Nortel Networks Corporation

Glenayre Electronics, Inc.

Derek Stephen Hilborn

Norman P Secord

Claudio Gustavo Rey

Jian Cui

Robert Richard Leyendecker

David Kent Bonds

Paul Andrew Goud

David E Jones

Mark A Walker

Patricia Fern Kavanagh

Thomas L Frederick

David W Kroeger

Charles Brian Cox

Vladimir Pavlovic

Jay Jui-Chieh Chen

Theron Lee Jones

Alan J Carter

Richard Johnathan Hinkle

Joel Richard Dierks

Flaviu C Costescu

Ray Mr Sewlochan

Emre Tapucu

Terry Lee Hinkle

Wayne Douglas Duello

A maximal correlation symbol estimation (MCSE) method for estimating the symbols that are modulating an information signal component of a received signal, which can be applied to received signals that additionally contain an interference signal component, is disclosed. The method is achieved by correlating the received signal with all possible reference signals, each reference signal being one of a closed set of all possible information signals recognized by the given digital modulation scheme, and selecting as an estimate of the information signal the reference signal whose correlation with the received signal most closely resembles a weighted average of correlations between previously estimated information signals and their corresponding received signals. Demodulators that implement this method are adapted to perform many functions, including the estimation of symbols modulating frequency modulated (FM) received signals prior to the signals being FM demodulated. The embodiment of the MCSE demodulator adapted to carry out this last function, is designed to reduce inter-symbol interference caused by filter responses in the transmitter and receiver, and to permit each symbol to modulate a non-integer average number of signal samples.

Maximal correlation symbol estimation demodulator

Co-channel interference in an AMPS (Advanced Mobile Phone System) receiver, having at least two diversity paths each for producing a received signal, is reduced by determining weights for combining the received signals in dependence upon the received signals and a reference signal, combining the received signals in accordance with the determined weights to produce a combined received signal, demodulating the combined received signal, and producing the reference signal by amplitude limiting the combined received signal or modulating the demodulated signal or a signal derived from the demodulated signal, so that the reference signal is produced from the combined received signal with amplitude variations reduced and with frequency variations of the desired signal substantially maintained.

Co-channel interference reduction

A linear transmitter (101) using predistortion includes a modulator (103), a predistorter (107), a digital quadrature modulator (111), an upconverter (113), a power amplifier (115), and an antenna (117). In addition, the transmitter (101) has a feedback loop including a coupler (119), a downconverter (123), a digital quadrature demodulator (125), and a trainer (131). The digital data to be transmitted is provided into the modulator (103), which converts the digital data into in-phase and quadrature component signals. The in-phase and quadrature component signals are then provided to the predistorter (107), which 'predistorts' the component signals prior to amplification. The digital quadrature modulator (111) converts the component signals into a single analog signal. The upconverter (113) upconverts this signal from the predistorter (107) into the desired frequency of transmission, which is provided to the power amplifier (115) and the antenna (117) for amplification and broadcast. The coupler (119) provides a portion of the amplified signal to the analog downconverter (123), which lowers the frequency of this signal to a range that is easily processed. The signal is then provided to the digital quadrature demodulator (125), which outputs the in-phase and quadrature component signals of the signal. These in-phase and quadrature component signals are provided to the trainer (131) which analyzes them with the output signals from the modulator. The trainer (131) compares these signals and updates the predistorter (107) so that the digital quadrature demodulator (125) output signals are substantially equivalent to the modulator (103) output signals.

Linear transmitter using predistortion

Growing community of inventors

Nepean, Canada

Derek Stephen Hilborn