www.radartutorial.eu Radar Basics

Master Oscillator

At fully coherent radar all frequencies produced internally have a defined phase shift. This is reached by this that all control pulses and also all frequencies are derived from a highly stable master oscillator. The master oscillator/frequency generator provides low phase noise local oscillators and the radar system clocks. The following wiring example shows the principle of operation of a master oscillator and the deriving of clocks and upward mixed frequencies. Both frequencies of the example given are needed for synchronous detection of the superheterodyne receiver of frequency diversity radar. (These frequencies are provided by a local oscillator otherwise.)

20 MHz Masterclock
60 MHz
frequency
fine adjust
15 MHz
60 MHz
82.5 MHz
7,5 MHz
67.5 MHz

Bild 1: Taktgenerator für Masterclock und Frequenz-Ableitungen für Demodulation und Exciter.

20 MHz Masterclock
TP 1
60 MHz
frequency
fine adjust
TP 2
TP 3
TP 4
TP 5
82.5 MHz
TP 6
TP 7
67.5 MHz

Figure 1: Masterclock generator and the deriving of frequencies for demodulation and the exciter.

Q P L F T3:1 T4:1 T2:1 F F F M M BF BF L L TP1 TP2 TP3 TP4 TP5 TP6 TP7
20 MHz Masterclock
TP 1
60 MHz
frequency
fine adjust
TP 2
TP 3
TP 4
82.5 MHz
TP 5
TP 6
TP 7
67.5 MHz

Figure 1: Masterclock generator and the deriving of frequencies for demodulation and the exciter.
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Both continuous wave frequencies (67.5 MHz and 82.5 MHz) are needed to the down conversion of the intermediate frequencies to the baseband. The video signals of the received echo signal arise at this down conversion.