GPS
#1
Hi All
My GPS was working fine, then it stopped. I did unplug it from the box to tidy up the cables. Now nothing. Any suggestions?
Many thanks
Chris
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#2
(2020-03-07, 08:33)tpweather Wrote: Hi All
My GPS was working fine, then it stopped. I did unplug it from the box to tidy up the cables. Now nothing. Any suggestions?
Many thanks
Chris

I had one situation couple of years ago.... I found the barrel part of the onboard connector had broken loose *threaded shield* from the housing. Took a pair of side cutters, and gently 'creased' the barrel part a couplle of times.  Used pliers to press the two parts together.... no more issues... hope you can viisualize that:
[Image: jack.png]

If you've NOT done a complete, cold (power removed) restart of the controller, and allowed time for the system to completely stabilize with full GPS availability, you might want to do so..  

This particular attached example took an extremely long time to completely stabilize, (unusual) though It did start 1PPS at about 65% ... may ot start 1PPS untial a995% or higher.... so be patient!


Also we have this generic info here:  http://sferics.us/GPSinfDat.html


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#3
(2020-03-07, 08:33)tpweather Wrote: Hi All
My GPS was working fine, then it stopped. I did unplug it from the box to tidy up the cables. Now nothing. Any suggestions?
Many thanks
Chris

Thanks mate. I did a cold reboot as you said and left it overnight. GPS kicked in but now no reception. I guess its because of where I live.
I've attached screenshots and a pi of the antenna I'm using.
Cheers


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#4
(2020-03-08, 02:36)tpweather Wrote:
(2020-03-07, 08:33)tpweather Wrote: Hi All
My GPS was working fine, then it stopped. I did unplug it from the box to tidy up the cables. Now nothing. Any suggestions?
Many thanks
Chris

Thanks mate. I did a cold reboot as you said and left it overnight. GPS kicked in but now no reception. I guess its because of where I live.
I've attached screenshots and a pi of the antenna I'm using.
Cheers
the photo of the gps there is that got a bnc plug ?was it of marine use ?
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#5
(2020-03-07, 08:33)tpweather Wrote: Hi All
My GPS was working fine, then it stopped. I did unplug it from the box to tidy up the cables. Now nothing. Any suggestions?
Many thanks
Chris
Try to reduce the GPS bus speed down.
Baudrate from 115200 to 57600 bits.
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#6
Turn on SBAS. You should receive more GPS satellites with it enabled.
Regards,
Mike W.
Stations: 1977, 2294
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#7
(2020-06-01, 14:54)kriu Wrote:
(2020-03-07, 08:33)tpweather Wrote: Hi All
My GPS was working fine, then it stopped. I did unplug it from the box to tidy up the cables. Now nothing. Any suggestions?
Many thanks
Chris
Try to reduce the GPS bus speed down.
Baudrate from 115200 to 57600 bits.

Reducing the baudrate I'd not expect to help anything regarding the reception of GPS satellites. This baudrate has effect only to the two signal lines GPS_RX and GPS_TX on the main PCB between the GPS ASIC and the micro controller. Not receiving satelleites is more a problem located on the side of the antenna / antenna cable / GPS-IN / RF_IN of the GPS ASIC.

My 2 cent.
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#8
(2020-06-01, 20:50)gerbold Wrote:
(2020-06-01, 14:54)kriu Wrote: Try to reduce the GPS bus speed down.
Baudrate from 115200 to 57600 bits.

Reducing the baudrate I'd not expect to help anything regarding the reception of GPS satellites. This baudrate has effect only to the two signal lines GPS_RX and GPS_TX on the main PCB between the GPS ASIC and the micro controller. Not receiving satelleites is more a problem located on the side of the antenna / antenna cable / GPS-IN / RF_IN of the GPS ASIC.

I agree, even though the frequency on the GPS feedline can be up to 30 MHz.

A lower baud rate might help if you had a very long RS-232 serial line. But your GPS coax is not that long.
Regards,
Mike W.
Stations: 1977, 2294
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#9
tpweather Wrote:
tpweather Wrote:Hi All
My GPS was working fine, then it stopped. I did unplug it from the box to tidy up the cables. Now nothing. Any suggestions?
Many thanks
Chris

Thanks mate. I did a cold reboot as you said and left it overnight. GPS kicked in but now no reception. I guess its because of where I live.
I've attached screenshots and a pi of the antenna I'm using.
Cheers
That is fairly old GPS firmware.
Mine is at Mediatek with 115200baud (FW: AXN_3.8_3333_16072100,8397)
You might want to try and upgrade.

There has also been posts about GPS week number roll-over issues. A firmware might or might not fix this. There are posts on this forum how to do the firmware upgrade.
GPS week number roll-over issue
The GPS system counts time in weeks since Sunday, 6 January 1980. A GNSS receiver reads this
week number for the current date from the GPS L1 C/A signal and then translates it to traditional
date presentation. E.g. the NMEA GPRMC message displays the current day, month and year.
Unfortunately the GPS L1 C/A signal presents the GPS week number with only 10 bits. Thus, the week
number rolls from 1023 to 0 every 19.6 years. It has now rolled over twice since start of the GPS era in
January 1980. These roll-overs have happened in August 1999, and now recently in April 2019. The
next one will happen in November 2038.
If the receiver uses only the GPS L1 C/A signal there is no way of knowing how many times the week
number has already rolled over, so the receiver cannot know if week number 10 means 16 Mar 1980,
31 Oct 1999, or 16 Jun 2019. The receiver tries to determine the correct date, but it may show a 20-year-old or 40-year-old date.
[Image: NOAARADlogoTXT80.png][Image: forfaviconTXT.png]

Station: 2100
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