Countersurveillance Probe Monitor (REI) CPM-700 (serial number 39492)

The CPM-700 is a broadband receiver for the detection and location of eavesdropping devices (bugs), developed and and built by Research Electronics Inc. (REI) in Cookeville (USA) around 1988. 

Once a room is sweeped, the unit can be set to monitor-mode and the treshold is adjusted so that the alarm is just silent. Whenever someone brings a new eavesdropping device into the area, or when a remote controlled or timed device becomes active, this will trip the acoustic alarm. Any eavesdropping device found, will be hear through the built-in speaker or, better, via headphones. Apart from using one of the probes to pick up RF signals, the CPM-700 can also be used to check any type of cable for acoustic (audio) or carrier bugs using the AUX input on the right side. This can be used, for example, to check analogue telephone lines (PSTN)