Simulated GPS data on nRF9160 DK Asset Tracker Example

[iotlight]

I found lines 766 - 768

CONFIG_GPS_SIM_DEV_NAME="GPS_SIM"
CONFIG_GPS_SIM_BASE_LATITUDE=6325280
CONFIG_GPS_SIM_BASE_LONGITUDE=1026201

in \ncs\nrf\samples\nrf9160\asset_tracker\build\zephyr\.config

 

Please let me know how to change to the location in US such as Los Angeles, California for my upcoming demo

34.0522° N, 118.2437° W

Thanks.

[AndreasF]

Hi.

CONFIG_GPS_SIM_BASE_LATITUDE is calculated by the following steps:

Start-point latitude for simulated GPS data, from which the generated data will continue.
Calculated by deg * 100000 + minutes * 1000, for example 63 deg 25.280’N will be 6325280. 
Positive values are North, while negative values are South.

So 32.0522° N will be 3200000 + 5220 = 3205220

CONFIG_GPS_SIM_BASE_LONGITUDE is calculated by the following steps:

Start-point longitude for simulated GPS data, from which the generated data will continue. 
Calculated by deg * 100000 + minutes * 1000, for example 10 deg 26.201’E will be 1026201. 
Positive values are East, while negative values are West.

So 118.2437° W will be 11800000 + 2437000 = -14237000 since West are negative values.

Best regards,

Andreas

[Markus Tacker (he/him)]

The correct values for longitude is -11814.622

The entire NMEA sentence for the coordinates is

$GPGGA,134708.200,3405.217,N,-11814.622,E,1,12,1.0,0,0,M,0,0,M,,*45

[iotlight]

I used Los Angeles decimal coordinates 34.0522308, -118.2436829

The messages seems correct, but the map is shown Japan, not Los Angeles, California.

Below is using Los Angeles DMS Coordinates as you suggested -11814621 in longitude

Please advise.

[AndreasF]

Hi.

I've looked at the NMEA sentences in your log on both the pictures, and they appear to be correct, we are looking into the issue with the map.

Best regards,

Andreas

[iotlight]

Hi,

Any progress on this issue?  We are planning our demo early next week, it will be nice to show Los Angeles in the map.  Thanks.

[Markus Tacker (he/him)]

We have started to investigate the issue. At the moment I have no ETA on when it will be fixed.

[hmolesworth]

Try this:

// LA 34.05217,-118.14622
#define CONFIG_GPS_SIM_BASE_LATITUDE  3405217
#define CONFIG_GPS_SIM_BASE_LONGITUDE 1181462 // -ve so 'W'

LA is West, so instead of using '-' and 'E', use instead 'W':

	snprintf(tmp_str, GPS_NMEA_SENTENCE_MAX_LENGTH,
//		"$GPGGA,%02d%02d%02d.200,%8.3f,N,%09.3f,E,1,"
		"$GPGGA,%02d%02d%02d.200,%8.3f,N,%09.3f,W,1," // <== Use 'W' instead of 'E' and negative numbers
		"12,1.0,0.0,M,0.0,M,,*", hour, minute, second, lat, lng);

[iotlight]

Yes, it works now.  Thank you very much.