[time-nuts] Z3801A Problem

[Hal Murray]

lists at rtty.us said:
> If the firmware is fine tuning something, (like s/n or elevation) that would
> explain the first issue. If it's something like s/n where they may be
> averaging values, then a single bad packet *could* mess up their averaging
> and "turn it all off". 

What can the firmware do if it decides that it doesn't like a satellite?  The 
GPS receiver does the math and sends over the PPS.  How would the firmware 
adjust that calculation to not use a particular satellite?

You can set the elevation mask angle.  I don't see a way to set a S/N filter. 
 (I assume the mask angle gets passed to the GPS receiver.)

You can tell it to ignore specific satellites.  I assume that list gets 
passed to the receiver.  The firmware might be able to use that mechanism for 
S/N filtering, but the timing seems wrong.  If the S/N for a sat is too low, 
the firmware would have to ignore the data for that second, tell the receiver 
to ignore that sat, and hope the data for the next second is good.

It might work if S/N only changes slowly, but I don't think that's the case 
for things like multipath.



-- 
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