[TangerineSDR] New Dual-Freq GPS Module

John Ackermann N8UR jra at febo.com
Thu Apr 23 10:04:22 EDT 2020

Thanks, Gerry!

From the testing I've done on the ZED-F9P and ZED-F9T, the timing
performance is quite spectacular -- using software sawtooth correction,
an order of magnitude plus better than what are used to as "GPS PPS"

I just got my SkyTraq board yesterday and hope to fire it up soon.


On 4/23/20 9:51 AM, Gerry Creager - NOAA Affiliate wrote:
> I chatted with Gary Miller, the primary developer active these days on
> gpsd, about the uBlox Zed-f9 and the SkyTraq PX1122R dual frequency
> products. Gary's used more of the OEM boards than anyone else I know,
> and because of the ongoing work with gpsd, has a lot of hands-on time
> making code work.
> Gary's very impressed with the SkyTraq engineering, but said,
> essentially, that post-sales support and quality control were not good.
> Assuming this is a family forum, I'll not be literal.
> His impression of the Zed-F9 was a little muted, as he's not yet laid
> hands on one, but has extensive uBlox experience. He's of the impression
> that this system is likely both of higher quality and more readily
> supported than the SkyTraq. 
> 73
> Gerry N5JXS
> On Fri, Apr 17, 2020 at 1:38 PM John Ackermann N8UR via TangerineSDR
> <tangerinesdr at lists.tapr.org <mailto:tangerinesdr at lists.tapr.org>> wrote:
>     Just FYI --
>     I just discovered that SkyTraq has a new GPS module, PX1122R, that seems
>     very comparable to the uBlox ZED-F9P, with a couple of exceptions noted
>     below.
>     It's dual frequency and has a built-in RTK processing engine -- that
>     means you can feed it correction data and get corrected results in
>     real-time.  The claimed accuracy is 1.5m CEP autonomous, or 1 cm plus 1
>     ppm when in RTK mode.
>     There is a PPS signal with claimed 12 ns accuracy.
>     The good news is that the module is $99 quantity 1 (they also have a
>     breakout board for $125 and an evaluation board for $150).
>     The bad news is that, at least from the data sheet, it's unclear what
>     data outputs it provides -- there are a limited number of NMEA sentences
>     listed, but it also supports RTCM 3.1 and "Skytraq raw data binary".
>     I *think* but am not sure that the RTCM message output provides the raw
>     data needed to create RINEX files and generate TEC (I'm happy for input
>     on that point).  And I don't know whether the binary protocol provides a
>     sawtooth or quantization error correction message to improve the PPS
>     quality.
>     I ordered one of the evaluation boards to test, but depending on the
>     data output capabilities this device may not be well suited for
>     timekeeping or the TangerineSDR.
>     Links:
>     Data sheet:     http://navspark.mybigcommerce.com/content/PX1122R_DS.pdf
>     Module:
>     http://navspark.mybigcommerce.com/px1122r-multi-band-quad-gnss-rtk-module/
>     Breakout board:
>     http://navspark.mybigcommerce.com/ns-hp-gn2-px1122r-multi-band-quad-gnss-rtk-breakout-board/
>     Eval Board:
>     http://navspark.mybigcommerce.com/px1122r-evb-px1122r-multi-band-quad-gnss-rtk-evaluation-board/
>     John
>     -- 
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>     TangerineSDR at lists.tapr.org <mailto:TangerineSDR at lists.tapr.org>
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> -- 
> Gerry Creager
> 405.325.6371
> ++++++++++++++++++++++
> /The way to get started is to quit talking and begin doing./
> /   Walt Disney/

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