Quasonix Compact RDMS Dokumentacja Pobierz pdf (Strona 55)

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Compact RDMS

Telemetry Receiver

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41 Quasonix, Inc.

13 Appendix D – Phase Noise Compensation

13.1 Trellis Demodulation Basics

Legacy Single-Symbol Detection:

 Uses basic Limiter-Discriminator operation

 Frequency in this bit above nominal → data = 1

 Frequency in this bit below nominal → data = 0

 Makes no use of adjacent symbols for error correction

Trellis Detection:

 Uses the phase tree for data detection

 Uses adjacent symbols to help decide on “iffy” bits

 Improves BER performance by 3.5 to 5.0 dB

The Phase Tree shown in Figure 14, shows all of the possible paths the phase trajectory can take over a period of

seven bits. Figure 15 shows the two unique paths, based on whether the second bit is a 1 or 0.

Figure 14: Ideal PCM/FM Phase Tree (h = 0.7)

1 2 ... 50 51 52 53 54 55 56 57 58 59 60 ... 63 64

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Quasonix Compact RDMS Dokumentacja Strona 55