198 results about "Amplitude-shift keying" patented technology

An RFID system includes a hybrid backscatter-based RFID tag protocol-compatible with existing 802.11x/Bluetooth Standards as well as RFID standards. The tag is linked to a multi-protocol Interrogator via a generated RF Continuous Wave (CW) field. The tag includes an antenna coupled to an RFID and a Bluetooth/802.11x transceiver section. A Protocol Processor services RFID and transceiver sections and is coupled to the antenna via a backscatter switch. The Interrogator can switch the tag to an RFID backscatter radiation mode where the processor switches the antenna impedance to reflect the CW signal. For transceiver operation the processor switches antenna impedance in synchronization with a frame organized bit stream. For reception, the RFID section utilizes demodulation techniques, typically Amplitude Shift Keying (ASK), and provides a wake up mode within a predetermined distance of the Interrogator. The transceiver may operate in a backscatter or regular mode as directed by an Access Point.

A communications system, such as part of a real-time location system, includes a transmitter that can be part of a location processor, tag emission reader or tag interrogator that generates a frequency shift key (FSK) modulated wireless communication signal representative of digital data and transmits the communications signal over a wireless communications channel. A receiver such as incorporated within a tag transceiver used in the real-time location system receives the FSK modulated communication signal. The receiver includes a circuit for calculating the magnitude of low and high tones of the FSK modulated communication signal and a threshold for amplitude shift keyed (ASK) channel data and FSK channel data to derive the digital data even in the presence of on-tone jammers in the communications channel.

A short-range inter-vehicle communication and warning apparatus comprises a forward radar and a backward radar. The apparatus uses the radars to generate Frequency Modulation/Continuous Wave (FMCW) signals, uses amplitude shift keying for data modulation and arranges a special packet format, to realize such a low cost and fast response device of collision avoidance for vehicles. The invention has the dual capabilities of detecting and communicating simultaneously. It can also measure the relative speed of a preceding/rear vehicles and the relative inter-vehicle distance. The invention also exchanges the real-time traffic information with the preceding/rear vehicles at the same time. It is applicable to a one-to-one or one-to-many inter-vehicle channel model.

A demodulation circuit for an Amplitude Shift Keyed (ASK) modulated signal includes an envelope detector, an alternating voltage amplifier, a differentiator circuit, and a comparator having a hysteresis connected in series. The envelope detector produces an envelope signal from the received ASK signal. The amplifier blocks the DC component of the envelope signal and amplifies AC components of the envelope signal to obtain a steeper slope of the rising and falling edges. The differentiator circuit then processes the transition edges to provide a differentiated signal having positive and negative electrical pulses. The comparator converts the pulses into a binary data stream which corresponds to the transmitted data stream. The combination of the differentiated signal and comparator having a hysteresis enables better stability and sensitivity of the ASK demodulation circuit.

Provided is an ultra low-power wake-up receiver capable of reducing an operating time of an analog receiver by controlling operation on/off of the analog receiver according to a clock signal from a digital receiver in an amplitude-shift keying (ASK) or on-off keying (OOK) radio receiver. The ultra low-power wake-up receiver includes: a clock generator generating a clock signal having a predetermined frequency; an operation controller controlling analog operation-on for a predetermined time according to the clock signal from the clock generator; an analog receiver maintaining an operation-on state for a predetermined time according to the analog operation-on control performed by the operation controller, and being operated off after the predetermined time; and a digital receiver being operated on while the analog receiver maintains the operation-on state

The present invention relates to an optical modulating device with frequency multiplying technique for electrical signals, which primary comprises a mixer, which generates a mixed data signal from a first electrical signal and a second electrical signal. The mixed data signal is then received by a first phase shift device to have its phase shifted and becomes a first shifted signal. The first electrical signal is further received by a second phase shift device to have its phase shifted and becomes a second shifted signal. The present invention further comprises an integrated electro-optic modulator (Mach-Zehnder modulator), which is used to receive an input optical signal, the mixed data signal, the first shifted signal, the second shifted signal and the first electrical signal mentioned above, the integrated electro-optic modulator will then modulates the input optical signal into a frequency multiplying output optical signal that carries the first electrical signal and the second electrical signal. The present invention can carry and transmit amplitude shift keying signals and vector modulation signals, thereby provides a more advanced optical communication transmission service.

