Technique for providing compatibility between high-definition and conventional color television

• US 4,476,484 A
• Filed: 06/24/1982
• Issued: 10/09/1984
• Est. Priority Date: 06/24/1982
• Status: Expired due to Term

• Current Assignee: AT&T Intellectual Property I LP (AT&T, Inc.)
• Original Assignee: AT&T, Inc.
• Inventors: Haskell, Barin G.
• Primary Examiner(s): Martin, John C.
• Assistant Examiner(s): McDowell, E. A.
• Application Number:
  US06/391,973
• Time in Patent Office: 838 Days
• Field of Search: 358/11, 358/12, 358/141, 358/142, 358/16
• US Class Current: 348/437.1
• CPC Class Codes: H04N 11/24 High-definition television systems
• CPC Class Codes: H04N 7/06 Systems for the simultaneous transmission of one television signal, i.e. both picture and sound, by more than one carrier H04N7/084, H04N7/087 take precedence

Abstract

The present invention relates to a compatible high-definition television (CHDTV) color picture signal which is capable of conversion by simple and inexpensive means into either a HDTV composite color picture signal for use by a HDTV receiver or an associated conventional television system (ACTS) color picture signal for use by an ACTS receiver. The present CHDTV color picture signal comprises (a) a first line scan rate which is the same as that of the ACTS signal, (b) a first line signal of a HDTV camera signal produced at a second line scan rate which is time stretched and transmitted as is at the first line scan rate in a first portion of the CHDTV signal bandwidth, and (c) a second line signal of the HDTV camera signal which is time streched and transmitted as a line differential signal on a vestigial sideband carrier signal in a second portion of the HDTV signal bandwidth.

Claims

1. An arrangement for generating a compatible high-definition television (CHDTV) color picture signal including a predetermined bandwidth and format, the arrangement comprising:

means, responsive to a HDTV composite color picture signal as generated by HDTV camera color tubes at a first line scan rate, for stretching each of at least a first and a second sequential line signal of the HDTV composite color picture signal in time by a factor which is a predetermined submultiple of the first line scan rate to generate respective line signals which are at the same line scan rate as that of an associated conventional television system picture signal;

means, responsive to the at least first and second time stretched line signals from the time stretching means, for transmitting the first stretched line signal as is in a first portion of the predetermined bandwidth of the CHDTV color picture signal and, concurrent therewith, for transmitting the second stretched line signal either one of as is or as a line differential signal in a second portion of the predetermined bandwidth of the CHDTV color picture signal on a vestigial sideband carrier signal which is separated from a color subcarrier of the first line signal by a frequency which is substantially equal to that of a baseband color subcarrier frequency of the associated conventional television system color picture signal.

2. An arrangement for generating a CHDTV color picture signal according to claim 1 wherein the transmitting means is further capable of transmitting an audio signal associated with the CHDTV color picture signal in a frequency band which is associated with an audio subcarrier comprising a frequency substantially equal to the addition of an audio subcarrier frequency and a color subcarrier frequency of the associated conventional television system color picture signal format.

3. An arragement for generating a compatible high-definition, television (CHDTV) color picture signal according to claim 1 wherein the arrangement further comprises:

means capable of being responsive to color signals associated with the HDTV camera color tubes for generating a HDTV composite picture signal to the time stretching means comprising a frequency scaled up version of the associated conventional system color picture signal including a lumiance bandwidth capable of providing a number of picture line signals at the first line scan rate which is a predetermined multiple of the line scan rate of the associated conventional television system color picture signal, a frame and field rate which is the same as that of said associated conventional television system color picture signal, and chrominance information comprising first and second chroma components which are formed on sidebands of a separate color subcarrier within said luminance bandwidth which is a fixed multiple of the line scan rate of the associated conventional television system color picture signal and includes a ratio of each of the chroma component bandwidths to the luminance bandwidth which is similar to that of the associated conventional television system color picture signal.

4. An arrangement for generating a CHDTV color picture signal according to claim 3 wherein the means capable of generating a HDTV composite picture signal comprises:

means capable of converting the color signals (R,G,B) from the HDTV camera color tubes into appropriate luminance (Y) and first and second chromiance (I,Q) signal components; and

means responsive to the luminance and chrominance signal components from the converting means for modulating each of the first and second chrominance components into appropriate sideband signals of a predetermined color subcarrier frequency, which modulated first and second chrominance signal components are added to the luminance signal for producing the HDTV composite picture signal.

