transmit a beep followed by a period of silence. The receiving beacon
uses the strength of the "beep-beep-beep" signal to locate
the buried transceiver. The period between the beeps should be silent.
Most older analog beacons (e.g., the
and F2) and
some of the newer digital beacons (e.g., the
and early versions of the
transmit a weak signal during what should be the "silent"
period. This continuous background tone is sometimes referred to
as "continuous carrier." The red line in the following
picture illustrates this continuous background signal.
Of course, the receiving beacon always receives some ambient
background "noise," but the continuous signal described
here is actually transmitted by the transceiver.
You can test if a beacon is transmitting a continuous background
signal as follows:
||Set the beacon in question to Transmit.
||Set an analog beacon to Search.
||Move the beacons two or three meters
apart. You should hear the beep-beep-beep of the transmitting
||Now move the beacons closer together.
Listen for either silence between the beeps (a good thing)
or for a faint-but-continuous tone in the background (a
The background signal is not a huge problem with a single burial,
but it can cause major problems for digital transceivers during
a multiple burial, because the background signal will mask the other transmitters.
This is most obvious when the transceiver that is emitting a
continuous carrier is closer to the searcher than the second
transmitter (i.e., when the searcher attempts to "mark" the
continuous carrier transmitter). A continuous carrier can also
cause digital beacons to mistakenly report that there is more
than one transmitter (i.e., "ghosts").
The Pieps DSP beacons
blink the little man icon
when it senses a background signal (i.e., an "old device").
See the users manual