Electronic Fundamentals for Aircraft Maintenance

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EASA Part-66 Aviation Maintenance Maintenance Technician Technician Certification Series NO COST REVISION/UPDATE SUBSCRIPTION PROGRAM

Complete EASA Part-66 Aviation Maintenance Technician Certification Series

NO COST REVISION/UPDATE PROGRAM Aircraf Airc raf t Technica l B ook Comp Company any is offe ring a revi revision sion/update /update prog program ram to our o ur custom ers who purc purchase hase an EASA Module from the EASA Aviation Maintenance Technician Certification Series. The update is good for two (2) years from time of registration of any EASA Module or EASA bundled kits. If a revision occurs within two (2) years from date of registration, we will send you the revised pages FREE of cost to the registered email. Go to the link provided at the bottom of this page and fill out the form to be included in the EASA Revision/Update Subscription Program. In an effort to provide quality customer service please let us know if your email you register with changes so we can update our records. If you have any questions about this process please send an email to: [email protected] HERE’S HOW IT WORKS 1. All EASA Module Series textbooks textbooks contain an EASA subscription page explaining the subscription update process and provide a web site link to register for the EASA Revision/Update Subscription Program. 2. Go to the link provided below and fill out the web based form with your first and last name, current email if applicable. address, add ress, a nd school sc hool if 3. 4. 5.

From the time of of purchase, if a revision occurs to the the Module you have registered for, for, a revised PDF file containing the pages with edits will be sent to the registered email provided. Please note that that we try to keep our records as current as possible. If your email address provided at time of registration changes please let us know as soon as possible so we can update your account. This service is FREE of charge for two (2) years from date of registration.





















































MODULE 04 FOR B1 CERTIFICATION

ELECTRONIC FUNDAMENTALS

Aviation Maintenance Technician Technician Certification Series

72413 U.S. Hwy 40 Tabernash, CO 80478-0270 USA www.actechbooks.com



























AVAILAB AV AILABLE LE IN

Printed Edition and Electronic (eBook) Format

AVIATION AVIA TION MAINTENANCE MAINTENANCE TECHNICIA TECHNICIAN N CERTIFICATI CERTIFICATION ON SERIES Author Layout/Design Layout/Desig n

Thomas Forenz Forenz Michael Amrine

Copyright © 2016 — Aircraft Technical Book Company. All Rights Reserved.

No part of this publication may be reproduced, stored in a retrieval system, transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the publisher.

To order books or for Customer Service, please call +1 970 726-5111.

www.actechbooks.com

Printed in the United States of America



























WELCOME WEL COME Te publishers of this Aviation Maintenance echnician Certification Series welcome you to the world of aviation maintenance. As you move towards EASA certification, cert ification, you are required to gain gai n suitable knowledge and experience in your chosen area. Qualification on basic subjects for each aircraft maintenance license category or subcategory is accomplished in accordance with the following matri x. Where applicable, subjects are indicated ind icated by an "X" in the column below the license heading. Forr other educational tools created to prepare candidates for licensure, contact Aircraft echnical Book Company. Fo Company. We wish you good luck and success in your studies and in your aviation career!

REVISION LOG VERSION

0 01 0 02

EFFECTIVE DATE

DESCRIPT ION OF CHANGE

2016 01 2017 01

Module Creat ion a nd Release Format Update





























FORWARD PAR AR-66 -66 and the Acceptable Means of Compliance (AMC) and Guidance Gu idance Material (GM) of the European Eu ropean Aviation Safety Agency (EASA) Regulation (EC) No. 1321/2014, Appendix 1 to the Implementing Rules establishes the Basic Knowledge Requirements for those seeking an aircraft maintenance license. Te information in this Module of the Aviation Maintenance echnical Certification Series published by the Aircraft echnical Book Company meets or exceeds the breadth and depth of knowledge subject matter referenced in Appendix 1 of the Implementing Implementing Rules. However, the order of the material presented is at the discretion of the editor in an effort to convey the required knowledge in the most sequential and compreh comprehensible ensible manner. Knowledge levels required for Category A1, B1, B2, and B3 aircraft maintenance licenses remain unchanged from those listed in Appendix 1 Basic Knowledge Requirements. ables from Appendix 1 Basic Knowledge Requirements are reproduced at the beginning of each module in the series and again at the beginning of each Sub-Module. How numbers are written in this book: Tis book uses the Interna International tional Civil Avia Aviation tion Organizatio Organization n (ICA (ICAO) O) standard of writing numbe numbers. rs. Tis metho method d displays large numbers by adding add ing a space between each group of 3 digits. Tis T is is opposed to the American method which uses commas and the European method which uses periods. For example, the number one million is expressed as so: ICAO Standard ICAO European Standard American Standard

1 000 000 1.000.0000 1.000.00 1,000,000 1,000,0 00

SI Units: Te International System of Units (SI) developed and maintained by the General Conference of We Weights ights and Measures (CGPM) shall be used as the standard system of units of measurement for all aspects of international civil aviation air and ground operations. Prefixes: Te prefixes and symbols listed in the table below below shall be used to form names and symbols of the decimal multiples multiples and submultiples of International System of Units (SI) un its. MULTIPLICATION FACTOR

PREFIX

SYMBOL



























EASA LICENSE LICEN SE CATEGORY CATEGORY CHART Module Number and Title

A1 Airplane Turbine

B1.1 Airplane Turbine

B1.2 Airplane Piston

B1.3 Helicopter Turbine

B2 Avionics

1

Mathematics

X

X

X

X

X

2

Physics

X

X

X

X

X

3

Electrical Fundamentals

X

X

X

X

X

4

Electronic Fundamentals

X

X

X

X

5

Digital Techniques / Electronic Instrument Systems

X

X

X

X

X

6

Materials and Hardware

X

X

X

X

X

7A

Maintenance Practices

X

X

X

X

X

8

Basic Aerodynamics

X

X

X

X

X

9A

Human Factors

X

X

X

X

X

10

Aviation Legislation

X

X

X

X

X

11A

Turbine Aeroplane Aerodynamics, Structures and Systems

X

X

11B

Piston Aeroplane Aerodynamics, Structures and Systems

12

Helicopter Aerodynamics, Structures and Systems

13

Aircraft Aerodynamics, Structures and Systems

X

14

Propulsion

X

15

Gas Turbine Engine

16

Piston Engine

17A

Propeller

X X

X

X

X X

X

X

X

MODULE 04 SYLLABUS AS OUTLINED IN PART-66, APPENDIX 1.

