What is the difference between a scanner and a receiver?

Question

What is the difference between a scanner and a receiver?

Answer 1

A scanner is a specialized receiver with features for effectively monitoring many frequencies, classically by tuning to each in rapid succession (scanning) and stopping when a signal is found, then continuing when the signal ends. The scan function can of course be disabled to use it as a receiver for a single channel.

Scanners as commonly discussed are typically used to monitor the communications of public safety services (police, fire department, etc.) because those organizations use many two-way radios on many channels transmitting intermittently. Modern scanners may include the ability to monitor “trunked” radio systems, which have a centralized control channel containing frequency allocations which the individual users' radios automatically follow; this is a feature which is generally unique to scanners as opposed to other types of receivers.

However, scanning is also an incidental feature on many digitally controlled receivers or transceivers — not what they're sold for, but a convenient extra.

• On amateur radio transceivers, scanning is useful to efficiently monitor many memorized local repeaters or simplex frequencies, or to continuously sweep across a HF band rather than having to spin the big knob by hand.

• Car stereos have scan functions, which you can use when you're out of your usual area to find stations. In addition to an actual scan button, there's probably a function to find the next adjacent station, skipping over dead channels — this is also based on scanning.