A Spectrum Prediction Technique for AM Pulses of Arbitrary Shape

The accuracy of predicting spectra for pulsed AM systems is greatly improved by merely describing the time-domain signal with more accuracy. Specifically, a series of straight lines is used to approximate an arbitrary signal shape. Experimentally, a pulse-shaping network and spectrum analyzer were used to generate and record various time- and frequency-domain shapes. These results were compared to the theoretical plots generated by the straight line approximation technique. The improvement of this technique over the method of assigning a perfect square pulse is illustrated by plots and photographs. The theoretical results are good enough to almost eliminate the need for a frequency- spectrum signature if the signal can be observed in the time domain (by an oscilloscope).