LEVELS CERTIFICATION CATEGORY

Sub-Module 01 - Sem iconducto iconductors rs

4.1.1 - Diodes

¦

B1




























¦

B1

clampers, ful fulll and half wave rectifiers, bridge rectifiers, voltage doublers and triplers; Detailed operation and characteristics of the following devices: silicon controlled rectifier (thyristor) thyristor),, light emitting diode, Schottky diode, photo conductive diode, varactor diode, varistor, rectifier diodes, Zener diode. 4.1.2 - Transitors (a) ransistor symb symbols; ols; Componentt description and orientatio Componen orientation; n; ransistor ransist or characteristics and properties.

(b)

Construction and operation of PNP and NPN transistors; Base, collector and emitter configurations; esting of transistors; Basic appreciation of other transistor typ types es and their uses; Application of transistors: classes of amplifier (A, B, C); Simple circuits including: bias, decoupling, feedback and stabilisation; Multistage circuit principles: cascades.

4.1.3 - Integrated Circuits (a)) Description and operation of logic circuits and linear circuits/ope (a circuits/operational rational amplifiers;

(b)

Description and operation of logic circuits and linear circuits; Introduction to operation and function of an operational amplifier used as: integrator, diff differentiator, erentiator, voltage follower, comparator; Operation and amplifier stages connecting methods: resistive capacitive, inductive (transform (transformer) er),, inductive resistive (IR), direct; Advantages and disadvantages of positive and negative feedback.

1

-

2 -

Sub-Module 02 - Printed Circuit Boards

Description and use of printed circuit boards.

1




























¦

B1

Addendum 01 - Radio Communication - ELT ELT and ADS-B

Radio communication communication - radio waves, ty types pes of radio waves, loading information information onto onto a radio wave, amplitude amplitude modulation (AM), frequency frequency modulation (FM), single side band (SSB (SSB); ); Radio transmitters and receivers, transmitters, receivers, receivers, transceivers, antennas, antennas, length, polarization, directivity, and field field pattern, pattern, types, dipole antenna, marconi marconi antenna, antenna, loop loop antenna, antenna, transmission lines; Automa Automatic tic Dependent Survei Surveillance llance Broadcast Broadcast (ADS-B (ADS-B); ); Emergency Locator ransmitter (EL).

-























































CONTENTS ELECTRONIC FUNDAMENTALS Welcome ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ Revision Log ‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥ ‥‥ Forward‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥ Contents Conten ts ‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥

iii iii iv ix

SUB-MODULE 01 SEMICONDUCTORS

Knowledge Requiremen Requirements ts ‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥ 1. 1.11 Semiconductors Semicond uctors‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥ 1.2 Solid-Stat SolidStatee Devices ‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥ 1.2 Semiconductors Semicond uctors ‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥ ‥‥ 1.2 Majority Majori ty and Minority Carriers ‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥ ‥‥‥ 1.5 PN Junction Junctionss and the Basic Diode ‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥ 1.5 Unbiased Unbia sed PN Junction ‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥ ‥‥ 1.5 Forward Bias PN Junction ‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥ 1.6 Reverse Biased PN Junction ‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥ 1.7 Semiconductor Semicond uctor Diodes ‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥ 1.7 Characteristics Characteristi cs and Properties‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥ 1.7 Diode Symbols‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥ 1.8 Diode Identifica Identification tion‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥ 1.8 Diode Behavior ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 1.10 1.10

Buffer Gate‥‥‥‥‥‥‥ Gate‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥ ‥‥ AND Gate ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ OR Gate ‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥ ‥‥ NAND Gate Gate ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥ NOR Gate Gate ‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥ ‥‥ EXCLUSIVE EXCLU SIVE OR Gate ‥‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥ ‥‥ Negative Logic Gates ‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥ ‥‥ Digital Circuits ‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥ Integrated Integrat ed Circuits ‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥ ‥‥ Dual In-Line Package Package Standard (DIP) (DIP) ‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥ Linear Circuits/O Circuits/Operatio perational nal Amplifier ‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥ Questions ‥‥‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥ Answerss ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ Answer ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥

1.28 1.28 1.29 1.29 1.29 1.29 1.30 1.30 1.31 1.31 1.32 1.33 1.34

SUB-MODULE 02 PRINTED CIRCUIT BOARDS

Knowledge Requiremen Requirements ts ‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥ Printed Circuit Boards ‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥ ‥‥ Questions ‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥ ‥‥ Answerss ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ Answer ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥

SUB-MODULE 03 SERVOMECHANISMS

2.1 2.2 2.5 2.6



























CONTENTS

Receivers ‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥ ransceivers ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ Antennas ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ Length ‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥ ‥‥‥‥ Polarization, Po larization, Directivity Directivity and Field Pattern‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥ ypes  ypes ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ Dipolee Antenna‥‥‥‥‥‥ Dipol ‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥ ‥‥‥‥ Marconi Antenna ‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥ Loop Antenna ‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥ ransmission Lines ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ Auto dependent surveill sur veillance ance broadcast (ADS-B) (A DS-B) ‥‥‥‥ Emergency Emergen cy Locator Locator ransmitter ransmitter (EL (EL) ) ‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥ Questions ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ Answerss ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ Answer

4.8 4.9 4.9 4.9 4.100 4.1 4.11 4.111 4.1 4.12 4.12 4.12 4.13 4.166 4.1 4.19 4.20

Acronym Index Inde x ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 4.25 Index ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥ ‥‥‥ 4.27



























S R O T C U D N O C I M E S

PART-66 SYLLABUS LEVELS CERTIFICATION CATEGORY

¦

B1

Sub-Module 01

SEMICONDUCTORS

Knowledge Requirements

4.1.1 - Diodes (a)) Diode symbols; (a Diode characteristics and properties; Diodes in series and parallel; Main character characteristics istics and use of silicon controlled recti rectifiers fiers (thyristors), light emitting diode, photo conductive diode, varistor, recti rectifier fier diodes; Functional testing of diodes.

