Abstract: In a protection device of a current amplifier circuit, to protect the current amplifier circuit against more high-speed operation than recovery time of a relay device and to protect operation of the current amplifier circuit in a wide range from low frequency side to high frequency side. A protection device 30 includes a detection circuit 32 that detects an abnormal current value of a current amplifier circuit 14 and outputs a first abnormality detection signal. The protection device 30 outputs a second abnormality detection signal continuously for predetermined time that starts from output timing of the first abnormality detection signal, turns down an input voltage value to the current amplifier circuit 14 at receiving timing of the second abnormality detection signal, and outputs a cutting command signal to a relay device 36 at the same timing.

Abstract: According to one embodiment, a mobile wireless terminal, which makes a wireless communication with a base station accommodated in a network, includes a receiver, a communication module, and a controller. The receiver is configured to receive and frequency-convert a wireless signal transmitted from the base station, and to detect a beacon signal transmitted from the base station based on a reception signal obtained by the frequency conversion. The communication module is configured to receive a wireless signal transmitted from the base station, to acquire identification information of the base station by decoding a reception signal obtained from the wireless signal, and to communicate with the base station. The controller is configured to activate the communication module in accordance with a reception result of the beacon signal by the receiver, and to control the communication module to acquire identification information from the base station.

Abstract: A device previously configured as a registrar and that has established an independent ad-hoc network is automatically discovered by another device also previously configured as a registrar. To form an ad-hoc wireless network between these two devices, each device periodically enters a scanning mode to scan for and intercept beacons transmitted by the other device. Upon such interception, one of the devices becomes an enrollee in accordance with a predefined condition and in response to a user selected option. Subsequently, the enrollee modifies its beacons to include an attribute, such as the MAC address, associated with the other device. After intercepting the modified beacon, the remaining registrar prompts it user to decide whether to allow the enrollee to join the registrar's network. If the user responds affirmatively, a handshake is performed between the two devices and a subsequent attempt is made by the enrollee to join the registrar's network.

Abstract: The dual mode receiver channel select filter includes a filter for a dual mode Bluetooth/Wireless Local Area Network (WLAN) receiver portion of a BT/WLAN transceiver. The filter is a 4th order complex filter and is digitally programmable and reconfigurable. Implemented as the channel select filter for dual-mode receivers, the filter adopts low-IF for Bluetooth and zero-IF for WLAN (IEEE 802.11b). It is based on simple active elements, such as current and voltage followers. The center frequency is digitally tuned through programming active current division networks (CDNs).

Abstract: Determining and simultaneously using a base station coupled to a mobile device, the base station comprising a detector for receiving a first identification signal corresponding to a first module and a second identification signal corresponding to a second module from the mobile device. A transmitter for sending a plurality of signals to the mobile device, said plurality of signals is configured to set up communication between the mobile device and the base station. A receiver for receiving a plurality of parameters for determining whether the second module is able to attach to the base station; and a processor for connecting the first and second module in the mobile device to the base station simultaneously in response to a plurality of slots by time multiplexing and the plurality of parameters when the second module is acceptable by the base station, wherein said plurality of slots are determined by the base station.

Abstract: A method and apparatus taught herein reduce the peak-to-average ratio (PAR) of a complex-valued signal based on detecting peaks in the signal that are above a peak threshold, characterizing the detected peaks in Cartesian coordinates, generating cancellation pulses in Cartesian coordinates based on the detected peak characterizations. PAR reduction processing continues with canceling the detected peaks by combining the cancellation pulses with a correspondingly delayed version of the signal. Advantageously, peak detection may be performed in polar form using a computationally efficient peak detection algorithm that avoids calculation of the I and Q peak waveforms unless a signal peak beyond a defined threshold is present. In one or more embodiments, the generation and use of asymmetric and/or shaped cancellation pulses offers further performance advantages.

