Abstract: A radio communications system includes a transmitter and a receiver. The transmitter generates or receives digital symbols having a given symbol rate associated with a corresponding symbol period; and generates, every S digital symbols generated/received (S>3), a respective multi-mode digital signal, which has a predefined time length shorter than S times the symbol period, which is sampled with a predefined sampling rate higher than the symbol rate, and which carries the S digital symbols by a plurality of orthogonal harmonic modes including a main mode which is a real harmonic mode and carries P of the S digital symbols (P<S). The receiver receives and processes the radio frequency signal to obtain a corresponding incoming digital signal; and extracts, from successive, non-overlapped portions of the incoming digital signal sampled with the predefined sampling rate, the S digital symbols respectively carried by each incoming digital signal portion by the orthogonal harmonic modes.

Abstract: One embodiment of the present invention relates to a combined mixer filter circuit. The circuit includes a sampler, a plurality of filter branches, and a coefficient generator. The sampler is configured to provide a sampled signal by sampling a received signal at a specified rate. The plurality of filter branches has selectable filter coefficients. The plurality of filter branches are configured to receive the sampled signal and generate a mixed and filtered output signal without a separate mixer component. The coefficient generator is coupled to the plurality of filter branches. The coefficient generator is configured to assign filter coefficient values to the selectable filter coefficients to yield a selected mixing function for the mixed filtered output signal.

Abstract: A modulator, a demodulator and a modulator-demodulator are provided. A modulator includes a first intermediate signal processing path adapted to route a first intermediate signal; a second intermediate signal processing path adapted to route a second intermediate signal; a first amplifier coupled into the first intermediate signal processing path; a second amplifier coupled into the second intermediate signal processing path; and a chopper circuit coupled into the first intermediate signal processing path; wherein the chopper circuit is adapted to process the first intermediate signal in dependence on first baseband data; wherein the first amplifier is adapted to amplify the first intermediate signal processed by the chopper circuit in dependence on second baseband data; and wherein the second amplifier is adapted to amplify the second intermediate signal in dependence on the second baseband data.

Abstract: A method of demodulating a signal on which is modulated, using a quadrature amplitude modulation scheme, a plurality of information symbols, the method including: determining at least one QAM detection threshold corresponding to one or more of said information symbols; and demodulating each information symbol on the basis of at least one respective QAM detection threshold.

Abstract: A FM-AM demodulator includes a FM signal amplifier, a local oscillator, an image oscillator, a first selector, a first orthogonal mixer, an AM signal amplifier, a first frequency divider, a second frequency divider, a second selector, a second orthogonal mixer, a third selector, a first filter, a first amplifier, a fourth selector, a second filter, a second amplifier, a first gain controller, an I/Q compensation unit, an IF oscillator, a third orthogonal mixer, an adder, a channel filter configured to extract a signal with a predetermined frequency band output from the adder, a third amplifier, a second gain controller, a demodulator, and an I/Q compensation controller configured to generate an I/Q compensation signal to use for adjusting phase and gain of the I signal used in an I/Q compensation unit by detecting amplitude of the output signal from the demodulator, and output the generated signal to the I/Q compensation unit.

Abstract: An exemplary amplitude shift keying (ASM) demodulator and a radio frequency identification (RFID) system using the same are provided. The ASM demodulator is adapted to demodulate an alternating current input signal and generate a demodulated envelope signal. The ASM demodulator includes a signal input terminal group, an input rectifier circuit, a current mirror circuit electrically coupled to the input rectifier circuit, an output stage electrically coupled to the current mirror circuit, and a low pass filter electrically coupled to the output stage. The input rectifier circuit is electrically coupled to the signal input terminal group and adapted to perform a rectifying operation applied to the alternating current input signal. The input rectifier circuit includes a plurality of electrically coupled transistors and a gate electrode of each of the transistors is unconnected with a source electrode and a drain electrode itself.

Abstract: In general, this disclosure describes techniques for demodulating wireless signals. In particular, the techniques of this disclosure dynamically select between two or more demodulators based on channel quality information measured over a plurality of measurement periods. For example, a wireless communication device (WCD) may switch from a first demodulator to a second demodulator when the channel quality information associated with the demodulators indicates a better channel quality for the second demodulator than the first demodulator for a consecutive number of measurement periods. As another example, the WCD may compute, for each measurement period, the difference between the channel quality information associated with each of the demodulators, sum the differences, and switch demodulators when the total accumulation of the differences exceeds a threshold.