2



























PART-66 PART -66 SYLLABUS LEVELS CERTIFICATION CATEGORY B1 ¦

4.1.3 - Integrated Circuits (a)) Descr (a Description iption and operation of logic circuits and linear circuits/operational circu its/operational amplifiers;

1

(b) Description Descr iption and operation of logic circuits and linear circuits; circu its; Introduction to operation and funct function ion of an operational amplifier used as: integrator, differe differentiator, ntiator, voltage follower, comparator; Operation and amplifier stages connectin connectingg methods: resistive capacitive, inductive (transformer), inductive resistive (IR), direct; Advantages and disadva disadvantages ntages of positive and negative feedback.

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Level 1

A famil iari iarization zation with t he principa l elements of the subje ct.

Level 2

A general genera l knowledge of t he theoretic al and prac tical a spects of t he subject and an ability to apply that knowledge.

Objectives:

(a)

Te applicant should be fami familiar liar with the basic elements of the subject. (b) Te applicant should be able to give a simple description of the whole subject, u sing common words and ex amples. (c) Te applicant should be able to use typic al terms.

Objectives: (a) Te applicant should be able to understa nd the theoret theoretical ical fundamentals of the subject. (b) Te applicant should be able to give a genera generall descr iption of the subject using, as appropriate, typical examples. (c) Te applicant should be able to use mathemat ical formula in conjunction conjun ction with physical laws describing the subject. (d) Te applicant should be able to read and understa nd sketche s, drawings and schematics describing the subject. (e) Te applicant should be able to apply his knowledge in a practic al manner using detailed procedures.



























Te outer most orbita orbitall shell of any atom's electrons elec trons is called the valence shell. Te number of electrons in the valence shell determines deter mines the t he chemical properties of the material. When the valence shell has the maximum number of electrons, it is complete and the electrons tend to be bound strongly to the nucleus. Materials with wit h this characteristic are chemically stable. It takes a large amount of force to move the electrons in this situation from one atom valence shell to that of another. Since the movement of electrons is called electric current, substances with complete valence shells are known as good insulators because they resist the flow of electrons (electricity). ( Figure 1-2)

atoms share electrons to fill out the valance shell of each Figure ure 1-4 1- 4 ) Tis to the maximum of eight electrons. ( Fig unique symmetric alignment a lignment of silicon atoms results in a crystalline structure. Krypton Argon Neon Helium Ar

Ne

He

Kr

Figure 1-2. Elements with full valence shells are good insulators.

In atoms with an incomplete valence shell, that is, those with wi thout out th thee ma maxi ximum mum nu numbe mberr of ele elect ctron ronss in th thei eirr valence shell, the electrons are bound less strongly to the nucleus. Te material is chemically chemical ly disposed to combine with other materials or other identical atoms atoms to fill in the unstable valence configuration and bring the number of electrons in the t he valence shell to maximum. wo or more substances may share the electrons in their valence va lence shells and form covalent bond. A covalent cova lent bond is the method by which atoms complete complete their valence shells by sharing shar ing valence electrons with other atoms. atoms.

Most insulators used in aviation are compounds of two or more elements that share electrons to fill their valence shells.

Al

Cu

Ag

Au

Aluminum Copper

Silver

Gold

Figure 1-3. The valence shells of elements that are common conductors have one (or three) electrons.






























Once bound together, the valence shells of each silicon atom are complete. In this state, movement of electrons does not occur easily. Tere are no free electrons elect rons to move to another atom and no space in the valence shells to accept a free electron. Terefore, silicon in this form is a good insulator. Silicon is a primary material used in the manufacture of semiconductors. Germanium and a few other materials are also used.

When sil silicon icon is doped with an element or compound c ompound containing five electrons in its valence va lence shell, the result is a negatively charged material due to the excess free electrons, and the fact that electrons are negatively charged. his is known as an N-type semiconductor material. It is also known as a donor material because, when wh en it is us used ed in el elec ectr tron onic ics, s, it don at ates es th thee ex t ra electrons to current flow.

Since silicon is an insulator, it must be modified to become a semiconductor. he process often used is called doping. Starting with ultra-pure silicon crystal, arsenic, phosphorus, or some other element with five valence electrons in each atom is mixed into the silicon. sil icon. Te result is is a silicon lattice with flaws. ( Figure 1-5 ) Te elements bond, but numerous free electrons are present

Doping silicon can also be performed with an element that has only three valence electrons, such as boron, gallium, gall ium, or indium. Valence Valence electron sharing still occurs, and the silicon atoms with interspersed doping element atoms form a lattice molecular structure. However, in this case, there are many valence shells where there are only seven electrons and not eight. his greatly



























MAJORITY AND MINORITY CARRIERS

Both N-type and P-type semiconductors are able to conduct electricity. electricity. In the N-type material, current flows primarily like it does in any conductor. he valence electrons move from from one one valence shell to another as they progress through the material. Due to the surplus of electrons, the electrons are considered the majority current carriers in N-type N-ty pe semiconductors. semiconductors. Any movementt of current in N-type material by the movemen t he filling fillin g of holes is considered the minority current carrier. car rier. In P-type material, current primarily flows by valence electrons filling holes that exist in the doped lattice. Tis makes holes holes the majority carrier in PP-ty type pe material. material. Any current flow in P-type P-type material that occurs without holes (valence electrons exchanging with other valence

hole movement. he valence electron in the structure wil w il l pr prog ogre ress ss a lon g a pa path th de deta ta il iled ed by th thee ar ro rows ws.. Holes, however, move along a path opposite that of the electrons. Combining N-type and P-type semiconductor material in certain ways can produce very useful results. A look look at various semico semiconductor nductor devices follows. follows. PN JUNCTIONS AND THE BASIC DIODE

