| 摘要 |
A method and apparatus for encoding and convolutionally decoding a data word of a data word sequence. Each data word has k bits. An encoder selects, using a trellis encoding algorithm and a previous data word, a 2k subset of signal points from a square set of M by M signal points having X coordinates and Y coordinates. The square set of M by M signal points includes a constellation of 2k+l signal points. The encoder selects, using the data word, a signal point from the selected subset of signal points. A modulator generates a first frequency-shift-keying (FSK) signal and a second FSK signal from the selected signal point. A demodulator demodulates the first FSK signal as a received X coordinate and the second FSK signal as a received Y coordinate. A decoder estimates, using a second processor, a 2k received subset of signal points using the convolutionally decoding algorithm and a previously received data word. The decoder estimates a received data word from the received X coordinate, the received Y coordinate, and the estimated-received subset of signal points.
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