Tom, Thanks for the information and your comments as to the suitability of these units. First hand knowledge is always appreciated. I had already figured out that there were four models :-)
I was reading the documentation from ublox and the time stamping interrupt caught my eye. However, it is listed as only being available on the R model. I can't find anyone selling that model. Timestamping a message to the nearest 100 ns is what I am after. If I can't do it directly with the ublox, I'll have to look at the PRU on the Beaglebone. It has a 200 Mhz clock and single cycle instructions. Joe Gray W5JG On Oct 24, 2014 1:39 PM, "Tom Van Baak" <t...@leapsecond.com> wrote: > Joe, et al. > > I put some info at: http://leapsecond.com/pages/reyax/ > > Here's what you need to know about those Reyax GPS boards: > > 1) These are simple, well-made, low-cost, tiny GPS boards. Four models are > available, based on three u-blox chips. The prices are $14 $16 $20 $27. > > 2) The 3 chips are u-blox MAX-7C, NEO-7N, NEO-M8N. See > http://www.u-blox.com for chip info. Board documentation: > http://www.reyax.com/Module/GPS/RYN25AI/RYN25AI.pdf > http://www.reyax.com/Module/GPS/RY725AI/RY725AI.pdf > http://www.reyax.com/Module/GPS/RY825AI/RY825AI.pdf > > 3) The 4 boards available: > http://www.ebay.com/itm/171493874434 > http://www.ebay.com/itm/181553452840 > http://www.ebay.com/itm/181562403752 > http://www.ebay.com/itm/181566850426 > > 4) The only difference between the $14 RYN25AI and $16 RYN25DI is that > RYN25DI adds a ±10 V RS232 transceiver. The other 3 boards have a typical > "inverted" logic-level (3.3V) serial interface, suitable for uP or SBC or > UART/USB interface chip. > > I have no affiliation with seller "reyax" but their boards seem a step > above some of the other GPS stuff on eBay. In general I gravitate to > low-cost GPS receiver breakout boards with serial I/O and clean 1PPS > output. It's amazing how well these integrated antenna boards work: a truly > "3-pin" timing solution: power, ground, 1PPS. > > Note these are not "timing receivers" in the sense of RINEX output or > external clock input or position-hold with sawtooth correction. But for > less demanding work, the ±20 ns level that many of these receivers offer > more than enough. > > 5) You can also find similar boards from US sellers such as > http://parallax.com/ , http://adafruit.com/ , http://sparkfun.com/ > > 6) All of this is grossly overkill for NTP (at the 1 ms or even 1 us > level). But if some of you are pushing NTP to sub-microsecond limits, cheap > GPS/1PPS receivers like this are of interest. > > For more details, including almost medical-grade photos of a GPS patch > antenna, see: > http://leapsecond.com/pages/reyax/ > > /tvb > > ----- Original Message ----- > From: "Joseph Gray" <jg...@zianet.com> > To: <brian.ing...@systematicsw.ab.ca>; "Discussion of precise time and > frequency measurement" <time-nuts@febo.com> > Sent: Thursday, October 23, 2014 9:18 PM > Subject: Re: [time-nuts] GPS for ntp > > > > OK, I see source of the confusion. There is a difference of "one" > character > > in the two part numbers. The RYN25 has the older Ublox chipset. The RY725 > > has the Neo-7N chipset. There is only a $6 difference in price. I think > > I'll get a few to play with. > > > > Joe Gray > > W5JG > > _______________________________________________ > 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.