Hi One gotcha with TISP <-> NEMA is that they use different units for things like position. Yes it’s just math to translate them. No it’s not trivial on a little tiny PIC. If the GPS in your GPSDO is a NEMA (or NEMA like) device, you either will have a mix of TISP and NEMA or a lot of translation ...
Bob On Jun 26, 2014, at 5:38 AM, REEVES Paul <paul.ree...@uk.thalesgroup.com> wrote: > Chris, > NMEA is a good 'general purpose' interface for GPS units but I thought this > thread was about the GPSDO interface. Not quite the same - TSIP/SCPI would > make rather more sense here, especially with all those Thunderbolts about :-) > Most GPS receivers still supply at least one serial interface even if a USB > interface is included too. Consumer grade 'very small' navigation type GPS > units may dispense with the serial ports but we are not too worried about > those devices, surely? I don't see why a serial to USB converter would be > needed - serial ports are still available on a reasonably large number of > motherboards, especially if you are using mini-ITX or similar for embedded > projects, and a hardware UART is a much more reliable interface. USB/serial > adaptors 'still' give erratic results and scanning usb ports for new devices > is also a bit of a lottery at times. > A serial interface is also the easiest to convert to a more 'robust' physical > media for electrically 'unpleasant' environments .... and DB9/25 connectors > are a LOT more reliable than USB connectors too! > > regards, > > Paul G8GJA > -----Original Message----- > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On > Behalf Of Chris Albertson > Sent: 26 June 2014 08:13 > To: Bob Stewart; Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] GPSDO standard interface? > > If you want a common interface for GPS receivers it's "NMEA" and it's > relatively easy to implement. I certain would NOT translate to TSIP as > that is rather obscure. NMEA is a very common standard and many GPSes can > output NMEA. > > Also you talked about "serial". I hate to say it but "who in 2014 wants a > serial device? USB is the only reasonable interface to a computer. If you > used serial then you would just need to buy a serial to USB adapter so you > may as well build that into your controller. In 2014 those old DB9 and > DB25 connectors should be banned from all new designs. > > Realistically the user interface in most home made gear is a few "#ifdef" > in the code at the top of the file. You change those and recompile and > send the new software to the controller. It's not bad having to re-compile > in order to support a different GPS receiver. You would not want to swap > the brand of GPS in a user interface. You do that with solder and wires > and recompiling > > > On Wed, Jun 25, 2014 at 8:14 PM, Bob Stewart <b...@evoria.net> wrote: > >> After reading Chris's response, it dawned on me that I'm treading a >> different path from what I've seen on the list. It's not so much a GPSDO >> as a general purpose GPSDO engine. It uses a number of ideas from Bert's >> board, like the dual-rail op-amp output, but it also has a TIC, so it will >> have sawtooth correction. I have included 2 TTY ports: one for the >> receiver and one for the PC interface. I'm going to use the DAC on the >> dsPIC, but there will be an SPI port that can be used to drive an off-board >> DAC, instead. There's also the possibility of switching some stuff around >> and having an I2C port, and the ICSP header could also hook up to an >> additional thermistor or two, or perform other digital functions. >> >> >> So, there will be some minor user fiddling, like with Bert's board, due to >> the flexibility of the OCXO. But, I'll be using the P and D from the PID >> control system, so it shouldn't be difficult to setup. There will be a >> power LED, an output enable LED, and a bi-color LED to signify status, but >> only the status would be necessary. I'll do what I can to make it smart >> enough to plug and play for most circumstances, but I only have the one >> OCXO brand to test with at the moment. I do have 3 receivers to test with >> now: Adafruit, UT+, and LEA-6T. Keep in mind that I don't expect this to >> be a lucrative commercial business venture, so my budget is almost >> nonexistent. >> >> >> I'll look into both SCPI and TSIP, and therein lies the reason for my >> original post. Essentially, have they been patented, and if so, have those >> patents expired? Some companies guard their interfaces very rigorously to >> forestall competitive disruption. I don't want to suddenly get a cease and >> desist letter or a notice of lawsuit over a hobbyist kit. It's one thing >> to provide open source software to monitor/control a successful product. >> It's an entirely different thing to provide an alternative product with an >> identical user interface. >> >> I just ordered the first prototype boards today, but the software should >> be just a rewrite of what I did for the TIC on Bert's board, with a lot of >> extras thrown in. Not that that doesn't mean a lot of work, of course. >> >> >> Bob >> >> >> >> ________________________________ >> From: Tom Van Baak <t...@leapsecond.com> >> To: Discussion of precise time and frequency measurement < >> time-nuts@febo.com> >> Sent: Wednesday, June 25, 2014 9:02 PM >> Subject: Re: [time-nuts] GPSDO standard interface? >> >> >> Bob, >> >> A couple of different ideas: >> >> 1) No UI at all. The surplus GPSDO favorites over the years (like the HP >> SmartClock's and Trimble Thunderbolt) work with no UI. Yes, there is a PC >> program you can use to monitor and control it, or even debug it, but it is >> completely optional. Many GPSDO work out of the box. Maybe, like HP, have >> one green LED to say all-is-well. >> >> 2) A very simple 9600 baud command set that you can use with any terminal >> program. Adding LCD is fine too. But make sure everything on the LCD is >> also available over RS232. Not everyone wants to visually monitor the LCD >> of every piece of gear on their bench; let a PC log and archive all the >> data, check for problems, make plots, etc. >> >> 3) Mimic enough of HP's SCPI command set so that GPScon and other tools >> like that can be used, transparently. I forget if your GPSDO includes a >> receiver or not. >> >> 4) Mimic enough of Trimble's TSIP so that LH and other tools like that can >> be used, transparently. >> >> Please write enough code so that the GPSDO, by default, can work "out of >> the box". I'm evaluating a prototype GPSDO right now that requires all >> sorts of user input just to get it started and to keep it going. That gets >> old. My bias is: time spent creating clever adaptive algorithms to make a >> human unnecessary is better than time spent creating an elaborate UI that >> requires a user (and operation manual) and constant monitoring or adjusting. >> >> /tvb >> >> >> ----- Original Message ----- >> From: "Bob Stewart" <b...@evoria.net> >> To: "Discussion of precise time and frequency measurement" < >> time-nuts@febo.com> >> Sent: Wednesday, June 25, 2014 5:10 PM >> Subject: [time-nuts] GPSDO standard interface? >> >> >> In an offline communication, I suddenly realized that I hadn't given any >> thought to the user interface for my GPSDO. Is there an accepted standard >> interface for GPSDOs, or is that a murky Microsoft-esque world of patents >> and lawyers? >> >> >> Bob - AE6RV >> >> >> _______________________________________________ >> 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. >> _______________________________________________ >> 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. >> > > > > -- > > Chris Albertson > Redondo Beach, California > _______________________________________________ > 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. > _______________________________________________ > 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. _______________________________________________ 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.