Digital transmission system for television video signals

• US 4,215,369 A
• Filed: 12/15/1978
• Issued: 07/29/1980
• Est. Priority Date: 12/20/1977
• Status: Expired due to Term

• Current Assignee: Nippon Electric Company Limited (NEC Corporation)
• Original Assignee: Nippon Electric Company Limited (NEC Corporation)
• Inventors: Iijima, Yukihiko
• Primary Examiner(s): Richardson, Robert L.
• Application Number:
  US05/970,051
• Time in Patent Office: 592 Days
• Field of Search: 358/141, 358/142, 358/146
• US Class Current: 375/240.01
• CPC Class Codes: H04L 5/24 with start-stop synchronous converters
• CPC Class Codes: H04N 21/2365 Multiplexing of several video streams
• CPC Class Codes: H04N 21/4347 Demultiplexing of several video streams

Abstract

A digital transmission system for television video signals of the type which comprises a transmitter and a receiver, the transmitter having a plurality of input terminals for receiving respective television video signals to be transmitted, a plurality of encoding units for encoding the respective video signals into digitized video signals, and a multiplexers for multiplexing the respective digitized video signals in a time division manner, and the receiver having a demultiplexer for receiving the multiplexed video signal from the multiplexer and for separating the same into said digitized video signals, and a plurality of decoding units for decoding the digitized video signals into said respective television video signals, is disclosed.

Claims

1. In a digital transmission system for television video signals, which comprises a transmitter and a receiver, said transmitter comprising a plurality of input terminals for receiving respective television video signals to be transmitted, a plurality of encoding units for encoding said respective television video signals into digitized video signals, and a multiplexer for multiplexing said respective digitized video signals in a time division manner;

and said receiver comprising a demultiplexer for receiving the multiplexed video signal transmitted from said multiplexer and for separating the same into said digitized video signals, and a plurality of decoding units for decoding said respective digitized video signals given from said demultiplexer into said respective television video signals, the improvement wherein;

each of said encoding units comprises a synchronization pulse separator for separating synchronization pulses in said television video signal, an encoder responsive to the separated synchronization pulses for encoding said television video signal into predetermined codes, a generator for generating video-frame-synchronization codes each indicative of the end of one picture frame of said television video signal, first means for multiplexing said video-frame-synchronization codes and the encoded codes of said encoder, a first buffer memory for temporarily storing the multiplexed codes given from said first means, a first read/write controller for supplying write-in and read-out address signals to said first buffer memory and for measuring a buffer-occupancy state of said first buffer memory to produce a buffer-occupancy code, second means for measuring a time interval from a time point when said video-frame-synchronization code is written into said first buffer memory to a time point when read out from the first buffer memory and for producing a first time-indicating code representative of said time interval, and third means for multiplexing the codes read out from said first buffer memory and said first time-indicating code and for supplying the output therefrom to said multiplexer; and

each of said decoding units comprises a second buffer memory for temporarily storing said digitized video signal supplied from a corresponding encoding unit, a second read/write controller for producing write-in address signals for writing said multiplexed codes and said time-indicating code into said second buffer memory and for producing read-out address signals for reading out the codes stored in said second buffer memory, fourth means for detecting said first time-indicating code in said digitized video signal, fifth means for measuring a time interval from a time point when said video-frame-synchronization code is written into said second buffer memory to a time point when read out of the second buffer memory and for producing a second time-indicating code, and a buffer memory controller for comparing said first and said second time-indicating codes and for controlling said read-out address signals based on the comparison operation.

5. The improvement in a digital transmission system for television video signals as recited in claim 1, 2, 3 or 4, wherein said encoder generates writing pulses and said first multiplexer generates reading pulses, said first read/write controller comprising a first counter for counting said writing pulses, a second counter for counting said reading pulses, and a subtractor connected to said first and second counters for producing said buffer-occupancy code.

6. The improvement in a digital transmission system for television video system as recited in claim 1, 2, 3 or 4, wherein said multiplexer comprises a register which stores at least the most significant bits of said buffer-occupancy code from each of said plurality of encoding units, a channel-assignment-signal generator coupled to said register for producing a channel-assignment signal in response to an output of said register, means for generating clock pulses and a frame sync signal for transmission control, a counter for counting said clock pulses, said counter being reset by said frame sync signal, a read-out controller coupled to said channel-assignment-signal generator and said counter for producing gate pulses, first gating means controlled by said read-out controller for supplying said clock pulses to said read/write controller through said third means of each of said encoding units, and second gating means controlled by said read-out controller for transmitting the multiplexed codes from said third means of each of said encoding units, said channel-assignment signal and said frame sync signal.

