Video signal processing system using common digital filter in plural manners

• US 5,132,781 A
• Filed: 01/04/1991
• Issued: 07/21/1992
• Est. Priority Date: 10/27/1987
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Yagisawa, Toshihiro, Shimokoriyama, Makoto
• Primary Examiner(s): Shepperd, John W.
• Application Number:
  US07/638,352
• Time in Patent Office: 564 Days
• Field of Search: 358/340, 358/13, 358/138, 360/32, 360/39
• US Class Current: 375/240.01
• CPC Class Codes: H04N 9/79 Processing of colour television signals in connection with recording
• CPC Class Codes: H04N 9/81 the individual colour picture signal components being recorded sequentially only

Abstract

A digital video signal processing device, comprises a first processor for subsampling a digital video signal to produce a subsampled signal, a second processor for producing an expanded signal from a signal input thereto, a digital filter for limiting the bandwidth of a digital video signal input thereto, and a switch for switching over the operation of device between a first state in which the digital video signal input to the device is input to the digital filter and the digital filter output is supplied to the first processor and a second state in which the expanded signal produced by the second processor is supplied to the digital filter.

Claims

1. A digital video signal processing device, comprising:

(a) first signal processing means including subsampling means for subsampling a digital video signal to produce a subsampled signal;

(b) second signal processing means including expansion means for receiving a subsampled signal to produce an expanded signal;

(c) a digital filter for limiting the bandwidth of a digital video signal input thereto;

(d) inputting means for inputting a digital video signal; and

(e) switch-over means for switching over the operation of said device between a first state in which the digital video signal from said inputting means is input to said digital filter and the digital video signal output from said digital filter is supplied to said first signal processing means and a second state in which the expanded signal produced by said second signal processing means is supplied to said digital filter.

2. A device according to claim 1, wherein said first signal processing means further includes bandwidth compression means for compressing the bandwidth of said subsampled signal utilizing correlation thereof to produce a compressed signal.

3. A device according to claim 2, wherein said second signal processing means further includes bandwidth expanding means for expanding the bandwidth of said compressed signal by processing said compressed signal in a manner reverse to that in which the signal is processed in said bandwidth compression means to supply the subsampled signal to said expansion means.

4. A device according to claim 5, wherein said switch-over means supplies said expanded signal to said digital filter from said zeros inserting means in said second state.

5. A device according to claim 1, wherein said expansion means comprises zeros inserting means for inserting zeros between words of the subsampled signal to produce the expanded signal.

6. A digital video signal transmitting system, comprising:

(a) inputting means for inputting a digital video signal;

(b) a digital filter for limiting the bandwidth of a digital video signal;

(c) first signal processing means including subsampling means for subsampling a digital video signal to produce a subsampled signal;

(d) a transmitting portion for transmitting said subsampled signal;

(e) a receiving portion for receiving said subsampled signal transmitted through said transmitting portion, said receiving portion including second signal processing means including expansion means for receiving said subsampled signal and producing an expanded signal therefrom; and

(f) switch-over means for switching over the operation of said device between a first state in which the digital video signal from said inputting means is input to said digital filter and the digital video signal output from said digital filter is supplied to said first signal processing means and a second state in which the expanded signal produced by said second signal processing means is supplied to said digital filter.

7. A system according to claim 6, further comprising:

a simplified digital filter having a smaller circuit size than that of said digital filter.

8. A system according to claim 7, wherein said switch-over means supplies said expanded signal in said first state to said simplified digital filter.

9. A system according to claim 6, wherein said first signal processing means further includes bandwidth compression means for band compressing said subsampled signal utilizing correlation thereof to produce a compressed signal.

10. A system according to claim 9, wherein said second signal processing means further includes bandwidth expanding means for expanding the bandwidth of said compressed signal in a manner reverse to that in which said subsampled signal is processed in said bandwidth compression means.

11. A system according to claim 10, further comprising:

a simplified digital filter having a circuit size smaller than of said digital filter.

14. A system according to claim 6, wherein said transmitting portion includes an error correction code encoder for applying an error correction code to said subsampled signal and wherein said receiving portion includes an error correction code decoder for correcting a code error of a signal transmitted through said transmitting portion using said error correction code.

15. A system according to claim 6, wherein said transmitting portion includes modulating means for digital modulating of a signal in said transmitting portion and wherein said receiving portion includes demodulating means for digital demodulating of a signal in said receiving portion.

16. A device according to claim 6, wherein said expansion means comprises zeros inserting means for inserting zeros between words of the subsampled signal to produce the expanded signal.

12. A system according to clain 11, wherein said transmitting portion includes further circuitry for receiving said compressed signal and said receiving portion includes further circuitry for receiving signals transmitted by said transmitting portion and providing input to said bandwidth expanding means, said system providing, in said first state, for the supply of said compressed signal to said bandwidth expanding means without said compressed signal being processed by said further circuitry of said transmitting portion and said further circuitry of said receiving portion and for the connection of said said bandwith expanding means to said simplified digital filter.

13. A system according to claim 12, wherein said switch-over means supplies to said simplified digital filter said expanded signal in said first state.