EC25 modem and GPS signal loss after a while

IoT Modules LTE Standard Module
1

Hello,

I’m opening this topic to search for some help/advice.

I use EC25 Revision: EC25EFAR06A11M4G with the lates firmware and I do the following to activate the GPS:

AT+QGPSEND
AT+QGPSXTRA=1
AT+QFDEL="RAM:*"
<here I upload the `xtra3grc.bin` to the RAM:>
AT+QFUPL="RAM:xtra3grc.bin",22258,60
AT+QGPSXTRATIME=0,"<date/time>",1,1,3500
AT+QGPSXTRADATA="RAM:xtra3grc.bin"
AT+QGPSSUPLURL="supl.google.com:7276"
AT+QGPSCFG="plane",0
AT+QGPS=2

The xtra3grc.bin is downloaded from one of the following sites:

# http://xtrapath4.izatcloud.net/xtra3grc.bin
# http://xtrapath5.izatcloud.net/xtra3grc.bin
# http://xtrapath6.izatcloud.net/xtra3grc.bin

The LTE module is use outside, in car (it is part of a small dash cam), on the windshield and has direct access to the sky.

So, the GPS works fine in the beginning, when the unit starts, but at one point, the GPS signal loss after a while. Here is example how the GPS has a fix and then lost the fix, even there are many Satellites (10) in view. So, can you please tell me if this behavior is expected and why the GPS is so unstable? Do I miss any options or settings that I have to configure the AT commands?

