Wednesday, March 29, 2006

Policy statement from the SAMAA Management Committee on the use of the 2,4 GHz radio spectrum

Cell phone technology is now catching up with our model radio control equipment and these new systems are soon to be released onto the South African market. It is a Spread Spectrum transmitter and receiver operating on 2.4 Gigahertz band.
A similar three-channel system is already on the market and is being used very successfully in model cars. The latest development is a six-channel, 10 model memory set designed for small model aircraft. The transmitter has all the usual trims and mixers, and except for the short stubby aerial, it looks very much like the standard 35mHz equipment we are used to.
This equipment has been in use in the USA for a while with encouraging results but there are quite a few limitations with its use
The 2.4GHZ band is license free and the use thereof does not need to be approved by ICASA or SAMAA.
For those who are interested in the workings of these sets, some of the finer points are as follows: -
1) They use some 80 spots on the 2.40Ghz band.
2) When switched on they automatically search and find an unused open spot and latch on to it.
3) The transmitter and the receiver must be "bound" to each other before its first use. Once bound the receiver will only obey the signals from its "bound" master transmitter.
4) More than one receiver may be bound to a transmitter
5) They operate on that spot almost interference free (according to the manufacturers)
6) They have a range limitation, dependant on the weather, the terrain and the number of sets of the same type transmitting at the same time.
7) The useful operating range of these sets reduces with the number of sets in use at the same time. (These range limitations are still to be verified and confirmed but with many sets in use simultaneously, it could be as little as 200 metres).
As these sets are coming, it is inevitable that they will appear at our flying fields, so it is proposed to set down a frequency control procedure for SAMAA registered clubs to control these 2.4ghz sets.


1. 2.40ghz transmitters are approved for use at SAMAA registered fields.
2. The frequency control system of "Card/peg on" or "Card/Peg Off" will remain in force.
3. When not in use transmitters will be switched off and returned to the TX pound.
4. A maximum of four (4) 2.40ghz sets may be operated simultaneously.
5. This radio equipment may only be used with Shock Flyers, Park Flyers and Electric Micro Helicopters.
6. Any of the model aircraft types specified in (5) fitted with this equipment should not operate at a distance of more than 300 metres from the pilot when flying at a SAMAA registered field.
NOTE. These are provisional rules only and may change, as and when the equipment in question is in use and other limitations, if any, are found.
For the frequency control board at the clubs, the suggestion is that a sticker be made in Green and marked "Spread Spectrum". This sticker will cover pegs on the frequency board and could be applied over some of the now extinct 60mHz frequency spots.

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