Microwave, RF & LF Signal Sources & Sensor Systems

Spectral Line Systems Ltd

Research, Custom Design & Manufacture

Frequency Synthesizers

9880.5 MHz Frequency Synthesizer
Photograph 1
Output Spectrum, Span 100 MHz, 10 dB / div.
2-Source Phase Noise without 3 dB Correction
Frequency Channels at 7 KHz Increments

Spectral Line Systems Ltd specialises in high spectral purity low phase noise synthesizers generating a relatively small number of channels. This type of synthesizer finds applications in Doppler radar and other systems where noise and spurious signals must be kept to a minimum.


Synthesizer Example

The photograph opposite shows an example of a low noise synthesizer generating a number of frequency channels centred on 9880.5 MHz.


This synthesizer was made for use as the receiver local oscillator in a customer's research programme investigating the effects of phase perturbations in the propagation path of signals received from communications satellites. In addition to a requirement for exceptionally low phase noise and spurious signals, the output signal long term frequency stability had to be much better than obtainable from the ultra-low phase noise crystal oscillator multiplied up to the final output frequency. A further requirement was that the output frequency should be adjustable in 7 KHz steps over a small range, to compensate for ageing and Doppler shift in the signal transmitted by the satellite. An auxiliary 10 MHz output signal locked to the microwave signal was also required for the synchronisation of other instrumentation.


The block diagram below illustrates the technique employed to meet all of the above requirements.