Communications receiver

A communications receiver is a type of radio receiver used as a component of a radio communication link. This is in contrast to a broadcast receiver which is used to receive radio broadcasts. The difference between the two is that broadcast receivers only receive broadcast bands, such as the medium wave and/or longwave AM broadcast bands and the VHF FM broadcast band, while a communication receiver receives a wider part of the radio spectrum not used for broadcasting, that includes amateur, military, aircraft, marine, and other bands. They are often used with a radio transmitter as part of a two way radio link for shortwave radio or amateur radio communication, although they are also used for shortwave listening.

Commercial communications receivers are characterized by high stability and reliability of performance, and are generally adapted for remote control and monitoring. For marketing purposes, many hobby-type receivers are advertised as a "communications receivers" although none are suited for heavy-duty, reliable 24-hour use as the primary form of communication for an isolated station.

Typically, a communications receiver is of the superheterodyne type in double, triple or, more rarely, quad conversion. It features multiple RF and IF amplification stages and may have at least one IF stage that is crystal controlled. It usually has a BFO and a product detector for SSB and CW reception. The frequency coverage of receivers of this type is typically in the range of 500 kHz to 30 MHz. Communication receivers are suited for operation near powerful transmitting facilities and so must have good internal shielding, front-end filtering. They have design features to provide high selectivity and stability. Rejection of unwanted signals (images, intermodulation products) will typically be much greater than a consumer-type general coverage or broadcast receiver.

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