Method and apparatus for simultaneously retrieving portions of a data stream from different channels

• US 7,027,520 B2
• Filed: 08/30/2001
• Issued: 04/11/2006
• Est. Priority Date: 08/30/2001
• Status: Expired due to Term

• Current Assignee: InterDigital Patent Holdings, Inc. (InterDigital, Inc.)
• Original Assignee: Thomson Licensing (Vantiva SA)
• Inventors: Pugel, Michael Anthony
• Primary Examiner(s): PHU, PHUONG M
• Application Number:
  US09/942,810
• Publication Number:
  US 20030165200A1
• Time in Patent Office: 1,685 Days
• Field of Search: 375/316, 375/340, 375/342, 375/343, 375/346, 375/349, 375/350, 375/260, 324/67.21, 341/11
• US Class Current: 375/260
• CPC Class Codes: H04N 21/4348 Demultiplexing of additional data and 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

Abstract

An apparatus and method for simultaneously processing each of a plurality of carrier signals having data modulated thereon, wherein a complete data stream is formed by extracting at least portions of at least two of the modulated signals and combining the extracted portions. Each of the portions of the complete data stream comprises a plurality of packets having associated with them respective stream identification and sequence codes, where the stream identification identifies the complete bit stream to be formed, and the sequence codes identify the order or position within the complete bitstream that the associated data packets should be inserted.

Claims

1. A method for processing a received analog signal having a plurality of carrier signals modulated thereon, comprising:

band limiting the received analog signal to obtain a band limited analog signal;

converting the band limited analog signal into a digital data stream representative of the plurality of carrier signals;

extracting from said digital data stream, data carried by at least two of the plurality of carrier signals; and

combining at least portions of the data extracted from said at least two carrier signals to form a complete bitstream, said extracted data having associated with it stream identifier and sequence code information for, respectively, identifying the complete bitstream corresponding to the extracted data and determining the position of the extracted data within the complete bitstream.

2. The method of claim 1, wherein said complete bitstream comprises a transport stream, said method further comprising:

selecting transport packets within the extracted data having a stream identifier corresponding to said complete bitstream; and

arranging the selected packets according to the respective sequence codes to form said complete bitstream.

3. The method of claim 1, wherein the extracted data comprise transport stream packets according to a first transport format, and the complete bitstream comprises a transport stream packet of the first transport format.

4. The method of claim 1, wherein the extracted data comprise transport stream packets according to a first transport format, and the complete bitstream comprises a transport stream of a second transport format.

5. The method of claim 4, wherein transport stream packets according to said first transport stream format are carried within a payload portion of transport stream packets according to said second transport format.

6. The method of claim 5, wherein said stream identifier and said sequence code is stored in a header portion of said transport stream packets according to said first format.

7. The method of claim 1, wherein said extracting step comprises:

derotating each of the digitized plurality of carrier signals to produce respective derotated carrier signals; and

demodulating each of at least two filtered carrier signals to extract therefrom respective data bearing streams.

8. The method of claim 7, wherein said extracting step further comprises:

filtering each of the derotated carrier signals to reduce non-channel spectral energy; and

decimating each of the filtered signals to reduce the number of data-representative samples.

9. The method of claim 1, wherein some of said extracted data has associated with it channel identification and time of transmission information for, respectively, indicating which of said plurality of carrier signals will carry portions of said complete bitstream and the time said portions will be carried.

10. The method of claim 1, wherein said extracting step includes:

identifying a carrier signal having data corresponding to a desired complete bitstream; and

processing said identified carrier signal to extract said data corresponding to said desired complete bitstream.

11. The method of claim 10, wherein said extracting step further includes:

determining a time when said identified carrier signal will include said data corresponding to said desired complete bitstream, said identified carrier signal being processed at said determined time.

12. The method of claim 10, wherein some of said extracted data has associated with it channel identification information for indicating which of said plurality of carrier signals will carry said data corresponding to said desired complete bitstream.

13. The method of claim 12, wherein said extracted data is associated with said channel identification information and also is associated with time of transmission information for indicating the time when said identified carrier signal will include said data corresponding to said desired complete bitstream.

14. The method of claim 6, wherein some of said transport stream packets according to said first format have stored therein within said header portion channel identification and time of transmission information for, respectively, indicating which of said plurality of carrier signals carry portions of said complete bitstream and the time said portions will be carried.

