Ooh, now into a subject I know a lot about as RF was work until I retired. Radio transmissions don't stop when they reach a National border so have to be coordinated. Hence the way the radio spectrum is used in the UK has to be coordinated with western Europe, which has to be coordinated with Eastern Europe and so on. The US only has land borders with Canada, who have had to accept the same spectrum allocations as the US, and Mexico that they don't care about. Hence the use of the radio spectrum in the US is totally different to the rest of the world. So they chose to use 315MHz, which was unused in the US but is in the military air band in the rest of the world. Their mobile phone bands are different to the rest of the world and the frequency used by their DECT cordless telephones, wireless headsets, baby alarms, etc are in the band used in Europe by 3 as a mobile uplink frequency. So anyone using US spec equipment in Europe can completely kill a local mobile phone site. I used to spend many a happy hour tracing these......
Going back to when RF was initially used for car security, it was different in just about every country, UK used 418MHZ and there were 3 other frequencies used in Europe alone causing a lot of grief for the motor manufacturers. So, CEPT (Committee European Postes and Telecommunications) proposed a standardised frequency for Europe of 433.8-439MHz for momentarily operated short range devices. There was one slight problem with this as it is within the amateur 70cms allocation of 430 - 440MHz but the primary user of the band is the MoD so the hams had to put up with it. What made it worse was that while amateur repeaters in that part of the band all use a 1.6MHz duplex split, in the UK it is base Tx low and mobile Tx high but in Europe it is the other way round. So the output of the base transmitter, usually running 25W, is on 433.0-433.375 with the input 1.6MHz higher up the band compared with Europe where the base Tx is upwards of 434.6. So in Europe the problem we suffered here doesn't happen as the base transmitters are far enough away to not really cause a problem. Initially, my employers at the time, the Radiocommunications Agency, mandated that these frequencies could only be used for RAKE (Remote Access Keyless Entry) devices but CEPT got a bit offended by this and insisted that it must be allowed for all short range devices, hence wireless doorbells, burglar alarms, remote controls, kids toys and numerous other devices all using the same bit of spectrum. So while these other devices shouldn't cause problems, as they are not something that will transmit permanently and are restricted to the same power outputs as the car keyfob, parking next to a site that happens to have a 70cms amateur repeater on it won't be a problem in Europe but will be a big problem here. Car manufacturers eventually moved to a dedicated part of the 868MHz band and in the last couple of years a lot, including Land Rover, have moved over to a far more secure spread spectrum system.
Most video relay stuff operated in a dedicated 10MHz chunk centred on 1394MHz but as 10MHz isn't wide enough for analogue video, it wasn't used much so 2400-2480MHz is used instead for video senders even though it is also used by WiFi. There was some illegal Chinese stuff that found its way here that operated in the 10GHz band but that was a bit of a problem as it is used for aero navigation. Another one that I spent more happy hours tracing.
Peterborough, Cambs
- '93 Range Rover Classic 4.2 LSE, sold
- '97 Range Rover 4.0SE, in Oxford Blue with a sort of grey/blue leather interior sold as two is plenty.....
- '96 4.6HSE Ascot - now sold
- '98 4.0SE in Rioja Red
'98 Ex-Greater Manchester Police motorway patrol car, Range Rover P38 4.0, in Chawton white - the everyday car
All running perfectly on LPG
- Proud to be a member of the YCHJCYA2PDTHFH club.