Importance

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Abstract

An MSK receiver includes a downconverter for downconverting the received MSK signals. The phase drift or phase error per bit of the message preamble is determined. The reference carriers are generated, and the phase of the reference signals is adjusted during message demodulation under the control of the estimated rate of phase change across the preamble portion. In accordance with another aspect of the invention, the downconverted MSK signal burst is digitized and the digitized burst signal is stored in memory, following which it is read repeatedly so that bit timing, start-of-message timing, carrier phase, and carrier drift processing may be performed in a desired sequence, using all the available information for more accurate demodulation. According to a yet further aspect of the invention, a second order tracking loop is used to adjust the phase of the demodulation reference signals.

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First Claim