GPS jammer
A GPS Jammer ( dt. "GPS jammer") is a jammer for the signals of the Global Positioning System (GPS), a satellite-based system for global positioning, which the Ministry of Defense of the United States is operated.
Due to the relatively low transmission power of the satellites and the orbit at an altitude of 20,200 kilometers above the earth's surface, the GPS signals can only be received with an extremely low field strength . Interfering signals with low field strength can therefore prevent the reception of the GPS satellites. Additional modulation (e.g. noise modulation) from a jammer can temporarily or completely prevent GPS reception. Due to the low level of interference required, a GPS jammer for the near field (approx. 10 m) can be very small.
A practical structure of a simple GPS jammer can be found in the online magazine Phrack . Government agencies such as the UK Ministry of Defense also test GPS jammers. The GPS can also be unintentionally disturbed: For example, the 15th harmonic (14th overtone) of the mixer oscillator falls exactly on the civil GPS frequency L1 (1575.42 MHz ) if a frequency of 94.3 MHz is set on a VHF radio is. This can lead to reception errors on the GPS receiver in the immediate vicinity of the radio .
In contrast to a GPS jammer, the much more complex GPS spoofing not only disrupts the satellite signal, but sends manipulated GPS data.
The GPS navigation system is a military system. The term navigation warfare (Navwar, meaning "warfare via navigation") summarizes strategies to use GPS against an enemy and to exclude him from using the system. One scenario is based on throwing a large number of small jammers over a crisis area and thus interfering with the reception of the C / A signal on the ground.
At the end of 2011, a US reconnaissance drone is said to have been “hijacked” by Iran using GPS manipulation.
Defense against GPS whining
The signal strength of GPS is extremely weak at around −155 dBW . A jammer of a few watts suppresses practically every navigation signal in the reception area.
In order to minimize the effect of GPS whining, GPS antennas with pronounced directional characteristics can be used in certain applications (e.g. in flight technology) . These antennas only receive signals from the desired direction - and thus not the interference signals from GPS jammers that are on the ground. Another way to reduce the effect of GPS whining is to combine it with other navigation systems, such as an inertial navigation system (INS) .
Individual evidence
- ↑ Building instructions for an inexpensive and portable GPS jammer . Phrack edition 0x3c (60), Article 13, 2002
- ↑ The UK Ministry of Defense tested a GPS-jamming system in the UK's West Country on 7 and 8 June 2007 (engl.)
- ↑ Heise Online - News of December 23, 2011 2012: the year in which the big drones arrive