$GPGSA,A,3,08,10,32,,,,,,,,,,2.8,2.6,1.0,1*28
$GPGSV,3,1,10,01,28.8,291.1,19.7,02,49.9,305.2,15.2,03,10.5,237.7,17.0,08,66.8,239.1,22.1,1*6C
$GPGSV,3,2,10,10,45.0,47.8,21.7,32,50.6,108.3,15.0,14,5.6,322.0,,23,3.5,54.8,,1*6C
$GPGSV,3,3,10,24,,,,27,45.7,171.6,,1*51
$GPGGA,170805.00,4241.141726,N,02317.612010,E,1,03,2.6,596.3,M,37.0,M,,*6A
$PQXFI,170805.00,4241.141726,N,02317.612010,E,596.3,187.24,115.79,2.99*5B
$GPVTG,0.0,T,357.1,M,0.0,N,0.0,K,A*23
$GPRMC,170805.00,A,4241.141726,N,02317.612010,E,0.0,0.0,180325,2.9,E,A,V*45
$GPGSA,A,3,08,10,32,,,,,,,,,,2.8,2.6,1.0,1*28
$GPGSV,3,1,10,01,28.8,291.1,19.7,02,49.9,305.2,15.2,03,10.5,237.7,17.0,08,66.8,239.1,20.5,1*6A
$GPGSV,3,2,10,10,45.0,47.8,20.5,32,50.6,108.3,15.0,14,5.6,322.0,,23,3.5,54.8,,1*6F
$GPGSV,3,3,10,24,,,,27,45.7,171.6,,1*51
$GPGGA,170806.00,4241.141731,N,02317.612017,E,1,03,2.6,596.3,M,37.0,M,,*68
$PQXFI,170806.00,4241.141731,N,02317.612017,E,596.3,206.46,119.81,3.06*5B
$GPVTG,0.0,T,357.1,M,0.0,N,0.0,K,A*23
$GPRMC,170806.00,A,4241.141731,N,02317.612017,E,0.0,0.0,180325,2.9,E,A,V*47
$GPGSA,A,3,08,10,32,,,,,,,,,,2.8,2.6,1.0,1*28
$GPGSV,3,1,10,01,28.8,291.1,19.7,02,49.9,305.2,15.2,03,10.5,237.7,17.0,08,66.8,239.1,20.5,1*6A
$GPGSV,3,2,10,10,45.0,47.8,23.2,32,50.6,108.3,15.0,14,5.6,322.0,,23,3.5,54.8,,1*6B
$GPGSV,3,3,10,24,,,,27,45.7,171.6,,1*51
$GPGGA,170807.00,4241.141733,N,02317.612022,E,1,03,2.6,596.3,M,37.0,M,,*6D
$PQXFI,170807.00,4241.141733,N,02317.612022,E,596.3,226.40,123.47,3.16*58
$GPVTG,0.0,T,357.1,M,0.0,N,0.0,K,A*23
$GPRMC,170807.00,A,4241.141733,N,02317.612022,E,0.0,0.0,180325,2.9,E,A,V*42
$GPGSA,A,3,08,10,32,,,,,,,,,,2.8,2.6,1.0,1*28
$GPGSV,3,1,09,01,28.8,291.1,19.7,02,49.9,305.2,15.2,08,66.8,239.1,21.0,10,45.0,47.8,20.7,1*58
$GPGSV,3,2,09,32,50.6,108.3,15.0,14,5.6,322.0,,23,3.5,54.8,,24,,,,1*73
$GPGSV,3,3,09,27,45.7,171.6,,1*5F
$GPGGA,170808.00,4241.141731,N,02317.612020,E,1,03,2.6,596.3,M,37.0,M,,*62
$PQXFI,170808.00,4241.141731,N,02317.612020,E,596.3,246.61,126.79,2.77*5C
$GPVTG,0.0,T,357.1,M,0.0,N,0.0,K,A*23
$GPRMC,170808.00,A,4241.141731,N,02317.612020,E,0.0,0.0,180325,2.9,E,A,V*4D
$GPGSA,A,3,08,10,32,,,,,,,,,,2.8,2.6,1.0,1*28
$GPGSV,3,1,10,01,28.8,291.1,19.7,02,49.9,305.2,15.2,08,66.8,239.1,21.9,10,45.0,47.8,21.9,1*56
$GPGSV,3,2,10,32,50.6,108.3,15.0,03,10.5,237.7,,14,5.6,322.0,,23,3.5,54.8,,1*4B
$GPGSV,3,3,10,24,,,,27,45.7,171.6,,1*51
$GPGGA,170809.00,,,,,0,,,,,,,,*4F
$PQXFI,170809.00,,,,,,,,*53
$GPVTG,,T,,M,,N,,K,N*2C
$GPRMC,,V,,,,,,,,,,N,V*29
$GPGSA,A,1,,,,,,,,,,,,,,,,*32
$GPGSV,3,1,09,02,49.9,305.2,15.2,08,66.8,239.1,21.9,10,45.0,47.8,22.1,32,50.6,108.3,15.0,1*5E
$GPGSV,3,2,09,03,10.5,237.7,,14,5.6,322.0,,23,3.5,54.8,,24,,,,1*67
$GPGSV,3,3,09,27,45.7,171.6,,1*5F
$GPGGA,170810.00,,,,,0,,,,,,,,*47
$PQXFI,170810.00,,,,,,,,*5B
$GPVTG,,T,,M,,N,,K,N*2C
$GPRMC,,V,,,,,,,,,,N,V*29
$GPGSA,A,1,,,,,,,,,,,,,,,,*32
$GPGSV,3,1,10,02,49.9,305.2,15.2,08,66.8,239.1,20.0,10,45.0,47.8,21.6,32,50.6,108.3,15.0,1*5A
$GPGSV,3,2,10,01,28.8,291.1,,03,10.5,237.7,,14,5.6,322.0,,23,3.5,54.8,,1*51
$GPGSV,3,3,10,24,,,,27,45.7,171.6,,1*51
$GPGGA,170811.00,,,,,0,,,,,,,,*46
$PQXFI,170811.00,,,,,,,,*5A
$GPVTG,,T,,M,,N,,K,N*2C
$GPRMC,,V,,,,,,,,,,N,V*29
$GPGSA,A,1,,,,,,,,,,,,,,,,*32
$GPGSV,3,1,10,02,49.9,305.2,15.2,08,66.8,239.1,20.0,10,45.0,47.8,21.7,32,50.6,108.3,15.0,1*5B
$GPGSV,3,2,10,01,28.8,291.1,,03,10.5,237.7,,14,5.6,322.0,,23,3.5,54.8,,1*51
$GPGSV,3,3,10,24,,,,27,45.7,171.6,,1*51
$GPGGA,170812.00,,,,,0,,,,,,,,*45
$PQXFI,170812.00,,,,,,,,*59
$GPVTG,,T,,M,,N,,K,N*2C
2

