Performance of an implemented complex correlator with a simulated stationary dispersive radio channel

A hardware real-time complex correlator has been designed to be included in a radio modem with a decision feedback equaliser (DFE). Multiplexing of the two input signals has been used to implement the whole complex correlator with only one shift register with a doubled length and two sets of coefficients. Measurements on eight nondispersive channels with different phase shifts reveal a slight unbalance in the correlator. The absolute mean value (n=10) of the peak for the different channels is within 0.5 dB (5%) from mean of all the channels at high C/N (carrier-to-noise) ratio with standard deviation (n=10) less than 1 dB for each channel. At 6-dB C/N ratio, the mean absolute value of the peak decreases about 1 dB and the difference between channels is within 1 dB from the mean. The mean phaseshift is within 6 degrees from nominal. At 3-dB C/N ratio, the mean absolute value of the peak decreases about 1.5 dB and the difference between channels is within 1 dB from the mean. The mean phaseshift is within 12 degrees from nominal.<
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