GPS Accuracy Question

End-of-Life Product Cellular IoT HAT
1

Hi

We are interested in the Raspberry Pi Cellular IoT HAT – LTE-M & NB-IoT & eGPRS and need details on unit beyond what is on the web page. Specifically;

What is the accuracy in meters, of the GPS?
What is the position update rate of the GPS?

Thank you

2

Hello @cnevarez,

Parameter Description Conditions Typ. Unit
Accuracy(GNSS) CEP-50 Autonomous @open sky < 2.5 m

The module supports standard NMEA-0183 protocol and outputs NMEA sentences at a 1Hz data update rate via USB interface by default.

Best regards.

3

Thank you. How many channels does the GPS support? what constellations is it using? Is it possible to configure the GPS chip set to increase the update rate to 3 or 6 Hz?

4

Hello @cnevarez,
How many channels does the GPS support?

  • This is a complicated question. The channel is a condition that usually affects the receiver. The channel of the receiver is more important.

What constellations is it using?

  • GPS, GLONASS, BeiDou/Compass, Galileo, QZSS

Is it possible to configure the GPS chip set to increase the update rate to 3 or 6 Hz?

  • Max. 1 Hz data update rate.

Best regards.

5

Hi - I’ve just got the Cellular IoT HAT set up, and im testing the GPS data using the instructions at https://docs.sixfab.com/page/read-gnss-gps-data-with-sixfab-hat. When running python3 GPS.py I’m getting values returned back which are at least 8 miles / ~13km out from the actual location.

Can I please check, @ensar are you saying in your response above i should be expecting values < 2.5 meters? If so, can you help me understand what may be wrong with my setup? Where would i start debugging this?

6

Hi @andy_brace,
About your issue, please confirm the following information:

  • Good sky view or anything in the way? Do you keep the Pi clock close to the correct time?
  • Could you take some pictures to show your test environment?
  • What kind of antenna do you use? Is it active or passive?
  • Please confirm you have connect the GPS antenna, and place it in outside environment.
  • It is better to check the satellite signal quality via NEMA sentence.
  • The following GNSS manual for your reference. Please check the values returned using AT command by following the reference. Thank you.