A si singl nglee t yp e of sem semicon iconduc ductor tor mat mater eria iall by its itsel elff is not very useful. But, applications have been developed when whe n P-t P-typ yp e an and d N-t N-typ yp e mat mater eria ials ls ar aree joi joined ned th that at have revolutionized electrical and electronic devices. Te boun boundar dar y where the P-typ P-typee mater material ial touche touchess the N-type material is called the junction or PN junction. Interesting and useful usefu l phenomenon phenomenon occur at this contact region. Furthermore, when joined, the entire two-




























P region. With so many holes in the P material, the electrons soon drop into a hole. When this occurs, the hole then disappears. A negatively charged ion is created since there is now one more electron than the number of protons in the nucleus of the boron (or gallium or indium) atom to which the hole belonged. Meanwhile, in the N material near the junction, the valence electrons that t hat departed depa rted for the PP-ty type pe material materia l leave behind a band of positive ions since there are now more positively charged protons in the nucleus of the arsenic (or phosphorous, etc) atoms than there are electrons in their shells. hus, each time an electron crosses the PN junction, it creates a pair of ions. In Figure Fig ure 1-9, this is shown in the area outlined by the dash lines. Te circled plus signs and the circled negative

Because holes and electrons must overcome this field to cross the junction, the electrostatic field is usually called a barrier or potential hill. As the diffusion of electrons and holes crosses the junction, the strength of the electrostatic field increases until it becomes strong enough to prevent more electrons or holes from f rom crossing over. At this point, a state of equilibrium exists and there is no further movement across the junction. he PN junction and the entire entire PN device is said to be unbiased. FORWARD BIAS PN JUNCTION

h e t wo sem icon he iconduc ductor torss joi joined ned at th thee PN ju junct nct ion form a diode that can be used in an electrical circuit. When a voltage source (battery) is attached to the diode with wit h the neg negati ative ve ter termin minal al con connec nected ted to the N-ty pe semiconductor material and the positive terminal



























zone widens, the electrostatic field strength is restored and current flow ceases. Note that the potential hill or barrier is reduced when connected to the battery as explained but it still exists. A voltage of approximately 0.7 volts is needed to begin the current flow over the potential hill in a silicon semiconductorr diode and about 0.3 semiconducto 0. 3 volts in a germanium german ium semiconductor diode. Tereafter, current flow is linear with the voltage. Caution must be exercised because it is possible to overheat and “burn “bur n out” the semiconduct semiconductor or device at the junction with excessive current flow. Also note that temperature temperature has a significant sign ificant impact of current flow in semiconduct semiconductors. ors. REVERSE BIASED PN JUNCTION

Widened Depletion Zone P-Type

N-Type

Increased Potential Hill

-

+

Figure 1-11. 1-11. Reversed biased P N junction-no current flow.




























A brief description including the ty type pe of diode, the major area of application, and any special features is normally given. Of particular interest is the specific application for which the diode is suited. he manufacturer also provides a drawing of the diode which gives dimension, weight, and, if i f appropriate, any identification marks. A static operating table giving spot values of parameters under fixed conditions is often given and sometimes a Figure ure 1-12 characteristicc curve similar to the one in Fig characteristi is also supplied. (he graph shows how parameters var y over ov er the fu fullll operati operating ng rang range.) e.) Final Fi nally, ly, the diode ratings are given since they are the limiting values of operating conditions conditions outside of which the diode could be damaged. Te PN junction diodes are generally rated for the following: 1. Maximum Average Forward Forward Current - this refers

cycle of the AC but not during the t he other cycle. Te diode, therefore, becomes a rectifier and changes chan ges AC current to pulsating DC current. When the semiconductorr diode is forward semiconducto forw ard biased, electrons flow; when the AC cycles, the diode becomes reverse biased and electrons elect rons do not flow. flow. DIODE SYMBOLS Diode symbols used in circuit diagrams are shown in Fig ure 1-13. Different types of diodes have slightly altered symbols for identification. Tese will be shown as they are discussed.

Note that electron electron flow is typically discussed discuss ed in this text. Te conventional current flow concept where electricity is thought to flow from the positive terminal of the





























XNYYY XN

Component

YYY

Identification Number

X- Number of Semiconductor Junctions

S R O T C U D N O C I M E



























2 Digit Type (Black Band)

DIODE BEHAVIOR Semiconductor diodes have limitations as mentioned. heyy ar he aree rat rated ed for a ra range nge of cu curr rrent ent f low. Ab Above ove a certain level, the diode overheats and burns up. he amount of current that passes through the diode when forward biased is directly proportional to the amount of voltage applied. But, as mentioned, it is affected by



























Photodiode Symbol

Electron Flow

(+) Anode

Cathode (-)

Simple Coil Circuit




























Color

Wavelength (nm)

Infrared

Red

760

610

760

Voltage (V)

Semiconductor Material

∆V < 1.9

Gallium arsenide (GaAs) Aluminium gallium arsenide arsenide (AlGaAs)

1.63 < ∆V < 2.03

Aluminium gallium arsenide arsenide (AlGaAs) Gallium arsenide phosphide (GaAsP) Aluminium gallium indium indium phosphide (AlGaInP) (AlGaInP) Gallium(III) phosphide (GaP)



























+

Expoxy Lens/Case

−

Wire Bond P-Type Reflective Cavity Semiconductor Die

N-Type




































































































































































































































































































































































































































































































































































































































































































































































































is empty), or some ratio of fuel and air depending on how much fuel remains in the tank. Figure 3-9 shows a simplified illustration of this construction. Te voltage stored in a referenc referencee capacitor completely submerged in fuel is compared to the transmitter capacitor or group of capacitors wired in parallel. Te basic bridge circuit for this is shown in Figure 3-10 . Te difference is a signal which is translated for display on the flight deck.

Fuel Tank Probe

Inner Plate

Fuel 115 V 400 Hz AC

Indicator

Outer Plate

Reference Capacitor

Figure 3-9. The capacitance of tank probes varies in a capacitancetype fuel tank indicator system as the space between the inner and outer plates is filled with varying quantities of fuel and air depending on the amount of fuel in the tank.

Figure 3-10. A simplified capacitance bridge for a fuel quantity system.

S M S I N A H C E M O V R E S





















































QUESTIONS

3-11 Question: 3 rue or or False? An open loop loop system uses feedback to ensure that controlled mechanisms have been moved to the proper position.

