Citation
Abstract
A Weighted Integrate-and-Dump Filter (WIDF) is presented that results in reducing those losses in telemetry symbol SNR which occur in digital Integrate-and-Dump Filters (IDFs) when the samples are not phase locked to the input data symbol clock. The Minimum Mean Square Error (MMSE) criterion is used to derive a set of weights for approxtimating the analog integrate-and-dump filter, which is the matched filter for detection of signals in additive white Gaussian noise. This new digital matched filter results in considerable performance improvement compared to unweighted digital matched filters. An example is presented for a sampling rate of four times the symbol rate. As the sampling offset for phase) varies with respect to the data symbol boundaries, the output SNR varies 1 dB for an unweighted IDF, but only 0.3 dB for the optimum WIDF, averaged over random data patterns. This improvement in performance relative to unweighted IDF means that significantly lower sampling and processing rates can be used for given telemetry symbol rates, resulting in reduced system cost.
Details
- Volume
- 42-91
- Published
- November 15, 1987
- Pages
- 174–185
- File Size
- 463.7 KB