FQPSK-B viterbi receiver
An FQPSK-B receiver uses a simplified trellis system which uses combinations of FQPSK-B waveforms to correlate against an input signal. This enables reduction of the number of correlators that are used and the number of comparisons that are made by the correlators.
1. A receiver, comprising:
a plurality of averaged waveforms, each said averaged waveform comprising an average of a plurality of FQPSK waveforms;
a plurality of correlators, to correlate an input signal with each of said averaged waveforms of said plurality to form correlations; and
a trellis decoder using said correlations to make decisions on the transmitted signals.
2. A receiver as in claim 1 , wherein said plurality of averaged waveforms each represent four FQPSK waveforms.
3. A receiver as in claim 1 , further comprising an input filter which filters an input signal.
4. A receiver as in claim 1 , further comprising a demodulator, receiving an input signal, and producing demodulated complex signals.
5. A receiver as in claim 4 , wherein said demodulated complex signals include an in-phase signal and a quadrature signal component.
6. A receiver as in claim 2 , wherein there are four of said correlators to correlate said FQPSK waveforms.
7. A receiver as in claim 1 , wherein each of said plurality of averaged waveforms include a plurality of basic FQPSK waveforms which have similar characteristics.
8. A receiver as in claim 7 , wherein each averaged waveform comprised a combination average of four FQPSK waveforms.
9. A receiver as in claim 1 , wherein said FQPSK waveform are FQPSK or FQPSK-B, waveforms.
10. A method, comprising:
obtaining a plurality of basic waveforms which represent trellis waveforms for FQPSK or FQPSK-B;
averaging groups of said plurality of waveforms to form averaged waveforms, wherein a number of said averaged waveforms is less than a number of said plurality of waveforms; and
correlating an FQPSK-B input signal against said averaged waveforms to form a group of signals to be processed by a trellis decoder.
11. A method as in claim 10 , wherein said averaging groups comprises averaging tour of said PQPSK-B waveforms to form each averaged waveforms.
12. A method as in claim 10 , further comprising filtering an input signal, and wherein said correlating comprises correlating against a filtered input signal.
13. A method as in claim 10 , further comprising producing demodulated signals form input signals and a set of correlation from said demodulated signals.
14. A method as in claim 13 , wherein said demodulated signals include an in-phase signal and a quadrature signal.
15. A method as in claim 10 , wherein said correlating comprises using four of said correlators to correlated the demodulated inphase and quadrature input signal with said FQPSK-B waveforms.
16. A method as in claim 10 , wherein said plurality of averaged waveforms include a plurality of waveforms which have similar characteristics.
17. A method as in claim 10 , wherein each averaged waveforms comprise a combination of four FQPSK waveforms.
18. A receiver, comprising:
a filter element, receiving an input PQPSK-B signal and producing a filtered FQPSK-B signal; and
a Viterbi Algorithm receiver, producing demodulated signals based on said FQPSK-B input signals, wherein said Viterbi Algorithm receiver compares said filtered FQPSK-B signal with a plurality of averaged signals.
19. A method of receiving an FQPSK-B signal, comprising:
obtaining a plurality of basic FPQSK-B signals associated with modulation of an FQPSK-B signal;
averaging said plurality of basic FQPSK-B signals to form a plurality of averaged signals; and
comparing an input coded FQPSK-B signal with said plurality of averaged signals to carry out the modulation.
20. A method as in claim 19 , wherein there are 16 of said basic FQPSK-B signals, and wherein there are four of said averaged signals.