An experimental M-QAM modem using amplifier linearization and baseband equalization techniques
Abstract
A technique for removing AM/AM and AM/PM distortion in microwave amplifiers for digital M-QAM transmission is presented. This technique allows almost total elimination of these nonlinear distortions for peak drive levels approaching saturation in cases where post-amplifier filtering is acceptable for spectral containment. Also presented is a novel technique for baseband receiver equalization. Laboratory measurements are presented for performance of a breadboard modem using these techniques for 16- and 64-state QAM signalling. These signal types are important ones in the push toward higher spectral efficiency digital microwave transmission.
- Publication:
-
NTC 1982; National Telesystems Conference
- Pub Date:
- 1982
- Bibcode:
- 1982ntc..confR...3G
- Keywords:
-
- Amplitude Modulation;
- Microwave Amplifiers;
- Modems;
- Signal Distortion;
- Block Diagrams;
- Breadboard Models;
- Digital Techniques;
- Linearization;
- Quadratures;
- Electronics and Electrical Engineering