Hi @don.nasco

From the NEMA log, we can see the C/N value is too bad, normally it shouble be above 35.
Maybe you can compare it with the normal log.
$GPGSV,3,1,10,01,28.8,291.1,19.7,02,49.9,305.2,15.2,03,10.5,237.7,17.0,08,66.8,239.1,20.5,16A
$GPGSV,3,2,10,10,45.0,47.8,20.5,32,50.6,108.3,15.0,14,5.6,322.0,23,3.5,54.8,16F

BR,
Puck

3

Hi Puck,

Thanks for your reply.

So this bad SNR (C/N) values are due the modem/GPS module or a problem with the GPS antenna? What do you think?

Do I have any option(s) missing (to tune the GPS module)?

4

Hello again,

While I’m waiting for your feedback on my previous question(s) I noticed something weird - the Elevation and Azimuth of the $GPGSV sentence are float numbers while they should be integers (whole numbers). How is that possible?

(example)

$GPGSV,3,1,11,19,38.7,52.0,14.8,24,80.9,165.9,17.3,06,24.6,98.4,11,16.9,130.8,166
$GPGSV,3,2,11,12,60.5,286.9,13,1.4,167.3,15,15.5,198.3,17,12.0,40.8,16B
$GPGSV,3,3,11,22,8.4,71.7,25,23.9,270.0,32,14.8,319.2,1*56

And as a matter of fact the SNR (C/N) is also float.
So, I’m starting to think that something is wrong with my modem/GPS config.

5

Hey @Puck-Q any thoughts on my questions?
I’ll appreciate your help here:)

6

Hi,
When C/N does not meet the requirement. GNSS enginee cannot parse the GNSS signal correctly. At this moment, any data is meaningless. We don’t need to care that.

7

Thanks for your reply, but I’m not sure I follow you.

The unit got a GPS Fix (at some point) and even when it has Fix it still continue to show float values. And I’m sure that it has a fix because when I check the $GPRMC sentence it point to my position and it is some kind accurate.

I have another unit with the same modem/GPS (EC25-E) and it behaves the same way, i.e. has lower C/N (SNR) but it always returns integer values only, no matter if it has a GPS Fix or not.

Here is an example before it got a FIx:

$GPGSV,4,1,14,01,67,314,,02,82,133,,03,45,277,,04,12,206,,1*68
$GPGSV,4,2,14,08,25,196,,10,08,071,,14,,,,17,19,314,,1*54
$GPGSV,4,3,14,19,,,,22,01,303,,27,01,171,,28,23,099,,1*57
$GPGSV,4,4,14,31,15,127,,32,35,049,,1*69
$GPGGA,182051.64,,,,,0,,,,,,,,*45
$PQXFI,182051.06,,,,,,,,*5D
$GPVTG,,T,,M,,N,,K,N*2C
$GPRMC,,V,,,,,,,,,,N,V*29
$GPGSA,A,1,,,,,,,,,,,,,,,,*32

and here is after it has a Fix:

$GPGSV,3,1,12,01,86,322,19,02,63,144,29,03,59,298,25,04,29,209,22,1*63
$GPGSV,3,2,12,08,10,188,20,17,29,300,20,21,,,19,28,28,081,21,1*51
$GPGSV,3,3,12,31,26,112,29,09,,,,19,09,323,,32,19,045,,1*5A
$GPGGA,185922.00,4241.111042,N,02317.595691,E,1,08,1.0,598.8,M,37.0,M,,*6C
$PQXFI,185922.00,4241.111042,N,02317.595691,E,598.8,9.36,3.89,0.17*5A
$GPVTG,140.0,T,137.1,M,0.0,N,0.0,K,A*22
$GPRMC,185922.00,A,4241.111042,N,02317.595691,E,0.0,140.0,250325,2.9,E,A,V*43

also, the C/N (SNR) is not much better than the one from the unit from OP.

