Q2698 gps fix problem

Legacy Legacy AirPrime modules
1

Hi,
I am trying to use gps feature in Q2698 modem, but never get GPS FIX
Any idea why?
Many thanks in advance,
Igor

“DWL”," SWI6200T_01.02.03.06BT R2521 CNSZXD00000145 2013/02/07 17:07:24","",“Sierra Wireless”,0,"",“00000000”,“00000000”
“FW”,“FW_750_20_A2_3.Q268Fx”,“R7.50.0.A2.201302191346.Q2698”,“Sierra Wireless”,1658520,“021913 13:46”,“f6eaa2f2”,“10002020”
“MODEM 3G+”,“No Modem Firmware Version Available”
“OAT”,“1.0.0.20130730185743”,“GPS_AT_cmd Sample”,"",169084,“073013 18:58”,“de60b515”,“10700000”
-“Developer Studio”,“2.3.1.201306241059-R11859”
-“Open AT Application Framework package”,“2.50.0.A2.201302211600”
-“Open AT OS Package”,“6.50.0.A2.201302201737”
-“Firmware Package”,“7.50.0.A2.201302191346”
-“ExtendedATApplication Library Package”,“1.20.0.A2.201302191809”
-“Internet Library Package”,“5.53.0.A1.201212051411”
-“Location Library Package”,“1.4.3.201302051116”
-“Security Library Package”,“1.15.0.A1.201302081338”
“ROM”,“8400000”
“RAM”,“4000000”
“OATRAM”,“800000”
“DWLNAME”,“Q2698”

OK
AT+WMFM?

+WMFM: 0,2,1,1
+WMFM: 0,2,2,1
+WMFM: 0,2,3,1
+WMFM: 1,2,4,0
+WMFM: 1,2,4,1

OK
at+cclk?

+CCLK: “00/01/01,00:00:05”

OK
at+gpsstart

OK

+GPSEVINIT: 1

+GPSEVSTART: 1

+GPSEVPOS: 0
at+gpsnmea=3

OK
$GPGGA,0,66
$GPRMC,V,N53
$GPVTG,T,M,N,K,N*2C
$GPGSA,A,1,1E
$GPGGA,0,66
$GPRMC,V,N53
$GPVTG,T,M,N,K,N2C

2

Hiya,

A couple of physical things before you look into the software:

  • Does your antenna have a clear view of the sky?
  • Is your antenna an active antenna? If so, have you enabled power to it?
  • A cold start of the GPS can take up to 15 minutes to get a fix if it has to scan for ephemeris data to find which satellites to lock onto. Have you run the code for at least 15 minutes to see if it gets a fix?
  • Update the time (can be done through Developer Studio in the Target Management perspective or use the AT+CCLK command) - this will help the GPS attempt to work out when and where it is.

Hopefully this gets you on your way.

ciao, Dave

3

Hello,

Same problem here : [url]https://forum.sierrawireless.com/t/fx100-gps/6488/1]

Have you enabled the active antenna with the GPIO44 ?

Marc

4

Hi, thanks for your answers
The problem is seems that I’m using an active antenna which is not powered.
I have tried enable GPIO44 without effect. There is no voltage on GPS antenna.
Who knows how to turn on the power antenna (or which document describes how)?

5

Hi,

I am also having trouble enabling power on the GPS antenna.

Does anyone know how to do this on an MC8705?
WIOM and ANTSEL return error and not able to find anything in the forum topics

UPDATE: I have finally confirmed that MC8705 does not support an active GPS antenna. Our solution will use an external Bias T to inject the 5VDC power for the GPS antenna

6

According to our distributor, regarding the use of active gps antennas with the Q2698, you need to “be aware of how much gain is being pushed through the LNA components, 10-15 dB is usually alright whereas 20-30 dB is not recommended.”

Maybe this is behind some of the problems people have been having since most active gps antennas (at least that I’ve seen) have a gain in the 20-30 db range, exactly the range they say not to use! (needless to say potentially seriously limiting the usefulness of the Q2698 gps).

7

I would say the lack of documentation and application notes on implementing GPS on the Q2698 (not the FX100) also doesn’t help.

@jcameron: if you don’t mind me asking how did you design your Bias-T circuit?

8

Just have a look at the new HL6528-G. It explains you well, how to generate a supply voltage for your GPS antenna. Take care that the supply voltage is clean and has no ripple. Maybe it makes sense to read the IoT M2M Cookbook .

[size=150]Abstract of IoT M2M Cookbook[/size]
The example of a locating device based on cellular modules (GSM, HSPA, LTE) and GNSS modules (GPS, Glonass, All Galileo) explains how to develop a complex IoT / M2M-device with embedded antennas. The person, who has to develop a telemetry device, ignores the part of GNSS. The 20 years of experience in the development and consulting wireless devices is included in all chapters. The integration of antennas has been paid special attention. The antenna is the key to success with any wireless application. The simulation, and the result, is a quad-band GSM antenna and is explained in detail.

Each developer can easily copy the result without the use of mathematics. In the example of the vending machine, the self-made, integrated antenna not only saves the external antenna, but also the coaxial socket and installation as well. The same antenna can save the expensive SMT mount cellular chip antenna in a locating device and is easily adapted to the Epsilon R of the housing. Other sub-themes are power supply and choice of carrier (USSD, SMS, CSD, DTMF, GPRS) approvals. Typical mistakes of first-time users are addressed too.

The developer selects the antenna design first and then builds the device around the antenna. This results in a large cost saving for hardware and installation. At the vending project the estimated saving was 4,000 installations x $ 10 = $ 40,000. The integrated antenna with the optimised ground plane is so good that during redesign the switch and the coaxial socket to the external antenna were excluded.