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Abstract
Possibilities of the use of incoherent carriers for transmission of analogue and digital signals have been established. It has been shown that for analogue signals a message SNR of 60–70 db, with incoherent carrier, can be obtained by using compound pulse modulation and carrier clipping. The use of incoherent carriers eliminates the fading distortion, normally very disturbing with the coherent-carrier systems.
For On-Off digital transmission through noisy fading channels, an error rate of 1 × 10−5 has been obtained with incoherent carriers for a CNR of 17 db, the sine wave carriers under similar conditions require 53 db CNR for the single channel reception. Thus in effect, the noise carrier provides a signal gain of 36 db. Minimum noise-carrier bandwidths required to obtain fading protection have been obtained, and it was found to depend on the method of noise-carrier generation. Different methods of noise-carrier generation have been studied. The diversity effectiveness of noise-carrier systems has been evaluated and it has been shown to be equivalent to five-fold equal gain predetection combining system with independent fading channels.