A MODIFIED SERRODYNE TECHNIQUE TO PRODUCE PHASE MODULATION HAVING EQUIVALENT HIGH-MODULATION INDEX.
NAVAL POSTGRADUATE SCHOOL MONTEREY CALIF
Pagination or Media Count:
If a sawtooth wave is used as the modulating signal for the accelerating voltage of a traveling-wave tube, the input radio-frequency signal is phase modulated to produce a frequency shift in the output signal. The use of a sine wave as the modulating signal results in the familiar sine-wave-phase-modulated carrier as the output however, it is difficult to obtain a large phase-modulation index without objectionable amplitude modulation. Specifically, if the peak-to-peak voltage swing of the modulating wave produces a phase shift of more than 2 pi radians in the radio-frequency carrier, the amount of amplitude modulation becomes severe. To overcome this severe amplitude modulation and yet produce large phase deviations in the carrier signal, i.e., broadband phase modulation, it is possible to chop the modulating waveform just as a ramp is chopped into a sawtooth. This thesis presents a design for so modifying the modulating signal be it sine wave, sawtooth, exponential or complex, and shows the resultant output spectrum of a traveling-wave tube whose carrier has been modulated by a chopped sine wave. Author
- Electrical and Electronic Equipment