Park Air upgrades Mongolian radio network
The country is experiencing a large increase in over-flights, attributable to the opening of new polar routes between South East Asia and North America, and increased flights from North East Asia to Europe. To cope with the increased level of traffic, additional locations are being established to add to the eleven existing Remote Control Air-Ground (RCAG) communication sites. A total of fourteen Park Air radio sites will be made operational, providing contiguous coverage for both upper and lower airspace users within Mongolian airspace.
The new radio sites will be equipped with Park Air's latest generation digital multi-mode radios from the T6 Series and form part of a wide area coverage scheme. The transmission system operates on an offset carrier principle. A number of geographically dispersed transmitters operate simultaneously on the same nominal channel. Since each of the transmitters operates at a frequency marginally "offset" from its partners in the network, interference at the aircraft receiver is minimized. The advantage of the offset carrier system is that aircraft are able to travel long distances without having to change radio frequency.
Reception of transmissions from aircraft relies on a similar network of geographically dispersed receivers, all operating on the same frequency. When two or more receivers intercept the same signal, an electronic qualitative decision is made to determine which receiver is providing the best signal characteristic; this signal alone is routed to the ATC operator.
In the CAA Mongolia system such receiver voting is carried out within the GAREX Voice Communication Control System (VCCS) supplied by Park Air's sister organization Navia Aviation.
Edited by Don Parry
European Correspondent, AerospaceOnline.com