15. A method for processing a received analog signal having a plurality of carrier signals modulated thereon, comprising:

band limiting the received analog signal to correspond to a transmission frequency band of the received analog signal to obtain a band limited analog signal;

converting the band limited analog signal into a digital data stream representative of the plurality of carrier signals;

processing the digital data stream to pass a plurality of digitized carrier signals, each of said digitized carrier signals having modulated thereon, and within a channel bandwidth, a respective data bearing stream;

derotating each of the digitized carrier signals to produce respective derotated carrier signals;

demodulating each of at least two filtered carrier signals to extract therefrom respective data bearing streams; and

combining data from at least two data bearing streams into a resultant data stream, said at least two data bearing streams comprising respective portions of said resultant data stream.

16. The method of claim 15, further comprising:

filtering each of the derotated carrier signals to reduce non-channel spectral energy; and

decimating each of the filtered signals to reduce the number of samples representing each data bearing stream.

17. The method of claim 15, wherein said resultant data stream comprises a transport stream, said method further comprising:

identifying those transport packets within said first and second data bearing streams being associated with a stream identifier corresponding to said resultant stream; and

arranging the identified packets according to a respective sequence codes associated with said identified packets to form said resultant stream.

18. The method of claim 17, wherein each of said simultaneously demodulated data bearing streams are transport streams according to a first transport format, and said resultant data bearing stream is a transport stream according to a second transport format.

19. The method of claim 15, wherein the data bearing streams comprise transport streams according to a first transport format, and the resultant data stream comprises a transport stream of said first transport format.

20. The method of claim 15, wherein the data bearing streams comprise transport streams according to a first transport format, and the resultant data stream comprises a transport stream of a second transport format.

21. The method of claim 20, wherein data according to said second transport stream format is carried within a payload portion of data packets according to said second format.

22. The method of claim 21, wherein each of said data packets according to said second format includes, in a header portion, a stream identifier and sequence code for data carried within a respective payload portion.

23. A method for processing a received analog signal having a plurality of carrier signals modulated thereon, comprising:

band limiting the received signal to pass substantially those frequencies occupying a spectral transmission region between a first frequency f₁ and a second frequency f₂;

converting, using an analog-to-digital converter having a sampling rate f_s, the band-limited signal to produce a digital signal therefrom, said sampling rate f_s being greater than f₂;

derotating each of a plurality of data bearing signals within said digital signal to produce respective derotated signals;

filtering each of the respective derotated signals to remove channel energy outside of a respective defined channel;

decimating each of the filtered and derotated signals to reduce the number of samples representing each data bearing signal;

demodulating each of at least two filtered carrier signals to extract therefrom respective data bearing signal; and

combining at least respective portions of at least two of the resulting decimated data bearing signals into a single data signal.

24. Apparatus for processing a received analog signal having a plurality of carrier signals and respective data modulated thereon, comprising:

a band limiter, for band limiting the received analog signal to obtain a band limited analog signal;

an analog to digital converter, for converting the band limited analog signal into a digital data stream representative of the plurality of carrier signals and respective data;

a plurality of channel processors, for extracting from said digital data stream, data carried by respective carrier signals; and

a processor, for combining at least portions of said data extracted from at least two carrier signals to produce a complete bitstream, said extracted data having associated with it stream identifier and sequence code information for determining, respectively, the complete bitstream corresponding to the data and the sequence within the complete bitstream of the data.

25. The apparatus of claim 24, wherein each of said channel processors comprises:

a derotator, for derotating a respective digitized carrier signal to produce a respective derotated carrier signal; and

a demodulator, for demodulating said respective derotated carrier signal to extract therefrom a data stream.

26. The apparatus of claim 24, wherein each of said channel processors further comprises:

a filter, for filtering the respective derotated signals to remove channel energy outside of the respective defined channel; and

a decimator, for decimating each of the filtered and derotated signals to reduce the number of samples representing the respective data.

27. The apparatus of claim 24, wherein

said analog to digital converter utilizing a sampling rate less than twice the maximum frequency of interest within the plurality of data channels.

28. The apparatus of claim 24, wherein plurality of carrier signals substantially conform to a commonly polarized group of channels provided by a transponder.