Co-channel interference
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Co-channel interference or CCI is interference from 2 different television or radio transmitters on the same frequency. There can be several causes of CCI; three examples are listed here.By Oby- ostemjames@yahoo.co.uk
- Adverse weather conditions: During periods of abormally high pressure weather, signals which would normally exit through the atmosphere can instead be reflected by the troposphere. This will cause the signal to travel much further than intended; often causing interference to local transmitters in the areas affected by the increased range of the distant transmitter.
- Bad frequency planning: Poor planning of frequencies by broadcasters can cause CCI, although this is rare. A very localised example is Listowel in the south-west of Ireland. The RTÉNL UHF television transmitter systems in Listowel and Knockmoyle (near Tralee) are on the same frequencies but with opposite polarisation. However in some outskirts of Listowel town, both transmitters can be picked up causing heavy CCI. This problem forces residents in these areas to use alternative transmitters to receive RTÉ programming.
- Overly crowded radio spectrum: In many populated areas, there just isn't much room in the radio spectrum. Stations will be jam-packed in, sometimes to the point that one can hear loud and clear two, three, or more stations on the same frequency, at once.
