Phase-locked loop coherent combiners for phased array sensor systems
Abstract
A linearized model for a coherent combiner was employed to investigate the degradation in combiner performance caused by noise in the reference signal in a phased array when the reference signal is derived from the combiner output. A power coherence factor is defined for judging the performance of the combiner, which aligns the phases of the array element signals so they can be summed to obtain maximum amplitude or power. The model is appropriate for conditions of equal amplitude and angle modulated channel signals, with channel noise signals on an equal level, Gaussian distributed, and independent. Equations for the variance of the differential phase errors associated with combiner operation and the effects of the phase errors on the average combiner output power are developed. Comparison of results with a four channel combiner also described by a linear model demonstrate that limiters are effective in reducing combiner phasing errors.
- Publication:
-
IEEE Transactions on Communications
- Pub Date:
- October 1982
- Bibcode:
- 1982ITCom..30.2329G
- Keywords:
-
- Mixing Circuits;
- Performance Prediction;
- Phase Locked Systems;
- Phased Arrays;
- Signal Mixing;
- Transmission Efficiency;
- Amplitude Modulation;
- Channel Noise;
- Feedback Control;
- Phase Error;
- Phase Modulation;
- Remote Sensors;
- Signal To Noise Ratios;
- Variance (Statistics);
- Electronics and Electrical Engineering