Abstract: Methods and apparatus for sensing the presence of a transmission signal type within a wireless channel in a wireless communication system, such as those including the use of wireless microphones, are described. Sensing the transmission signal type includes calculating a spectral density estimate of a signal on the wireless channel. A first test value, derived from the calculated spectral density estimate, is compared to a first threshold. A preliminary determination of the presence of the transmission signal type is made if the first test value exceeds the first threshold. Sensing the presence of the signal type after preliminary determination of the presence of the signal type is made by determining that an observed spectral density of a prescribed signal added to the signal on the wireless channel matches a model estimate of the spectral density of the prescribed signal to a sufficient degree.

Abstract: An amplitude detecting device of the present art increases the slope of the change in output voltage corresponding to the change in amplitude of an input signal to improve the detection accuracy of amplitude change of input signal, without changing the dynamic range of the device. An amplitude detecting device of the art includes a plurality of amplifiers that amplify an input signal according to a predefined amplification rate, an amplitude detector that detects the amplitude of the signal amplified by the amplifiers, an operation circuit that operates the signal detected by the amplitude detector and obtains the amplitude value of the input signal, and a switch circuit that sets whether the signal detected by the amplitude detector is to be transmitted to the operation circuit or not.

Abstract: A method and apparatus taught herein reduce the peak-to-average ratio (PAR) of a complex-valued signal based on detecting peaks in the signal that are above a peak threshold, characterizing the detected peaks in Cartesian coordinates, generating cancellation pulses in Cartesian coordinates based on the detected peak characterizations. PAR reduction processing continues with canceling the detected peaks by combining the cancellation pulses with a correspondingly delayed version of the signal. Advantageously, peak detection may be performed in polar form using a computationally efficient peak detection algorithm that avoids calculation of the I and Q peak waveforms unless a signal peak beyond a defined threshold is present. In one or more embodiments, the generation and use of asymmetric and/or shaped cancellation pulses offers further performance advantages.

Abstract: A signal relay apparatus, method, application program, and computer readable medium adapted for wireless network are capable of saving power consumption due to failure of adjusting amplifying gain dynamically and solving the difficulty of demodulation since noise is also amplified during relay. For wireless access network, the present invention decreases the transmission power of mobile devices so that the battery of the mobile devices may keep working longer and the interference inside is reduced.

Abstract: A wireless transmission apparatus that can accurately select an optimal modulation scheme on a per block basis in a multi-carrier communication system in which block division of subcarriers and adaptive modulation are performed. In this wireless transmission apparatus, a propagation path characteristics acquisition section acquires the average SNR and SNR variance for each block, which are estimated by a wireless reception apparatus, using received signals inputted from a reception RF section and outputs these to an assignment section. The assignment section selects a modulation scheme for each block based on the average SNR and SNR variance of each block inputted from the propagation path characteristics acquisition section and modulation sections modulate multi-carrier signals included in each block, with the modulation scheme for each block selected by the assignment section.

Abstract: Disclosed are methods and systems for mitigating unwanted signal components. A received carrier signal is downconverted using a local reference signal that imposes an frequency perturbation or dither. Later, when an intermediate digitized signal is filtered to remove the DC offset that is an artifact of the sampling process, the dither in the carrier signal serves to distinguish the carrier from the unwanted offset. The preferred offset filter is a low pass filter with a passband that is narrow relative to the frequency range of the dither.

Abstract: A transmitter includes a first limiter for performing a first clipping in which an amplitude part at a level higher than an amplitude level based on a first clipping level is cut out from an input signal to be subjected to power amplification, a second limiter for performing a second clipping in which an amplitude part at a level lower than the amplitude level based on a second clipping level is cut out from a first signal that has undergone the first clipping, a separation section for separating a second signal that has undergone the second clipping into an amplitude modulated part and a constant amplitude part, a first amplifier for amplifying the amplitude modulated part, a second amplifier for amplifying the constant amplitude part, and a combiner for outputting a third signal obtained by combining the amplitude part amplified by the first amplifier and the constant amplitude part amplified by the second amplifier.

Abstract: Aspects of the method and system for rejecting single sided leakage into an amplitude modulated channel may comprise an AM demodulator for demodulating a received composite broadcast signal's control channel to generate an amplitude modulated (AM) component. A PM demodulator may demodulate a received composite broadcast signal's control channel to generate a phase modulated (PM) component. At least one subtractor may subtract an AM leakage component and a PM leakage component contributed by the single sided leakage in the received composite broadcast signal's control channel. The system may comprise at least one of each of AM and PM bandpass filters and envelope detectors that filter and detect envelopes of the AM and PM components at 982.5 Hz and 922.5 Hz.

