages. This allows one master device to send multiple transmissions while in control. The default value is true. S y n t ax Wire.endTransmission() Wire.endTransmission(stop) Pa ram et e rs stop :boolean. true will send a stop message, releasing the bus after transmission. false will send a restart, keeping the connection active. Ret u rn s byte, which indicates the status of the transmission: • • • •
0:success 1:data too long to fit in transmit buffer 2:received NACK on transmit of address 3:received NACK on transmit of data 45
•
4:other error
write() Desc ri p t i on Writes data from a slave device in response to a request from a master, or queues bytes for transmission from a master to slave device (in-between calls to beginTransmission() and endTransmission()). S y n t ax Wire.write(value) Wire.write(string) Wire.write(data, length) Pa ram et e rs value: a value to send as a single byte string: a string to send as a series of bytes data: an array of data to send as bytes length: the number of bytes to transmit Ret u rn s byte write() will return the number of bytes written, though reading that number is optional
Wire.available() Desc ri p t i on Returns the number of bytes available for retrieval with receive(). This should be called on a master device after a call torequestFrom() or on a slave inside the onReceive() handler. available() inherits from the Stream utility class. Pa ram et e rs None Ret u rn s The number of bytes available for reading.
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read() Desc ri p t i on Reads a byte that was transmitted from a slave device to a master after a call to requestFrom() or was transmitted from a master to a slave. read() inherits from the Stream utility class. S y n t ax Wire.read() Pa ram et e rs none Ret u rn s The next byte received
Wire.onReceive(handler) Desc ri p t i on Registers a function to be called when a slave device receives a transmission from a master. Pa ram et e rs handler: the function to be called when the slave receives data; this should take a single int parameter (the number of bytes read from the master) and return nothing, e.g.: void myHandler(intnumBytes)
Ret u rn s None
W ire.onRequest(ha ndler) Desc ri p t i on Register a function to be called when a master requests data from this slave device. Pa ram et e rs handler: the function to be called, takes no parameters and returns nothing, e.g.: void myHandler() Returns None
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Chapter 4 Block diagram and working 1. The project is specially designed for Jamming the Signals. 2. Bridge type full wave rectifier is used to rectify the ac Output of secondary of 230/12V step down transformer. 3. This voltage supply of 5volts dc is given to the microcontroller ATmega 328. 4. We are controlling this mobile jammer by means of a microcontroller. 5. And also we are interfacing 16x2 LCD display to the microcontroller to I/O ports. 6. The mobile jammer is interfaced to the controller through relay by using a transistor driver circuit.
Block Diagram 7. We are using Real time clock chip DS1307 is used to set the schedule. 8. The activation and deactivation time schedules can be programmed with microcontroller and displayed on the LCD display. 9. The EEPROM is used to store the predefined time schedules in it. 10. In this project we use a HFD27/005-S relay for automatic switching. 11. Here we are using 3control switches which are used to get the cursor position on the LCD, Increment and decrement switches for Increasing time, decreasing time. 12. For the given pre-set time with the help of the relay, Jammer is in ON condition and hence blocks all the signals in the range of 860MHz – 2170MHz.
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Chapter 5 Flow chart
START
INCLUDE ARDUINO FILES
INITIALIZE LCD MODULE
INITIALIZE I2C BUS
SET THE START AND STOP TIMES
UPDATE TIME
IF (START TIME = =REAL TIME) ?
JAMMER ON
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IF (START TIME
IF (STOP TIME = =REAL TIME) ?
JAMMER OFF
JAMMER ON
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chapter 6 Program Code #include "Wire.h" #include #include #include byte SW0 = A0; byte SW1 = A1; byte SW2 = A2; byte led = 13; byte rly = A3; LiquidCrystal lcd(12, 11, 4, 5, 6, 7);//GRRR int hour,minute,second; int ah1,am1,ah2,am2; void setup() { pinMode(SW0, INPUT); pinMode(SW1, INPUT); pinMode(SW2, INPUT); pinMode(led, OUTPUT); pinMode(rly, OUTPUT); digitalWrite(led, LOW); digitalWrite(rly, LOW); lcd.begin(16,2); digitalWrite(SW0, HIGH); digitalWrite(SW1, HIGH); digitalWrite(SW2, HIGH); 51
ah1=(i2c_read(8)); am1=(i2c_read(9)); ah2=(i2c_read(10)); am2=(i2c_read(11)); lcd.setCursor(0,1); lcd.print(ah1); lcd.print(':'); lcd.print(am1); lcd.print(" "); lcd.print(ah2); lcd.print(':'); lcd.print(am2); } void loop() { printTime(); if (digitalRead(SW0) != HIGH) { set_time(); // hold the switch to set time } if (digitalRead(SW1) != HIGH) { set_alarm(); // hold the switch to set ON Time & OFF Time } if(hour==ah1) { if(minute==am1) 52