5. An arrangement for generating a CHDTV color picture signal according to claim 3 or 4 wherein

the time stretching means is capable of receiving the at least first and second line signal of the HDTV composite signal in sequence and generating as an output at least a first and a second line signal in parallel on separate paths at the second line scan rate of the CHDTV color picture signal;

and

the transmitting means comprises;

means responsive to the output from said time stretching means for generating a line differential signal which is the difference between said second time stretched line signal and an approximation or prediction of said second time stretched line signal which is generated from a linear or other combination of the first and a third time stretched line signal, said first and third time stretched line signals being generated by the time stretching means from line signals occurring just before and after the second line signal in the HDTV composite signal; and

means for modulating the line differential signal onto a vestigial sideband carrier signal and adding the resultant vestigial sideband signal to the first time stretched line signal from said time stretching means for providing the CHDTV color picture signal.

6. A receiver for converting a compatible high-definition television (CHDTV) color picture signal into a HDTV composite color picture signal capable of use by a HDTV receiver, the CHDTV color picture signal comprising a predetermined bandwidth, a line scan rate which is the same as an associated conventional television color picture signal, a first line signal which is sent as is and containing a first color subcarrier frequency in a first portion of the predetermined bandwidth of the CHDTV color picture signal, and a second line signal which is sent concurrent with the first line signal in a second portion of the predetermined bandwidth of the CHDTV color picture signal either one of as is or as a line differential signal on a vestigial sideband carrier frequency which is separated from the first color subcarrier frequency by a frequency equal to that of a baseband color subcarrier frequency of the associated conventional television system color picture signal, the receiver comprising:

means for receiving the CHDTV color picture signal and separating the first CHDTV color picture line signal and the second CHDTV color picture line signal on the vestigial sideband carrier for transmission over separate paths;

means capable of transforming the second line signal received via the vestigial sideband carrier into a recovered second CHDTV color picture line signal within a frequency band of the received first CHDTV color picture line signal; and

time compression means capable of receiving the first CHDTV color picture line signal and the recovered second CHDTV color picture line signal in parallel at the CHDTV color picture line scan rate and generating as an output a first and a second HDTV composite color picture line signal in sequence at a line scan rate which is a predetermined multiple of the CHDTV color picture signal line scan rate.

7. A receiver according to claim 6 wherein the transforming means comprises:

demodulating means capable of demodulating the vestigial sideband line differential signal with the vestigial sideband carrier frequency to generate a line differential signal in the frequency band of the first CHDTV color picture line signal;

means capable of generating an approximation of the second CHDTV color picture line signal from both the first CHDTV color picture line signal from the separation means and a stored previous value of a first CHDTV color picture line signal received in the receiver in an immediately prior HDTV color picture signal; and

adding means responsive to the line differential signal from the demodulation means and the approximation of the second CHDTV color picture line signal from the generating means for providing a recovered second HDTV color picture line output signal.

8. A receiver for converting a compatible high-definition television (CHDTV) color picture signal into an associated conventional television system color picture signal, the CHDTV color picture signal comprising a predetermined bandwidth, a line scan rate which is the same as that of the associated conventional television color picture signal, a first line signal which is sent as is and containing a first color subcarrier frequency in a first portion of the predetermined bandwidth of the CHDTV color picture signal, and a second line signal which is sent concurrent with the first line signal in a second portion of the predetermined bandwidth of the CHDTV color picture signal either one of as is or as a line differential signal on a vestigial sideband carrier frequency which is separated from the first color subcarrier frequency by a frequency equal to that of a baseband color subcarrier frequency of the associated conventional television system color picture signal, the receiver comprising:

filtering means for passing only a frequency band within the first portion of the predetermined bandwidth of the CHDTV picture signal including a bandwidth substantially corresponding to a luminance bandwidth of the associated conventional color picture signal format; and

modulating means for modulating chrominance information signals associated with only the first line signal of the CHDTV color picture signal with the vestigial sideband carrier frequency to produce appropriate chrominance information signals within the luminance bandwidth of the associated conventional system color picture signal.

9. A receiver according to claim 8 wherein the modulating means comprises:

means capable of passing therethrough only a predetermined frequency band centered on the first color subcarrier frequency which is no wider than a chrominance bandwidth in the associated conventional system color picture signal while rejecting all other frequencies within the CHDTV color picture signal; and

a modulator capable of modulating the resultant signal from the frequency band passing means and the vestigial sideband carrier frequency to produce the appropriate chrominance information signals within the luminance bandwidth of the associated conventional system color picture signal.

