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.

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.