{ digitalWrite(led, HIGH); digitalWrite(rly, HIGH); } } if(hour==ah2) { if(minute==am2) { digitalWrite(led, LOW); digitalWrite(rly, LOW); } } } void printTime() { second = RTC.get(DS1307_SEC,true); minute = RTC.get(DS1307_MIN,true); hour = RTC.get(DS1307_HR,true); lcd.setCursor(0,0); lcd.print("TIME="); lcd.print(hour,DEC); lcd.print(':'); lcd.print(minute,DEC); lcd.print(":"); lcd.print(second,DEC); } 53
void set_time() { while (digitalRead(SW1) != 0) { if (digitalRead(SW2) == 0) hour++; if (hour > 23) hour = 0; delay(200); lcd.setCursor(5,0); lcd.print(hour,DEC); lcd.print(':'); } while (digitalRead(SW1) != 0) // set minutes { if (digitalRead(SW2) == 0) minute++; if (minute > 59) minute = 0; delay(200); lcd.setCursor(8,0); lcd.print(minute,DEC); lcd.print(':'); } RTC.set(DS1307_MIN,minute); RTC.set(DS1307_HR,hour);
//set the minutes //set the hours
RTC.set(DS1307_SEC,0); 54
} void set_alarm() { while (digitalRead(SW0) != 0) // set hours { if (digitalRead(SW2) == 0) ah1++; if (ah1 > 23) ah1 = 0; delay(200); lcd.setCursor(0,1); lcd.print(ah1,DEC); lcd.print(':'); } while (digitalRead(SW0) != 0) // set minutes { if (digitalRead(SW2) == 0) am1++; if (am1 > 59) am1 = 0; delay(200); lcd.setCursor(3,1); lcd.print(am1,DEC); } while (digitalRead(SW0) != 0) // set hours { if (digitalRead(SW2) == 0) 55
ah2++; if (ah2 > 23) ah2 = 0; lcd.setCursor(7,1); lcd.print(ah2,DEC); lcd.print(':'); } while (digitalRead(SW0) != 0) // set minutes { if (digitalRead(SW2) == 0) am2++; if (am2 > 59) am2 = 0; lcd.setCursor(10,1); lcd.print(am2,DEC); } i2c_write(8,ah1);
//set the minutes
i2c_write(9,am1);
//set the hours
i2c_write(10,ah2);
//set the minutes
i2c_write(11,am2);
//set the hours
} void i2c_write(byte baddr, byte data) { Wire.beginTransmission(DS1307_CTRL_ID); Wire.send(baddr); // reset register pointer Wire.send(decToBcd(data)); Wire.endTransmission(); 56
delay(5); } byte i2c_read(byte baddr) { Wire.beginTransmission(DS1307_CTRL_ID); Wire.send(baddr); Wire.endTransmission(); delay(5); Wire.requestFrom(DS1307_CTRL_ID, 1); delay(5); byte data = bcdToDec(Wire.receive()); return data; } byte decToBcd(byte val) { // Convert normal decimal numbers to binary coded decimal return ( (val/10*16) + (val%10) ); } byte bcdToDec(byte val) { // Convert binary coded decimal to normal decimal numbers return ( (val/16*10) + (val%16) ); }
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Chapter 7 APPLICATIONS AND ADVANTAGES Applications
•
Application of mobile phone Signal Jammer In theory, the cell phone signal jammer is applied to the place where are forbidden to use mobile phones. For example, cell phone signal jammers used in jails, prisoners can be effectively prohibited contacting with the outside via mobile phones and avoid the possibility of continued crime. Cell phone jammers used in gas stations, can effectively avoid the fire caused by using mobile phones. Mobile phone jammers used in the military, can effectively prevent leak important military secrets. Mobile phone signal blocker used in the examination rooms, can effectively prevent cheat through mobile communications. Cell phone signal blocker used in schools, can assure students to study without distraction and have a quiet rest. Cell phone jammer used in theaters, can make everyone en- joy the program without disturb. Mobile phone jammer used in meeting rooms or training rooms, can assure the effective of the meeting. Mobile phone blocker used in cars, can effectively prevent the GPS tracking ,etc . In fact, cell phone jammers is urgent needed in jails.At present, all countries in the world have regulations that forbidden use of mobile phones in prison, but due to the defect of management, it's difficult to do that. In some countries such as Brazil in order to using cell phone signal jammer in prisons even changed the law about forbidden to use mobile phone jammers in their country. Advantages
•
Easy to operate
•
Sophisticated security
•
Simple and Reliable Design
•
Scheduled time of operation can be programmed
•
Works with reference to Real Time Clock
• •
• • • • • • • •
•
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Chapter 8 Conclusion
In this project, with the help of Arduino and ATmega 328 microcontroller we can indicate Jamming of the Signals, with the help of Radio Waves. Hence, by designing this project GSM CDMA, 3G mobile phone signals are blocked within the given time schedule i.e. a range of 850MHz to 2170MHz frequencies are blocked.
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References
• • • • • •
www.arduino.cc www. howstuffworks.com Embedded System by Raj Kamal www.electronicsforu.com www.electronicprojects.com www.sparkfun.com
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