10. An arrangement for generating a high definition television (HDTV) composite color picture signal capable of use by a HDTV receiver, the arrangement comprising:

means responsive to color signals (R,G,B) from a HDTV camera color tubes for converting the camera color tube signals into appropriate luminance (Y) and first and second chrominance (I, Q) signal components; and

means responsive to the luminance and chrominance signal components from the converting means for generating the HDTV composite color picture signal comprising a frequency scaled up version of an associated conventional system color picture signal including a luminance bandwidth capable of providing a number of picture line signals and a line scan rate which is a predetermined multiple of the line scan rate of the associated conventional system color picture signal, a frame and a field rate which is the same as that of the associated conventional system color picture signal, and chrominance information comprising first and second chroma components which are formed on sidebands of a separate color subcarrier within the luminance bandwidth which is a fixed multiple of the line scan rate of the associated conventional system color picture signal and includes a ratio of each of the chroma component bandwidths to the luminance bandwidth which is similar to that of the associated conventional system color picture signal.

12. An arrangement according to claim 10 or 11 wherein the arrangement further comprises:

means capable of transforming the HDTV composite color picture signal into color signals (R, G, B) for use with a HDTV receiver, the transforming means comprising;

filtering means for passing therethrough only luminance signals of the HDTV composite picture signal;

first modulating means for modulating a first quadrature component of a color subcarrier frequency of the HDTV composite picture signal with the HDTV composite picture signal to produce a first chroma component signal;

second modulating means for modulating a second quadrature component of the color subcarrier frequency of the HDTV composite picture signal with the HDTV composite picture signal to produce a second chroma component signal; and

dematrixing means capable of converting the luminance and first and second chroma components into appropriate predetermined color signals for use by a HDTV receiver to produce a picture.

11. An arrangement for converting a conventional television system color picture signal including sequential line signals at a first line scan rate and audio signals disposed on a sound carrier above the line signals into a High Definition Television (HDTV) composite color picture signal for subsequent viewing on a HDTV receiver, the arrangement comprising:

means for separating the sequential line signals and the audio signals of the conventional television system color picture signal for propagation along separate paths to the HDTV receiver; and

means capable of converting each line signal of the conventional system color picture signal into at least two sequential line signals at the output thereof including a second line scan rate which is a predetermined multiple of the first line scan rate corresponding to the actual number of said at least two sequential lines, and luminance and chrominance component bandwidths which are the predetermined multiple of corresponding bandwidths of the conventional system color picture signal for producing the HDTV composite color picture signal.

13. A method of generating a compatible high-definition television (CHDTV) color picture signal including a predetermined bandwidth and format, the method comprising the steps of:

(a) generating from color signals associated with line signals of a picture as generated by HDTV camera color tubes at a first line scan rate, a CHDTV color picture signal which includes line signals at a second line rate that is both a submultiple of the first line scan rate and the same line scan rate as that of an associated conventional television system color picture signal by sending information associated with at least two lines from the camera color tubes in one signal segment by performing the steps of;

(a1) stretching each of the at least two lines in time by a factor which is the inverse of said submultiple of the first line scan rate;

(a2) forming a first line signal of said at least two time stretched lines as is for transmission within a first portion of the predetermined bandwidth of the CHDTV color picture signal; and

(a3) concurrent with step (a2), forming a second line signal of said at least two time stretched lines as a line differential signal for transmission in a second portion of the predetermined bandwidth of the CHDTV color picture signal on a vestigial sideband carrier signal which is separated from a color subcarrer of the first line signal by a frequency which is substantially equal to that of a baseband color subcarrier frequency of the associated conventional television system color picture signal.

14. The method of generating a CHDTV color picture signal according to claim 13 wherein the method comprises the further step of:

(b) transmitting an audio signal associated with the CHDTV color picture signal in a frequency band which is associated with an audio subcarrier which has a frequency substantially equal to the addition of an audio subcarrier frequency and a color subcarrier frequency of the associated conventional television system color picture signal format.

