Empathy List Archives

JH

Jim Harman

Sat, Dec 17, 2016 7:22 PM

Hi all,

I have experimented with LH 5 just monitoring a GPS receiver and am very
impressed with the results.

As a next step, I would like to use LH to monitor a homebrew GPSDO, and I
think it would be easier to modify the GPSDO firmware to emulate an
existing device rather than customize LH to work with the logging data that
my system currently produces.

In addition to NMEA data from the GPS, my system can output the DAC and TIC
(phase error) values as well as the temperature, Since I control the
firmware, I can produce pretty much any data format as long as it is
clearly documented, but I would prefer a text-based rather than binary
protocol and not to have to reformat all the NMEA data.

Does this approach make sense, and if so which of the several standard
GPSDOs would it be best to emulate?

Thanks in advance for your insights

--

--Jim Harman

Hi all, I have experimented with LH 5 just monitoring a GPS receiver and am very impressed with the results. As a next step, I would like to use LH to monitor a homebrew GPSDO, and I think it would be easier to modify the GPSDO firmware to emulate an existing device rather than customize LH to work with the logging data that my system currently produces. In addition to NMEA data from the GPS, my system can output the DAC and TIC (phase error) values as well as the temperature, Since I control the firmware, I can produce pretty much any data format as long as it is clearly documented, but I would prefer a text-based rather than binary protocol and not to have to reformat all the NMEA data. Does this approach make sense, and if so which of the several standard GPSDOs would it be best to emulate? Thanks in advance for your insights -- --Jim Harman

BC

Bob Camp

Sat, Dec 17, 2016 8:42 PM

Hi

There are a pretty small number of things that a GPSDO worries about that are
not in the standard NMEA data structures:

DAC
Temperature
Lock state
Time error
Maybe a “quality of lock” metric

A lot of GPSDO’s put out more than that in their status messages. There is a
lot of repetition between NMEA messages and that carries over to the custom
stuff.

More or less anything that starts with $P is considered a specialized / custom
message. You could easily have a $PTNT (for TimeNuts of course not for blowing
things up) message or set of messages. If you added a “version” field to the list above, and
a “number of fields to follow”, you probably would have a useful string to use.

$PTNT,1,5,32768,27.232,1.1.3,+22.868, -13.45,100 would be version 1, 5 fields, DAC 32768 out
of who knows how many (hmm…), State 1.1.3 (out of how many), Temp 22.868 C, time error -13.45 ns, lock
quality 100%.

You could take care of the dac issue by going to a float with a defied range of 0 to 1. State
is a bit more difficult. It depends a lot on how things are implemented. We probably would need
it a bit better defined or put it in another message.

Bob

On Dec 17, 2016, at 2:22 PM, Jim Harman j99harman@gmail.com wrote:

Hi all,

I have experimented with LH 5 just monitoring a GPS receiver and am very
impressed with the results.

As a next step, I would like to use LH to monitor a homebrew GPSDO, and I
think it would be easier to modify the GPSDO firmware to emulate an
existing device rather than customize LH to work with the logging data that
my system currently produces.

In addition to NMEA data from the GPS, my system can output the DAC and TIC
(phase error) values as well as the temperature, Since I control the
firmware, I can produce pretty much any data format as long as it is
clearly documented, but I would prefer a text-based rather than binary
protocol and not to have to reformat all the NMEA data.

Does this approach make sense, and if so which of the several standard
GPSDOs would it be best to emulate?