The present invention suppresses to a minimum the degradation of the transmission quality caused by chromatic dispersion characteristic of an optical transmission medium, and the interplay between the chromatic dispersion and non-linear optical effects in dense WDM transport systems. A baseband input data signal is pre-coded in advance by a pre-coding unit, phase modulation is carried out using a pre-coded signal by the optical phase modulating unit, and the phase modulated optical signal is converted to an RZ intensity modulated signal by the optical filter unit that performs phase-shift-keying to amplitude-shift-keying conversion. For example, an optical phase modulating unit generates an encoded DPSK phase modulated signal using a differential phase shirt keying (DPSK) format, and a phase modulated signal is converted to an RZ intensity modulated signal by the optical filter unit disposed downstream of the optical phase modulating unit.

The invention discloses an analog-digital mixing modulation recognition device and a digital modulation recognition device based on parallel judgment, belonging to the communication field. The invention aims to solve the problems of low precision rate and long recognition time for providing a judgment tree by A.K. N and E.E.A zzouz. The invention is characterized in that the parallelly judged analog-digital mixing modulation recognition device comprises the following steps: a modulation signal receiving module coarsely classifies the received modulation signals through an instantaneous characteristic normalization module and a modulation mode characteristic parameter extraction module, and then the received modulation signals are particularly classified through an amplitude shift keying modulation judgment ouput module, a phase shift keying modulation judgment output module and a frequency shift keying modulation judgment output module. Compared with the analog-digital mixing modulation recognition device, the digital modulation signals received by the digital modulation recognition device based on parallel judgment have different inner structures of the modules when coarse classification and particular classification are conducted.

For transmitting data, a receiving/backscattering arrangement receives, modulates and reflects or backscatters electromagnetic waves emitted by a base station. The modulation corresponds to the data to be transmitted and is carried out selectively using first and/or second different modulation methods depending on the received field strength of the received electromagnetic waves. Preferably, phase shift keying is used especially or at least at low field strengths at far range, while amplitude shift keying is used additionally or alternatively for high field strengths at close range. The two modulation methods can be superimposed. A circuit arrangement includes two different modulator arrangements to perform the two modulation methods depending on the received field strength. The second modulator arrangement preferably comprises a multi-stage voltage multiplier circuit with a modulated switching device intervening in one of the stages to achieve the modulation.

Systems, apparatus, modules, and methods of communicating with memory devices utilizing multi-band communication containing a baseband and one or more amplitude shift keyed (ASK) RF channels over each differential pair of off-chip transmission lines. Configurations are described for interfacing between microprocessors, or controllers and memory devices or modules, and within a DIMM and its DRAM devices, and between multiple DIMM memory modules.

The invention provides a method for reducing a peak average power ratio (PAPR) under APSK (Amplitude Phase Shift Keying) constellation diagram mapping in OFDM (Orthogonal Frequency Division Multiplexing) modulation. According to the method provided by the invention, as the amplitude of signals is limited on a time domain, when time domain signals are converted onto frequency domain constellation points, only the constellation points at an outer layer of the APSK are expanded, only the frequency domain constellation points expanding outwards are remained, and a process of time domain amplitude limitation-frequency domain selection expansion is iterated for a plurality of times. Therefore, the rate of occurring peak signals can be reduced, and the PAPR of the OFDM signals can be reduced. According to the algorithm, an expansion area and an expansion rule are designed under the APSK constellation diagram mapping, so that the error code property cannot be worsened under the APSK modulation. The method provided by the invention can be applied to an OFDM system under the APSK constellation diagram mapping, so that the effect of reducing the PAPR can be achieved well.

The invention discloses an ASK (Amplitude Shift Keying) demodulation circuit with a wide demodulation range used for passive RFID (Radio Frequency Identification) label chips. The ASK demodulation circuit comprises an envelope signal extraction circuit, a comparison circuit and a decision circuit, wherein the envelope signal extraction circuit is used for extracting two antenna voltage signals received by the RFID label chip to obtain two antenna envelope signals including a fast varying envelope signal and a slowly varying envelope signal; the comparison circuit is used for comparing the sampling voltages of the two antenna envelope signals outputted by the envelope signal extraction circuit to obtain envelope changing edges of the antenna envelope signals; the decision circuit is used for deciding the output voltage of the comparison circuit to obtain and output demodulation data. According to the ASK demodulation disclosed by the invention, the influence of overshoot of the antenna envelope signals on the demodulation circuit is completely eradicated, the precision of the demodulation circuit is improved, an ASK demodulation signal of which the depth is 7%-100% can be demodulated, and the demodulation circuit has stronger anti-noise performance, and can be widely applied in the passive RFID label chips.

