Mode S Technology





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Interview with Gene Wong - 10/31/00

· The FAA is deciding on how to revamp the ADSB. The GPS-squitter is one of many data links for air-to-air, air-to-ground, and ground-to-air communication.

· However, there are other competing technologies. The Universal Access Transeiver (UAT), a MITRE research project started 2-3 years ago, relies on GPS input, but uses 966 MHz or 981 MHz frequencies. The one drawback of the UAT is that these frequencies are also used by Distance Measuring Equipment (DME), making it susceptible to interference. However, the UAT is embraced by the General Aviation community (pilots of small planes, such as Cesnas), because this frequency sharing enables the integration of other services into the system, such as weather information (ground-to-air broadcast).

· In Sweden, a proposal was made for the VDL Mode4 Link. The VDL stands for very high frequency link, and uses a time-division multi-access channel (which I interpret to mean one channel that lots of people can use, but they only get a fixed time slot, sort of like time-sharing). The main benefit for the VDL is that it has a longer air-to-air communication range (around 200 miles).

· Right now, the FAA is doing lots of quantitative data collecting to decide which of these three technologies is most appropriate for the new ADSB design, and expect to finalize by mid-2001.

The Story of Mode S: An Air Traffic Control Data Link Technology last modified: 12.06.2000