Gnss over speed alert monitoring


I am using the quectel mc60 module and able to read the SPEED factor from the $GPRMC tag. But when i am checking the speed factor without moving the device the speed sometimes gives 3.0, 2.0, 13.0 like that.

If i keep my threshold with 10kmph which is not meeting sometimes. even in stationary mode the speed value sometimes changes.

My queries below, please answer to questions:

1). How to read the constant speed in pedestrian, vehicle moving position? Are there any settings?i am reading the speed value from $GPRMC tag

2). How should I get the overs speed count ?

3). Is there any speed limit threshold that can be set inside a module or from an application to read the speed first and check with our threshold?

4). how to find the device is moving or static?

5). how to measure the distance between two halts (Every 2 minutes i am reading and sending the data to my server). During 2 minutes the vehicle might have crossed more than 5km. how to capture and calculate the distance between last position to current position?



Hi Anil,

  1. For your working situation. I recommend you two navigation mode. Fitness mode for pedestrains. Normal mode for vehicles. In fitness mode, the module will be more sensitive for low speed. If you set a static speed threshold, it will be contradictory with fitness mode. So please set static speed threshold to 0 m/s(command is showed below) in Fitness mode situation.

  2. Set static speed threshold. This command aim to block some tiny speed caused by multipath effect etc. when the module actually keep static but RMC report 0.x m/s speed. It is recommended to set this value to 0.8m/s( up to your actual test ). That means if the module calculate a speed lower than 0.8m/s, this data will be blocked and RMC report 0m/s.

  3. You can also read speed from VTG message.

For this problem, I’m not sure about your test environment. It is a serious drift if the speed report 13.0. Maybe the module was in a bad signal environment.

Best regards.