GPS repeaters for Aircraft HangArs
The structure of an aircraft hangar can block the ingress of gps signals, making it impossible to test on-board navigation equipment without pushing the aircraft outside where it has a view of the sky.
GPS repeater in hangar
A GPS repeater system overcomes this physical barrier by transferring the outdoor signals to the interior of the hangar, which means all maintenance work can be carried out indoors.
A GPS repeater system installed in an aircraft hangar:
- Receives the satellite signals via an external GPS antenna.
- Sends the signals down a coaxial cable to a repeater unit (sometimes multiple units) inside the hangar.
- The repeater amplifies and re-radiates the signals indoors so that all GPS receivers within range can use the outdoor signals.
GPS REPEATER IN A MILITARY HANGAR
In a military situation, the same applies regarding the ability to carry out maintenance without leaving the safety of the hangar.
Additionally, a fighter jet would normally experience a satellite acquisition delay when exiting the hangar in a hurry – the time-to-first-fix (TTFF) could be a dangerously long period of time.
A GPS repeater ensures that fighters always have GPS lock when inside the hangar to ensure there is no satellite acquistion delay upon exit
The repeater unit has a built-in re-radiating antenna with a beam width >160 degrees.
The coverage area achieved is partly determined by the hight of the repeater above the ground.
Generally – one repeater unit placed 10M above ground level will provide coverage within a 35 – 40M radius.
This typical 150m x 75m hangar has virtually full coverage from two GPS repeater units mounted 12 metres above ground level
Repeaters can also be wall-mounted with their signal beaming horizontally across the indoor space; signal will reach up to 50m in clear space
GPS repeaters for fire stations
This is not necessarily an issue when the appliances are parked; however when they leave the station it can sometimes take several minutes to re-acquire a GPS fix.
During these first few crucial minutes on a callout the appliance would be transmitting incorrect (stale) location data to the command and control centre.
Any other satellite navigation kit (such as TomTom/Garmin devices, will be similarly affected, potentially increasing response time.
A GPS repeater system installed in a fire station ensures that:
- All appliances receive a “live” GPS satellite signal while parked.
- Satellite navigation equipment in all rescue vehicles is “locked on” to the GPS satellites at all times when indoors.
- When appliances leave the station they already have GPS lock and will transmit accurate location data to the command and control centre.
- There is zero satellite-acquisition delay when exiting the fire station.
- No need to reboot the on-board system while en-route to an incident.
GPS FREQUENCY BANDS COVERED
Repeater systems are available to cover the following frequencies:
- L1 (1575 MHz)
- L2 (1227 MHz)
- GLONASS (1602 MHz)
- Galileo (1575 MHz)
An L1 system is the most popular option; the addition of an L2 signal gives a much more accurate positional fix and is widely used in military and civil aviation applications.
The Russian GLONASS signals and European Galileo signals are also available.