Fake GNSS modules and timekeeping

[MarkMLl]

Like many other people, I've been stung by a breakout with a fake U-Blox module: overall product was badged "Bear" with a paw-mark. I spent too long waiting for the seller to respond and eBay washed their hands of it, leaving me with an electronic device of unknown (and potentially interesting) usability.

I append the first few seconds of NMEA output. Does anybody recognise this, and have pointers to any manuals (preferably in English)?

MarkMLl

Code: [Select]

$GPTXT,01,01,02,MA=CASIC*27
$GPTXT,01,01,02,IC=AT6558-5N-30-1C500000,J8A061C-B3-001821*53
$GPTXT,01,01,02,SW=URANUS4,V4.6.1.0*19
$GPTXT,01,01,02,TB=2017-11-23,14:56:17*4F
$GPTXT,01,01,02,MO=GB*77
$GPTXT,01,01,02,BS=SOC_BootLoader,V6.2.0.2*34
$GPTXT,01,01,02,CI=01B94154*04
$GNGGA,133416.452,<sanitized>,6,06,1.8,77.5,M,0.0,M,,*48
$GNGLL,<sanitized>,133416.452,A,E*44
$GPGSA,A,3,12,14,24,25,29,32,,,,,,,2.8,1.8,2.2*3C
$BDGSA,A,3,,,,,,,,,,,,,2.8,1.8,2.2*20
$GPGSV,3,1,09,02,17,104,,06,18,071,,12,80,053,42,14,29,310,38*76
$GPGSV,3,2,09,19,20,041,,24,48,127,48,25,59,255,43,29,15,191,40*70
$GPGSV,3,3,09,32,45,284,45*4F
$BDGSV,1,1,03,08,60,098,,13,24,073,,20,60,098,*51
$GNRMC,133416.452,A,<sanitized>,0.84,0.00,050320,,,E*7B
$GNVTG,0.00,T,,M,0.84,N,1.55,K,E*2A
$GNZDA,133416.452,05,03,2020,00,00*4F
$GPTXT,01,01,01,ANTENNA OK*35
$GNGGA,133417.452,<sanitized>,1,06,1.8,77.5,M,0.0,M,,*4E


[Theboel]

Hi,

Maybe we have same board.
all I can help is this.

[MarkMLl]

That's /very/ interesting, thanks very much. The NMEA output suggests that it's indeed the AT6558, and it's probably a reasonable start to assume that the commands in your second document are at least a subset of what it will accept. My breakout is the usual sort of thing targetted at Arduino etc. users, the size of a commemorative postage stamp, with both onboard antenna and SMA for a remote one.

The metal shield on my unit has a fairly good imitation of a U-Blox label, although I've not checked the 2D code type yet. There is still a visible difference, but I don't want to discuss it in an open forum.

I'm probably not doing more work on this for a few days, but I've been looking at the UK's MSF 60kHz timecode and it will be interesting to compare the offset between that and the GNSS module's PPS signal. There's obviously been a lot published on the jitter (less on the latency) of branded devices from u-Blox et al., but I think that an interesting general question is whether the signal is generated "close" to the solver of the position/time equations, or whether it's delayed by an arbitrary amount of less-important work related to formatting the NMEA output.

MarkMLl

[testpoint1]

AT6558 is chinese made, not ublox, please check its price.

[MarkMLl]

AT6558 is chinese made, not ublox, please check its price.

Please check first message in topic: "I've been stung by a breakout with a fake U-Blox module".

So if anything, it boils down to finding out whether it does anything useful that more reputable kit doesn't.

MarkMLl

[notfaded1]

How were these being sold?  What was it in or how was it listed?

B

[MarkMLl]

How were these being sold?  What was it in or how was it listed?

It's this on eBay:

https://www.ebay.co.uk/itm/NEO-7M-GPS-Module-Position-Satellite-Ublox-U-Blox-SMA-Ipex-STM32/202811871797

Code: [Select]

- Chip: u-blox NEO-7M
- Dual GPS Antenna Interface: SMA / IPEX
- Operating voltage: 3-5V
- 5 pin: VCC, GND, TXD, RXD and PPS
- Dimensions: 40 x 25 mm
Marque - Sans marque/Générique -
Numéro de pièce fabricant Non applicable
EAN Non applicable

I went for that module because it was fairly readily available (i.e. I didn't have to mess around setting up an account with somebody), had PPS, and had both onboard and SMA antenna.

The seller didn't respond to a complaint, I complained to eBay but they lost it (and since it was a webform I don't have an email log), and when I got onto eBay via "chat" they said that 30 days had elapsed so weren't interested.

Now obviously the photo shows a generic module, but what was shipped had a fairly accurate U-Blox label with (R) and (C) marks. There is one apparent physical difference from the genuine article which I don't want to discuss in an open forum (lest they fix it).

I'll be looking for genuine U-Blox (and possibly other) modules for production purposes, but I'm treating this as a potentially useful learning exercise so am not screaming at Paypal who would insist that I send it back.

MarkMLl

[Theboel]

Hi,

There is hundreds of this module available here in junk market. from the seller I got information the board is pull out from car/heavy equipment tracker. I am not sure this board do any good for timing but who knows I looking forward for any information about the result