7. The improvement in a digital transmission system for television video signals as recited in claim 6, wherein said demultiplexer comprises a frame-sync-signal detector for detecting said frame sync signal second means for generating clock pulses, a second counter coupled to said second means for generating clock pulses, said second counter being reset by the output of said frame-sync-signal detector, means coupled to said frame-sync-signal detector and said second means for generating clock pulses for producing a channel-assignment-signal-multiplexing pulse, a second register which stores the channel-assignment signal in the received multiplexed video signal in response to said channel-assignment-signal-multiplexing pulse, a write-in signal controller coupled to said second counter and said second register for producing gate pulses, and third gating means controlled by said write-in signal controller for passing clock pulses from said second means for generating clock pulses to said read/write controller of each of said decoding units.

2. In a digital transmission system for television video signals, which comprises a transmitter and a receiver, said transmitter comprising a plurality of input terminals for receiving respective television video signals to be transmitted, a plurality of encoding units for encoding said respective television video signals into digitized video signals, and a multiplexer for multiplexing said respective digitized video signals in a time division manner, said receiver comprising demultiplexer for receiving said multiplexed video signal transmitted from said multiplexer and for separating the same into said digitized video signals, and a plurality of decoding units for decoding said respective digitized video signals given from said demultiplexer into said respective television video signals, the improvement wherein:

each of said encoding units comprises a synchronization pulse separator for separating synchronization pulses in said television video signal, an encoder responsive to the separated synchronization pulses for encoding said television video signal into predetermined codes, a generator for generating video-frame-synchronization codes each indicative of the end of one picture frame of said television video signal, first means for multiplexing said video-frame-synchronization codes and the encoded codes of said encoder, a first buffer memory for temporarily storing the multiplexed codes from said first means, a first read/write controller for supplying write-in and read-out address signals to said first buffer memory and for measuring a buffer-occupancy state of said first buffer memory to produce a first buffer-occupancy code, a register for storing said buffer-occupancy code at a first predetermined time point, second means for counting the amount of said multiplexed codes read out from said first buffer memory from said first predetermined time point to a second predetermined time point, a subtractor for subtracting the output of said register from the output of said second means, and third means for supplying both the output of said subtractor and said codes read out from said first buffer memory to said multiplexer; and

each of said decoding units comprises a second buffer memory for temporarily storing said digitized video signal supplied from a corresponding encoding unit, second read/write controller for producing write-in address signals for writing said multiplexed codes into said second buffer memory and for producing read-out signals for reading out the codes stored in said second buffer memory and for measuring a buffer-occupancy state of said second buffer memory to produce a second buffer-occupancy code, fourth means for detecting and storing the output of said subtractor in said digitized video signal supplied from said corresponding encoding unit, and a buffer memory controller for comparing said second buffer-occupancy code with the output on said fourth means to control said read-out signals based on said comparison operation.

3. In a digital transmission system for television signals, which comprises a transmitter and a receiver, said transmitter comprising a plurality of input terminals for receiving respective television video signals to be transmitted, a plurality of encoding units for encoding said respective television video signals into digitized video signals and a multiplexer for multiplexing said respective digitized video signals in a time division manner;

said receiver comprising a demultiplexer for receiving the multiplexed video signal transmitted from said multiplexer and for separating the same into said digitized video signals, and a plurality of decoding units for decoding said respective digitized video signals given from said demultiplexer into said respective television video signals, the improvement wherein;

each of said encoding units comprises a synchronization pulse separator for separating synchronization pulses in said television video signal, an encoder responsive to the separated synchronization pulses for encoding said television video into predetermined codes, a generator generating video-frame-synchronization codes each indicative of the end of one picture frame of said television video signal, first means for multiplexing said video-frame-synchronization codes and the encoded codes of said encoder, a first buffer memory for temporarily storing the multiplexed codes from said first means, a first read/write controller for supplying write-in and read-out address signals to said first buffer memory and for measuring a buffer-occupancy state of said first buffer memory to produce a first buffer-occupancy code, and second means for supplying said first buffer-occupancy code at a first predetermined time point and said multiplexed codes read out from said first buffer memory to said multiplexer; and

each of said decoding units comprises a second buffer memory for temporarily storing said digitized video signal supplied from a corresponding encoding unit, second read/write controller for producing a write-in address signal for writing said multiplexed codes into said second buffer memory and for producing read-out address signal for reading out the codes stored in said second buffer memory and for measuring a buffer-occupancy state of said second buffer memory to producing a second buffer-occupancy code, third means for detecting and storing said first buffer-occupancy code in said digitized video signal supplied from said corresponding encoding unit, fourth means for counting the amount of write-in of said multiplexed codes from the detection of said first buffer-occupancy code to a second predetermined time point, a subtractor for subtracting the output of said third means from the output of said fourth means, and a buffer memory controller for comparing said second buffer-occupancy code with the output of said subtractor to control said read-out address signals of said second read/write controller.