3-22 Question: 3 Which describes the basic operation of a synchro system for remote position indication? A. A transmitter sends varying voltages to an indicator motor which moves a pointer. B. Resistances are compared in the transmitter and the result is sent to the indicator motor motor to position a pointer. C. A magnetic magnetic field in the transmitter is mirrored in the indicator where a magnetic rotor aligns with the magnetic field.

Question: 3-3 What three factors affect the amount of electricity that a capacitor can store?



























ANSWERS

3-11 Answer: 3False. Closed loop systems have feedback, open loop systems do not.

3-22 Answer: 3C.

Answer: 3-3 Area of the plates. Distance between the plates. Dielectric constant of the material between bet ween the plates.



























PART-66 SYLLABUS LEVELS CERTIFICATION CATEGORY

¦

B1

Addendum 01 Radio Communication - ELT and ADS-B

Knowledge Requirements

4.4 - Radio Communication C ommunication - ELT and ADS-B Radio communication - radio waves, types of radio waves, loading information onto a radio wave, amplitude modulation (AM), frequency modulation (FM), single side band (SSB); Radio transmitters and receivers, transmitters, receivers, transceivers, antennas, length, polarizatio polarization, n, directivity, and field pattern, types, dipole antenna, marconi antenna, loop antenna, transmission lines; Automatic Dependent Surveilla Sur veillance nce Broadcast (ADS-B); (ADS -B); Emergency Locator ransmitter (EL).

Note: Te contents contents of this Sub-Module are not specified as EASA knowledge k nowledge requirements and may not appear on an EASA E ASA examination for certification. certi fication. However, However, the authors include this sub-module because of the fundamental nature of its content and its association with higher level electronics concepts developed later in the EASA module series.

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N O I T B A C I S D N A U M D N M A O T C L O I E D A R





























RADIO COMMUNICATION Much of aviation communication and navigation is accomplished through the use of radio waves. Communication by radio was the first use of radio frequency transmissions in aviation.

RADIO WAVES Electromagnetic Spectrum Shorter

Wavelength (centimeters) 10

-10

10

-9

10

Gamma ray 10 Higher

20

-8

10

-7

X-ray 10

19

10

18

10

-6

Longer 10

-5

10

-4

10

Ultraviolet 10

17

10

16

-3

10

-2

10

-1

11

0

10 0

Infrared 10

Frequency (number of waves per second)

15

10

14

10

13

Visible

1,000 10,000

100,000

Radio 10

12

10 UHF

11

10

10

VHF

10

9

HF

10 MF

8

10

7

LF

10

6

VLF

Lower

Figure 4-1. Radio waves are just some of the electromagnetic waves found in space.

A ra d io w av e is in v is ib ible le to t he hu ma n ey e. It is electromagnetic in nature and part of the electronic spectrum of wave activity that includes gamma rays, x-rays, xrays, ultraviolet u ltraviolet rays, infra infrared red waves, waves , and visible light rays, as well all radio waves. ( Figure 4-1) Te atmosphere is fil filled led with these waves. Each wave occurs at a specific frequency and has a corresponding waveleng wave length. th. he relat relationsh ionship ip bet between ween freq frequenc uencyy and wavelength is inversely invers ely proportional. A high frequency wave has a short wave length and a low frequency f requency wave has a long wave length. In aviation, a variety of radio waves are used for for communication. communication. Figure 4-2 illustrates the radio spectrum that includes the range of common aviation radio frequencies and their t heir applications. NOE: A wide range of frequencies are used from

Te frequency f requency of an a n AC signa signall is the number of times t imes the AC cycles every ever y second. AC applied to the center of a radio antenna, a conductor half the wavelength waveleng th of the AC AC frequency, travels the length of the antenna, collapses, Radio Frequencies

Aviation Uses

300 GHz Extremely high Frequency (EHF) 30 GHz Super high Frequency (SHF) 3 GHz Ultra high Frequency (UHF) 300 MHz Very high

Weather Radar 9.375 GHz Doppler NAV 8.8 GHz Radar Sltimeter 4.3 GHz GPS 1.6 GHz Transponder 1030 & 1090 MHz DME 960 - 1215 MHz Glideslope 328 - 336 MHz VHF Comm 118 - 137 137 MHz



























and travels the length of the antenna in the opposite direction. Te number of times it does this every second is known as the radio wave signal frequency or radio frequency as shown in Figure 4-2. As the current flows

through the antenna, a ntenna, corresponding electromagnetic and electric fields build, collapse, build in the opposite 4- 3) direction, and collapse again. ( Figure 4-3

To transmit radio waves, an AC generator is placed at the midpoint of an antenna.

Antenna

Generator I

Magnetic Field

Electric Field

Electric Field Magnetic Field

I

As AC current builds and collapses in t he antenna, a magnetic field also builds and collapses around it.

An electric field also builds and su bsides as the voltage sh ifts from one end of the antenna to the other.

Both fields, the magnetic and the electric, fluctuate around the antenna at the same time.




























o transmit o t ransmit radio waves, an AC generator is placed pl aced at the midpoint of an antenna. As AC current builds and collapses in the antenna, a magnetic f ield also builds and collapses around it. An electric field also builds and subsides as the voltage shifts from one end of the antenna to the other. Both fields, the magnetic and the electric, fluctuate around the antenna at the same time. he anten antenna na is hal halff the wave waveleng length th of the AC signa si gnall received from the generator. At any one point along the antenna, voltage and current vary va ry inversely to each other. Because of the speed of the AC, the electromagnetic fields and electric fields created around the antenna do not have time to completely collapse as the AC cycles. Each new current flow creates new fields around the antenna that force the not totally collapsed fields from the previous AC cycle out into space. Tese are the radio waves. Te process is continuous continuous as long as AC AC is applied to the antenna. Tus, steady radio waves of a frequency determined by the input AC frequency propagate out into space. Radio waves are directional and propagate out into space at 186 000 miles per second. Te distance they travel depends on the frequency and the amplification of the signal AC sent to the antenna. Te electric field component compone nt and the electromagnetic field compone component nt are oriented at 90° to each other, and at 90° to the direction direct ion that the wave is traveling. ( Figure 4-4 4- 4 ) TYPES OF RADIO WAVES Radio waves of different frequencies have unique characteristics as they propagate through the atmosphere. Very low frequency (VLF), LF, and medium frequency (MF) waves have relatively long wavelengths and utilize

