[evlatests] VLA timing

[Hichem Ben Frej]

What Barry described is correct.
All deferred commands, with execution time in the future, are scheduled 
in the Sequencer. The execution time is translated into WaveGuide counts.
When the Waveguide counts for the command is >= to the current waveguide 
count and at the same time <= (1+ current waveguide count) The command 
get executed.
For the phase commands, the execution means that the value of the 
command get written to the phase command buffer. One phase command per 
antenna is sent every Wave guide cycle.

Hichem


Barry Clark wrote:
> According to my reading of the code, within a ten second cycle, early
> in the cycle, at about 0.5 sec TAI (7.5 sec UTC), the phase commands 
> for the cycle are calculated and sent to the CMP.  There are eight of
> these commands send, with execution times of 10.104, 11.354, 12.604, 
> etc., TAI.  The phases are calculated for times of 11.125, 12.250, 13.750,
> etc. TAI.
>
> In my interpretation of events, these sit in the CMP command queue for 
> slightly under 10 seconds before the first is executed.  At approximately 
> the execution time in the command, the values in the command are copied 
> into the phase command buffer in the CMP.  At waveguide cycles beginning
> at 10.990, 11.042, 11.093, 11.146 the phase commands are sent to the L7.
> At the waveguide cycle beginning 11.198 the phase command strobe is sent
> to the L7, which should result in these commands being used beginning at
> 11.125 seconds, the nominal time.
>
> Perhaps Hichem can review what is actually happening in the CMP and tell
> us if he agrees with this sequence.
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-- 
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Hichem Ben Frej - hbenfrej at aoc.nrao.edu

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