4. In a digital transmission system for television video signals, which comprises a transmitter and a receiver, said transmitter comprising a plurality of input terminals for receiving respective television video signals to be transmitted, plural encoding units for encoding said respective television video signals into digitized video signals, and a multiplexer for multiplexing said digitized video signals in a time division manner, said receiver comprising a demultiplexer for receiving said multiplexed video signal transmitted from said multiplexer and for separating the same into said digitized video signals, and plural decoding units for decoding said respective digitized video signals into said respective television video signals, the improvement wherein:

each of said encoding units comprises a synchronization pulse generator for separating synchronization pulses in said television video signal, an encoder responsive to the separated synchronization pulses for encoding said television video signal into predetermined codes, a generator for generating video-frame-synchronization codes each indicative of the end of one picture frame of said television video signal, first means for multiplexing said video-frame-synchronization codes and the encoded codes of said encoder, a first buffer memory for temporarily storing the multiplexed codes from said first means, a first read/write controller for supplying write-in and read-out address signals to said first buffer memory and for measuring a buffer-occupancy state of said first buffer memory to produce a first buffer-occupancy code, second means for counting the amount of write-in of both said encoded codes of said encoder and said video-frame-synchronization codes into said first buffer memory, a subtractor for subtracting the first buffer-occupancy code output of said first read/write controller from the output of said second means, and third means for supplying the output of said subtractor and the multiplexed codes read out from said first buffer memory to said multiplexer; and

each of said decoding units comprises a second buffer memory for temporarily storing said digitized video signal supplied from a corresponding encoding unit, a second read/write controller for producing write-in address signals for writing said multiplexed codes into said second buffer memory and for producing read-out address signals for reading out the codes stored in said second buffer memory and for measuring a buffer-occupancy state of said second buffer memory to produce a second buffer-occupancy code, fourth means for detecting and storing the output of said subtractor in said digitized video signal from said corresponding encoding unit, and a buffer memory controller for comparing said second buffer-occupancy code with the output of said fourth means to control the read-out address signals of said second read/write controller.

8. In a digital transmission system for a television video signal, which comprises a transmitter and a receiver, said transmitter comprising an input terminal for receiving a television video signal to be transmitted, an encoding unit for encoding said television viedo signal into a digitized video signal;

and said receiver comprising a decoding unit for decoding said digitized viedo signal into said television video signal, the improvement wherein;

said encoding unit comprises a synchronization pulse separator for separating synchronization pulses in said television video signal, an encoder responsive to the separated synchronization pulses for encoding said television video signal into predetermined codes, a generator for generating video-frame-synchronization codes each indicative of the end of one picture frame of said television video signal, first means for multiplexing said video-frame-synchronization codes and the encoded codes of said encoder, a first buffer memory for temporarily storing the multiplexed codes given from said first means, a first read/write controller for supplying write-in and read-out address signals to said first buffer memory and for measuring a buffer-occupancy state of said first buffer memory to produce a buffer-occupancy code, second means for measuring a time interval from a time point when said video-frame-synchronization code is written into said first buffer memory to a time point when read out from the first buffer memory and for producing a first time-indicating code representative of said time interval, and third means for multiplexing the codes read out from said first buffer memory and said first time-indicating code; and

said decoding unit comprises a second buffer memory for temporarily storing said digitized video signal supplied from said encoding unit, a second read/write controller for producing write-in address signals for writing said multiplexed codes and said time-indicating code into said second buffer memory and for producing read-out address signals for reading out the codes stored in said second buffer memory, fourth means for detecting said first time-indicating code in said digitized video signal, fifth means for measuring a time interval from a time point when said video-frame-synchronization code is written into said second buffer memory to a time point when read out of the second buffer memory and for producing a second time-indicating code, and a buffer memory controller for comparing said first and second second time-indicating codes and for controlling said read-out address signals based on the comparison operation.

