A Comparison of Modulation Techniques for Quantized Voice Communications

Using the requirements of a quantized multiple access voice communications system as a base, an investigation of several methods of modulation was conducted. Two frequency modulation (FM) techniques and one amplitude modulation (AM) technique were investigated in detail. The AM technique is the quantized pulse position modulation-AM (QPPM-AM) method used in the U. S. Army random access-discrete address (RADA) communications system. The quantized FM techniques were investigated as possible alternates to the RADA technique. Comparisons between the techniques are made in the areas of required transmitter power, RF bandwidth, circuit complexity, and several other areas relevant to communications systems of this type. The results indicate superior performance of one FM technique in several areas.