Skanti DSC 9001, Technical Manual, Page: 144 / 178

Single Channel Receiver 914:
The single channel receiver is fixed tuned to 2187.5 kHz. It the includes antenna input protection,
pre-selector, 1. mixer where the input signal is mixed with a 1.7325 MHz signal originating from the
master oscillator signal divided by 10, followed by a narrow-band crystal filter with a centre frequency
of 455 kHz, IF amplifier, and 2. mixer. The local oscillator signal for this is generated by a 7.2528 MHz
crystal oscillator the output of which is divided by 16 to produce a frequency of 453.3 kHz. The output
from the mixer is low-pass filtered and the AF signal centred around 1.7 kHz is finally amplified in an
AF amplifier. A self-test facility is included comprising injection of a test signal at the input of the receiver
and signal check at the AF output.
SMPS/Interconnection 930:
The Switched Mode Power Supply part includes control and protection circuit. The SMPS generates
all the voltages needed in the DSC 9000 galvanically isolated from the battery. The SMPS is protected
against wrong input voltage level and polarity.
The interconnection part includes a splitter for the antenna signal allowing an additional receiver to be
connected to the same antenna, and a relay which in standby directs modulation output from an
external modem to the transmitter.
TECHNICAL DESCRIPTION DSC UNIT, DU 9001
4-6 DSC 9000 TECHNICAL MANUAL