Research to Optimize Linked Compading Techniques for Noise Reduction in FM and FDM/FM Communications

Link Plux Corporation and TRW, Inc. have recently been successful in implementing miniaturized linked compander technology using digital signal processing (DSP). The current product removes noise from voice transmissions across HF SSB radio (documented US Government testing measures 22 dB average improvement in S/N, with 47 dB maximum). Current proven products apply to AM/SSB signals at MF, HF, VHF and UHF. The application of linked companding technology to improve the complex waveform generated by frequency modulation (FM) is new. Analysis and testing indicate a 6 to 9 dB improvement at threshold can be realized. This should translate into greater clarity and range for any FM radio. The commercial point-to-point FM radio market is one of the largest radio markets in the world. In the area of satellite communications, tests at RCA Laboratories have shown that the use of fixed ratio companders can more than double the capacity of an FDM/FM satellite transponder with no loss of quality. The linked companding product would utilize an infinite-ratio compressor and should have an even greater impact in increasing the capacity of FDM/FM satellite communications. Anticipated Benefits: Anticipated applications are for FM landmobile radios, FDM/FM satellite communications, and all other FM point-to-point radios.