A structure and method for demodulating two-level differential amplitude-shift-keying signals using simple adding operations are provided. Threshold values are dynamically adjusted according to the channel response. By comparing the threshold values and the differential amplitude values, it can be found whether the amplitude of the received signal is changed. Furthermore, it no needs to know the changed value of received signal amplitudes and the differential two-level amplitude-shift-keying signals can be demodulated by just detecting whether the amplitude of the received signal is changed. By this idea, the complexity of the receiver implementation is simplified and the demodulator can get better performance.

A data-aided, multi-symbol phase estimation (MSPE) scheme is described for improving receiver sensitivity in the direct-detection of optical differential multi-level phase-shift keying (ODmPSK) signals including optical differential quadrature phase-shift keying (ODQPSK) signals, ODQPSK signals with amplitude shift keying (ODQPSK+ASK), optical differential 8-level phase-shift keying (OD8PSK) signals with eight phase levels, and optical differential phase-shift keying signals with more than eight phase levels. The use of data-aided MSPE substantially reduces the “differential detection penalty,” with receiver sensitivity approaching that of coherent detection schemes.

The invention provides an amplitude shift keying (ASK)/on-off keying (OOK) radio frequency (RF) receiving circuit. The receiving circuit is characterized in that after a low noise amplifier amplifies the received signal, the amplified received signal and local oscillation generated by an oscillator are jointly input into a mixer; the mixer reduces the frequency output by the low noise amplifier to intermediate frequency; the intermediate frequency signal output by the mixer is demodulated and output by a peak detection module after being amplified by a primary intermediate frequency amplifier, filtered by an intermediate frequency bandpass filter and amplified by a secondary intermediate frequency amplifier; a charge pump is driven after the peak detection output potential is compared with the fourth reference potential Vref4; the charge pump charges and discharges a capacitor to obtain gain control signals; the gain control signals are fed back to the low noise amplifier, the primary intermediate frequency amplifier and the secondary intermediate frequency amplifier to form an automatic gain control loop; and the low noise amplifier, the primary intermediate frequency amplifier and the secondary intermediate frequency amplifier respectively input the first, second and third reference potentials. The receiving circuit solves the problem of blocking during close range remote control, and meanwhile, the antijamming capability of the receiving circuit is improved and the cost is saved.

The invention discloses a demodulator circuit of an electronic tag of an RFID system. Different from the conventional design, the demodulator circuit acquires a demodulation signal directly from a power supply PWR_DEMO outputted by a rectifier, and achieves demodulation, amplification, shaping and outputting of a weak signal by using an asymmetric circuit design. Specifically, the demodulator circuit conducts demodulation by using envelope detection method, and adopts a secondary comparison circuit. The demodulator circuit of the electronic tag of the RFID system provided by the invention can achieve demodulation of 10% ASK (amplitude shift keying) modulated signals, which are defined as type B according to the standard of ISO/IEC (International Organization for Standardization/International Electrotechnical Commission) 14443-3.

The invention relates to a differential 8-phase shift keying (D8PSK)/amplitude shift keying (ASK) orthogonal light label switching method based on differential biphasic codes, which is characterized in that loads in light group data are subjected to serial-to-parallel conversion to form three-path signals, and the three-path signals are respectively loaded to three phase-modulators for phase modulation after being subjected to differential precoding so as to generate D8PSK signals. Compared with an existing binary transfer system, the capacity of a system provided by the invention is three times of that of the binary transfer system; and label information in the light group data is loaded to the D8PSK signals by using a differential biphase encoding in an ASK mode so as to generate the D8PSK/ASK orthogonal modulating signals based on the differential biphasic codes. Differential biphasic code signals can be used to effectively improve the modulation extinction ratio of the orthogonal signals and strengthen the system performances.