intermittent vector synchronization
I'm having trouble synchronizing two vectors. They work together for several hours of bursts, then the slave skips a burst, then it works for a while, then the slave skips the first part of a burst, then it works for a while... Why does the slave work intermittently? What can I do to make them work together all of the time?
-Jon
Hi Jon,
The first thing I would check is to verify that the Vector slave has enough margin in its deployment start time compared to the master. This is explained on page 65 in the Vector manual (Rev. H). The slave must be set up to start a sufficient number of seconds before the master to accommodate for clock drift between the real time clocks (RTCs) of the two instruments. If the slave starts too late it would miss the first sync pulse(s) from the master which would again mean that it would have a few samples left to measure when the master is finished. The slave should still start over again on the next burst, but since it will then interrupt itself with the alarm from the RTC you might also loose data that is not flushed to the recorder.
A careful inspection of the sensor data file should otherwise reveal what the problem is. The slave will take one measurement of sensor data when it wakes up before waiting for sync input to start measuring velocity data. So the time between the first and second sensor sample (.sen-file) will tell you the margin the slave has before the master starts outputting sync pulses. The last sensor sample in a burst will together with the burst counter tell you if the slave has received all the sync pulses for its burst (assuming sample on sync measurement).
How were these instruments deployed, cable distance, power supply, sync method (sample or start on sync) etc.?
If you can send us the data files from the two instruments we can take a look at them.
Best regards,
Sven Nylund
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