Apparatus useful in radio communication of digital data using minimal bandwidth

United States Patent m

Petit

[54] APPARATUS USEFUL IN RADIO

COMMUNICATION OF DIGITAL DATA
USING MINIMAL BANDWIDTH

[75] Inventor: Raymond C. Petit, Oak Harbor, Wash.

[73] Assignee: Hal Communications Corp., Urbana,

m.

[21] Appl. No.: 113,861

[22] Filed: Aug. 30,1993

Related U.S. Application Data

[62] Division of Ser. No. 726,842, Jul. 8, 1991, Pat. No. 5,253, 270.

[51] IntCl.6 H04L7/00

[52] U.S. CI 375/358; 375/270

[58] Field of Search 375/45, 58, 50,

375/60, 109

[56] References Cited

U.S. PATENT DOCUMENTS

3,534,264 10/1970 Blasbalg et al 375/58

3,536,840 10/1970 Sullivan 375/58

3,593,142 7/1971 Freeny 375/109

3,646,518 2/1972 Weinstein 371/35

4,736,388 4/1988 Eguchi 375/58

4,756,007 7/1988 Qureshi et al 375/58

4,797,898 1/1989 Martinez 375/109

5,008,903 4/1991 Berts etal 375/60

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US005491727A [ii] Patent Number: 5,491,727 [45] Date of Patent: Feb. 13,1996

5,051,899 9/1991 Ikomaetal 371/34

5,128,965 7/1992 Henriksson 375/58

5,265,151 11/1993 Goldstein 375/58

Primary Examiner—Stephen Chin

Assistant Examiner—T. Ghebretinsae

Attorney, Agent, or Firm—Woodard, Emhardt, Naughton,

Moriarty & McNett

[57] 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.

7 Claims, 13 Drawing Sheets

Microfiche Appendix Included
(258 Microfiche, 3 Pages)

Fig. 1

* Adapted for Constant Phase, Non-constant Amplitude Tone Pulses Having any of

(1) No Frequency Spectrum Sidelobes,

(2) A Dolph-Chebyshev Function Envelope or

(3) More Than One Frequency of Tones with Offset Timing of Overlapping Pulses