User's Manual

14 The transceiver electronics comprise radar control and timing, waveform generator,
solid state transmitter, duplexer, low noise RF receiver, digital receiver, signal processor
and communications interface.
15 The waveform generator provides frequency modulated pulses at an intermediate
frequency (IF), whose characteristics are determined by the range modes. The IF pulses
are mixed with a local oscillator to provide an RF frequency signal to the solid state transmitter,
which provides an RF output at 170 W peak power to a duplexer located within the transceiver.
The signals from the duplexer are fed via a coaxial cable to the rotating joint and then to the
antenna.
16 Return signals from the antenna are fed through the rotating joint to the transceiver,
which routes the received signal via the duplexer to an internal low noise RF receiver,
digital receiver and signal processor. Sensitivity time control (STC) is applied to the RF receiver
to increase the dynamic range. The transceiver provides one analogue SYNC and one analogue
VIDEO coaxial output to the display system.
17 Internal monitoring of the transmitter and receiver performance is provided, therefore no
external components are required to ensure operation is satisfactory.
18 The power supply, located in the cast enclosure, provides the DC supplies for the
transceiver from the 110 V/220 V single phase mains input. The power supply is
autoranging, so no setting up is required for the input voltage.
Drive Con trol Unit
19 The Drive Control Unit provides a variable frequency 3 phase supply for the antenna
turning motor. The Drive Control Unit accepts a 220 V single phase mains supply. It
generates a 3 phase supply at either 25 Hz (for low speed antenna operation (22 RPM)) or 50 Hz
(for high speed antenna operation (44 RPM)), set up by links made on installation. The default
input frequency is 50 Hz to provide these output frequencies. If a different input frequency or
output frequency are used, the Drive Control Unit must be reprogrammed as described in
Chapter 5. The Drive Control Unit provides a 'soft start' of nominally 2 seconds, and a 'soft stop'
of nominally 10 seconds for the antenna. This reduces torque when the antenna is started and
stopped. If required, a transformer can be fitted to the mains input to enable the unit to be used
with 110 V mains.
20 The Drive Control Unit has two indicators and a switch on the top of the unit. The
indicators are MAINS ON, which is lit when the single phase mains input is present and
MOTOR ON, which is lit when the 3 phase output to the motor is present. The switch provides a
man aloft safety function, and is key operated. The key can only be removed when the switch is
set to OFF. When set to OFF, the 3 phase output is inhibited, thus preventing the antenna from
rotating. When set to ON the key is captive in the switch and the 3 phase power to the antenna
motor is enabled. Note that when the switch is set to OFF the MOTOR ON indicator will always
be unlit.
KH1264
Chap ter 1
Is sue 2 Page 1.5