Interleaver mode detection in a digital video receiver
View Patent ↗A method and apparatus for decoding received digital data representing video, audio, information or a combination thereof. After a forward error correction (FEC) frame sync lock is detected, a counter is incremented corresponding to the number of identical control words decoded from the received data. If the number of identical control words is above a threshold value, the control word is used to operate the decoder in a mode corresponding to the control word. Otherwise, the system repeats the operation of determining whether a FEC frame sync lock is detected.
1. A method for determining the operating mode used for decoding received packetized data comprising the steps of:
a) receiving a plurality of data packets, wherein each data packet has a control word;
b) extracting the control word from each packet as to capture a plurality of control words;
c) determining that a number of control words from said plurality of control words are identical;
d) using said control word to set a decoder operating mode when said determined number of identical control words is above a threshold number.
2. The method of claim 1 , wherein said operating mode is a deinterleaving mode selected from a plurality of deinterleaving modes.
3. The method of claim 2 , where said plurality of deinterleaving modes are compliant with the deinterleaving modes disclosed in at least one of: DVS-031 and ITU-T J.83B.
4. The method of claim 2 , wherein said method is used for a receiver capable of demodulating a signal modulated in at least one of: QAM, VSB, QPSK and OFDM.
5. The method of claim 1 , comprising an additional step of:
e) detecting an MPEG syndrome lock.
f) restarting the reception of the plurality of data packets if an MPEG syndrome lock is not detected within a time period.
6. The method of claim 5 wherein the MPEG syndrome lock results from syndrome decoding in the MPEG framer conformant with at least one of: DVS-031 and ITU-T J.83B.
7. The method of claim 1 , wherein said number of control words is a maximum number of control words that are identical when at least two different sets of identical control words are received.
8. The method of claim 1 , wherein said extracting step is preceded with a detection of a forward error correction frame sync lock.
9. The method of claim 8 , wherein said packets are a plurality of forward error correction frames where each frame has a corresponding frame sync trailer.
10. A method for determining a deinterleaver operating mode used by a receiver to decode received digital data comprising the steps of:
a) initializing a frame sync detector;
b) detecting a forward error correction sync lock from a received forward error correction frame using a frame sync trailer that corresponds to said frame;
c) capturing a plurality of control words from a plurality of forward error correction frames wherein each frame has a corresponding control word;
d) determining that a number of control words from said plurality of control words are identical control words and said determined number of identical control words is above a threshold number;
e) using said identical control word to set a deinterleaver mode selected from a plurality of deinterleaver modes upon determining said determined number of identical control words is above the threshold number.
11. The method of claim 10 , comprising an additional step of:
f) deinterleaving said received plurality of forward error correction frames using said selected deinterleaver mode.
12. The method of claim 10 , wherein an MPEG syndrome decoder lock is detected after selecting said deinterleaver mode step is performed.
13. The method of claim 12 , wherein said method is re-initialized after a predetermined duration of time if an MPEG syndrome decoder lock is not detected.
14. The method of claim 12 wherein the MPEG syndrome lock results from syndrome decoding in the MPEG framer conformant with at least one of: DVS-031 and ITU-T J.83B.
15. The method of claim 10 , wherein said method is used for a receiver capable of demodulating a signal modulated in at least one of: QAM, VSB, QPSK, and OFDM.
16. The method of claim 10 , where said plurality of deinterleaving modes are compliant with the deinterleaving modes disclosed in at least one of: DVS-031 and ITU-T J.83B.
17. The method of claim 10 , wherein said number of control words is a maximum amount of control words that are compared to said threshold number when at least two different sets of identical control words are received.