Low power FSK detection at low probability bit- errors

Abstract

For portable deep space communications applications where low power is a key requirement At the receiver, non coherent FSK quadrature detectors is suitable that enable to develop novel design and digitally implemented as VLSI circuits An important consideration in an FSK low power receiver is whether to use coherent detection or non coherent detection. This question arises because the carrier phase, while intentionally varied in the transmitter by the modulating waveform, can be altered by the channel and thus affects the accuracy of detection. When there is perfect time synchronization between the transmitter and the receiver, coherent reception can be implemented using coherent oscillators, matched filters, and amplitude detectors. When phase coherence cannot be assured, the demodulator and matched filter are followed by an envelope detector. At low power levels, in order to obtain a good quality signal, one must use a certain level of signal power while maintaining an acceptable Bit Error Rate (BER). This tradeoff is often measured as a function of energy per bit vs. noise power density (Eb/No) required at the receiver's input. Higher level modulation schemes (M-ary keying), except M-ary FSK, decrease bandwidth occupancy but increase the required received power, and hence trades power efficiency for bandwidth efficiency.