Evan J. Dutton, Thomas G. Hoople, and Michael P. Roadifer

Abstract: The error variability of received PSK (MSK), QAM and QPR modulations on digital microwave common carrier links resulting from transmitted power variations and the dispersive effects of terrain multipath using a two–ray model is analyzed. These results and an earlier prediction of long–term (annual) average symbol error rate (SYE) for the above modulations are used to predict median annual received symbol error rate. Since the average SYE was used earlier to represent median conditions, average and new median SYE’s are compared. Year-to–year variability of received power and BER of common carrier microwave transmissions caused by variation of annual refractivity gradient distributions on off–axis paths is also analyzed, and it is concluded that this variability is not significant vis–à–vis the annual variability discussed above.

Keywords: microwave links; digital modulation; error rate variability; reception variability; refractivity gradient distributions; terrain multipath

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