Wednesday, March 03, 2010

Letter to RadCom

Dear Sirs.

I understand that the trend in amateur radio these days is towards self regulation. However, recent events in the digital sub-bands lead me to believe that this is just a recipe for chaos. I refer to the recent appearance of ROS, a 2.2kHz wide digital mode apparently developed for weak signal work.

Soon after the ROS software was made generally available, chaos ensued with ROS users causing interference to IBP beacons, established APRS and ALE networks and Olivia users, not to mention other ROS users. Any chances of making DX low-power contacts were dashed by the number of people trying to use a limited number of frequencies to make short range QSOs that could have been accomplished using PSK31 and one twentieth of the bandwidth.

The band plans do not set aside specific sections of the digital sub-band for different modes. I am told that this is so as not to hinder experimentation. However, many popular modes such as PSK31, WSPR, Olivia etc. have established their presence on various parts of the bands and this is normally honoured by "gentleman's agreement." This all goes out the window when someone posts on the net that a new mode is available and hundreds of people download software and go mad with their new "toy" without any authoritative guidance as to where to operate.

The experience with ROS throws into question whether different digital modes can co-exist in the same band space. Many digital users seem to treat signals in another mode as QRM to be transmitted over rather than somebody else's contact. The problem in the case of ROS is exacerbated by the fact that the transmission of this mode is 2.2kHz wide, which makes it harder to avoid causing interference to somebody. I think we should also be asking if there ought to be a limit on the width of digital modes that can be used on the HF bands, because there just isn't enough space in the digital sub band for many people to each have a clear 2.2kHz wide channel.

I am not against experimentation, and would suggest that a small part of each band be set aside for experimental modes, experiments being conducted by the developer and a few chosen testers. However, before a mode can be made available for general use it should be approved by an international committee which would take into consideration the benefits of the mode, the amount of bandwidth it occupies and what frequencies it may be used on.

Julian, G4ILO

CC: Andy Talbot, G4JNT, Data Modes columnist


M0JEK said...

Nice letter Julian. I think it is clear and to the point.

M0XDF said...

I'm basically with you on this Julian, and agree about a section of the band to be used for testing.

I'm a little concerned about having to go before an international committee before use, purely because I think it might take a long time to be ratified. I agree some form of body should authorise it's general use. And until that happens, you have to stay in the test section of the band.
73 de M0XDF

Tjeerd, PA3GNZ said...

I agree with you.

73, Gose

Paul Stam PAØK said...

Hello Julian, a really good statement. 73 Paul

Steve GW7AAV said...

Good stuff Julian I agree with you 100%.

While I understand M0XDF's concern I think approval of new modes is essential to avoid breaching our licensing conditions. If I write software for a new data mode and only give it to a few of my mates we are using an encypted signal, which is not permitted. Packet radio was seen as illegal when it first appeared on the amateur bands and a change in the licence was made before the law abiding amongst us gave it a try, however new data modes seem to surface regularly these days and ROS is the first one were anyone questioned its legal position.