correspondingly long antennas. Radio waves produced at these frequencies ranging from 3kHz to 3mHz are known as ground waves or surface waves. Tis is because they follow the curvature of the earth as they travel from the broadcast antenna to the receiving antenna. Ground waves are particularly useful for long distance transmissions. Automatic direction finders (ADF) and LORAN navigational aids use these frequencies. ( Figure 4-5 ) High frequency (HF) radio waves travel in a straight line and do not curve to follow the earth's earth 's surface. Tis would limit tran transmissions smissions from the broadcast antenna to receiving antennas only in the line-of-sight of the broadcast antenna except for a unique characteristic. HF radio waves bounce off of the ionosphere layer of the atmosphere. Tis refraction extends the range of HF signals beyond line-of-sight. As a result, transoceanic aircraft often use HF radios for voice communication. communication. Te fre frequenc quencyy ran range ge is bet between ween 2 to 25 MHz MHz.. Tese kinds of radio waves are known as sky waves. ( Figure 4-5 ) Above HF transmissions, radio waves are known as space waves. Tey are only capable of line-of line-of-sigh -sightt transmission and do not refract off of the ionosphere. ( Figure 4-5 ) Most aviation communication and navigational aids operate with space waves. his includes VHF (30300MHz), UHF (300MHz-3GHz), and super high frequency (SHF) (3GHz- 30GHz) radio waves. VHF communication radios are the primary communication radios used in aviation. Tey operate in the frequency range from 118.0 MHz to 136.975MHz. Seven hundred and twenty separate and distinct channels



























Ionosphere

Repeater

Receiver

L i n e - o S p a f - S c e i g h t W a v ( V H e s F - U H F )

) H F ( e a v W y S k

v e

W a

d u n r o G

h t i g S f e - o n i L

( V L

F t o

M F

)

Receiver

Radio Station

Figure 4-5. Radio waves behave differently in the atmosphere depending in their frequency.

have been designated in this range with 25 kilohertz spacing between each channel. Further division of the bandwidth is possible, such as in Europe where 8.33 kilohertz separate each V HF communication communication channel. VHF radios are used for communications between aircraft and air traffic control (AC), as well as air-toair communication between aircraft. When using VHF, each party transmits and receives on the same channel. Only one party can transmit at any one time. LOADING INFORMATION ONTO A RADIO WAVE Te production and broadcast of radio r adio waves does not convey any significant information. Te basic radio wave

superimposed over the AC carrier wave signal. As the varying DC information signal is amplified, the amplifier output current varies proportionally. he oscillator that creates the carrier wave does so with this varying var ying current. Te oscillator frequency frequency output is consistent consiste nt because it is built into the oscillator circuit. But the amplitude of the oscillator output varies in relation to the fluctuating current input. ( Figure 4-6 4- 6) When the modulated carrier wave strikes str ikes the t he receiving antenna, voltage is generated that is the same as that which was applied applied to the transmitter antenna. However, However, the signal is weaker. It is amplified so that it can be demodulated.




























+

A. 121.5 mhz Carrier

+

0

−

A. Amplitude Modulated Carrier In Receiver 0 + − B. Varying DC Audio Information

0

B. Detected Modulated Carrier

+

+ 0

0

−

C. Demodulated Signal

C. Amplitude Modulated Carrier Leaving Transmitter

Figure 4-6. A DC audio signal modifies the 121.5 MHz carrier wave

+

as shown in C. The amplitude of the carrier wave (A) is changed in relation to modifier (B). This is known as amplitude modulation (AM).

FREQUENCY MODULATION (FM) Frequency modulation (FM) is widely considered superior to AM for carrying and deciphering information on radio waves. A carrier wave modulated by FM retains its constant amplitude. However, the information signal alters the frequency of the carrier wave in proportion to the strength of the signal. Tus, the signal signa l is represented as slight variations to the normally consistent timing of

0 D. Audio Frequency Signal In Speaker

Figure 4-7. 4-7. Demodulation of a received radio signal involves separating the carrier wave from the information signal.

Demodulation of an FM signal is similar to that of an AM receiver. Te signal captured by the receiving antenna is usually amplif ied immediately immediately since signal strength





























Modulating Signal

FM Signal

Figure 4-8. A frequency modulated (FM) carrier wave retains the consistent amplitude of the AC sign wave. It encodes the unique information signal with slight variations to the frequency of the carrier wave. These variations are shown as space variations between the peaks and valleys of the wave on an oscilloscope.

As use of the radio frequencies increases, more efficient allocation of bandwidth is imperative. Sending information via radio radio waves waves using using the narrowest bandwidth possib possible le is is the focus of engineering moving forward. At the same time, fully representing all of the desired information or increasing the amount of information conveyed is also desired. Various methods are employed to keep bandwidth to a minimum, many of which restrict the quality or quantity of information able to be transmitted. In lower frequency ranges, such as those used for ground wave and some sky wave broadcasts, SSB transmissions are a narrow bandwidth solution. Each side band represents the initial information signal in its entirety. Terefore in an SSB broadcast, the ca rrier wave and either either the upper or lower lower sidebands are filtered out. Only one sideband with its frequencies f requencies is broadcast since it contains all of the t he needed information. Tis cuts the bandwidth required in half ha lf and allows al lows more efficient efficient use of the radio spectrum. SSB transmissions also use less power to transmit the same amount of information over an equal distance. Many HF long distance aviation communications are SSB. ( Figure 4-10 )

N O I T B A C I S D N A U M D N M A O T C L O E I D A R



























RADIO TRANSMITTERS AND RECEIVERS Radio transmitters and receivers are electronic devices that manipulate electricity resulting in the transmission of useful information through the atmosphere or space. TRANSMITTERS A transmitter tr ansmitter consists of a precise oscillat oscillating ing circuit c ircuit or oscillator that creates an AC carrier carr ier wave frequency. Tis is combined with amplification circuits or amplifiers. Te distance d istance a carrier wave travels t ravels is direct directly ly related to the amplification of the signal sent to the antenna.

