Coordinated Repeater Models

Recently we’ve completed the modeling of all coordinated repeaters in Florida. This was scripted and database driven modeling. Right now the individual KMZ files are available at under the various bands. Each KMZ file has the service, interference and point of repeater, along with channel size and modulation type.

Most repeater owners/operators/trustees will look at the service contour which is in blue. This shows an area where at 1.83m (6′) above the ground, there is a 50% chance that location will have a signal, 50% of the time greater or equal to the service contour. This is typically the mobile service area of a repeater and designated (50, 50).

The green interference contour is modeled to show 50% of locations 10% of the time (50,10) where a signal will be 18 dB below the service contour. This de-rating to 10% makes the chances of receiving a signal much smaller and thus the interference contour is larger. No other co-channel users interference contour should overlap the service contour of any other repeater. This ensures a repeater in it’s protected service contour has a signal at least 18 dB greater than any co-channel repeaters.

In some cases there are adjacent contours, and these are used much like the interference contour. No adjacent contour should overlap another service contour. These are used on 144-146 and 146-148 MHz and for narrowband in 222-225 MHz.

The eventual goal is to have this database driven in real time. This is being worked on and we hope to have a much better interface shortly.

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