Abstract: A FM-AM demodulator includes a FM signal amplifier, a local oscillator, an image oscillator, a first selector, a first orthogonal mixer, an AM signal amplifier, a first frequency divider, a second frequency divider, a second selector, a second orthogonal mixer, a third selector, a first filter, a first amplifier, a fourth selector, a second filter, a second amplifier, a first gain controller, an I/Q compensation unit, an IF oscillator, a third orthogonal mixer, an adder, a channel filter configured to extract a signal with a predetermined frequency band output from the adder, a third amplifier, a second gain controller, a demodulator, and an I/Q compensation controller configured to generate an I/Q compensation signal to use for adjusting phase and gain of the I signal used in an I/Q compensation unit by detecting amplitude of the output signal from the demodulator, and output the generated signal to the I/Q compensation unit.

Abstract: A demodulation circuit and method are provided. The demodulation circuit includes a transformation circuit which is configured to transform the received signal into a modified signal representation in which both amplitude-varying information and frequency-varying information are converted to a uniform representation; and a processing circuit which is configured to process the modified signal representation to demodulate the received signal based on the uniform representation. The method includes transforming the signal into a modified signal representation in which both amplitude-varying information and frequency-varying information are converted to a uniform representation; and processing the modified signal representation to demodulate the signal based on the uniform representation.

Abstract: Embodiments of a frequency modulated (FM) demodulator and associated methods are generally described. According to but one example embodiment, an apparatus is disclosed comprising a receiver front-end, to receive a signal from one or more antenna(e) and generate quadrature components of the received signal, and a frequency-shifted, cross-multiplied differentiator demodulator, coupled with the receiver front-end, to generate a demodulated representation of the received signal centered at a select intermediate frequency.

Abstract: A wireless fading-channel demodulator using adaptive sub-array group antennas to combine beamforming and diversity gain, a signal receiving system and method for mobile communications using the wireless fading-channel demodulator. The wireless fading-channel demodulator eliminates interference signals arriving at different directions-of-arrival (DOAs) from undesired mobile stations (users) and provides strong immunity to fading. A high signal and interference-to-noise ratio SINR can be achieved even when the number of antennas is smaller than the number of mobile stations (users). The wireless fading channel modulator can be applied to any system receiving mobile communication information, such as a base station, a mobile station, etc.

Abstract: A demodulator for demodulating a modulated input signal transmitted at a carrier frequency includes a current mirror for receiving the modulated input signal and generating a first and a second current-mirror output signals of same amplitude and frequency as the modulated input signal. The demodulator further includes a first and a second switch-controlled sampling circuits connected to the current mirror for receiving the first and second current mirror output signals respectively. The demodulator further includes a switching signal generator provided for generating a first and a second switch control signals having a frequency substantially equals to the carrier frequency with a flexibly adjustable phase difference between the first and the second switch control signals.

Abstract: A demodulator arrangement, suitable to demodulate data symbols modulated in accordance with a predefined constellation diagram and sent as part of information bursts (A1, B1, C1, D1, A2, B2, C2, D2) over a transmission medium with substantially stable attenuation characteristics, detects the amplitude of the data symbols in a coherent way and detects the phase of the data symbols in a differential way.

Abstract: A network receiver is configured for receiving a modulated carrier signal representing a data frame from another network transceiver via a network medium, the modulated carrier signal may be either a pulse position modulated (PPM) carrier, a quadrature amplitude modulated (QAM) carrier, or a compatibility mode frame including both PPM and QAM portions. The network receiver is configured to select an A/D sampling clock frequency corresponding to the detected frame type.

Abstract: This invention discloses a demodulation method. The method includes steps of: A) Receiving a modulated input signal having an input signal frequency. B) Generating a first switch control signal at a first switching frequency substantially equal to the input signal frequency. C) Generating a second switch control signal having the same frequency as the first switch control signal and having a phase that is approximately 90 degrees different from a phase of the first switch control signal. And D) Controlling at least two switching circuits with the first and second switch control signals for obtaining at least two sets of sampled amplitudes of the input signals for generating switching output signals for each of the switching circuits defined by subtracting the sampled amplitudes when the first switch control signal is high by the sampled amplitudes when the first switch control signal is low for each of the switching circuits to generate demodulated output signals for the modulated input signal.

Abstract: In a demodulating method of demodulating amplitude-demodulated signals in an amplitude phase shift keying system for conducting an amplitude modulation by setting signal points as information codes on a complex plane representing a signal space of transmission signals onto circumferences of two concentric circles including a first circle having a first diameter and a second circle having a second diameter smaller than the first diameter on the complex plane, there are obtained, in accordance with an amplitude value of an amplitude component of each symbol of a received amplitude-modulated signal, a first threshold value and a second threshold value having a predetermined relationship with the amplitude value.

