User's Manual

System Overview
DSS-900-KT Digital Spread Spectrum Surveillance System 3
System Overview
Your DTC-900-KT enables communication from a bodywire or internal
microphone on the battery powered TX (transmitter) unit to a briefcase
receiver/recorder. The DSS, digital spread spectrum, transmission technique
is explained in detail in the DSS-900-KT Product Data Sheet. You can obtain a
copy of this sheet from your DTC representative, but you do not need to know
these details to use the equipment.
However, there is one point of major importance that you must know when
using digital spread spectrum transmission device:
CAUTION With digital spread spectrum, the signal does not
degrade slowly with range: Audio is present and
perfect, or it’s gone!
This go/no-go situation is diagrammed in Figure1.
Figure 1Reception Distances for DSS and Analog Transmission
With an Analog Signal, the quality of reception shown in the right side of
Figure1 gradually drops off as you move further away from the transmitting
point or when the transmitter and receiver antennas are not pointed at each
other.
As the left side of Figure1 shows, a Digital Signal provides perfect reception
until a threshold is reached, and then audio is totally lost. The DTC-900-KT
RX has signal strength LEDs on its front panel as well as an audible alarm
that must be monitored to keep you within listening range and direction.
Remember: Watch the green, yellow and red string of LEDs, and do not
disable the audible tone except when security so requires. When the LEDs
drop into the yellow zone, you may lose audio at any time. Close the range to
the agent.
Audio Signal Level
Range for DSS Signal
Audio Signal Level
Range for Analog Signal