Extender Radios - Motorola GM1200E Installation Manual

Noise Reduction Techniques
5.10

Extender Radios

Impulse noise (principally ignition noise) is heard as annoying "pops" along with a received
message. Each noise impulse excites the highly selective receiver tuned circuits which "ring" after
the noise impulse disappears. This "ringing" effectively extends the duration of the noise impulse as
it passes through the receiver. Motorola radios with the "Extender" feature have additional circuitry
which "blanks" the receiver for the duration of the undesired noise pulse so that annoying "pops" are
not heard. The "Extender" receiver effectively chops out the small portion of the message which
contains "pops". This type of receiver is effective in areas where other noisy vehicle ignition systems
interfere with received messages. However, even "Extender" receivers cannot cope with extremely
noisy environments because too much chopping can also destroy message intelligibility.
2-12 Reducing Noise Interference in Mobile Two-Way Radio Installations