Errors Resulting from Channel Filters and Adjacent Channel Crosstalk in DSB/SC Telemetry Systems

Abstract

The waveform distortion resulting from adjacent channel crosstalk and from amplitude and phase nonlinearity in channel filters limits the minimum channel spacing, and hence the bandwidth utilization efficiency of a double sideband/suppressed carrier (DSB/SC) telemetry link. The paper presents results of an analysis defining the minimum achievable mean-square error when Butterworth filters are used in the DSB demodulator/demultiplexer. With data inputs consisting of band-limited random signals, solutions are given for various combinations of data order, filter order, channel spacing, and filter cut-off. The trade-off between waveform distortion and channel spacing is illustrated, and optimum locations for the filter cut-off are defined. The irremovable error based on Weiner optimum filter theory is presented as an interesting basis for comparison.