US 5,491,727 AGranted

Apparatus useful in radio communication of digital data using minimal bandwidth

AssigneeHal Communications

InventorRaymond C. Petit

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Abstract

Apparatus useful for communicating digital data using a steady stream of pulses which achieve very high ratios of bit rate per occupied bandwidth using digital signal synthesis techniques to produce a stream of constant phase tone pulses having exceptional spectral compactness. An optimal pulse is formed having either no sidelobe energy in the frequency spectrum and few to no sidelobes in the time domain, or no sidelobes in the time domain and minimal sidelobe energy in the frequency spectrum. Each optimal pulse has a specially shaped, non-constant amplitude envelope. The embodiment having no sidelobes in the time domain uses both a pulse envelope corresponding to a Dolph-Chebyshev function and more than one frequency of tones with offset timing of overlapping tone pulses so that their envelopes go to zero at different times. The invention is particularly well suited for single sideband radio communication at frequencies below 30 MHz.

Claims7

Dependent claims

An adaptive system for adjusting operating parameters of a transmitter used for transmitting digital data which system is operable over marginal signal paths at high ratios of bit rate per occupied bandwidth comprising:

a transmitter for transmitting said digital data, said transmitter including:
adjusting means for adjusting the operating parameters of said transmitter in response to optimal operating parameter data transmitted from a receiver receiving said digital data, by selecting a data encoding format of said transmitted digital data;
a receiver for receiving said digital data separated from said transmitter by a signal path, said receiver including:
means for determining a quality of said signal path from at least two different reception parameters associated with said received digital data;
means for determining optimal operating parameters of said transmitter based upon said determination of the quality of said signal path;
and
means for relaying said optimal operating parameter data to said transmitter over said signal path.

4 more elements

Dependencies are inferred from the claim text.