AGPS issues with nRF9160 Dev Kit

[Chetan Kale]

Hello, 

I am using nRF9160 dev kit in Chicago (USA) and in Aldingen (Germany) where I am using same firmware for both DK to get GPS Fixes for location. But surprisingly in Aldingen without any single failure my Firmware works fine. But in Chicago the DK always gets stuck at  GPS_EVT_OPERATION_BLOCKED which will never get the GPS fix sometimes in 24 hours. Then next day if it gets the fix there are errors while downloading and feeding AGPS data to Modem. So can you please answer below question. 

Questions: 

1. If device is in Roaming status then is it will create an issues for GPS fixes? 

2. How to check the which operator we are connecting to?  

3. Does network operator can create issues for Dev Kits to be in PSM mode? Example: network operator can reject PSM mode settings even if Dev kit asks for 10 mins (TAU) of PSM mode and 1 minute of Active mode (RAT).

Console Logs:

GPS_EVT_SEARCH_STARTED 
GPS_EVT_AGPS_DATA_NEEDED 
[00:00:07.833,068] <dbg> nrf9160_gps.configure_antenna: MAGPIO set: AT%XMAGPIO=1,0,0,1,1,1565,1586
[00:00:07.833,740] <dbg> nrf9160_gps.configure_antenna: COEX0 set: AT%XCOEX0=1,1,1565,1586
[00:00:07.836,395] <dbg> nrf9160_gps.enable_gps: GPS mode is enabled
[00:00:07.845,153] <dbg> nrf9160_gps.start: GPS operational
[00:00:07.847,412] <dbg> nrf9160_gps.gps_thread: A-GPS data update needed
[00:00:07.849,792] <dbg> agps.init_supl: Using GPS driver to input assistance data
[00:00:07.849,822] <inf> agps: SUPL is initialized
[00:00:08.082,794] <dbg> agps.open_supl_socket: Connecting to 142.250.138.192 port 7276
[00:00:08.177,886] <inf> agps: Starting SUPL session
[00:00:08.180,053] <dbg> agps.supl_logger: ULP encoding length: 35
[00:00:08.180,664] <dbg> agps.supl_logger: Bytes sent: 35
[mqtt_evt_handler:391] MQTT PUBLISH result=0 len=7

