ADJACENT CHANNEL INTERFERENCE MEASUREMENTS WITH CPFSK, CPM AND FQPSK-B SIGNALS

Abstract

This paper will present measured data in an adjacent channel interference (ACI) environment for filtered continuous phase frequency shift keying (CPFSK or FM), multi-h continuous phase modulation (multi-h CPM or CPM for short) [1] and Feher’s patented quadrature phase shift keying (FQPSK-B) [2]. This paper is an extension of my 2001 International Telemetering Conference paper on this topic [3]. The quantity measured was bit error probability (BEP) versus signal energy per bit to noise power spectral density ratio (E(b)/N(o)). The interferers were CPFSK, CPM, or FQPSK-B signals. The results presented in this paper will be for a desired signal bit rate of 5 Mb/s, one interferer 20 dB larger than desired signal (a few tests included two interferers), and various center frequency spacings, interfering signals, receivers, and demodulators. The overall ACI test effort will collect data sets at several bit rates and with one and two interferers. The results will be useful to system designers and range operators as they attempt to maximize the number of Mb/s that can be simultaneously transmitted with minimal interference in the telemetry bands.