| Often not very much thought is given to the effective IF bandwidth of the receiver. The IF
filter 3 dB bandwidth should be chosen to accommodate the transmitted signal plus any
anticipated frequency drift for both the receiver and transmitter. Often this calculation is not
performed; and any readily available filter, that is several times wider than this minimum value, is
chosen, which can severely reduce system range.
The inverse of the effective receiver bandwidth has the same effect on range as an equivalent
change in transmitter power. Increasing the transmitter power by four, or reducing the effective
bandwidth by four, doubles system range. The difference between these approaches is costly.
Increasing transmitter power can be expensive. Decreasing the effective bandwidth of the receiver
can occasionally be free.
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