Technique for demodulating level II hierarchical data
A technique for demodulating secondary data from a hierarchically modulated signal includes a number of steps. A gray coded eight phase shift key (8-PSK) hierarchically modulated signal is received that includes primary data and secondary data. An imaginary portion of the signal is determined and a real portion of the signal is determined. An absolute value of the real portion of the signal may then be subtracted from an absolute value of the imaginary portion of the signal to provide the secondary data. The gray coded 8-PSK hierarchically modulated signal may be a uniform gray coded 8-PSK hierarchically modulated signal or a non-uniform gray coded 8-PSK hierarchically modulated signal.
1. A method for demodulating secondary data from a hierarchically modulated signal, comprising the steps of:
receiving a gray coded eight phase shift key (8-PSK) hierarchically modulated signal that includes primary data and secondary data;
determining an imaginary portion of the signal;
determining a real portion of the signal; and
subtracting an absolute value of the real portion of the signal from an absolute value of the imaginary portion of the signal to provide the secondary data or subtracting an absolute value of the imaginary portion of the signal from an absolute value of the real portion of the signal to provide the secondary data.
2. The method of claim 1 , wherein the gray coded 8-PSK hierarchically modulated signal is a uniform gray coded 8-PSK hierarchically modulated signal.
3. The method of claim 1 , wherein the gray coded 8-PSK hierarchically modulated signal is a non-uniform gray coded 8-PSK hierarchically modulated signal.
4. The method of claim 1 , wherein the secondary data is low priority data and the primary data is high priority data.
5. The method of claim 1 , wherein the secondary data is encoded with a different forward error correction scheme than the primary data.
6. The method of claim 1 , wherein a digital one is indicated when the absolute value of the imaginary portion of the signal is greater than the absolute value of the real portion of the signal.
7. The method of claim 1 , wherein a digital zero is indicated when the absolute value of the imaginary portion of the signal is less than the absolute value of the real portion of the signal.
8. The method of claim 1 , wherein a digital one is indicated when the absolute value of the real portion of the signal is greater than the absolute value of the imaginary portion of the signal.
9. The method of claim 1 , wherein a digital zero is indicated when the absolute value of the real portion of the signal is less than the absolute value of the imaginary portion of the signal.
10. A receiver for demodulating secondary data from a received hierarchically modulated signal, comprising:
a tuner for down-converting a received gray coded eight phase shift key (8-PSK) hierarchically modulated signal that includes primary data and secondary data; and
a demodulator for demodulating the gray coded 8-PSK hierarchically modulated signal, wherein the demodulator determines an imaginary portion and a real portion of the signal, and wherein the demodulator subtracts an absolute value of the real portion of the signal from an absolute value of the imaginary portion of the signal to provide the secondary data.
11. The receiver of claim 10 , wherein the gray coded 8-PSK hierarchically modulated signal is a uniform gray coded 8-PSK hierarchically modulated signal.
12. The receiver of claim 10 , wherein the gray coded 8-PSK hierarchically modulated signal is a non-uniform gray coded 8-PSK hierarchically modulated signal.
13. The receiver of claim 10 , wherein the secondary data is low priority data and the primary data is high priority data.
14. The receiver of claim 10 , wherein the secondary data is encoded with a different forward error correction scheme than the primary data.
15. The receiver of claim 10 , wherein a digital one is indicated when the absolute value of the imaginary portion of the signal is greater than the absolute value of the real portion of the signal.
16. The receiver of claim 10 , wherein a digital zero is indicated when the absolute value of the imaginary portion of the signal is less than the absolute value of the real portion of the signal.
17. The receiver of claim 10 , wherein a digital one is indicated when the absolute value of the real portion of the signal is greater than the absolute value of the imaginary portion of the signal.
18. The receiver of claim 10 , wherein a digital zero is indicated when the absolute value of the real portion of the signal is less than the absolute value of the imaginary portion of the signal.
19. A receiver for demodulating secondary data from a received hierarchically modulated signal, comprising:
a tuner for down-converting a received gray coded eight phase shift key (8-PSK) hierarchically modulated signal that includes primary data and secondary data;
a filter including an input coupled to an output of the tuner; and
a demodulator coupled to an output of the filter, wherein the demodulator determines an imaginary portion and a real portion of the gray coded 8-PSK hierarchically modulated signal, and wherein the demodulator subtracts an absolute value of the real portion of the signal from an absolute value of the imaginary portion of the signal to provide the secondary data.
20. The receiver of claim 19 , wherein the gray coded 8-PSK hierarchically modulated signal is a uniform gray coded 8-PSK hierarchically modulated signal.
21. The receiver of claim 19 , wherein the gray coded 8-PSK hierarchically modulated signal is a non-uniform gray coded 8-PSK hierarchically modulated signal.
22. The receiver of claim 19 , wherein the secondary data is low priority data and the primary data is high priority data.
23. The receiver of claim 19 , wherein the secondary data is encoded with a different forward error correction scheme than the primary data.
24. The receiver of claim 19 , wherein a digital one is indicated when the absolute value of the imaginary portion of the signal is greater than the absolute value of the real portion of the signal.
25. The receiver of claim 19 , wherein a digital zero is indicated when the absolute value of the imaginary portion of the signal is less than the absolute value of the real portion of the signal.
26. The receiver of claim 19 , wherein a digital one is indicated when the absolute value of the real portion of the signal is greater than the absolute value of the imaginary portion of the signal.
27. The receiver of claim 19 , wherein a digital zero is indicated when the absolute value of the real portion of the signal is less than the absolute value of the imaginary portion of the signal.
28. The receiver of claim 19 , further comprising:
a source decoder for decoding the secondary data.