No abstract

Adaptive transversal equalization is an effective and relatively new countermeasure for dispersive multipath propagation in terrestrial digital radio networks. In this paper we describe the design and performance of a five‐tap baseband analog equalizer developed for a family of 16‐QAM, 90‐Mb/s radio systems. Laboratory measurements and field evaluation during a five‐month fading season in Palmetto, Georgia, indicate that the use of this adaptive transversal equalizer can significantly reduce the need for costly space‐diversity equipment.

The IF main amplifier is the output amplifier for the TH‐3 microwave radio receiver. The amplifier provides a 3‐ to 49‐dB gain range under control of an associated AGC circuit to compensate for radio signal fading. It was designed to operate with a carrier frequency of 70 MHz with extremely flat transmission characteristics over a 53‐ to 87‐MHz band.

TD‐3 IF circuits are designed to operate with a carrier frequency of 70 MHz with extremely flat transmission characteristics over the 60–80 MHz band. The automatic gain control of the IF main amplifier and the excess gain of the limiter together provide an effective AGC range of more than 40 dB. The units are designed to provide low noise figures and low AM‐PM conversion.