Author Topic: GPS No Fix - 22 satellites in view - 0 used - left on for 1:40hr - FIXED  (Read 1447 times)

s.laughter

Cautious about posting but I've done a good bit of reading and can't find any suitable pointers. Screenshot attached.

It's a Rosetta of a few years old, last used best part of two years ago, SW updated to 20230316, license till next year.

I have moved about 200 miles since last use.

The smaller of the Anker bricks is the PSU and the original Rosetta cable is in use.

Because of a house move etc, I've left the unit on minding it's own business for 100+ minutes, powered off and on but it just has no GPS fix.

Any suggestion gratefully rcvd.

I was limbering up to start using the device again and thinking of ordering an iGrid WiFi dongle, so if there is no simple fix, I'd probably order a replacement power cable & GPS module.

Thks
« Last Edit: August 28, 2023, 05:51:53 pm by s.laughter »

steveu

Re: GPS No Fix - 22 satellites in view - 0 used - left on for 1:40hr
« Reply #1 on: August 22, 2023, 09:50:03 am »
When was this screenshot taken?

The date is wrong so the GPS almanac will not work as I understand it?

Until the GPS has made the time and date correct, it may not work.

The real engineers will be along shortly...

s.laughter

Re: GPS No Fix - 22 satellites in view - 0 used - left on for 1:40hr
« Reply #2 on: August 22, 2023, 10:20:24 am »
The date/time is possibly indicative of the last time I used the unit and is clearly not current and adds to the sense that the GPS module may have been a GPS module for too long!

The screen shot is a few hours prior to my posting.

I suppose as I'm ready to pay for a replacement GPS module anyway, I could unplug it from the Rosetta and leave it plugged into the Anker brick all day with a good view of the southern sky. It is after all a standalone sub-system that just squirts out a never ending text stream (or not in this case). It had been connected for 100+ minutes in the Rosetta.

Any input gratefully rcvd.

Thanks

Mike

s.laughter

Re: GPS No Fix - 22 satellites in view - 0 used - left on for 1:40hr
« Reply #3 on: August 22, 2023, 11:48:54 am »
Popped the GPS module into a laptop and PuTTY reveals the following

$GPGGA,102656.00,5040.79457,N,00415.18894,W,1,05,2.06,127.0,M,50.6,M,,*4B
$GPGSA,A,3,02,32,21,03,22,,,,,,,,3.49,2.06,2.81*00
$GPGSV,4,1,13,01,68,093,36,02,52,109,25,03,74,235,21,04,19,175,17*7A
$GPGSV,4,2,13,06,01,289,,08,07,161,,14,14,248,,17,48,297,14*7D
$GPGSV,4,3,13,21,43,110,27,22,22,270,24,28,09,075,,31,00,101,*7D
$GPGSV,4,4,13,32,20,042,19*46
$GPGLL,5040.79457,N,00415.18894,W,102656.00,A,A*78
$GPRMC,102657.00,A,5040.79419,N,00415.18879,W,1.181,,220823,,,A*69
$GPVTG,,T,,M,1.181,N,2.187,K,A*26

With almost no knowledge of NMEA, to me this looks like the GPS dongle thinks its back in 1970 and somewhere arround Plymouth.

I think it's the newer module with the larger ceramic top and the green led blinks at approx 1 second intervals.

I'll leave the GPS module in a window for the day plugged into the Anker power brick and if it's still lost in time tonight I'll order a replacement. Of course the power draw of the GPS module may be so low that the Anker shuts down, we'll see.

Any suggestions?

JCurtis

Re: GPS No Fix - 22 satellites in view - 0 used - left on for 1:40hr
« Reply #4 on: August 22, 2023, 12:39:39 pm »
If it’s modern double glazing with heat reflection, it may block the GPS signals. The signals are really quite weak, I’m always amazed it works at all.
Designer and maker of charge4.harkwood.co.uk, smart universal USB chargers designed for aviation.  USB Type-A and USB-C power without the RF interference. Approved for EASA installs under CS-STAN too.

steveu

Re: GPS No Fix - 22 satellites in view - 0 used - left on for 1:40hr
« Reply #5 on: August 22, 2023, 02:12:38 pm »
+1 with JCurtis, leave outside in plain sight of the sky.

Then replace, perhaps?

What settings did you use for PuTTY, please?

s.laughter

Re: GPS No Fix - 22 satellites in view - 0 used - left on for 1:40hr
« Reply #6 on: August 22, 2023, 07:03:12 pm »
It had another couple of hours outside and it started to work within Rosetta, left it powered off for a few hours, tried again within Rosetta and it's suffering No Fix again. Time for a replacement GPS module.

PuTTY? - plugged GPS module into a Windows 10 lappy and it reported configuring COM3, so from memory set PuTTY to serial, COM3 and left it at defaults of 9600, 8, 1 & none.

JCurtis

Re: GPS No Fix - 22 satellites in view - 0 used - left on for 1:40hr
« Reply #7 on: August 22, 2023, 08:05:22 pm »
A good GNSS module should get a fix in a few minutes from a cold start.  With the modules I've been designing into gear of late, something is wrong if I don't get a fix within 90 seconds of a cold start.  I don't have a backup battery on the modules.

The USB dongle GNSS often seen with the PAW devices, has a tiny cell in them, which may be rechargeable or may not be.  Either way, they don't last more than a couple of years before giving up.

Just swap it out.
Designer and maker of charge4.harkwood.co.uk, smart universal USB chargers designed for aviation.  USB Type-A and USB-C power without the RF interference. Approved for EASA installs under CS-STAN too.

s.laughter

Re: GPS No Fix - 22 satellites in view - 0 used - left on for 1:40hr
« Reply #8 on: August 22, 2023, 09:08:35 pm »
Yes, the orders in already  :)

s.laughter

Re: GPS No Fix - 22 satellites in view - 0 used - left on for 1:40hr
« Reply #9 on: August 28, 2023, 05:51:20 pm »
New GPS rcvd and the Rosetta wakes up in a minute or so - problem solved.