BLOCKING

Blocking is en electronics / wireless term whereby one radio receiver can be "blocked" by the presence of a strong transmitter nearby - even if that other transmitter is operating on a different frequency.

Frequently receivers will allow a band (number) of frequencies to be input into its circuitry.  However, there are limits to how much dynamic range that real electronic parts such as transistors can handle.  If a signal is strong enough - even if it is not the exact signal the receiver is looking for - the strong signal may take over the first transistor stages in a radio, overwhelming them, and not allowing any movement for the correct signal.

Fixing blocking can be done either by removing the unwanted frequencies or by improving the dynamic range of the receiver that is being blocked.  Removing the unwanted frequency in some cases can be done by a filter in front of the circuit that can block unwanted frequencies but allow only the correct ones to reach the circuit.