April 2010 HF Tomorrow and - ALE IV There was a time when a number of people thought that the days of HF radio were numbered. The advent of first the high orbiting geostationary satellites systems like Inmarsat providing marine and military telephone services and traffic monitoring services on ships at sea, the success of GSM mobile terrestrial cellular telephone networks, and the promises of the low earth orbiting Iridium satellite telephone system, all seemed to confirm it. Communications, once the preserve of the highly skilled professional, had suddenly became user friendly and available to the masses. While the improvements provided by 3G ALE are significant, the retention of 2G is not only for the purposes of backwards compatibility and interoperability. There are still some features of 2G that work better in some circumstances. Therefore today’s systems support both 2G and 3G ALE to provide best solutions and 3G ALE incorporates embedded control protocols for many popular transceiver types. Where signal to noise ratios (SNRs) are low, the slower synchronous scan, short link establishment transmission and high frame error rates of 3G makes linking possible in poor conditions. However, where SNRs are average to good, the fast asynchronous scan, longer link establishment transmission and low frame error rates provides comparable or better performance. Moreover, the time delay in waiting for the desired frequency dwell to happen in the 3G synchronous system can have a significant impact.
A radical feature of today’s 3G HF technology is that all components are interdependent to a significant degree and cannot easily be separated out to mix and match with other components and form different product, as with the multi-vendor 2G system. For example, modems, ARQ and ALE are tightly coupled. Where battle force email applications are concerned it is important to note that 3G HF with xDL does not use non ALE HF radio and is not compatible with existing NATO/US cryptographic devices placed between the ARQ output and the physical transmission medium. Also, it only partially supports asynchronous operation with minimal pre co-ordination. All these features are supported by STANAG 5066 compliant HF. xDL ARQ protocols are time rather than event driven with automatic adaptive coding rate adjustment to match channel conditions, which require dual demodulation at the waveform level and strict timing constraints. The need for interoperability between new and previous generation technology is stressed. Combined Endeavour, an exercise organised through NATO’s Partnership for Peace program, sponsored by the US European Command, plays a significant role in ensuring systems are compatible for humanitarian and peacekeeping operations and disaster relief. Now in its 15th year (2009), this exercise is essentially a communications and information systems interoperability test between and among Partnership for Peace and NATO nations. The focus is on deliberate planning process, communications information systems interoperability, and development of a road map for future interoperability improvement among participants. Compact Guyed MF System
- type 150MF
Avoid Noise Interference
- in receive systems
- type MRA RX Transformer
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