Spectral Stability of Radio Transmitters in Point-to-Multipoint Access Systems

Abstract

Stability of microwave (MW) transmitters is discussed in the paper. Similarly to existing definitions of frequency and output power stability [1], we introduce spectral stability. To characterize spectral stability of radio transmitters a simple but efficient technique is shown. Presented results confirm that spectral stability gives an evident measure of MW transmitter stability under real operation conditions. Spectral stability can be measured even in the cases when frequency or output power stability can not be measured, it is difficult to measure or it does not represent well real operation conditions. A good example is shown in time domain multiple access (TDMA) point-to-multipoint (PMP) systems, where burst mode operation of terminal station (TS) transmitters is often combined with QAM modulation and automatic transmitter power control (ATPC).