Mitel Semiconductor Limited

Christopher R Shepherd

Michael J Pearce

Bernard C Duggan

A 4-level direct conversion receiver demodulator comprises an edge detector , a finite impulse response filter , an N-bit path , a data slicer and automatic frequency control device . The edge detector receives Limited I (LIMI) and Limited Q (LIMQ) signals on respective ones of first and second input leads and from a direct conversion receiver arrangement R. The edge detector contains logic to provide an EDGE signal, comprising a short pulse when any edge is detected in either of the LIMI and LIMQ signals, on a line and an I Lead Q (ILQ) signal, indicative of which of the LIMI and LIMQ signals has the leading phase, on a line to the filter . The edge detector thus determines both the frequency and the relative phase of the signals provided by the limited output direct conversion receiver R without the use of analogue to digital conversion circuitry. The N-bit path output from the filter is provided to both the data slicer and to the AFC device . A demodulated output signal is provided in the form of an MSB and an LSB on respective ones of demodulator outputs and

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Bassingham, United Kingdom

Christopher R Shepherd