Received Data from Server: No Data
[00:00:08.280,212] <dbg> agps.supl_logger: Bytes received: 30, total 30
[00:00:08.280,761] <dbg> agps.supl_logger: ULP ossDecode success, choice 3
[00:00:08.280,883] <dbg> agps.supl_logger: SUPL server responded using version 2.0.4
[00:00:08.280,975] <dbg> agps.supl_logger: SUPL response received
[00:00:08.281,158] <dbg> agps.supl_logger: ULP encoding length: 54
[00:00:08.281,799] <dbg> agps.supl_logger: Bytes sent: 54
[00:00:08.642,700] <dbg> agps.supl_logger: Bytes received: 708, total 708
[00:00:08.643,249] <dbg> agps.supl_logger: ULP ossDecode more input 4
[00:00:08.757,629] <dbg> agps.supl_logger: Bytes received: 708, total 1416
[00:00:08.758,148] <dbg> agps.supl_logger: ULP ossDecode more input 4
[00:00:08.981,079] <dbg> agps.supl_logger: Bytes received: 708, total 2124
[00:00:08.981,597] <dbg> agps.supl_logger: ULP ossDecode more input 4
[00:00:09.135,406] <dbg> agps.supl_logger: Bytes received: 708, total 2832
[00:00:09.135,925] <dbg> agps.supl_logger: ULP ossDecode more input 4
[00:00:09.191,772] <dbg> agps.supl_logger: Bytes received: 242, total 3074
[00:00:09.192,657] <dbg> agps.supl_logger: ULP ossDecode success, choice 5
--- 3 messages dropped ---
[00:00:09.203,155] <dbg> nrf9160_gps.agps_write: Sent A-GPS data to modem, type: 2
--- 7 messages dropped ---
[00:00:09.216,003] <dbg> nrf9160_gps.agps_write: Sent A-GPS data to modem, type: 2
--- 7 messages dropped ---
[00:00:09.231,140] <dbg> nrf9160_gps.agps_write: Sent A-GPS data to modem, type: 2
--- 7 messages dropped ---
[00:00:09.240,478] <dbg> nrf9160_gps.agps_write: Sent A-GPS data to modem, type: 2
--- 15 messages dropped ---
[00:00:09.286,163] <dbg> nrf9160_gps.agps_write: Sent A-GPS data to modem, type: 2
--- 47 messages dropped ---
[00:00:09.313,873] <dbg> nrf9160_gps.agps_write: Sent A-GPS data to modem, type: 3
--- 13 messages dropped ---
[00:00:09.313,873] <dbg> agps.inject_agps_type: Injected A-GPS data, type: 3, size: 32
[00:00:09.314,666] <dbg> nrf9160_gps.agps_write: Sent A-GPS data to modem, type: 3
[00:00:09.314,697] <dbg> agps.inject_agps_type: Injected A-GPS data, type: 3, size: 32
[00:00:09.315,246] <dbg> nrf9160_gps.agps_write: Sent A-GPS data to modem, type: 3
[00:00:09.315,246] <dbg> agps.inject_agps_type: Injected A-GPS data, type: 3, size: 32
[00:00:09.315,826] <dbg> nrf9160_gps.agps_write: Sent A-GPS data to modem, type: 3
[00:00:09.315,856] <dbg> agps.inject_agps_type: Injected A-GPS data, type: 3, size: 32
[00:00:09.316,436] <dbg> nrf9160_gps.agps_write: Sent A-GPS data to modem, type: 3
[00:00:09.316,436] <dbg> agps.inject_agps_type: Injected A-GPS data, type: 3, size: 32
[00:00:09.317,138] <dbg> nrf9160_gps.agps_write: Sent A-GPS data to modem, type: 3
[00:00:09.317,138] <dbg> agps.inject_agps_type: Injected A-GPS data, type: 3, size: 32
[00:00:09.317,901] <dbg> nrf9160_gps.agps_write: Sent A-GPS data to modem, type: 3
[00:00:09.317,901] <dbg> agps.inject_agps_type: Injected A-GPS data, type: 3, size: 32
[00:00:09.318,634] <dbg> nrf9160_gps.agps_write: Sent A-GPS data to modem, type: 3
[00:00:09.318,634] <dbg> agps.inject_agps_type: Injected A-GPS data, type: 3, size: 32
[00:00:09.319,213] <dbg> nrf9160_gps.agps_write: Sent A-GPS data to modem, type: 3
[00:00:09.319,213] <dbg> agps.inject_agps_type: Injected A-GPS data, type: 3, size: 32
[00:00:09.319,976] <dbg> nrf9160_gps.agps_write: Sent A-GPS data to modem, type: 3
[00:00:09.319,976] <dbg> agps.inject_agps_type: Injected A-GPS data, type: 3, size: 32
[00:00:09.320,709] <dbg> nrf9160_gps.agps_write: Sent A-GPS data to modem, type: 3
[00:00:09.320,709] <dbg> agps.inject_agps_type: Injected A-GPS data, type: 3, size: 32
[00:00:09.321,289] <dbg> nrf9160_gps.agps_write: Sent A-GPS data to modem, type: 3
[00:00:09.321,289] <dbg> agps.inject_agps_type: Injected A-GPS data, type: 3, size: 32
[00:00:09.321,350] <dbg> agps.supl_logger: No integrity data available
[00:00:09.322,296] <dbg> nrf9160_gps.agps_write: Sent A-GPS data to modem, type: 4
[00:00:09.322,326] <dbg> agps.inject_agps_type: Injected A-GPS data, type: 4, size: 8
[00:00:09.323,059] <dbg> nrf9160_gps.agps_write: Sent A-GPS data to modem, type: 7
[00:00:09.323,059] <dbg> agps.inject_agps_type: Injected A-GPS data, type: 6, size: 144
[00:00:09.323,669] <dbg> nrf9160_gps.agps_write: Sent A-GPS data to modem, type: 8
[00:00:09.323,669] <dbg> agps.inject_agps_type: Injected A-GPS data, type: 7, size: 16
[00:00:09.323,730] <dbg> agps.supl_logger: SUPL POS received
[00GPS_EVT_OPERATION_BLOCKED 
:00:10.323,181] <dbg> agps.supl_logger: read again
[00:00:10.430,084] <dbg> agps.supl_logger: Bytes received: 30, total 30
[00:00:10.430,603] <dbg> agps.supl_logger: ULP ossDecode success, choice 6
[00:00:10.430,664] <dbg> agps.supl_logger: SUPLEND:
[00:00:10.430,725] <dbg> agps.supl_logger: 	Mask: 0
[00:00:10.430,786] <dbg> agps.supl_logger: 	Status: 0
[00:00:10.430,847] <dbg> agps.supl_logger: SUPL END received
[00:00:10.430,938] <dbg> agps.supl_logger: SUPL session internal resources released
[00:00:10.430,969] <dbg> agps.supl_logger: SUPL session finished
[00:00:10.430,969] <inf> agps: SUPL session finished successfully
[00:00:10.431,488] <dbg> nrf9160_gps.gps_thread: Waiting for time window to operate

TracMile GPS Search Crossed 6 Seconds. 

