Communication system

• US 4,358,857 A
• Filed: 05/09/1958
• Issued: 11/09/1982
• Est. Priority Date: 05/09/1958
• Status: Expired due to Term

• Current Assignee: Hughes Electronics Corporation (Rtx Corporation)
• Original Assignee: Magnavox (Koninklijke Philips N.V.)
• Inventors: Gleason, Joseph P., Posthumus, Harry G.
• Primary Examiner(s): Birmiel, Howard A.
• Application Number:
  US04/735,089
• Time in Patent Office: 8,950 Days
• Field of Search: 178/22, 250/6.6, 250/95, 179/1.5, 179/1.5 R, 179/1.5 S, 455/26, 455/30
• US Class Current: 380/31
• CPC Class Codes: H04K 1/006 by varying or inverting the phase, at periodic or random intervals

Abstract

1. In combination, a first source for producing a first signal representative of intelligence to be transmitted from one point to another, second source for producing a binary carrier signal having a first voltage level and a second voltage level, means responsive to the first signal and to the binary carrier signal for frequency-modulating the carrier signal in accordance with the first signal to produce a modulated intelligence signal having first and second voltage levels and exhibiting transitions between the same, a third source for producing a binary encoding signl having first and second voltage levels and exhibiting transitions between such levels in conformance with an apparently random predetermined sequence of variations in the encoding signal between the first and second voltage levels at different multiples of a particular time interval, and circuit means coupled to said modulating means and to said third source for inverting the voltage level of the encoding signal from the first voltage level to the second voltage level and from the second voltage level to the first voltage level and upon the simultaneous occurrence of the second voltage level in the intelligence signal to produce an encoded intelligence signal.

Claims

1. In combination, a first source for producing a first signal representative of intelligence to be transmitted from one point to another, a second source for producing a binary carrier signal having a first voltage level and a second voltage level, means responsive to the first signal and to the binary carrier signal for frequency-modulating the carrier signal in accordance with the first signal to produce a modulated intelligence signal having first and second voltage levels and exhibiting transitions between the same, a third source for producing a binary encoding signal having first and second voltage levels and exhibiting transitions between such levels in conformance with an apparently random predetermined sequence of variations in the encoding signal between the first and second voltage levels at different multiples of a particular time interval, and circuit means coupled to said modulating means and to said third source for inverting the voltage level of the encoding signal from the first voltage level to the second voltage level and from the second voltage level to the first voltage level and upon the simultaneous occurrence of the second voltage level in the intelligence signal, to produce an encoded intelligence signal.

2. In combination, a first source for producing a first signal representative of intelligence to be transmitted from one point to another, a second source for producing a rectangular-wave carrier signal having a first voltage level and a second voltage state, means responsive to the first signal and the carrier signal for frequency-modulating the carrier signal in accordance with the first signal to produce a modulated intelligence signal having a rectangular-wave shape, a third source for producing an encoding signal having a rectangular-wave shape and having first and second voltage levels and exhibiting transitions between such levels in conformance with an apparently random predetermined sequence of variations in the encoding signal between the first and second voltage levels at different multiples of a particular time level, and circuit means coupled to said modulating means and to said third source for modifying the voltage of the encoding signal in conformance with the transitions in the voltage of the modified intelligence signal to produce an encoded intelligence signal exhibiting first voltage transitions corresponding to voltage transitions in the encoding signal during the first voltage level in the modulated intelligence signal and exhibiting further voltage transitions opposite to the voltage transitions in the encoding signal during the second voltage level in the modulated intelligence signal.

3. In a coded communication system, the combination of, a first source for producing a first signal representative of intelligence to be transmitted, a second source for producing a rectangular-wave binary carrier signal, means responsive to the first and second signals for frequency-modulating the carrier signal with the first signal to produce a rectangular-wave binary frequency-modulated signal having a first voltage level and a second voltage level and exhibiting voltage transitions between such levels at frequencies at any instant dependent upon the intelligence to be transmitted, a third source for producing a series of regularly recurring clock timing pulses, means responsive to the clock pulses and to the modulated intelligence signal for causing each of the voltage transitions of the modulated intelligence signal to occur in timed coincidence with the clock pulses, a fourth source for producing a binary rectangular-wave encoding signal having first and second voltage levels and occurring at different multiples of a particular time interval, means responsive to the clock pulses and to the encoding signal for obtaining each transition in the encoding signal in timed coincidence with a corresponding one of the clock pulses, and circuit means responsive to the encoding signal and to the modulated intelligence signal for modifying the encoding signal in conformance with the transitions in the modulated intelligence signal to produce a rectangular wave binary encoded intelligence signal exhibiting first voltage transitions corresponding to voltage transitions in the encoding signal during the first voltage level in the modulated intelligence signal and exhibiting further voltage transitions opposite to the voltage transitions in the encoding signal during the second voltage level in the modulated intelligence signal.

4. In a coded communication system in which a rectangular wave frequency-modulated binary coded signal is transmitted to a remote point, such coded signal having first and second voltage levels and exhibiting transitions between such levels in correspondence with a modulated intelligence signal having frequency modulations representing the transmitted intelligence and in accordance with apparently random predetermined transitions in a rectangular wave binary encoding signal wherein the encoded intelligence signal has voltage levels corresponding to the voltage levels in the encoding signals during the occurrence of the first voltage levels in the intelligence signals and wherein the encoded intelligence signal has voltage levels opposite to the voltage levels in the encoding signal during the occurrence of the second voltage level in the intelligence signal and where the random transitions occur at different multiples of a particular periodicity between the successive voltage variations in the encoding signal, the combination of, a source for producing a rectangular wave binary decoding signal synchronized with the encoding signal and having first and second voltage levels and apparently random transitions therebetween conforming to the same code sequence as the encoding signal, a balanced decoder coupled to the source and responsive to the decoding signal and to the encoded intelligence signal for causing the voltage levels of the encoded intelligence signal to be inverted by the decoding signal during the second voltage level in the intelligence signal to obtain the modulated intelligence signal, and discriminator means coupled to the balanced decoder and responsive to the frequency modulations in the modulated intelligence signal for recovering the intelligence from the modulated intelligence signal.

5. The combination defined in claim 4 in which a band pass filter is interposed between the balanced decoder and the detector means to pass the modified signal to the detector means.