Other circuits are used in a transmitter to accept the input information signal and process it for loading onto the carrier wave. Modulator circuits modify the carrier wave with the processed information information signal. Essentially, this is all there is to a radio transmitter. NOE: Modern transmitters are highly refined devices with extremely precise frequency oscillation and modulation. Te circuitry for controlling, filtering, amplifying, modulating, and oscillating electronic signals can be complex. A transmitter prepares and sends signals to an antenna that, in the process described

RECEIVERS Antennas are simply conductors conductors of lengths propo proportional rtional to the wavelength of the oscillated frequency put out by the transmitter. An antenna captures the desired carrier wave as well well as many other radio waves that are presen presentt in the atmosphere. A receiver is needed to isolate the desired carrier wave with its information. Te receiver also has circuitry to separate the information signal from the carrier wave. It prepares it for output to a device, such as speakers or a display screen. Te output is the information signal originally introduced into the transmitter.

A common rece receiver iver is the supe superr heter heterody odyne ne rece receiver. iver. As with w ith any a ny receiver, it must amplify ampli fy the desired de sired radio r adio frequency captured by the antenna since it is weak from traveling through the atmosphere. An oscillator in the receiver is used to compare and select the desired frequency out of all of the frequencies picked up by the antenna. Te undesired frequencies are sent to ground. A local loc al oscil oscillator lator in the receiver produces a frequenc frequencyy that is different than the radio frequency of the carrier wave. Tese two frequencies frequencies are mixed in the mixer. Four frequencies result from this mixing. Tey are the radio



























RF Amplifier

Mixer

IF Amplifier

Detector Demodulator

AF Amplifier

Local Oscillator

Figure 4-12. The basic stages used in a receiver to produce an output from a radio wave.

they would not fit in the flight deck. oday, many avionics devices are small enough to be mounted in the instrument panel, which is customary on most light aircraft. Because of the number of communication and navigation aids, as well as the need to present an uncluttered interface to the pilot, most complicated aircraft retain an area away from the flight deck for the mounting of avionics. Te control heads of these units remain on the flight deck.

TRANSCEIVERS A transceiv t ransceiver er is i s a communicat communication ion radio ra dio that tran transmits smits and receives. he same frequency is used for both. When W hen tr tran ansmi smitt tt in ing, g, th thee rec receiv eiver er doe doess not fu nct ion. he pus push h to ta talk lk (P (P  ) sw switch itch bloc blocks ks the rece receiv iving ing circuitry and allows the transmitter circuitry to be active. In a transceiver, some of the circuitry is shared by the transmitting and receiving functions of the device. So is the antenna. Tis saves space and the number of components used. ransceivers are half duplex systems where whe re com commun mun ica icati tion on ca can n occ ur in bot h di rec recti tions ons but only one party can speak while the other must listen. VHF aircraft aircraf t communication communication radios are usual ly transceivers. ( Figure 4-13)




























is half the wavelength of the correspon corresponding ding AC frequency is able to allow full voltage and full current flow for the positive phase of the AC signal in one direction.  he n eg at i v e ph a s e of t he f u l l AC s ig n w av e i s he accommodated by the voltage and current simply changing direction in the conductor. Tus, the applied AC frequency flows through t hrough its entire wavelength, waveleng th, first in one direction and then in the other. Tis produces the strongest signal to be radiated by the transmitting antenna. It also facilitates capture of the wave and maximum induced voltage in the receiving antenna. ( Figure 4-14 ) Most radios, especially communication radios, use the same antenna for transmitting and receiving. Multichannel radios could use a d ifferent length antenna for each frequency, however, this is impractical. Acceptable performance performance can exist from f rom a single antenna half the t he wavelength of a median frequency. Tis antenna can be made effectively shorter by placing a properly rated capacitor in series with the transmission line from the transmitter or receiver. his electrical ly shortens the resonant circuit of which the antenna is a part. An antenna may be electrically lengthened by adding an

use a more efficient tuning circuit. It uses switches to combine frequencies from crystal controlled circuits to create a resonant frequency that matches the desired frequency. Either way, the physical antenna length is a compromise compr omise when using a multichannel communication or navigation device that must be electronically tuned for the best performance. A formula can be b e used to find the ideal length lengt h of a half ha lf wavelength antenna required requi red for a particular par ticular frequency as follows: Antenna Length (feet) =

468 F MHz

Te formula is derived from the speed of propagation propagation of radio waves, which is approximately 300 million meters per second. It takes into account the dielectric effect of the air at the end of an antenna that effectively shortens the length of the t he conductor required. required. VHF radio frequencies used by aircraft communication radios are 11 118–136. 8–136.975 975 MHz. he corresponding half wavelengths of these frequencies are 3.96–3.44 feet (47.5–41.2 inches). Terefore, VHF antennas are relatively long. long. Antennas one-quarter of the wavelength w avelength



























Al l ant antenn ennas as,, ev even en tho those se th that at ar aree omn omni-d i-dire irect ctiona iona l, radiate a stronger signal in some direction compared to other directions. his is known as the antenna field directivity. Receiving antennas with the same polarization as the transmitting antenna generate the strongest signal. A vertically polarized antenna is mounted up and down. It radiates waves out from it in all directions. o receive the strongest signal from these waves, the receiving antenna should also be positioned p ositioned vertically vertical ly so the electromagnetic compon component ent of of the radio wave can cross it at as close close to a 90° angle as possible possible for most of the possible proximities. ( Figure 4-15 )

Up

N

E W

Down

Horizontally polarized antennas a re mounted side to side (horizontally). Tey radiate in a donut-like donut-like field. Te strongest signals come from, or are received at, 90° 9 0° to the length of the antenna. Tere is no field generated off of the end of the antenna. Figure 4-16 4 -16 illustrates the field produced by a horizontally polarized antenna. Many vertical and horizontal antennas on aircraft are mounted at a slight angle off plane. his allows the antenna to receive a weak signal rather than no signal at all when the polarization of the receiving antenna is not identical to the transmitting antenna. ( Figure 4-17 )

S

Figure 4-15. 4-15. A ver tically polarized antenna radiates r adio waves in a donut-like pattern in all directions.

