Approximate Design Formulae and Procedures for Designing Hybrid Telemetry Systems Using an FM Carrier

Abstract

Approximate engineering design formulae are presented. These are based on Rice's model of pop plus fluctuation noise in FM receivers. Several design examples are given. One hybrid system contains a baseband acoustic signal plus a PCM/FM subcarrier and another system contains a baseband PCM signal plus two PCM/FM subcarriers. Depending on carrier modulation parameters, the design formulae show that either pop noise or fluctuation noise in the carrier discriminator output may predominate in determining the bit error probability in the baseband and/or subcarrier services. Examples of each are given. The hybrid systems mentioned above were simulated in the laboratory. Test results are presented and show satisfactory agreement with the design formulae.