DETAILED CPM-700 PROCEDURE
27
REI
CPM-700
VLF PROBE
The VLF Probe detects and locates very low frequency devices, also known
as carrier current transmitters. These transmitters use the AC power lines as
a transmission path by placing a carrier signal on the line (FM wireless
intercoms sold through electronics dealers are an example of a carrier
current transmitter). Carrier current devices can also use other
miscellaneous wires, cables, or phone lines.
Some equipment with switching power supplies, such as computers,
copiers, fax machines, etc. may produce VLF signals on the power lines.
Selectively turn off these products one at a time to isolate which one may
be causing the interference. Unless you are sure the interference is from a
switching power supply, you must inspect the suspect equipment.
1.
Install the Headphones and turn the Audio GAIN Control to a low
(counter-clockwise) position. The status display reads:
2.
Check the Meter Calibration. The bar graph should read two or
three segments on HIGH GAIN.
3.
First, plug the VLF Probe into an AC outlet in a low security setup
area. Select HIGH or LOW GAIN as necessary. It is normal to
have three to seven segments of AC hum. (Note the level on the
bar graph for comparison.) It isolates the AC voltage while band
passing the 15 kHz to 1 MHz frequencies to the CPM-700.
4.
Plug the VLF Probe into
an outlet in the “target
area” and compare the
level displayed on the
bar graph to the level
obtained from the “set-
up area.”
5.
Adjust the Audio GAIN Control to a comfortable monitoring level
and listen for the known sound source.