External Clock Reference Alarm Handling Alarm Description This alarm is reported when a BTS fails to perform clock synchronization because external reference clock signals are lost, when the reference clock is unavailable, or when there is a large frequency oset between the reference clock and the local oscillator
Alarm !"#$%&%&% 'xternal (lock )eference *roblem, Speci+c *roblem 'xcessive -requency .ierence between (lock )eference and "ocal (rystal /scillator
Possible Cause 0 Transmissio ransmission n quality unstable unstable Transm Transmissio ission n instability instability is the ma1or cause of this alarm % (loc (lock k Sou Sourc rce e "os "ost t 2 3#*T45T 3#*T45T#6 #6 board board is faulty7 the the frequency frequency output output of the crystal crystal oscillato oscillatorr can8t trace and lock the upper level reference clock which leads to clock reference alarm 4.
(on+guration issue
Handling Procedure 3G SIE Step ! (heck clock status The *"" status should be equal to "/(9'. to clear the alarm which means that the local oscillator is getting its clock from the source -rom the result below, the clock is in -ree running instead of "ocked %%DSP CLKSTAT: SN=7;%% Display System Clock Status --------------------------Cabinet No = ! Sub"ack No = ! Slot No = 7 Cu""ent Clock Sou"ce = Line Clock Cu""ent Clock Sou"ce Sou"ce State State = #"e$uency Deiation Clock &o"kin' (o)e = (anual PLL Status = #"ee "unnin' *Numbe" o+ "esults = , ---
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N/T.: Please c0eck PLL status "e+e"ence on t0e last pa'
(heck k the the cloc clock k reso resour urce ce (hec (heck k othe otherr site sites s of the the ):( ):( if also also Step Step "# (hec experi experienc encing ing clock clock probl problem em ;f ma1ori ma1ority ty of sites sites are are normal normal,, clock clock resou resourc rce e is
working without any problem, if not check the ):( interface board and clock source
Step 3# (heck if there is fault or sync issue in the transmission network Step $# #odify the value of the (urrent .! to ad1ust the value of the frequency oset to zero Theoretically we can only ad1ust the frequency oset from $0< to 0< 0 /pen the #aintenance (lient for the :odeB (lick on the #!;:T':!:(' and expand the )'!"T;#' S*'(;-;( #/:;T/);:5 Tree to get on the ("/(9 T'ST % .ouble click on the ("/(9 T'ST ! window will prompt up Set (abinet :o =, Subrack :o =, Slot :o > ?3#*T board@ and then click /9 This will show the current frequency oset4dierence of the internal oscillator to the source clock Aou can choose the chart graph to see how the frequency oset move when you ad1ust the current .! value Aou should ad1ust the current .! to make the dierence as close to zero
2 .isplay the ("/(9 .! and take note of the (urrent .! value %%DSP CLKDA: SN=7;%% Display Clock DA ---------------Cabinet No = ! Sub"ack No = ! Slot No = 7
1nitial DA = 232,4 Cente" DA = 23!35 Cu""ent DA = 23!35 *Numbe" o+ "esults = , ---
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6se the formula below to calculate for the value of the new current .! to ad1ust the -requency dierence to =
New Current DA Value = Current DA – (65535/40 Hz) * Ave. Frequen! "#$et C #odify the value of the current .! with the result from the formula Aou can change further the .! value until the dierence is almost = %%(/D C6DA: SN=78 DA=2774!;%% ---
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%%(/D C6DA: SN=78 DA=27959;%% ---
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& 3hen the dierence is almost =, modify the (enter .! according to the (urrent .! "ist the clock record to check on the *"" status ;t takes time before the clock will locked to the source ?about % D 2 hours@, the alarm will clear after this time ?The *"" status will be changed from -ree )unning
(apture -ast Tracking "ocked, see reference on the last page@ %%(/D C.NT.DA: SN=78 DA=27959;%% ---
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%%LST CLK.C/D: SN=7;%% List Clock eco") ----------------Time
PLL Status
Cu""ent DA Cente" DA
3!,3-!7-!4 ,!:3:39 DST #ast t"ackin' 27959
27959
3!,3-!7-!4 ,!:2!:92 DST #"ee "unnin' 2774!
23!35
3!,3-!7-!4 ,!:2!:,5 DST #"ee "unnin' 293
23!35
3!,3-!7-!4 ,!:35:35 DST #"ee "unnin' 2459
23!35
3!,3-!9-37 !2:34:25 DST #"ee "unnin' 23!35
23!35
3!,3-!9-37 !2:34:25 DST #"ee "unnin' 23!35
23!35
3!,3-!9-37 !,:94: DST #ast t"ackin' 23!35
23!35
3!,3-!9-37 !,:9,:2 DST #"ee "unnin' 23!35
23!35
3!,3-!9-37 !,:9,:2 DST #"ee "unnin' !
23!35
*Numbe" o+ "esults = , ---
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> 3e can forced the clock to -ast track the source by setting the clock working mode to -ree )unning then setting back to #anual %%LST CLK(/D.:;%%
List Clock &o"kin' (o)e ----------------------Clock &o"kin' (o)e = (anual Selecte) Clock Sou"ce = Line Clock Clock Sou"ce No = ! *Numbe" o+ "esults = , ---
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%%S.T CLK(/D.: (/D.=#..;%% ---
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%%S.T CLK(/D.: (/D.=(AN6AL8 CLKSC=L1N.CLK;%% ---
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%%LST CLK.C/D: SN=7;%% List Clock eco") ----------------Time
PLL Status
Cu""ent DA Cente" DA
3!,3-!7-!4 ,!:99:94 DST #ast t"ackin' 27959
27959
3!,3-!7-!4 ,!:9:9, DST #ast t"ackin' 2723
23!35
3!,3-!7-!4 ,!:9:! DST #ast t"ackin' 245!
