Masterclock GPSPCI Spécifications télécharger pdf (Page 33)

APPENDIX A. INSTALLATION 32

A.4.4 Using the hs master

This program is used to drive the synchronization mechanism on all computers. After a

successful installation you can start the hs master program on all ”master” computers

hosting GPS cards. Before trying anything else you should set the clock cards in READ TIME

mode: clock test 1 3 . Then you should check with dump hslclock.sh if the clocks

are counting.

After this you can start the hs master program and synchronize the boards. You decide

upon a reference time for all com puters and then you choose one of the 2 synchronization

options. Option 1 resets the clocks at the speciﬁed time and after this the clocks are running

freely (driven by the 10MHz signal from the GPS cards). T he recommended synchronization

option is option (6) which uses the PPS synchronization thread that keeps the clocks from

drifting apart.

NOTE: The global synchronization is not possible if the PPS Sync thread is already active

- you have to disable it ﬁrst before trying to synchronize the clocks again. To disable it you

use the command clock test 1 14 [ DISABLE PPS SYNC THREAD (14) ] on all the

computers in the system. After this you can try to synchronize the clocks again.

To te st the synchronization you can use one of the global testing options. If the PPS thread

is NOT active you can use options (3)-Global testing or (5)-Continuous testing. For option

(5) you can use hsdaemon log.sh to s ee the results in real-time. In the resulting ﬁles you

should see similar values from all clock cards in the system.

If the PPS Synchronization Thread is active (if you have chosen option (6) for synchro-

nization) then you have to use another method for testing. The PPS Sync Thread makes a

correction of the clock at each second. Because of this if we read directly the clock at each

second we’ll see only ”ideal” values. To see the values before the correction from the PPS

sync thread you have to run the following commands:

clock_test 1 1 6 [ SET_READMODE_LAST_BAD_CLOCK_VALUE (16) ]

and then

dump_hslclock.sh 1

Please note that dump hslclock.sh tries to read the clock once per second but it uses

the sleep UNIX command so the timing is not very accurate. Sometimes you will some

samples missing. The program dump hslclock.sh writes the results to some ﬁles in the

”res” directory. In the table below you can see some sample outputs when the PPS Sync

Thread was active. Notice that the diﬀerences b etween the clocks are very small.

Clock 1 Clock 2

3843919866 3843919863

3883919867 3883919867

3923919867 3923919868

3963919867 3963919868

4003919867 4003919867

4043919867 4043919867

4083919867 4083919867

4123919867 4123919868

4163919868 4163919867

1 2 ... 28 29 30 31 32 33 34 35 36 37 38 ... 43 44

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Masterclock GPSPCI Spécifications Page 33

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