GPS SUPL CLIENT

[Bhavya]

Hi!

I'm  using ncs v1.5.0 and mfw 1.3.0 on a nRF9160 DK v0.15.0.

I'm using gps sample with supl_clint_library enabled

1. Things work reasonably well, but I am confused by the log output from supl_session

  D: Injected AGPS data, type: 7, size: 16
  D: MCC location info injected, MCC: 405
  D: Lat: 2133502 Lon: 3710095
  D: Unc semiminor/semimajor: 125/125
  D: Unc altitude: 127
  D: Confidence: 100
  D: Orientation: 0
  D: SUPL POS received

Converted the latitude and longitude values with the below formula and they seems inaccurate where as MCC value is fine

Latitude = 2133502 / (2^23/90) = 22.889993191
Longitude = 3710095 / (2^24/360) = 79.610002041

2.Is there something I can do to let it work in indoor locations as well?

3.And on what pa-rams my time to first fix depends upon because I'm not getting the fix at all if i am in indoor space?

[JONATHAN LL]

Hi,

2.Is there something I can do to let it work in indoor locations as well?

 It wont work indoors, the GPS signal does not penetrate buildings that well so unless you are outside(or have the antenna outside) then there is unlikely to work. 

 

3.And on what pa-rams my time to first fix depends upon because I'm not getting the fix at all if i am in indoor space?

 You have to go out side, GPS is not an indoor/inside positioning system. Best performance is in a open space with good access to clear sky and nothing obstructing the antenna. 

Regards,
Jonathan

[Bhavya]

Hi Jonathan,

Yes I am aware that GPS doesn't work indoors

: Injected AGPS data, type: 7, size: 16
  D: MCC location info injected, MCC: 405
  D: Lat: 2133502 Lon: 3710095
  D: Unc semiminor/semimajor: 125/125
  D: Unc altitude: 127
  D: Confidence: 100
  D: Orientation: 0

What is this data meant to?I am in an assumption that this data is for network location

[JONATHAN LL]

Do you mean modem firmware 1.2.3 ? 

Injected AGPS data, type: 7, size: 16. 
-  AGPS will help you get ephemeris and almanac, which will help in terms of time to first fix, but it will not help if there is no GPS signal to receive.

MCC location info injected, MCC: 405 = your location India, AirTel.

You can check out the source code:
https://github.com/nrfconnect/sdk-nrf/blob/37bee18ca1738056b12ddc592cd549217b0c8e69/subsys/net/lib/nrf_cloud/src/nrf_cloud_agps_utils.c#L105 

Converted the latitude and longitude values with the below formula and they seems inaccurate where as MCC value is fine

 we often see that the value is the centre of the country, so that's why the country is correct and not the location, it just defaults to country origo.

But the values are used to get the GPS information so it does not need spend time to search for available gps satellites. 

Regards,
Jonathan

[Bhavya]

When i am using the AT+COPS? I received  "+COPS: 0,2,"405874",9"

In which i believe 405 is my mcc code 874 is my mnc code .but the value for mnc is not correct it should be 15 based upon my location and network operator. Can you please let me know how to correct this.

Regards.

Bhavya

[JONATHAN LL]

Ok so the command returns whet the modem knows and that is given by the network, depending on the network that it is connected to the values will vary. Some network operators have more then on MNC. 

From this list: https://en.wikipedia.org/wiki/Mobile_Network_Codes_in_ITU_region_4xx_(Asia)#India_-_IN_-_405 

Looks like you think that you are supposed to be connected to Reliance network but it is in fact the Jio network.



If there is a bug then if you could do a modem trace and send it to us so that we can find where the error potentially is.
How to get modem trace using “Trace Collector” in nRF Connect - Getting started - Cellular IoT guides - Nordic DevZone (nordicsemi.com)

Regards,
Jonathan