Showing papers on "Continuous phase modulation published in 1968"

Dual pilot control for re-phasing a signal carrier

Abstract: In a communication system transmitting both the lower sideband of a modulated signal and the carrier, the phase shift of the recovered carrier relative to the signal spectrum can be adjusted to improve signal demodulation. Two pilot frequencies, one higher than and one lower than the signal frequencies to be transmitted and having a known phase relationship are mixed with the signal for modulation by the carrier and transmission. In the receiver, the signal is demodulated with a recovered carrier signal and the pilot frequencies are phase compared to determine the magnitude and direction of their relative phase shift. The recovered carrier signal is then phase shifted to reduce the relative phase shift of the pilot frequencies to within a limited range.

On the bandwidth of a waveguide

Abstract: The fundamental question of what waveguide run length can be used to carry a modulated carrier with a given modulation bandwidth down the guide without serious distortion is pragmatically answered by appealing to the known solution for the propagation of a pulsed carrier down the same waveguide. Universal-type curves of usable bandwidth (normalized to the carrier frequency) versus waveguide length (normalized to the free space wavelength at the carrier frequency) with the cutoff-to-carrier frequency as a parameter are given.