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The | ==GNSS Jamming== | ||
[[File:GNSS Jamming configurator.png|right]] | |||
GNSS Jamming is the transmission of radio signals that disrupts | |||
communications between tracker and satellites by decreasing the signal to noise ratio. When a device detects GNSS signal jamming, it activates the GNSS Jamming scenario. The device then generates and sends a record to the server, depending on hardware model activates Digital Output and optionally sends SMS notification to configured GSM number. After device regains GNSS signal, Digital Output is immediately deactivated and a new record is sent to the server. This Digital Output activation can be used to trigger measures to disrupt potential thieves using GNSS signal jamming to steal your vehicle. GNSS Jamming record is 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. | |||
It is important to note, that Jamming Detection can go from any state to any other in 1 second intervals. It is completely dependent on received NMEA data by GNSS receiver. Therefore, it is possible in repeated jamming scenario for the state to rapidly go from 0 to 2 and backwards. Also, GNSS Jamming functionality is capable to separate indoor areas (e.g. underground parking) from events when jamming is actually happening. This is possible because in-band jamming will affect internal PGA (Programmable Gain Amplifier) degrade, as a result, CNR (Carrier-to-noise ratio) will degrade as well. On the other hand, if CNR degrade is degraded only because of underground or signal covered, internal PGA gain will keep almost the same. | |||
Eventual Records parameter can be configured: when it is disabled scenario status value will appear in each AVL record, otherwise, it will be appended only to eventual records. | |||
From '''04.01.00.Rev.01''' Jamming Detection Delay parameter has been introduced. This parameter controls the time needed for the device to register a change in GNSS data to switch states. | |||
For example, with timeout set to a default value of 60, if GNSS is not being jammed, the device needs to register a jamming warning or jamming detected for 60 seconds for the device to consider jamming as ongoing (during this time, device can register warning and jamming states, this will not reset the counter). If no jamming is detected during the configured Jamming Detection Delay period at least once, the counter is reset to 0 and the countdown begins again. | |||
===Additional Notes=== | |||
*GNSS Jamming is only available from '''03.28.03.Rev.03 or newer''' firmware version. | |||
== | *GNSS Jamming is '''not available on 3.80, 3.82 but available on 5.10, 5.1.5, 5.1.8 or newer GNSS module firmware versions.''' GNSS module version can be checked by SMS\GPRS command – '''''getver'''''. | ||
*This scenario will not work with [[{{{model}}}_Sleep_modes#Deep_Sleep_mode|Deep Sleep]], [[{{{model}}}_Sleep_modes#Ultra_Deep_Sleep_mode|Ultra Deep Sleep]] and [[{{{model}}}_Sleep_modes#Online_Deep_Sleep_mode|Online Deep Sleep]] modes.''' '''since they disable the device's GNSS module to save power'''. | |||
Latest revision as of 15:29, 5 June 2026
GNSS Jamming
GNSS Jamming is the transmission of radio signals that disrupts communications between tracker and satellites by decreasing the signal to noise ratio. When a device detects GNSS signal jamming, it activates the GNSS Jamming scenario. The device then generates and sends a record to the server, depending on hardware model activates Digital Output and optionally sends SMS notification to configured GSM number. After device regains GNSS signal, Digital Output is immediately deactivated and a new record is sent to the server. This Digital Output activation can be used to trigger measures to disrupt potential thieves using GNSS signal jamming to steal your vehicle. GNSS Jamming record is 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.
It is important to note, that Jamming Detection can go from any state to any other in 1 second intervals. It is completely dependent on received NMEA data by GNSS receiver. Therefore, it is possible in repeated jamming scenario for the state to rapidly go from 0 to 2 and backwards. Also, GNSS Jamming functionality is capable to separate indoor areas (e.g. underground parking) from events when jamming is actually happening. This is possible because in-band jamming will affect internal PGA (Programmable Gain Amplifier) degrade, as a result, CNR (Carrier-to-noise ratio) will degrade as well. On the other hand, if CNR degrade is degraded only because of underground or signal covered, internal PGA gain will keep almost the same.
Eventual Records parameter can be configured: when it is disabled scenario status value will appear in each AVL record, otherwise, it will be appended only to eventual records.
From 04.01.00.Rev.01 Jamming Detection Delay parameter has been introduced. This parameter controls the time needed for the device to register a change in GNSS data to switch states.
For example, with timeout set to a default value of 60, if GNSS is not being jammed, the device needs to register a jamming warning or jamming detected for 60 seconds for the device to consider jamming as ongoing (during this time, device can register warning and jamming states, this will not reset the counter). If no jamming is detected during the configured Jamming Detection Delay period at least once, the counter is reset to 0 and the countdown begins again.
Additional Notes
- GNSS Jamming is only available from 03.28.03.Rev.03 or newer firmware version.
- GNSS Jamming is not available on 3.80, 3.82 but available on 5.10, 5.1.5, 5.1.8 or newer GNSS module firmware versions. GNSS module version can be checked by SMS\GPRS command – getver.
- This scenario will not work with [[{{{model}}}_Sleep_modes#Deep_Sleep_mode|Deep Sleep]], [[{{{model}}}_Sleep_modes#Ultra_Deep_Sleep_mode|Ultra Deep Sleep]] and [[{{{model}}}_Sleep_modes#Online_Deep_Sleep_mode|Online Deep Sleep]] modes. since they disable the device's GNSS module to save power.