So, how is it even possible for the GNSS engine to return float values (for GSV) while the NMEA-0183 standard is not allowing it?

image
image895×729 68.4 KB

8

$GPGSV,3,1,12,01,86,322,19,02,63,144,29,03,59,298,25,04,29,209,22,163
$GPGSV,3,2,12,08,10,188,20,17,29,300,20,21,19,28,28,081,21,151
$GPGSV,3,3,12,31,26,112,29,09,19,09,323,32,19,045,1*5A

Per fix log, its signal is much better than failure log on some satellites. Please note, for CN, greater than 1 means the signal is better for 10 times. If CN is 5 greater than previous value that means signal is stronger than previous situation 100000 times. It is very big improvement. Even in above sginal condition, it is not a good signal. Position may be not accurcy or loss sometimes.

For float value, will it disappear if you put device in place with good signal? But now it is confirmed the device has a bad signal status. Please try to solve this issue firstly.

9

Here is how the unit behaves under a clear sky. It has a Fix but still, the values for Elevation, Azimuth and C/N (SNR) in $GPGSV sentence are float (instead of integer):

$GPGSV,3,1,10,11,39.4,64.7,34.3,12,57.0,80.2,33.5,20,10.5,98.4,27.3,24,19.0,164.5,27.0,15E
$GPGSV,3,2,10,29,50.6,241.9,18.3,06,16.9,39.4,25,72.4,333.3,28,30.9,309.4,148
$GPGSV,3,3,10,31,8.4,319.2,32,15.5,264.4,156
$GPGGA,084550.00,4241.111113,N,02317.604098,E,1,05,1.6,609.2,M,37.0,M,6E
$PQXFI,084550.00,4241.111113,N,02317.604098,E,609.2,43.83,18.26,1.7955
$GPVTG,110.1,T,107.2,M,0.0,N,0.0,K,A26
$GPRMC,084550.00,A,4241.111113,N,02317.604098,E,0.0,110.1,270325,2.9,E,A,V4D
$GPGSA,A,3,11,12,20,24,29,1.9,1.6,1.0,12D

10

May I know your test situation?
You have two EC25. One works fine and another one has this float issue at the same place.Is my understanding correct?
Have you tried to update firmware and test again?

11

Hi Rodney,

Yes, that is correct - two units, the one with float values is not working stable, i.e. it got a FIx but can’t keep it much, also, its position is not as accurate as it should be.
The other unit with the correct integer values works fine. It get a fix much quicker and once it has it, it is much accurate and it is not losing it.

I do the test on the same place, on my balcony under a clear sky.

Both modems already have the same firmware version EC25EFAR08A06M4G_20.201.20.201 which I believe is the latest one, or not?

Please let me know if you need more details on this.

12

Hi,
Have you tried to flash firmware again? If it still has the same issue. It might be hardware issue.

13

Hi,

I have flashed three or four times with different firmwares but it is always like that.
Can you please confirm with is the latest firmware so I can try to reflash it again?

Also, what do you mean by “hardware issue” - something with the modem chip itself or another problem?

Thanks in advance,
Atanas

14

EC25EFAR08A06M4G_20.201.20.201 is the latest firmware.
I mean may be some components inside the module is not working.

15

So, you can’t do anything further in this case, right?

Can I run any command to factory reset or something like that (if there is such a thing at all)? I’m just wondering if something can be tried to debug this issue further.

Best wishes,
Atanas

16

Yes. For hardware issue, you need deliver module back to Quectel for analysis. Please contact Quectel local support resource.

17

Okay, Rodney,

Thanks for your help here.
Best wishes,
Atanas