Abstract: A digital mixer-filter-decimator (MFD) is disclosed which is reconfigurable so that it can be used in both modes of operation of a dual mode receiver such as an AM/FM receiver. In either mode of operation the MPD performs filtering and decimation operations on separate data streams containing alternate samples of a digital input data stream. In the FM mode a mixing operation is also enabled to produce a complex output comprising in-phase and quadrature components. The mixing operation is disabled in the AM mode and the filtered and decimated outputs are combined to provide a real output. The same decimator filter can be used in both modes.

Abstract: A DMUX 11 outputs data in a digital FM signal in a circulation to produce signals S1 to S4. An MUX 14 alternately outputs inverted signals of the signals S1 and S3, obtaining a signal Si.sub.(k). An MUX 15 alternately outputs inverted signals of the signals S2 and S4, obtaining a signal Sq.sub.(k). An interpolation circuit 17 inserts data having a value of zero between individual data in the output signal of the MUX 14, and cuts off the high-frequency component of the resultant signal, obtaining a signal Si.sub.(i). A second interpolation circuit 19 inserts data having a value of zero between individual data in the output signal of the MUX 15, and cuts off the high-frequency component of the resultant signal, obtaining a signal Sq.sub.(i). An arithmetic operation circuit 2 computes SI.sub.(i-1) .multidot.SQ.sub.(i) -SI.sub.(i) .multidot.Sq.sub.(i-1), and integrates it to obtain a digital demodulated signal.

Abstract: A multiple-modulation communication system includes a transmitter that modulates and transmits communication signals modulated by a first modulation technique and communication signals modulated by a second modulation technique. The first modulation technique and the second modulation technique are different. The communication system also includes a receiver capable of receiving the communication signals modulated by the first modulation technique and the communication signals modulated by the second modulation technique and demodulating the communication signals.

Abstract: Method and apparatus for improving an estimate of a message being carried by a frequency modulated dominant carrier in the presence of co-channel interference from a subdominant carrier. An envelope detector provides an envelope signal E(t). A frequency demodulator provides a demodulated frequency signal F(t). In one embodiment, a comparator compares the envelope signal to a threshold voltage V.sub.T. A switch is operated when the envelope signal is less than V.sub.T. The signal F applied to the switch is held by a holding circuit while the switch is open. Interpolation and lowpass filtering improve the quality of the output signal. In another embodiment of the invention, the frequency demodulated signal F is summed with an unfiltered signal to provide a first summed signal. The first summed signal is summed with an unfiltered signal to provide a second summed signal which is an estimate of the message on a co-channel subdominant carrier.

Abstract: A demodulator receives a radio signal and causes a carrier signal reproducing circuit to reproduce the carrier signal of the received signal. One amplifier amplifies the amplitude of the reproduced carrier signal by K, and another amplifies the amplitude of the reproduced carrier signal by (K+2). An adder adds the reproduced carrier signal, amplified by K, and the received signal. A subtracter subtracts the received signal from the reproduced carrier signal amplified by (K+2). The output signal of the adder is demodulated by a first FM demodulator and the output signal of the subtracter is demodulated by a second FM demodulator. Another subtracter outputs the difference between the demodulated signals from the first and second FM demodulators as a demodulated signal of the received signal.

Abstract: The order statistic signal processor obtains continuing estimates of amplitude, phase, or frequency of an input signal based on order statistics. By way of definition, the P'th order statistic for a set of samples from a continuously distributed process is the P'th largest of the samples. Where a signal parameter fluctuates with time as a result of contamination by noise and interference and where the noise fluctuation rate is much greater than the rate at which changes in a signal parameter occur, an order statistic associated with a set of signal parameter samples can serve as an estimate of the signal parameter. The order statistic signal processor is based on an iterative process whereby the prior estimate of a signal parameter, i.e. amplitude or phase, is subtracted from each of a plurality of signal parameter samples obtained over a period of time. The differences are converted to quantities of fixed magnitude with signs corresponding to the differences.

Abstract: A digital demodulator for demodulating baseband signals in a radio receiver. The demodulator includes a digital signal processing module for forming a mathematical series adapted for generating demodulation functions. The selection of coefficients for this series is controlled to provide specific demodulation functions as required for the demodulation of different kinds of signals such as amplitude modulated or angle modulated signals using one computational block or element. When demodulating amplitude modulated signals, the coefficients used in the mathematical series provide an approximation to the square root function. When demodulating phase or frequency modulated signals, the coefficients used provide an approximation to the arctangent function.