[00:00:14.364,410] <dbg> nrf9160_gps.gps_thread: GPS has time window to operate
[00:00:14.368,499] <dbg> nrf9160_gps.print_satellite_stats: Tracking: 0 Using: 0 Unhealthy: 0
[00:00:14.368,499] <dbg> nrf9160_gps.print_satellite_stats: Seconds since last fix 14
[00:00:15.256,622] <dbg> nrf9160_gps.print_satellite_stats: Tracking: 0 Using: 0 Unhealthy: 0
[00:00:15.256,652] <dbg> nrf9160_gps.print_satellite_stats: Seconds since last fix 15
[00:00:16.256,774] <dbg> nrf9160_gps.print_satellite_stats: Tracking: 0 Using: 0 Unhealthy: 0
[00:00:16.256,774] <dbg> nrf9160_gps.print_satellite_stats: Seconds since last fix 16
[00:00:17.259,002] <dbg> nrf9160_gps.print_satellite_stats: Tracking: 0 Using: 0 Unhealthy: 0
[00:00:17.259,002] <dbg> nrf9160_gps.print_satellite_stats: Seconds since last fix 17
[00:00:18.256,500] <dbg> nrf9160_gps.print_satellite_stats: Tracking: 0 Using: 0 Unhealthy: 0
[00:00:18.256,530] <dbg> nrf9160_gps.print_satellite_stats: Seconds since last fix 18
[00:00:19.256,652] <dbg> nrf9160_gps.print_satellite_stats: Tracking: 0 Using: 0 Unhealthy: 0
[00:00:19.256,683] <dbg> nrf9160_gps.print_satellite_stats: Seconds since last fix 19
[00:00:20.257,293] <dbg> nrf9160_gps.print_satellite_stats: Tracking: 0 Using: 0 Unhealthy: 0
[00:00:20.257,324] <dbg> nrf9160_gps.print_satellite_stats: Seconds since last fix 20
[00:00:21.257,568] <dbg> nrf9160_gps.print_satellite_stats: Tracking: 0 Using: 0 Unhealthy: 0
[00:00:21.257,568] <dbg> nrf9160_gps.print_satellite_stats: Seconds since last fix 21
[00:00:22.257,232] <dbg> nrf9160_gps.print_satellite_stats: Tracking: 0 Using: 0 Unhealthy: 0
[00:00:22.257,232] <dbg> nrf9160_gps.print_satellite_stats: Seconds since last fix 22
[00:00:23.256,469] <dbg> nrf9160_gps.print_satellite_stats: Tracking: 0 Using: 0 Unhealthy: 0
[00:00:23.256,469] <dbg> nrf9160_gps.print_satellite_stats: Seconds since last fix 23
[00:00:24.256,988] <dbg> nrf9160_gps.print_satellite_stats: Tracking: 0 Using: 0 Unhealthy: 0
[00:00:24.257,019] <dbg> nrf9160_gps.print_satellite_stats: Seconds since last fix 24
[00:00:25.256,958] <dbg> nrf9160_gps.print_satellite_stats: Tracking: 0 Using: 0 Unhealthy: 0
[00:00:25.256,958] <dbg> nrf9160_gps.print_satellite_stats: Seconds since last fix 25
[00:00:26.423,004] <dbg> nrf9160_gps.print_satellite_stats: Tracking: 0 Using: 0 Unhealthy: 0
[00:00:26.423,034] <dbg> nrf9160_gps.print_satellite_stats: Seconds since last fix 26
[00:00:27.425,262] <dbg> nrf9160_gps.print_satellite_stats: Tracking: 0 Using: 0 Unhealthy: 0
[00:00:27.425,262] <dbg> nrf9160_gps.print_satellite_stats: Seconds since last fix 27
GPS_EVT_OPERATION_BLOCKED 
[00:00:28.483,489] <dbg> nrf9160_gps.gps_thread: Waiting for time window to operate
[mqtt_evt_handler:512] default: 9
[mqtt_evt_handler:512] default: 9

TracMile GPS Search Crossed 139 Seconds. 

