Data Rate Reduction Using a Digital Anti-Aliasing Filter

Abstract

In this paper we explore the limits of data rate or sample rate reduction that can be accomplished by sharp cutoff band limiting filters in a PCM data acquisition system. The results with practical analog filtering techniques are compared with those possible with digital filtering techniques. A typical 2:1 reduction in telemetry bit rate is shown to be practical using digital vs analog techniques. The resultant sample rates as low as 2.5 times the filter cutoff frequency has implications in the reconstruction algorithms which are also discussed. It is shown that by using practical and appropriate interpolation techniques or sample rate multiplication processes the data fidelity can be preserved. Thus the data user is assured that no information is being lost.