U-blox Neo 6M GPS module not getting fix

Other Hardware Sensors
1

Hi folks, hope someone can give me a useful pointer here…

I'm having trouble getting a GPS fix with a Neo 6M GPS module which I'm using to build a retro-styled (7-segment display) dashboard clock.

More specifics: it's a GY-GPS6MV2, hooked up to an Arduino Nano.

I'm a bit of a bodger rather than experienced coder, and have had some input from a more experienced friend on the coding side of this… long story short: I had the basics working previously (ie. module getting a fix, reading the UTC time from the GPS data, and using this to set the clock time) but with some display problems. Now that I've returned to it and resolved the display issues, the board just doesn't seem to be able to get a fix.

I haven't changed the hardware, and I don't think it is a code issue, nor a problem with the GPS board being damaged, as running a simple sketch to return data to the serial monitor will show me this kind of thing, over and over:

$GPRMC,,V,,,,,,,,,,N53
$GPVTG,,,,,,,,,N30
$GPGGA,,,,,,0,00,99.99,,,,,,48
$GPGSA,A,1,,,,,,,,,,,,,99.99,99.99,99.9930
$GPGSV,1,1,0079
$GPGLL,,,,,,V,N64
$GPTXT,01,01,02,u-blox ag - www.u-blox.com50
⸮$GPTXT,01,01,02,u-blox ag - www.u-blox.com50
$GPTXT,01,01,02,HW UBX-G60xx 00040007 FF7FFFFFp53
$GPTXT,01,01,02,ROM CORE 6.02 (36023) Oct 15 2009 16:52:0856
$GPTXT,01,01,02,ANTSUPERV=AC SD PDoS SR20
$GPTXT,01,01,02,ANTSTATUS=DONTKNOW33

The "ANTSTATUS=DONTKNOW*33" part of it makes me wonder whether there's a problem with the antenna, but that seems a rather unlikely part of the system to be damaged by anything I've done - which is, basically, nothing hardware-wise apart from moving the test system outside so I can get a getter look at the sky (have always had trouble getting a fix indoors)

Any thoughts?

2

zogster:
Any thoughts?

Damadged antenna and or GPS.

You did take static precautions when handling the GPS ?

3

Thanks – I did when assembling the project in the first place, but probably haven't been as careful subsequently… tbh it didn't really cross my mind to take static precautions once it was assembled and almost working

But those boards are pretty cheap, I'll just get another one and swap it in

4

For a satellite fix, you need to be outdoors, with a clear view of the sky.

5

zogster:
Thanks – I did when assembling the project in the first place, but probably haven't been as careful subsequently… tbh it didn't really cross my mind to take static precautions once it was assembled and almost working

But those boards are pretty cheap, I'll just get another one and swap it in

There are warnings in the Ublox datasheets about the antenna input being particularly sensitive to static. I for sure have seen the Ubloxes going from working and seeing strong signals, to not working with no signals, following a bit of 'handling'

In any case since you were testing outdoors, a very weak or no signal response does suggest a damadged antenna or GPS. A bit of substitution testing is about the only practical way of testing, and I have aslo come across dodgy antennas.

6

Interesting that the antenna is so sensitive - I would have expected it to be relatively robust, but on reflection it's clearly a much more sophisticated device than a couple of pieces of bent wire. I guess there are chips in there that are doing something, and if they have to deal with satellite signals then there have to be some very sensitive elements

7

jremington:
For a satellite fix, you need to be outdoors, with a clear view of the sky.

Depends on your location/building. I get a fix just fine from inside my house with no view of the sky, and the position is quite accurate.

8

zogster:
Interesting that the antenna is so sensitive - I would have expected it to be relatively robust, but on reflection it's clearly a much more sophisticated device than a couple of pieces of bent wire. I guess there are chips in there that are doing something, and if they have to deal with satellite signals then there have to be some very sensitive elements

The most sensitive RF devices dont have a lot of the protection we take for granted on some MOSFET stuff.

In times gone by the very sensitive (high gain and low noise) MOSFETs, used for RF front ends, used to come with a removeable spring around the leads to protect them from static damage while handling and soldering into place.

GPS have to deal with extremly weak signals at 1.575Ghz, so they are not like a lot of RF devices.

9

I get a fix just fine from inside my house

Most people on this forum report getting nothing, and we have to explain the problem.

10

MK1888:
Depends on your location/building. I get a fix just fine from inside my house with no view of the sky, and the position is quite accurate.