[00:02:27.456,115] <dbg> nrf9160_gps.gps_thread: GPS has time window to operate
[00:02:27.460,296] <dbg> nrf9160_gps.print_satellite_stats: Tracking: 0 Using: 0 Unhealthy: 0
[00:02:27.460,296] <dbg> nrf9160_gps.print_satellite_stats: Seconds since last fix 147
[00:02:28.456,146] <dbg> nrf9160_gps.print_satellite_stats: Tracking: 0 Using: 0 Unhealthy: 0
[00:02:28.456,146] <dbg> nrf9160_gps.print_satellite_stats: Seconds since last fix 148
[00:02:29.454,742] <dbg> nrf9160_gps.print_satellite_stats: Tracking: 0 Using: 0 Unhealthy: 0
[00:02:29.454,742] <dbg> nrf9160_gps.print_satellite_stats: Seconds since last fix 149
[00:02:30.455,780] <dbg> nrf9160_gps.print_satellite_stats: Tracking: 0 Using: 0 Unhealthy: 0
[00:02:30.455,810] <dbg> nrf9160_gps.print_satellite_stats: Seconds since last fix 150
GPS_EVT_OPERATION_BLOCKED 
[00:02:31.690,460] <dbg> nrf9160_gps.gps_thread: Waiting for time window to operate
[mqtt_evt_handler:512] default: 9

TracMile GPS Search Crossed 195 Seconds. 

[00:03:23.456,848] <dbg> nrf9160_gps.gps_thread: GPS has time window to operate
[00:03:23.461,029] <dbg> nrf9160_gps.print_satellite_stats: Tracking: 0 Using: 0 Unhealthy: 0
[00:03:23.461,059] <dbg> nrf9160_gps.print_satellite_stats: Seconds since last fix 203
[00:03:24.457,427] <dbg> nrf9160_gps.print_satellite_stats: Tracking: 0 Using: 0 Unhealthy: 0
[00:03:24.457,427] <dbg> nrf9160_gps.print_satellite_stats: Seconds since last fix 204
[00:03:25.456,970] <dbg> nrf9160_gps.print_satellite_stats: Tracking: 0 Using: 0 Unhealthy: 0
[00:03:25.456,970] <dbg> nrf9160_gps.print_satellite_stats: Seconds since last fix 205
[00:03:26.457,855] <dbg> nrf9160_gps.print_satellite_stats: Tracking: 0 Using: 0 Unhealthy: 0
[00:03:26.457,855] <dbg> nrf9160_gps.print_satellite_stats: Seconds since last fix 206
GPS_EVT_OPERATION_BLOCKED 
[00:03:27.671,905] <dbg> nrf9160_gps.gps_thread: Waiting for time window to operate

NCS version : 1.7.0

Modem Firmware version: 1.3.1

Device Revision : NRF9160_xxAA_REV2

Board Version : PCA10090

SIM used: iBasis

Thank you !

Regards,

Chetan

[Albrecht Markus Schellenberger]

Hello Chetan, 

Chetan Kale said:

1. Can you please explain what is wrong with 1st and 2nd observation logs of Chicago Unit ?

In the 2nd observation, the A-GPS request obviously failed: 

[00:00:57.209,106] <err> agps: SUPL session failed, error: -13 
[00:00:57.209,564] <err> agps: SUPL request failed, error: -13 

leaving the modem doing a manual fix, which appears to be a bigger challenge due to frequently blocking. Additionally, signal quality issues and positioning of the satellites could potentially aggravate the process. 

Regarding the 1st observation, that is not possible for me to say without a modem trace.

Chetan Kale said:

2. What is the meaning / abbreviation for "A21B" and "4119" in CEREG response? 

As described in the documentation of +CEREG, ‘A21B’ & ‘4119’ is the Tracking Area Code.

Chetan Kale said:

Solution I thought: 

I have created an alternative to solve this issue which is mentioned in below steps: 

1. Connect to LTE.

2. Download the AGPS data.

3. Deactivates LTE without shutting down GNSS services.

4. Get the AGPS fix.

5. Activates LTE without changing GNSS.

6. Stop. 

Please provide your suggestion if there are any additional steps are require or need to take care to make the firmware more robust. Or please suggest any other alternatives are there with you. 

I’m not sure what the last step ‘Stop’ implies though, but for getting a first fix this should work. However, the GNSS services have to become operational once in a while depending on how much the device is moving to update its position. The assistance is recommended to be updated occasionally as well, normally every 2h. 

So, I do not have a universal answer for you here, as it depends on a lot of factors. One thing that you might want to consider though is GNSS priority mode.

FYI: Since many of my colleagues currently are out of office due to summer vacation period in Norway, delayed answers are to be expected.

Regards, 

Markus