9. In a digital transmission system for a television video signal, which comprises a transmitter and a receiver, said transmitter comprising an input terminal for receiving a television video signal to be transmitted, an encoding unit for encoding said television video signal into a digitized video signal;

and said receiver comprising a decoding unit for decoding said digitized video signal into said television video signal, the improvement wherein;

said encoding unit comprises a synchronization pulse separator for separating synchronization pulses in said television video signal, an encoder responsive to the separated synchronization pulses for encoding said television video signal into predetermined codes, a generator for generating video-frame-synchronization codes each indicative of the end of one picture frame of said television video signal, first means for multiplexing said video-frame-synchronization codes and the encoded codes of said encoder, a first buffer memory for temporarily storing the multiplexed codes from said first means, a first read/write controller for supplying write-in and read-out address signals to said first buffer memory and for measuring a buffer-occupancy state of said first buffer memory to produce a first buffer-occupancy code, a register for storing said buffer-occupancy code at a first predetermined time point, second means for counting the amount of said multiplexed codes read out from said first buffer memory from said first predetermined time point to a second predetermined time point, a subtractor for subtracting the output of said register from the output of said second means, and third means for multiplexing the output of said subtractor and said codes read out from said first buffer memory; and

said decoding unit comprises a second buffer memory for temporarily storing said digitized video signal supplied from said encoding unit, second read/write controller for producing write-in address signals for writing said multiplexed codes into said second buffer memory and for producing read-out address signals for reading out the codes stored in said second buffer memory and for measuring a buffer-occupancy state of said second buffer memory to produce a second buffer-occupancy code, fourth means for detecting and storing the output of said subtractor in said digitized video signal supplied from said encoding unit, and a buffer memory controller for comparing said second buffer-occupancy code with the output on said fourth means to control said read-out address signals based on said comparison operation.

10. In a digital transmission system for a television signal, which comprises a transmitter and a receiver, said transmitter comprising an input terminal for receiving a television video signal to be transmitted, an encoding unit for encoding said television video signal into a digitized video signal;

and said receiver comprising a decoding unit for decoding said digitized video signal into said television video signal, the improvement wherein;

said encoding unit comprises a synchronization pulse separator for separating synchronization pulses in said television video signal, an encoder responsive to the separated synchronization pulses for encoding said television video signal into predetermined codes, a generator for generating video-frame-synchronization codes each indicative of the end of one picture frame of said television video signal, first means for multiplexing said video-frame-synchronization codes and the encoded codes of said encoder, a first buffer memory for temporarily storing the multiplexed codes from said first means, a first read/write controller for supplying write-in and read-out address signals to said first buffer memory and for measuring a buffer-occupancy state of said first buffer memory to produce a first buffer-occupancy code, and second means for multiplexing said first buffer-occupancy code at a first predetermined time point and said multiplexed codes read out from said first buffer memory; and

said decoding unit comprises a second buffer memory for temporarily storing said digitized video signal supplied from said encoding unit, second read/write controller for producing a write-in address signal for writing said multiplexed codes into said second buffer memory and for producing read-out address signal for reading out the codes stored in said second buffer memory and for measuring a buffer-occupancy state of said second buffer memory to produce a second buffer-occupancy code, third means for detecting and storing said first buffer-occupancy code in said digitized video signal supplied from said encoding unit, fourth means for counting the amount of write-in of said multiplexed codes from the detection of said first buffer-occupancy code to a second predetermined time point, a subtractor for subtracting the output of said third means from the output of said fourth means, and a buffer memory controller for comparing said second buffer-occupancy code with the output of said subtractor to control said read-out address signals of said second read/write controller.

11. In a digital transmission system for a television video signal, which comprises a transmitter and a receiver, said transmitter comprising an input terminal for receiving a television video signal to be transmitted, an encoding unit for encoding said television video signal into a digitized video signal;

and said receiver comprising a decoding unit for decoding said digitized video signal into said television video signal, the improvement wherein;

said encoding unit comprises a sychronization pulse separator for separating synchronization pulses in said television video signal, an encoder responsive to the separated synchronization pulses for encoding said television video signal into predetermined codes, a generator for generating video-frame-synchronization codes each indicative of the end of one picture frame of said television video signal, first means for multiplexing said video-frame-synchronization codes and the encoded codes of said encoder, a first buffer memory for temporarily storing the multiplexed codes from said first means, a first read/write controller for supplying write-in and read-out address signals to said first buffer memory and for measuring a buffer-occupancy state of said first buffer memory to produce a first buffer-occupancy code, second means for counting the amount of write-in of both said encoded codes of said encoder and said video-frame-synchronization codes into said first buffer memory, a subtractor for subtracting the first buffer-occupancy code output of said first read/write controller from the output of said second means, and third means for multiplexing the output of said subtractor and the multiplexed codes read out from said first buffer memory; and

said decoding unit comprises a second buffer memory for temporarily storing said digitized video signal supplied from said encoding unit, a second read/write controller for producing write-in address signals for writing said multiplexed codes into said second buffer memory and for producing read-out address signals for reading out the codes stored in said second buffer memory and for measuring a buffer-occupancy state of said second buffer memory to produce a second buffer-occupancy code, fourth means for detecting and storing the output of said subtractor in said digitized video signal from said encoding unit, and a buffer memory controller for comparing said second buffer-occupancy code with the output of said fourth means to control the read-out address signals of said second read/write controller.