[time-nuts] Lady Heather for homebrew GPSDO

Mark Sims holrum at hotmail.com
Sun Dec 18 22:01:36 EST 2016

The Z3801A does have a request for getting/setting the DAC value as a absolute (hex) number.  Heather uses the percentage version of the message.  Neither format tells you what you really want to know...  the actual DAC voltage.  There is nothing to prevent you from sending a DAC percentage with 10 digit resolution...

Heather gets the Z3801A satellite position/signal level info by requesting the "SYST:STAT?" message once a minute at xx:xx:33  and parsing out the values from the status screen (ugh... another reason the Z3801A was never intended to have a computer monitor and control it).   This takes the receiver 3 seconds to send.  During that time no time codes, etc come in and you can't request any other information.  At least the device has a (kludgy) way of getting the information... the Datum StarLoc II says all sats are at az/el 0,0 ... at least it does give a signal level.

--The EFC value is given as an integer percent -100 to 100, so there is not
enough resolution to really tell what the DAC is doing.

-- It does not have the satellite position and C/N data that is reported in
the NMEA GSV sentence, so LH can't make its nice satellite plots.

More information about the time-nuts mailing list