GPS Jamming and Interference Detection
Table of Contents
Applies to:
Device | Firmware Version |
Bolt2-4G | All Versions |
Dart3-2G and Dart3-4G | All Versions |
G120-2G and G120-4G | All Versions |
G150-Global | All Versions |
G70-2G and G70-4G | All Versions |
Our wired devices support GPS Jamming and GPS interference detection. The available parameters are split into 2 tabs in OEM.
For 4G Devices, the GPS Jamming (Adv) tab sets what constitutes 'jamming' or 'interference'
1 = Interference Parameters
2 = Jamming Parameters
For 2G Devices, GPS Jamming (Adv) tab does not let you configure the thresholds but rather uses its own GPS Jamming parameter set.
*The G120 2G, however, has the same parameters for configuring jamming as the G120 4G.
GPS Interference
GPS 'interference' is represented with a Digital Input. Defaults should generally work well, and are best left untouched unless you know what you are doing.
GPS signals are broadcast at specific frequencies, and GPS receivers (i.e. the device) are tuned to pick these up. Generally, they won't be very strong (they are coming from satellites orbiting about 20 000km away!). So if the module detects signals in this frequency range that are much stronger, or that make up a large proportion of the total signal, it can consider this interference and report it.
GPS Jamming
When a wired device is in trip, it will leave its GPS on, getting regular fixes and calculating heading, speed, odometer etc. with this data. So if GPS signal is lost for a long time, there is likely a problem, so we flag jamming.
This is set by the Warning Timeout parameter.
GPS Jamming IOs - these parameters determine what action to take should jamming or interference be detected. By default, devices will flag interference, and record a log.
![](https://static.helpjuice.com/helpjuice_production/uploads/upload/image/14099/2712909/bOgweSys5SZQWbc3CNgFUTxzm012176WOA__1_.png)
With these parameters we can set which digital inputs the Interference and Jamming flags are mapped to. Defaults: 5 and 6 are default*.
*G120 defaults are 7 & 8.
By default, as soon as jamming/interference is detected, a log is created - this will appear as a Digital Input Changed log.
We can set the device to immediately upload if this is detected - however when in trip, the device will be connected to the network anyway - so even with this not set, if detected in trip this will be uploaded immediately.
Explanation of Parameters
4G-GPS jamming(adv)
- Broadband Delta Threshold (dB): This setting defines the threshold above the baseline signal level for detecting broadband jamming. Broadband jamming typically involves noise or interference spread over a wide range of frequencies. Setting this threshold determines how sensitive the system is to detecting such jamming signals. A lower value means higher sensitivity to potential jamming signals.
- CW Delta Threshold (dB): This threshold is for detecting continuous wave (CW) jamming, which involves a constant signal at a specific frequency aimed at disrupting GPS signals. The CW Delta Threshold sets the dB level above the baseline at which CW jamming is assumed to occur. Higher sensitivity (lower threshold value) means the system can detect weaker jamming signals.
- CW Absolute Threshold (%): This parameter specifies the absolute threshold for continuous wave jamming detection in percentage terms. A value of 0 means the detection is disabled. A higher percentage means the system will trigger a jamming detection alert only when the jamming signal is significantly strong.
- Signal Power Threshold (%): This setting defines the total signal power above which jamming is assumed to occur, expressed as a percentage. Similar to CW Absolute Threshold, a higher percentage means only strong jamming signals will trigger the detection mechanism.
- Debounce Time (s): This parameter sets the duration in seconds for filtering the interference indicator. It helps avoid false positives by requiring the jamming signal to be consistently above the threshold for the specified debounce time before an alert is triggered.
- Warning Timeout (s): This setting specifies the number of seconds of signal loss before a jamming warning is issued. If the GPS signal is lost for this amount of time, the system assumes jamming or severe interference and triggers a warning.
2G-GPS jamming(adv)
- Debounce Time (s): This parameter sets the duration in seconds for filtering the interference indicator. It helps avoid false positives by requiring the jamming signal to be consistently above the threshold for the specified debounce time before an alert is triggered.
GPS Jamming IOs
Jamming/Interference In OEM Server
If JAMW log reason is seen in the device logs, then GPS Jamming/Interference was detected.
Jamming/Interference In Telematics Guru
Alerting on GPS Jamming
Hard-wired devices are already configured to report jamming/interference by default. So we can just set up an alert on TG if we wish to be notified. Simply create an alert and select the input from the list.
Note, these inputs may become active a bit more than you think. Other electrical signals may cause interference. So it might not be malicious operators with jammers each time you get an alert.
Display on the Live View
We can edit the I/O mappings to display if interference or jamming is detected on the live view
Check for evidence of jamming in the Telemetry
Maybe we have some mysterious events where trips weren't recorded. We can check if the IOs are active in the telemetry.
In telemetry, there are 32 total bits. However, in binary, we start counting from 0, right to left, meaning we have bits 0-31. So working right to left 0, 1, 2, 3, 4, we can see bits 5 and 6 highlighted below.