Robust reception of digital broadcast transmission

• US 20050024543A1
• Filed: 07/17/2002
• Published: 02/03/2005
• Est. Priority Date: 07/19/2001
• Status: Abandoned Application

• Current Assignee: Thomson Licensing SA (Vantiva SA)
• Original Assignee: Thomson Licensing SA (Vantiva SA)
• Inventors: Ramaswamy, Kumar, Cooper, Jeffrey Allen, Knutson, Paul Gothard
• Application Number:
  US10/486,400
• Publication Number:
  US 20050024543A1
• Time in Patent Office: Days
• US Class Current: 348/723
• CPC Class Codes: H04H 20/16 Arrangements for broadcast or for distribution of identical information repeatedly
• CPC Class Codes: H04H 20/28 Arrangements for simultaneous broadcast of plural pieces of information
• CPC Class Codes: H04H 20/40 Arrangements for broadcast specially adapted for accumulation-type receivers
• CPC Class Codes: H04H 60/11 Arrangements for counter-measures when a portion of broadcast information is unavailable
• CPC Class Codes: H04H 60/27 Arrangements for recording or accumulating broadcast information or broadcast-related information
• CPC Class Codes: H04L 1/02 by diversity reception
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/895 in combination with error concealment
• CPC Class Codes: H04N 21/23406 involving management of server-side video buffer
• CPC Class Codes: H04N 21/234327 by decomposing into layers, e.g. base layer and one or more enhancement layers
• CPC Class Codes: H04N 21/2365 Multiplexing of several video streams
• CPC Class Codes: H04N 21/2383 Channel coding or modulation of digital bit-stream, e.g. QPSK modulation arrangements for detecting or preventing errors in the information received by adapting the channel coding H04L1/0009; analogue front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002
• CPC Class Codes: H04N 21/25816 involving client authentication restricting access to computer systems by authenticating users using a predetermined code G06F21/33; cryptographic authentication protocols H04L9/32; networks authentication protocols H04L63/08; authentication in wireless network security H04W12/06
• CPC Class Codes: H04N 21/2585 Generation of a revocation list, e.g. of client devices involved in piracy acts
• CPC Class Codes: H04N 21/4181 for conditional access
• CPC Class Codes: H04N 21/42684 Client identification by a unique number or address, e.g. serial number, MAC address, socket ID network arrangements, protocols or services for addressing or naming H04L61/00
• CPC Class Codes: H04N 21/4331 Caching operations, e.g. of an advertisement for later insertion during playback
• CPC Class Codes: H04N 21/4347 Demultiplexing of several video streams
• CPC Class Codes: H04N 21/4382 Demodulation or channel decoding, e.g. QPSK demodulation analog front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002
• CPC Class Codes: H04N 21/44209 Monitoring of downstream path of the transmission network originating from a server, e.g. bandwidth variations of a wireless network arrangements for maintenance or administration in data switching networks involving bandwidth and capacity management H04L41/0896
• CPC Class Codes: H04N 21/6112 : involving terrestrial transmission, e.g. DVB-T
• CPC Class Codes: H04N 21/6187 : involving transmission via a telephone network, e.g. POTS
• CPC Class Codes: H04N 21/6402 : Address allocation for clients address allocation in data networks H04L61/50

Abstract

A method and apparatus for improving the reception of digitally modulated signals. A main signal and a supplemental signal are provided in the transmitter. The signals may be substantially identical except that the supplemental signal is advanced in time with respect to the main signal. The main and supplemental signals are sent from the transmitter to the receiver modulated on a signal. At the receiver, the supplemental signal is stored in a buffer. If the main signal is undesirably changed during transmission, corresponding portions of the supplement signal are substituted for the undesired portions of the main signal.

Claims

1. A method for improving the reception of transmitted digital broadcast signals, comprising the steps of:

producing a first set of program material from a first source in a transmitter;

producing a second set of program material from said first source in said transmitter;

time delaying said first set with respect to said second set before transmission;

transmitting the first and the second set of program materials on a signal for reception by a receiver;

applying said first set of program materials received in said receiver to normal reception channels of said receiver;

storing said second set of program materials received in said receiver in a buffer in said receiver;

detecting an undesired change in said received first set of program materials; and

substituting corresponding portions of said signal stored in said buffer for any undesirably changed portions of said first set of program materials.

2. A method as claimed in claim 1 wherein said first and second sets of program material are identical.

3. A method as claimed in claim 1 wherein said first set of program material is produced with a different quality than said second set of program material.

4. A method as claimed in claim 3 wherein the quality of said first set of program material is higher than the resolution of said second set of program material.

5. In a receiver, a method for improving the reception of signals transmitted in the form of synchronously encoded main and supplemental signals, said signals being staggered in time with said supplemental signal being in advance of said main signal, comprising the steps of:

storing said supplemental signal in a buffer in the receiver;

processing said main signal in said receiver in a normal manner;

detecting an undesired change in the processed main signal; and

substituting corresponding portions of said stored supplemental signal for any undesirably changed portions of said main signal.

6. A method as claimed in claim 5 wherein said undesired change is related to a quality of said processed main signal and said change is detected by a quality measure of said processed main signal.

7. A method as claimed in claim 6 wherein said quality measure is one or more of a signal-to-noise ratio, bit error rate or packet error rate measure.

8. A method as claimed in claim 5 wherein said main signal and said supplemental signal have different resolutions.

9. A method as claimed in claim 8 wherein the resolution of said main signal is higher than the resolution of said supplemental signal.

11. A system as claimed in claim 9 wherein said first and second sets of program material are identical.

12. A system as claimed in claim 9 wherein the resolution of said first set of program material is different from the resolution of said second set of program material.

13. A system as claimed in claim 11 wherein the resolution of said first set of program material is higher than the resolution of said second set of program material.

15. Apparatus as claimed in claim 13 wherein said undesired change in said main signal is a measure of the amplitude of said main signal and said detector includes one or more of a signal-to-noise ratio, bit error rate and packet error.

10. A system for improving the reception of a digital signals comprising:

means for producing a first set of program material from a source in a transmitter;

means for producing a second set of program material from said source in said transmitter;

means for delaying said first set in time with respect to said second set;

means for transmitting a signal carrying said delayed first set and said second set of program material;

a receiver having a first and a second channel for receiving said transmitted signal, said second channel having a buffer circuit for storing said second set of program material, and said first channel including means for processing said first set of program material;

a detector in said receiver for detecting any undesired change in said processed first set; and

means in said receiver for substituting corresponding portions of said stored second set for any undesirably changed portions of said first set.

14. A receiver for improving the reception of a signal transmitted in the form of synchronously encoded main and supplemental signals, said signals being staggered in time with said supplemental signal being in advance of said main signal, comprising:

a buffer in said receiver for storing said supplemental signal;

a signal processor in said receiver for processing said main signal in a normal manner;

a detector in said receiver for detecting any undesired change in said processed main signal; and

means coupled to said detector for substituting corresponding portions of said stored supplemental signal for any undesirably changed portions of said main signal.