User's Manual

Trans ceiver (DTX-A115)
11 The transceiver uses solid state components and provides a signal generator and
frequency synthesiser, up-converter, solid state RF power amplifier, duplexer, low noise
RF receiver, down-converter, digital receiver, digital signal processor and a LAN interface. The
transceiver produces a peak power output of ³170 W. The solid state design provides excellent
reliability and has no lifed items. Note that the unit is not repairable in the field and must be
returned to the manufacturer for repair. The following description is for information only.
12 The transceiver is capable of transmitting and receiving pulses of RF energy whose
centre frequency is contained in the band 9.22 to 9.48 GHz and is capable of inhibiting
the transmission of pulses of RF energy over an azimuth sector defined by the display system.
Timing Circuits and Azimuth Data Processing
13 There are two reference clock outputs, which output squarewaves with a frequency of
80 MHz ± 80 Hz. The local oscillator is phase locked to the reference clock. All the clock
and timing circuits are derived as multiples of this reference clock.
14 The local oscillator produces a sinusoidal output with a frequency of 640 MHz ± 1.3 kHz.
This is used with the transmit and receive circuits for up- and down-conversion.
Transmitter Circuits
15 The signal generation and frequency synthesis circuits use a waveform generator that
provides frequency modulated pulses at an intermediate frequency. The characteristics
of the pulses are determined by the range and rotation modes, i.e. the instrumented range selected
and the antenna rotation speed selected. The waveform generator employs digital synthesis
techniques and outputs frequency modulated pulses with a centre frequency of 60 MHz ±200 Hz.
The within pulse frequency modulation is phase contiguous.
16 The up-converter converts the IF signals from the waveform generator to RF frequency
in three stages. The bandwidth of the first intermediate frequencies within the up
converter are 60 MHz ±12 MHz and 140 MHz ±12 MHz. The bandwidth of the second
intermediate frequencies within the up converter are 500 MHz ±20 MHz and 580 MHz
±20 MHz. The bandwidth of the third intermediate frequencies within the up converter are
1140 MHz ±20 MHz and 1220 MHz ±20 MHz.
17 The RF frequency signal is fed to the solid state power amplifier, which provides an RF
output at ³170 W peak power to a duplexer located within the transceiver. Note that the
power amplifier stage is switched off between sending each of the pulses in order to maximise
receiver sensitivity. The signals from the duplexer are fed via a coaxial cable to the rotating joint
and then to the antenna.
KH1264
Chap ter 3
Is sue 2 Page 3.7