Thanks in advance for your insights

--

--Jim Harman

time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Hi There are a pretty small number of things that a GPSDO worries about that are not in the standard NMEA data structures: 1) DAC 2) Temperature 3) Lock state 4) Time error 5) Maybe a “quality of lock” metric A lot of GPSDO’s put out more than that in their status messages. There is a lot of repetition between NMEA messages and that carries over to the custom stuff. More or less anything that starts with $P is considered a specialized / custom message. You could easily have a $PTNT (for TimeNuts of course not for blowing things up) message or set of messages. If you added a “version” field to the list above, and a “number of fields to follow”, you probably would have a useful string to use. $PTNT,1,5,32768,27.232,1.1.3,+22.868, -13.45,100 would be version 1, 5 fields, DAC 32768 out of who knows how many (hmm…), State 1.1.3 (out of how many), Temp 22.868 C, time error -13.45 ns, lock quality 100%. You could take care of the dac issue by going to a float with a defied range of 0 to 1. State is a bit more difficult. It depends a lot on how things are implemented. We probably would need it a bit better defined or put it in another message. Bob > On Dec 17, 2016, at 2:22 PM, Jim Harman <j99harman@gmail.com> wrote: > > Hi all, > > I have experimented with LH 5 just monitoring a GPS receiver and am very > impressed with the results. > > As a next step, I would like to use LH to monitor a homebrew GPSDO, and I > think it would be easier to modify the GPSDO firmware to emulate an > existing device rather than customize LH to work with the logging data that > my system currently produces. > > In addition to NMEA data from the GPS, my system can output the DAC and TIC > (phase error) values as well as the temperature, Since I control the > firmware, I can produce pretty much any data format as long as it is > clearly documented, but I would prefer a text-based rather than binary > protocol and not to have to reformat all the NMEA data. > > Does this approach make sense, and if so which of the several standard > GPSDOs would it be best to emulate? > > Thanks in advance for your insights > > -- > > --Jim Harman > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there.

BS

Bob Stewart

Sat, Dec 17, 2016 10:39 PM

Hi Jim,
A couple of years ago, I asked the group if there was a standard UI that I should use for the GPSDO that I was developing. Everyone said no, just do what works. I don't think it occurred to anyone, certainly not to me, just how big a role that LH plays in the world of GPSDOs. So, here I am at the end of the development cycle, and this question has become very important to me. Obviously, I'm very interested in where this thread goes.

Mark, if you decide to handle this offline, could you make me a part of that discussion?
Bob
-----------------------------------------------------------------
AE6RV.com

GFS GPSDO list:
groups.yahoo.com/neo/groups/GFS-GPSDOs/info

  From: Jim Harman <j99harman@gmail.com>

To: time-nuts@febo.com
Sent: Saturday, December 17, 2016 1:22 PM
Subject: [time-nuts] Lady Heather for homebrew GPSDO

Hi all,

I have experimented with LH 5 just monitoring a GPS receiver and am very
impressed with the results.

As a next step, I would like to use LH to monitor a homebrew GPSDO, and I
think it would be easier to modify the GPSDO firmware to emulate an
existing device rather than customize LH to work with the logging data that
my system currently produces.

In addition to NMEA data from the GPS, my system can output the DAC and TIC
(phase error) values as well as the temperature, Since I control the
firmware, I can produce pretty much any data format as long as it is
clearly documented, but I would prefer a text-based rather than binary
protocol and not to have to reformat all the NMEA data.

Does this approach make sense, and if so which of the several standard
GPSDOs would it be best to emulate?

Thanks in advance for your insights

--

--Jim Harman

time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Hi Jim, A couple of years ago, I asked the group if there was a standard UI that I should use for the GPSDO that I was developing. Everyone said no, just do what works. I don't think it occurred to anyone, certainly not to me, just how big a role that LH plays in the world of GPSDOs. So, here I am at the end of the development cycle, and this question has become very important to me. Obviously, I'm very interested in where this thread goes. Mark, if you decide to handle this offline, could you make me a part of that discussion? Bob ----------------------------------------------------------------- AE6RV.com GFS GPSDO list: groups.yahoo.com/neo/groups/GFS-GPSDOs/info From: Jim Harman <j99harman@gmail.com> To: time-nuts@febo.com Sent: Saturday, December 17, 2016 1:22 PM Subject: [time-nuts] Lady Heather for homebrew GPSDO Hi all, I have experimented with LH 5 just monitoring a GPS receiver and am very impressed with the results. As a next step, I would like to use LH to monitor a homebrew GPSDO, and I think it would be easier to modify the GPSDO firmware to emulate an existing device rather than customize LH to work with the logging data that my system currently produces. In addition to NMEA data from the GPS, my system can output the DAC and TIC (phase error) values as well as the temperature, Since I control the firmware, I can produce pretty much any data format as long as it is clearly documented, but I would prefer a text-based rather than binary protocol and not to have to reformat all the NMEA data. Does this approach make sense, and if so which of the several standard GPSDOs would it be best to emulate? Thanks in advance for your insights -- --Jim Harman _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.

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Lady Heather for homebrew GPSDO