Digital HF modem performance measurements using HF link simulators

One testing technique is that of using channel simulators which can provide identical statistical stress on the modems under test. A recommended set of tests, which include testing with simulated interference conditions, has been included as Annex B in the proposed NATO Standard 4285. Although not perfect, this set of tests is believed to be a reasonable compromise between required test time and modem characterization. If one examines this section of the Standard, however, he discovers that some of the recommended tests (those involving bit error rate vs. average signal-to-noise ratio) require what might be considered an unreasonable time to conduct. The authors discuss the basis of those time recommendations and some of the logical consequences of them.<>