An Analysis of the Compatibility of Spread-Spectrum and Narrowband FM Mobile Radio Systems in the 156- to 162-MHZ Band

摘要

It has been suggested that the present limited availability of channels for VHF-UHF land-mobile voice radio communication in urban areas might be alleviated by using spread-spectrum (SS) systems in the same frequency bands and geographic areas presently used by frequency-multiplexed, narrowband, frequency-modulated (FM) systems. This report presents an analysis of the compatibility of FM and direct-sequence SS systems under these conditions, and applies the results to a specific case: SS communication with ships in the Mississippi River in the New Orleans area. The analysis shows that SS and FM systems in the same frequency band and geographic area cause intolerable mutual interference that makes them incompatible. Some alternative possibilities which may be worth further investigation are given.