9 0 °

Minimum Radiation

Maximum Radiation






























A co comm mmon on d ip ipol olee a nt nten en na is t he V-sh ap ed V HF navigation antenna, known as a VOR antenna, found on numerous aircraft. Each arm of the V is one-fourth wavelength creating a half wave antenna a ntenna which is fed in the center. Tis antenna is horizontally polarized. For a dipole receiving antenna, this means it is most sensitive to signals approaching the antenna from f rom the sides rather than head-on in the direction of flight. ( Figure 4-18 ) MARCONI ANTENNA

A Mar Marconi coni anten antenna na is a one-fou one-fourt rth h wav wavee ante antenna nna.. It achieves the efficiency of a half wave antenna by using the mounting surface of the conductive aircraft skin to create the second one-fourth wavelength. Most aircraft VHF communications antennas are Marconi antennas. Tey are vert vertical ically ly pola polariz rized ed and create a field that is

of the loop. However, However, the polarity polarit y of the current flows is opposite each other. Tis causes them to cancel out and produce no signal. Wh en a rad io wav When wavee st stri rikes kes th thee loop ant anten enna na in li line ne with wit h the pla plane ne of the loop, cu curre rrent nt is gener generated ated f irs irstt in one side, and then in the other side. Tis causes the current flows to have different phases and the strongest signal can be generated from this angle. he phase difference (and strength) of the generated current varies proportionally to the angle at which the radio wave strikes the antenna loop. Tis is useful and is discussed further in the section on automatic direction finder (ADF) navigational aids. ( Figure 4-20 ) TRANSMISSION LINES



























Plane of loop perpendicular to direction of wave travel. Plane of loop parallel to direction of wave travel.

Minimum Reception Loop Orientation A

Maximum Reception Loop Orientation

B

Figure 4-20. A loop antenna is highly direction-sensitive. A signal origin perpendicular or broadside to the loop creates a weak signal (A). A signal origin parallel or in the plain of the loop creates a strong signal (B).

N O I T B A C -



























wo d if fe fere rent nt f re requ quen enci cies es a re us ed to ca r r y t he hese se broadcasts with data link capability. he first is an expanded use of the 1090 MHz Mode-S transponder protocol known as 1090 ES. Te second, largely being introduced as a new broadband solution for general aviation implementation of ADS-B, is at 978 MHz. A 97 9788 un iv er ersa sa l ac acce ce ss tr an sc scei eive verr ( UA UA)) is us ed to accomplish accomplish this. An omni-directional antenna is required in addition to the GPS antenna and receiver. Ai rb rbor orne ne rec receiv eiv er erss of an AD ADS-B S-B bro broad adca cast st us usee th thee information to plot the location and movement of the

transmitting aircraft on a flight deck display similar to CAS. ( Figure 4-24 ) Inexpensive ground stations (compared to radar) are constructed in remote and obstructed areas to proliferate ADS-B. Ground stations share informatio information n from airborne ADS-B broadcasts broadcas ts with w ith other ground stations that t hat are a re part of the air traffic management system (AMS). Data is transferred with no need for human acknowledgement. Microwave and satellite transmissions are used to link l ink the network. For traffic separation and control, ADS-B has several advantages over conventional ground-based radar. Te first is the entire airspace can be covered with a much lower expense. Te aging AC radar system that is in place is is expensive



























Figure 4-24. A cockpit display of ADS-B generated targets (left). ADS-B airborne receiver with antenna (right).

A DS-B ADS -B IN of offe fers rs fe feat atur ures es not av avai ai la labl blee in C CAS AS.. Equipped aircraft are able to receive abundant data to enhance situational awareness. raffic information

ground stations is sent via ADS-B IN to the t he flight deck. Tis provid provides es a more complete pictu picture re tha than n air-to-a air-to-air ir only collision avoidance. Flight information services

N O I T B A C -



























ADS-B test units un its are available ava ilable for trained tra ined maintenance personnel to verif y proper operation of ADS-B equipment. Tis is critical since close tolerance of air traffic separation depends on accurate data from each aircraft and throughout all components of the ADS-B system. ( Figure 4-26)

Figure 4-26. An ADS-B test unit.

EMERGENCY LOCATOR TRANSMITTER (ELT) A n e me r g e n c y l o c a t or t r a n s m it t e r ( E L ) i s a n An independent battery powered transmitter activated

in maintenance records including the new expiration date of the battery. Tis must also be recorded on the





























GOES

MSG

GEO Satellites

INSAT

LEO Satellites

COSPAS

SARSAT



























Modern ELs may also transmit a signal on 121.5 MHz. Tis is an analog transmission that can be used for homing. Prior to 2009, 121.5 MHz was a worldwide emergency frequency monitored by the CORPASSARSA satellites. However, it has been replaced by the 406 MHz standard. ransmission on 121.5 MHz are no longer received and relayed via satellite. Te use

It must be noted that older 121.5 MHz analog signal ELs often also transmit an emergency signal on a frequency of 243.0 MHz. his has long been the military emergency frequency. Its use is being phased out in favor of digital EL signals and satellite monitoring. Improvements in coverage, location accuracy, identif identif icatio ication n of false fa lse alerts, and shortened



























QUESTIONS

4-11 Question: 4 Te relationship between frequency and wavelength is __________________ proportional.

Question: 4-5 VHF communication radios are the primary communication radios used in aviation. Tey operate in the frequency range from ________ MHz to ________ MHz.



























ANSWERS

4-11 Answer: 4inversely.

Answer: 4-5 118.0. 136.975.



























QUESTIONS

Question: 4-9 When two AC signals are mixed together, such as when a carrier wave is modulated by an information signal, three main frequencies result; they are?

Question: 4-13 A __________________ is a communication communication radio that transmits and receives.













































































































































































Electronic Fundamentals for Aircraft Maintenance

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