International Telemetering Conference Proceedings / October 25-28, 1993 / Riviera Hotel and Convention Center, Las Vegas, Nevada / A composite PCM/FM+FM/FM system combines the spectral efficiency of the analog system with the accuracy of a PCM system when needed for specific sensors and allows the direct transmission of binary computer words if necessary. A PCM/FM+FM/FM system combines the bit sequence with the modulated subcarriers at baseband and the resultant modulates the carrier. In the design of the composite system it is of importance to determine the impact of the subcarriers on the bit error rate of the bit sequence and to determine the degradation of the output signal-to-noise ratio of the subcarrier channels caused by the bit sequence.