Digital radio: Its time has come

The performance of digital radio will be examined along with some of the benefits accruing from its use, and finally some long-term prognostications of its future will be made. Although this article focuses primarily on 6 GHz digital radio, the reader should recognize that 2 and 11 GHz digital radio have also found widespread use. 2 CHz is used primarily for small cross sections, often finding use as a feeder for 6 and 11 GHz. Both 6 and 11 CHz areu sed for short-haul applications up to several hundred miles. 11 GHz digital radio was introduced first because the wider bandwidth available in that band eased someof the design difficulties. 6 CHz now would normally be the facility selected because of the longer hop length over which it can be engineered. This reduces the number of repeaters required and hence reduces cost. However, due to frequency congestion, 11 GHz must often be used instead. There are, in addition, 18 GHz radio systems. These systems tend to haveu nique applicationsa nd consequently have not found widespread acceptance in the United States.