Speech component coded multiplex carrier wave transmission

• US 3,991,273 A
• Filed: 10/04/1943
• Issued: 11/09/1976
• Est. Priority Date: 10/04/1943
• Status: Expired due to Term

• Current Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Original Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Inventors: Mathes, Robert C.
• Primary Examiner(s): Farley, Richard A.
• Assistant Examiner(s): Birmiel, H. A.
• Application Number:
  US02/504,899
• Time in Patent Office: 12,090 Days
• Field of Search: 250/9.28, 250/17.410, 179/15.3, 179/171.5-171.13, 179/1.5 R, 179/1.5 FS, 179/15 BM, 179/15 FD
• US Class Current: 380/38
• CPC Class Codes: G10L 21/00 Speech or voice signal processing techniques to produce another audible or non-audible signal, e.g. visual or tactile, in order to modify its quality or its intelligibility G10L19/00 takes precedence
• CPC Class Codes: H04K 1/04 by frequency scrambling, i.e. by transposing or inverting parts of the frequency band or by inverting the whole band

Abstract

1. In a secret telephone transmission system in which speech waves are analyzed into component speech-defining low frequency signals which are coded in stepped wave form, a group of frequency modulators of the same type and same average frequency, means to impress said signals of stepped wave form on the respective frequency modulators to produce a plurality of frequency modulated waves of the same average frequency, and means to translate said last waves into frequency modulated waves accurately positioned at different frequency levels comprising a separate amplitude modulator for shifting the frequency of each such frequency modulated wave, and means to supply to said amplitude modulators carrier waves of accurately spaced frequency comprising a source of base frequency waves of highly constant frequency and a harmonic generator for fixing the frequencies of said supplied carrier waves.

Claims

1. In a secret telephone transmission system in which speech waves are analyzed into component speech-defining low frequency signals which are coded in stepped wave form, a group of frequency modulators of the same type and same average frequency, means to impress said signals of stepped wave form on the respective frequency modulators to produce a plurality of frequency modulated waves of the same average frequency, and means to translate said last waves into frequency modulated waves accurately positioned at different frequency levels comprising a separate amplitude modulator for shifting the frequency of each such frequency modulated wave, and means to supply to said amplitude modulators carrier waves of accurately spaced frequency comprising a source of base frequency waves of highly constant frequency and a harmonic generator for fixing the frequencies of said supplied carrier waves.