Friday, May 25, 2007

Radio Frequencies: what happened? -- Piet le Roux

At this stage our the 35MHz band, is unreliable because it is also being used illegally by two- way radio channels which were issued by the old Department of Communications. The 53.3 to 53.9 MHz band (channel 31 to 43) has just disappeared without anyone noticing it!

In 1997 the old Department of Communication started to implement project SABRE, this mainly impacted on the 60 MHz users and they had to be migrated. Foot note 3.32 in this report said the following:
South Africa currently uses the frequency band 60.1375 - 60.375 MHz for the control of model aircraft, which differs from bands used elsewhere in the world. In order to allow the model aircraft community to benefit from international economies of scale, to facilitate international competitions, etc, it is proposed that the model aircraft control band will be moved to be in line with the European band at 35 - 35.25 MHz.

The existing model aircraft control band could be released in the medium term. It should be noted that the new band will not be available immediately for use for model aircraft control, as existing users will need to be migrated out.”

So it acknowledged that there were users between 35 and 35.25 MHz and that they had to be moved but it makes no provision for the users between 35.25 to 35.5 MHz because at this stage they wanted our band to be the same as Europe (35 to 35.25)

But there were two 60 MHz bands 60.1375 to 60.375 (for aircraft) and 60.025 to 60.125 MHz (for model control).We were given 35 to 35.25 for the 60.1375 to 60.375 band but after 2000 when ICASA took over, they realized that they needed the whole 60 MHz band, so the gave us 35.25 to 35.5 MHz for the 60.025 to 60.125 band .But 60.025 to 60.125 was for model control, meaning everyone, so the 35.25 to 35.5 should have been for general use. This was done without checking that the users on 35 to 35.25 had been migrated and without making any provision to migrate the users on 35.25 to 35.5 MHz. At the end the whole 35 to 35 .5 MHZ band were given to model aircraft control. This was not a well thought thru plan because such a big band will cause problems with receivers using a 455 KHz intermediate frequency.

ON the 24th of March 2004 all changes were published in the government gazette and became law. For some unknown reason the 53.3 to 53.9 MHz band were not published in the government gazette. It looks to me like they just forgot because nowhere in any document is it mentioned that that band would be taken away. Nevertheless they way that the South African Table of Frequency Allocations reads at this time is that 50 to 54 MHz is for ham radio use and they would share 53 to 54 MHz with Wireless microphone use. The only 50 MHz frequency for model control is 54.45 to 54.55 MHz. If you want to use 53.3 to 53.9 you would have to get a class A radio amateur license.

The Two-way radios currently using 35 to 35.5 MHz can not be simply moved to above 35.5 MHz because that band is reserved for the base station leg of a repeater setup. The nearest single frequency mobile bands available are 33.25 to 33.5 MHz or 36.825 - 38.5 MHz. The 36 to 38 MHz band is the nearest but is mostly still used by the government.

Safe Flying

Piet Le Roux

No comments:

Blog Archive

Total Pageviews


Web site terms and conditions

Copyright of material on all the pages of this site is vested in the SAMAA or the original authors. You may use the material in terms of the Creative Commons license for non-commercial purposes on the condition that you acknowledge its origin.

This work is licensed under a Creative Commons License

The views expressed on this web site, or on any directly or indirectly linked site, are not necessarily those of the SAMAA Committee, or the web editor. The information provided on this site is provided for recreational purposes only. The SAMAA and the authors of presented content assume no liability whatsoever on the use of information contained in this site. The information on this site is provided on an "as-is" basis, without warrantee of any kind. Links provided on this site will let you leave the SAMAA web site. The linked sites are not under the control of the SAMAA, and the SAMAA is not responsible for the contents of any linked site, or any link contained within a linked site, or updates to such sites.