Adaptor for inter-relating an external audio input device with a standard television receiver, and an audio recording for use therewith

• US 4,040,088 A
• Filed: 02/09/1976
• Issued: 08/02/1977
• Est. Priority Date: 01/10/1974
• Status: Expired due to Term

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: RCA Corporation (General Electric Company)
• Inventors: Hannan, William James
• Primary Examiner(s): Curtis, Marshall M.
• Application Number:
  US05/656,285
• Time in Patent Office: 540 Days
• Field of Search: 178/5.8, 178/5.4, 178/6.6 A, 340/324 AD, 360/19, 360/29, 358/127, 358/129, 325/45, 325/60, 325/66, 325/145, 325/344, 325/345
• US Class Current: 386/204
• CPC Class Codes: G09B 5/065 Combinations of audio and video presentations, e.g. videotapes, videodiscs, television systems
• CPC Class Codes: G09G 1/002 Intensity circuits G09G1/06 - G09G1/28 take precedence
• CPC Class Codes: G09G 5/222 Control of the character-code memory

Abstract

A standard audio cassette may be employed to provide various types of binary-coded video information, such as alphanumeric symbols and graphic elements, for display on a standard television receiver and also provide analog audio information as respective first and second components of a single composite signal applied to a suitable adaptor for inter-relating an external standard cassette player with a standard television receiver. The present invention is concerned with various improvements in the cassette recording and the adaptor. These improvements include (1) a cassette recording for simultaneous transmission of both binary-coded video information and analog audio information over a single channel, and improved coupling means in the adaptor which is responsive to such simultaneous binary and audio transmission; (2) improved coupling means in the adaptor for preventing the switching between sequentially transmitted analog audio information and binary-coded video information from being heard as audio clicks; (3) improved means for translating binary-coded alphanumeric video information which compensates for the limited video bandwidth of some standard television receivers, and (4) an improved graphic display capability, in addition to the conventional alphanumeric display capability, of a display provided on a standard television receiver.

Claims

1. A recording medium having recorded thereon on the same portion of a single channel thereof both binary coded video information and analog audio information in a predetermined form which permits said video information and said audio information to be separated on playback of said recording medium, said predetermined form comprising a first carrier at a given audio frequency phase-shift-keyed with said binary-coded video information so that a first binary value is manifested by said first carrier having a given phase and a second binary value is manifested by said first carrier having a phase of substantially 180°

with respect to said given phase, and said predetermined form further comprising a second carrier at said given audio frequency having a phase which is substantially in quadrature with said given phase, said second carrier being amplitude-modulated by said analog audio information.

2. The recording medium defined in claim 1, wherein in those recorded intervals in which all video information is absent said first carrier persists with said given phase.

3. An adaptor for inter-relating an external audio input device with a standard television receiver, wherein said device plays back simultaneously over a single channel both a first carrier and a second carrier, wherein said first carrier consists of a given audio frequency phase-shift-keyed with binary-coded video information so that a first binary value is manifested by said first carrier having a given phase and a second binary value is manifested by said first carrier having a phase of substantially 180°

with respect to said given phase, said first carrier persisting with said given phase in those recorded intervals in which all video information is absent, and said second carrier consists of said given audio frequency having a phase which is substantially in quadrature with said given phase, said second carrier being amplitude-modulated by analog audio information;

said adaptor comprising;

a video-information channel;

an audio-information channel, and

phase-sensitive coupling means responsive to the phase of said given audio frequency applied thereto over said single channel from said device for simultaneously supplying solely said first carrier to said video-information channel and solely said second carrier to said audio information channel.

4. The adaptor defined in claim 3, wherein said coupling means includes a phase-locked oscillator operating at a nominal frequency equal to said given audio frequency, first and second phase detectors, a frequency doubler, a frequency halver, means for applying said signal input in common as the signal input to both said first and second phase detectors and as the input to said frequency doubler, means for applying the output from said frequency doubler as the input to said frequency halver, means for phase-locking said phase-locked oscillator with the output from said frequency halver, means for applying the output from said phase-locked oscillator directly as an in-phase reference input to said first phase detector, and means including a 90°

phase-shifter for applying the output from said phase-locked oscillator as a quadrature reference input to said second phase oscillator as a quadrature reference input to said second phase detector, whereby the output from said first phase-detector manifests substantially solely said binary-coded video information and the output from said second phase detector manifests substantially solely said analog audio information.