15. A method of generating a compatible high-definition television (CHDTV) color picture signal capable of being converted into either one of a high-definition televeision (HDTV) composite color picture signal or an associated conventional television system color picture signal, the method comprising the steps of:

(a) generating from color signals from a HDTV camera a HDTV composite picture signal comprising a frequency scaled up version of the associated conventional television system color picture signal including a luminance bandwidth capable of providing a number of picture lines and a line scan rate which is a predetermined multiple of the number of picture lines and line scan rate, respectively, of the associated conventional television system color picture signal, a frame and a field rate which is the same as that of said associated conventional television system color picture signal, and chrominance information including first and second chroma components which are formed on sidebands of a separate color subcarrier within said luminance bandwidth which is a fixed multiple of the line scan rate of the associated conventional television system color picture signal and includes a ratio of each of the chroma component bandwidths to the luminance bandwidth which is similar to that of the associated conventional television system color picture signal; and

(b) transforming the HDTV composite color picture signal into a CHDTV color picture signal including a line scan rate which is the same as the associated conventional television system color picture signal format by sending information associated with at least two lines of the HDTV composite picture signal in one signal segment by stretching each HDTV composite line signal in time by a factor corresponding to said predetermined multiple and forming a first line signal as is within a first portion of a predetermined bandwidth of the CHDTV color picture signal which is both within, and a predetermined submultiple of, the luminance bandwidth of the HDTV composite picture signal and a second line signal which is formed as a line-differential signal in a second portion of the predetermined bandwidth of the CHDTV color picture signal on a vestigial sideband carrier signal which is separated from the color subcarrier of the first line signal by a frequency equal to that of a baseband color subcarrier frequency of the associated conventional system color picture signal.

16. A method of generating a CHDTV color picture signal according to claim 15 wherein the method comprises the further steps of:

(c) in performing step (b), performing the steps of;

(c1) receiving at least a first and a second line signal of the HDTV composite signal in sequence and generating as an output at least a first and a second line signal in parallel on separate paths at the second line scan rate;

(c2) generating a line differential signal of said second line signal in parallel which is the difference between the second line signal in parallel and an approximation of the second line signal in parallel which is generated from a linear or other combination of the first and a third line signal occurring just before and after the second line signal in the HDTV composite signal;

(c3) modulating the line differential signal onto a vestigial sideband carrier signal; and

(c4) adding the resultant vestigial sideband signal to the first line signal in parallel generated in step (c1) to provide the CHDTV color picture signal.

17. A method of converting a compatible high-definition television (CHDTV) color picture signal into a HDTV composite color picture signal for use by a HDTV receiver, the CHDTV color picture signal including a predetermined bandwidth wherein a first line signal of at least two line signals is received as is in one portion of the bandwidth at a first line scan rate and a second line signal of the at least two line signals is received as a line differential signal in a second portion of the bandwidth at the first line scan rate which is the same as the line scan rate of a conventional television system color picture signal, the method comprising the steps of:

(a) separating the first and the second line signals of the received CHDTV color picture signal for transmission over a first and a second path, respectively;

(b) demodulating the second line signal to provide a line differential signal within the bandwidth of the received first line signal;

(c) generating an approximation of the second line signal from two sequential received first line signals;

(d) generating a recovered second line signal from the resultant signals of steps (b) and (c); and

(e) time compressing the first and the second line signals froms steps (a) and (d) received in parallel at the first line scan rate into a first and a second line signal in sequence at a second line scan rate which is a predetermined multiple of the first line scan rate to produce the HDTV composite color picture signal.

18. A method of converting a compatible high-definition television (CHDTV) color picture signal into an associated conventional television system color picture signal for use by a conventional system television receiver, the CHDTV color picture signal including a predetermined bandwidth wherein a first line signal of at least two line signals containing a first color subcarrier frequency is received as is in a first portion of the bandwidth at a first line scan rate which is the same as the line scan rate of the associated conventional television system color picture signal and a second line signal of the at least two line signals is received on a vestigial sideband carrier frequency as a line differential signal in a second portion of the bandwidth at the first line scan rate and the first color subcarrier frequency and the vestigial sideband carrier frequency are separated by a frequency equal to a color subcarrier frequency of the associated conventional television color picture signal, the method comprising the steps of:

(a) filtering the received CHDTV color picture signal to pass only a frequency band within the first portion of the bandwidth of the CHDTV color picture signal substantially corresponding to a luminance bandwidth of the associated conventional color picture signal and comprises only a luminance signal of the first line signal; and

(b) demodulating chrominance information signals associated with only the first line signal of the CHDTV color picture signal with the vestigial sideband carrier frequency to produce appropriate chrominance information signals within the luminance bandwidth of the associated conventional television system color picture signal.