Emergency Cell Network

[CharlesHarris]

The units I am familiar with stacked a pair of ICOM 25 watt UHF mobile radios with a simple diplexer and controller, which was assembled in weatherproof and shock resistant mountings in a Pelican crate, with four Siemens SM20 solar panels and a pair of Hawker Energy SBS30 batteries and a simple 1/4 wave ground plane antenna with roof tripod and 3 metre telescoping mast. These crates weighed about 30kg, including batteries and could be set up on a building roof or any high location in under 30 minutes. This is the same equipment used for putting out portable repeaters for search & rescue or wildland fire fighting purposes. With the solar panels for battery charging these will run for about a year with no maintenance as long as they aren't struck by lightning.

The portable repeaters are coordinated on the "Shared, Non-Protected Pair" or SNP channel, using a continuous tone controlled squelch system to prevent interference from nearby units. The access tone would be determined based upon a regional plan, and the handheld radios distributed to volunteer aid workers would have the SNP programmed in with the several tone options needed for the repeaters in their area of operations. It was also possible to "link" repeaters info a local area network, and they could be used either for voice or data operations.

Generally data operations would be conducted on UHF with horizontal polarization using TCP/IP transmissions at 9600 baud, and voice operations would be vertically polarized using VHF-FM. UHF and VHF repeaters were typically co-located so that shelter logging and medical logistics traffic could be keyboarded over the air while getting simultaneous voice confirmation of the traffic. This also permitted simple voice queries as to personnel and resource status.

While channel allocations in the Land Mobile Radio Services are commonly used for Red Cross, Salvation Army, and other NGO's, amateur radio has the same capablities and many rural localities use "ham" radio operators and equipment to provide similar service. In some parts of the US groups such as REACT provide emergency communications using the UHF General Mobile Radio Service, the VHF Multi-Use Radio Service or the 27 Mhz Citizens Band radios.