FMB920 GNSS jamming repeated alerts

TELEMATICS
1

I am using FMB920 with firmware 03.29.00.Rev.14 and enabled GNSS jamming alert. I am getting the alert GNSS jamming val:1 and GNSS jamming Val:0 every consecutive second. The device is reporting the location without any error, but the jamming alerts looks to be without any hysteresis and disruptive. Any idea in which scenario GNSS jamming is detected?

3

Dear @vinodcombat,

Welcome back to Crowd Support Forum. GNSS Jamming records stored in AVL ID 318 parameter and has 3 possible values:

  • 0 - No Jamming,

  • 1 - Jamming warning status, which means that signal and accuracy is disrupted but device is able to hold GPS fix for at least 5 seconds.

  • 2 - Jamming critical status, which means that device is not able to acquire GPS fix.

In this case, it is normal to received Location without any error as the device is still able to hold the GPS Fix. However, if you received a value of 2 this means that the device could not acquire GPS fix.

For more information you may refer on this link: FMB920 Features settings - Wiki Knowledge Base | Teltonika GPS

I hope this helps.

Kind regards,
Patrick

4

Dear Patrick

Thanks for the info. What is the condition to generate a warning of value 1. I am getting repeated alerts switching between 0 and 1 multiple times within 5 seconds too.

5

Dear Vinod,

Good day! Based on the description provided above, if there were repeated alerts on the device this means that signal and accuracy are disrupted but the device can hold GPS fix for at least 5 seconds.

I recommend checking the location where the device was installed, there could be some metals in the surroundings or radio that interrupts the GNSS signal of the device.

Kind regards,
Patrick

6

The vehicle does have a Lora Radio installed at 865Mhz. If the interference is due to radio, how can I filter it.

7

Hello,

I believe that this Lora Radio probably interferes with the GNSS connectivity of the device. In this case, you may try to change the location of the GPS device or the Lora Radio to check however if the signal strength of the Lora Radio is strong GNSS signal of the device could still be interrupted.

Kind regards,
Patrick

8

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