23!35
3!,3-!7-!4 ,!:3:39 DST #ast t"ackin' 2774!
23!35
3!,3-!7-!4 ,!:2!:92 DST #"ee "unnin' 2774!
23!35
3!,3-!7-!4 ,!:2!:,5 DST #"ee "unnin' 293
23!35
3!,3-!7-!4 ,!:35:35 DST #"ee "unnin' 2459
23!35
3!,3-!9-37 !2:34:25 DST #"ee "unnin' 23!35
23!35
3!,3-!9-37 !2:34:25 DST #"ee "unnin' 23!35
23!35
3!,3-!9-37 !,:94: DST #ast t"ackin' 23!35
23!35
3!,3-!9-37 !,:9,:2 DST #"ee "unnin' 23!35
23!35
3!,3-!9-37 !,:9,:2 DST #"ee "unnin' !
23!35
*Numbe" o+ "esults = , ---
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E 3e can see that the alarm will clear in few minutes but the clock working state will stay to -ast Tracking until it is locked to the source ;f after sometime and the clock cannot locked to the external source the clock state will come back to the -ree running state and the alarm will reappear
%%LST CLK.C/D: SN=7;%% List Clock eco") ----------------Time
PLL Status
Cu""ent DA Cente" DA
3!,3-!7-!4 ,2:3:37 DST Locke)
274,4
27959
3!,3-!7-!4 ,3:9:,7 DST Locke)
274,9
27959
3!,3-!7-!4 ,3:9:,7 DST Locke)
27959
27959
3!,3-!7-!4 ,!:99:94 DST #ast t"ackin' 27959
27959
3!,3-!7-!4 ,!:9:9, DST #ast t"ackin' 2723
23!35
3!,3-!7-!4 ,!:9:! DST #ast t"ackin' 245!
23!35
3!,3-!7-!4 ,!:3:39 DST #ast t"ackin' 2774!
23!35
3!,3-!7-!4 ,!:2!:92 DST #"ee "unnin' 2774!
23!35
3!,3-!7-!4 ,!:2!:,5 DST #"ee "unnin' 293
23!35
3!,3-!7-!4 ,!:35:35 DST #"ee "unnin' 2459
23!35
3!,3-!9-37 !2:34:25 DST #"ee "unnin' 23!35
23!35
3!,3-!9-37 !2:34:25 DST #"ee "unnin' 23!35
23!35
3!,3-!9-37 !,:94: DST #ast t"ackin' 23!35
23!35
3!,3-!9-37 !,:9,:2 DST #"ee "unnin' 23!35
23!35
3!,3-!9-37 !,:9,:2 DST #"ee "unnin' !
23!35
*Numbe" o+ "esults = 3, ---
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Step %# )eset4 replace the 3#*T board
"G SIE
Same principle works with %5 but the alarm handling is slightly dierent
Step ! #odify the value of the (urrent .! to locked the BTS clock to the external source !# /pen the BS( "#T /n the BTS .evice *anel, right click on the 5T#6 and select F6')A B/!). ;:-/)#!T;/: 3e can see that the (lock is free oscillating ?same with -ree running in 25@ (lock Source is T)!(' BS( ("/(9 which means that the BTS gets its clocking from the BS( through !bis "ink
"# )ight click again on the 5T#6 then select #!;:T!;: ("/(9 Take note of the (lock -actory Galue and the (urrent .! value
3# #odify the (urrent .! value by running the command below Set the (alibration Galue to the (lock -actory Galue
%%S.T L(T=D1SA
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$# Then save the BTS clock by running the command below %%SA?
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%# 3ait until the alarm clears and check on the clock working state to change to "ocked ;t will be changed from -ree /scillation
(apture "ocked
&# ;f the clock working state changed to "ocked then we can enable back the (lock Source to the BS( clock and setting the calibration value to the current .! value %%S.T L(T=.NA
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'# Save again the BTS clock by running the command below %%SA?
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P(( State )ode 0 -ree )unning •
;f no reference clock source is con+gured of the reference clock sources are unavailable, the *"" works in free running state
•
;f there8s an available reference clock source, the BS( 1udges the reference clock source for %&= seconds ;f the source remains stable for more than %&= seconds, the *"" shifts to quick capture state /therwise, the *"" still works in free running state
% Fuick (apture •
;f the reference clock source is available and remains stable for a period ?longer than == seconds for a 5*S source or %== seconds for any source other than the 5*S source@, the *"" shifts to tracking state
•
;f the reference clock is lost, the *"" shifts back to free running state
2 -ast Tracking "ocked
Di*erence bet+een CE,ER and C-RRE, DA 3hen the :' clock works in -ree running mode, the current .! will be changed according to the (enter .! ;f the :' uses a clock source, the current .! changes with the frequency of the clock source ;f the external clock source stays locked for seven consecutive days, this shows that the clock source is very stable ;n this case the clock module overwrites the center .! with the current .!
