Blind identification of advanced modulation and coding modes

1. A method for acquiring and demodulating a data stream transmitted in a communication system, comprising:

finding a boundary of a physical layer frame (PLFrame) in the data stream;

finding a first 26 bits of a Unique Word (UW) associated with the data stream;

finding a scrambling code utilizing the UW; and

using a decoding procedure to determine a modulation type and code rate used for desired signals within the data stream.

2. The method of claim 1 , wherein the data stream is a downlink signal from a satellite.

3. The method of claim 2 , wherein the scrambling code further comprises a Gold code used to scramble a payload portion of the data stream.

4. The method of claim 3 , wherein finding the boundary of the PLFrame further comprises finding a coarse boundary of the PLFrame.

5. The method of claim 4 , wherein finding the boundary of the PLFrame further comprises finding a Start Of Frame (SOF) of the PLFrame.

6. The method of claim 5 , wherein finding the SOF comprises normalizing a conjugate product of a last symbol of a physical layer header and a first symbol of the physical layer header.

7. The method of claim 6 , wherein finding the first 26 bits of the UW comprises normalizing the first 26 symbols of the data stream after the SOF such that a first symbol has a known phase.

8. The method of claim 7 , wherein finding a scrambling code comprises looking up the scrambling code associated with the UW.

9. An apparatus for acquiring and demodulating a data stream transmitted in a communication system, comprising:

a demodulator for finding a boundary of a physical layer frame in the data stream and for finding a first 26 bits of a unique word associated with the data stream;

a descrambler, coupled to the demodulator, for finding a scrambling code utilizing the unique word; and

a decoder, coupled to the descrambler, for determining a modulation type and code rate used for desired signals within the data stream and for decoding the data stream.

10. The apparatus of claim 9 , wherein the data stream is a downlink signal from a satellite.

11. The apparatus of claim 10 , wherein the scrambling code further comprises a Gold code used to scramble a payload portion of the data stream.

12. The apparatus of claim 11 , wherein finding the boundary of the physical layer frame further comprises finding a coarse boundary of the physical layer frame.

13. The apparatus of claim 12 , wherein finding the boundary of the physical layer frame further comprises finding a start-of-frame of the physical layer frame.

14. The apparatus of claim 13 , wherein finding the start-of-frame comprises normalizing a conjugate product of a last symbol of a physical layer header and a first symbol of the physical layer header.

15. The apparatus of claim 14 , wherein finding the first 26 bits of the unique word comprises normalizing the first 26 symbols of the data stream after the start-of-frame such that a first symbol has a known phase.

16. The apparatus of claim 15 , wherein finding a scrambling code comprises looking up the scrambling code associated with the unique word.

17. A system for transmitting and receiving a data stream, comprising:

a transmitter, the transmitter further comprising:

an encoder, the encoder accepting the data stream and generating an encoded version of the data stream including a physical layer header and a payload portion;

a scrambler, coupled to the encoder, for accepting the encoded version of the data stream and creating a scrambled version of the data stream; and

a modulator, coupled to the encoder, for modulating the scrambled version of the data stream onto a carrier; and

a receiver, the receiver further comprising:

a demodulator for finding a boundary of a physical layer frame in the scrambled version of the data stream and for finding a first 26 bits of a unique word associated with the scrambled version of the data stream;

a descrambler, coupled to the demodulator, for applying a scrambling code to the scrambled version of the data stream utilizing the unique word to re-create the encoded version of the data stream; and

a decoder, coupled to the descrambler, for decoding the encoded version of the data stream using a modulation type and code rate that extracts desired signals within the data stream.

18. The system of claim 17 , wherein scrambling the encoded version of the data stream scrambles only the payload portion of the encoded version of the data stream.

19. The system of claim 18 , wherein the data stream is a downlink signal from a satellite.

20. The system of claim 19 , wherein the scrambling code further comprises a Gold code used to scramble a payload portion of the data stream.