Yes that is the case sometimes, but it does depend on the GPS and its particualr antenna, and the particular indoors.

Of the people who report 'problems' with GPSs a very very high percentage of them expect them to work indoors and most of the time they dont, which is as expected. If they are working indoors they can be on the very edge of failure.

The No1 troubleshooting step for those reporting reception problems with GPSs as in "my GPS does not get a fix?" is to take them outside.

I am entirely in agreement with @jremington, if you have a problem with a GPS TAKE IT OUTDOORS

I appologise for shouting.

11

Re. the inside/outside thing (I'm in a London Victorian house), when I had this project kind of working before, I usually had to take it outside to get a fix. It would sometimes work inside, but it was pretty hit and miss. This time around I've waited over half on hour outside to see if it would get a fix, on several occasions, but never anything, so I can believe the antenna or board has developed a fault

12

so I can believe the antenna or board has developed a fault

I agree, and thanks for clarifying.

The modules are pretty cheap these days, so unless you can spot a repairable bad connection or other obvious problem on the PCB, my recommendation is to just buy another.

13

I buy these, and only these, for these reasons:

1061×714 108 KB

2: 4-40 mounting holes. mount it rigidly and it does not swiveln
a proper SMA connector. not a puny u.fl snap on pop off joke. a proper brass connector with threads.

I stocked up a while back. I asked the vendor to send me 3 with no header or SMA connector so I could arrange them to meet the needs of my enclosure. they should sell pro versions of all modules like this.

I compared the four modules I can find and discovered it's a waste to extract more than 4 decimal points of position data. 1 of the four modules returns time, but not location.

14

When we say outside, we mean outdoors with a clear view of the sky, not just outside. Leafy trees and clouds can also obstruct the signal.

15

I buy these, and only these, for these reasons:

it's a waste to extract more than 4 decimal points of position data. 1 of the four modules returns time, but not location.

Interesting contradiction, but I'll avoid those modules. Thanks!

16

zogster,

In this batch of sentences are the bootup messages. If these are repeating then the module is repeatedly rebooting. In that condition it will never achieve a fix.

zogster:
$GPRMC,,V,,,,,,,,,,N53
$GPVTG,,,,,,,,,N30
$GPGGA,,,,,,0,00,99.99,,,,,,48
$GPGSA,A,1,,,,,,,,,,,,,99.99,99.99,99.9930
$GPGSV,1,1,0079
$GPGLL,,,,,,V,N64
$GPTXT,01,01,02,u-blox ag - www.u-blox.com50
⸮$GPTXT,01,01,02,u-blox ag - www.u-blox.com50
$GPTXT,01,01,02,HW UBX-G60xx 00040007 FF7FFFFFp53
$GPTXT,01,01,02,ROM CORE 6.02 (36023) Oct 15 2009 16:52:0856
$GPTXT,01,01,02,ANTSUPERV=AC SD PDoS SR20
$GPTXT,01,01,02,ANTSTATUS=DONTKNOW33

A cause of this can be undervoltage at the board's VCC pin. I experimented on this a few months ago and found a couple of things.

First, the threshold at the VCC pin was 4.8v. At 4.8v or lower the board repeatedly reboots. Also, the on board LED dims and flickers rapidly.

Second, the voltage at the 5v pin of my non-genuine UNO and non-genuine Nanos was 4.8v. The voltage at the USB connector was 5.0v but at the 5v pin it was 4.8v or lower.

I now never power the GPS board from the 5v pin of the Arduino board.

Jumper wires can introduce a voltage drop, so I am wary with a breadboard setup. Soldered connections are best followed by screwed terminals or deep header pins.

John.

1 Like
17

Thanks – I really appreciate the help here!

I've ordered a new module… the same as I'm using now, though I might try that 7M also. Looks more compact because of the integrated antenna, therefore just a little better packaging-wise as it has to fit behind the dashboard. And I guess the 5th pin has the PPS signal which I could use to get better timing accuracy, if I want to go down that road. Power-wise I think I'm OK – I'm using the 3.3V output from the Arduino board, which I'd read was safer for the module than 5V, and as it was working before I think the reason for things breaking was probably my careless handling rather than the way it's wired up

18

zogster:
I might try that 7M also.

From what I understand there are problems with the 7M and people either use the 6M or 8M.

19

MK1888:
From what I understand there are problems with the 7M and people either use the 6M or 8M.

What problems ?

20

It might have been in this video, I haven't rewatched to see.

#22 Comparison of precision between Neo-M8N and Neo-6M Modules