5. In an adaptor for inter-relating an external audio input device with a standard television receiver;

wherein said device plays back a time-division-multiplexed audio information and frequency-shift-keyed binary-coded video information for deriving a serial signal which is applied as the signal input to said adaptor;

wherein any sequence of video information is immediately preceded by a preamble code comprising a given length of a single one of the frequency-shift keying tones, and wherein said adaptor comprises a video-information channel, an audio-information channel, coupling means for initially coupling said audio-information channel to said signal input, a preamble code detector coupled to said coupling means for continuously monitoring said signal input, and control means coupled to said preamble code detector, said coupling means and said video-information channel for decoupling said audio-information channel from said signal input and coupling said video-information channel thereto in response to the detection of said preamble code by said preamble code detector;

the improvement for eliminating crosstalk between said channels, wherein said coupling means comprises;

a normally open gate having its output coupled to said audio-information channel,

a delay means providing a given delay substantially equal to the duration of said given length preamble code coupled between said signal input and said normally open gate for passing said input signal to said audio channel only after it has experienced said given delay, and

means coupling said gate to said control means to close said gate in response to the detection of said preamble code.

6. In an adaptor for inter-relating a binary-coded video-information signal input with a raster-scan display means consisting of a television receiver which may have limited video bandwidth;

said adaptor comprising signal-translation means including a read-only-memory dot-matrix character generator responsive to a binary-coded video-information signal manifesting any given alpha-numeric character for deriving a video signal component for display of said given alpha-numeric character by said television receiver;

the improvement;

wherein said signal-translation means includes video-signal distorting means for sufficiently increasing the relative duration of those components of said video signal contributing to the display of any first line-portion of a character which is oriented normal to the direction of a raster scan line with respect to the duration of those components of said video signal contributing to the display of any second line-portion of a character which is oriented along a raster scan line to make the displayed contrast exhibited by said first-line portion substantially the same as the contrast exhibited by said second-line portion despite the limited video bandwidth of said television receiver.

7. The adaptor defined in claim 6, wherein said first line-portion is a vertical line-portion and said second line-portion is a horizontal line-portion.

8. The adaptor defined in claim 6, wherein said video-signal distorting means comprises a predetermined font for defining the shape of the characters stored in said read-only-memory dot-matrix character generator, wherein the width of any first line-portion of any character in said predetermined font is increased by at least one extra dot with respect to the first line-portion width which would be required to substantially identically display that first line-portion of that character in the absence of limited video bandwidth of said television receiver.

9. The adaptor defined in claim 6, wherein said video-signal distortion means comprises signal-delay means coupled to the output of said read-only-memory dot-matrix character generator and responsive to each successive character-manifesting segment of an indicated video signal output from said generator as it occurs for deriving a distorted video signal composed of corresponding character segments each of which begins at the same time as the undistorted segment with which it corresponds and which terminates a given fixed time interval after the termination of the undistorted segment with which it corresponds.

10. The adaptor defined in claim 9, wherein said signal-delay means includes means for adjusting the duration of said given fixed time interval.

11. In a raster-scan video display apparatus of the type including a page memory for storing at each of predetermined addresses character-information binary codes for display in a predetermined format of contiguous character spaces each of which uniquely corresponds to a different one of said predetermined addresses, each character space being composed of a predetermined two-dimensional arrangement of a given number of dot positions, and said apparatus including readout means including a dot-matrix read-only-memory character generator coupled to said page memory for deriving a video signal in accordance with said stored binary coded character information to be displayed in said predetermined format of contiguous character spaces;

the improvement;

wherein any individual one of said dot positions is uniquely specified by a respective one of a group of said character-information binary codes, and

wherein said dot-matrix read-only-memory character generator when addressed by anyone of said group of character information codes during readout of said page memory derives a video signal for displaying only a single dot in the dot position specified by the addressing one of said character-information binary codes of the displayed character space corresponding to the predetermined address of said page memory which stores said addressing one of said character-information binary codes.

12. The apparatus defined in claim 11, wherein an individual one of a set of alpha-numeric characters is uniquely specified by a respective one of a second group of said character-information binary codes, and

wherein said dot-matrix read-only-memory character generator when addressed by any one of said second group of character-information codes during readout of said page memory derives a video signal for displaying an alpha-numeric charcter specified by the addressing one of said second-group character-information binary codes in a portion of the displayed character space corresponding to the predetermined address of said page memory which stores said addressing one of said second-group character-information binary codes.

13. The apparatus defined in claim 12, wherein said read-only-memory character generator includes first and second separate read-only memory units, one of which is responsive solely to character-information codes of said first-mentioned group and the other of which is responsive solely to character-information codes of said second group.