An Experimental Evaluation of PAM-NRZ/FM

Abstract

The results of a hardware evaluation of PAM-NRZ/FM are presented along with a description of the conditions under which the data were taken. State-of-the-art commutators, transmitters and receivers procured from commercial sources were utilized in the evaluation tests. The principal characteristics of PAM-NRZ/FM considered were data channel response, performance at low signal-to-noise ratios compared to equivalent FM/FM and PCM/FM systems, linearity, crosstalk, overmodulation, transmission noise, data resolution, decommutator synchronization and a comparison of performance at commutation rates of 25,000, 100,000 and 250,000 samples per second. The test data indicates that PAM-NRZ/FM is capable of 2 to 5 percent data transmission accuracy and that performance at low RF levels is comparable to that of FM/FM or PCMJFM under the test conditions specified.