Abstract: An exemplary embodiment of the present invention described and shown in the specification and drawings is a transceiver with a receiver, a transmitter, a local oscillator (LO) generator, a controller, and a self-testing unit. All of these components can be packaged for integration into a single IC including components such as filters and inductors. The controller for adaptive programming and calibration of the receiver, transmitter and LO generator. The self-testing unit generates is used to determine the gain, frequency characteristics, selectivity, noise floor, and distortion behavior of the receiver, transmitter and LO generator. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or the meaning of the claims.

Abstract: At the transmitter of a transmitter and receiver apparatus for Multiple Input/Multiple Output MultiCarrier-Code Division Multiple Access (MIMO MC-CDMA) systems, modified orthogonal transmit diversity (MOTD) encoders are used for increasing space and time transmission diversity. A P-way combiner is used to connect the MOTD encoders and P multi-carrier modulators. Each modulator is connected to a set of antennas. At the receiver, each multi-carrier demodulator has an amplitude/phase compensator to compensate distortion at every sub-carrier. Similarly, a combiner is used to connect the demodulators and the MOTD decoders. As a result, space, time, and frequency diversity can be explored.

Abstract: A method of estimating the carrier frequency of a signal is disclosed. The method comprising the steps of initializing a time average vector to zero, selecting a user-selectable time segment to divide a received signal into. A signal is received, and divided into the user-selectable time segments. A spectral peak vector is calculated by performing a spectral estimation process on the user-selectable time segment divided signal. A first correlation vector is calculated on the spectral peak vector, and a second correlation vector is calculated from the spectral peak vector and the first correlation vector. The time average vector is appended with the result from the second correlation vector, and the process repeats for each time segment the received signal was broken into. The carrier is estimated using the most commonly occurring frequency in the time average vector.

Abstract: The invention relates to an apparatus of transmitter and receiver for Multiple Input/Multiple Output MultiCarrier-Code Division Multiple Access (MIMO MC-CDMA) systems. At the transmitter, modified orthogonal transmit diversity (MOTD) encoders are used for increasing space and time transmission diversity. A P-way combiner is used to connect the MOTD encoders and P multi-carrier modulators. Each modulator is connected to a set of antennas. At the receiver, each multi-carrier demodulator has an amplitude/phase compensator to compensate distortion at every sub-carrier. Similarly, a combiner is used to connect the demodulators and the MOTD decoders. Upon the invention, the space, time, and frequency diversity can be explored.

Abstract: A system for spur cancellation comprises an input, an output, a memory, and a summer. A value corresponding to an energy level of a spur is stored in the memory. The summer is configured to receive an input signal from the input, to receive the value from the memory, to subtract the value from the input signal, and to convey an output signal to the output. The output signal is a difference of the value subtracted from the input signal.

Abstract: A transmitting/receiving module includes a first amplifier for amplifying a transmission signal, a second amplifier for amplifying a receiving signal, and a low reflection limiter provided on an input side of said second amplifier. There may be further provided a radiator from which the transmitting signal is to be radiated into an air and to which the receiving signal is to be received, and a circulator having a first terminal, a second terminal and a third terminal, in which the transmitting signal is inputted to the first terminal, the receiving signal is received by the radiator connected to the second terminal, the third terminal is connected to the second amplifier, and the low reflection limiter is provided between the circulator and the second amplifier.

Abstract: The invention indicates a method for signal processing of an amplitude-modulated and/or phase-modulated high-frequency signal (RF signal), in which the RF signal is broken down into two signals (FM1 and FM2) by relative phase displacement by an angle +? and ?? and the signals are amplified before they are added to form a transmission signal, and to a circuit arrangement in which the pure phase-modulated RF signal is multiplied in a first branch by cos ? and in a second branch by sin ? and the two signals (FM1, FM2) are obtained by respective summation and subtraction of the multiplied signals.

Abstract: A polyphase receiver comprises an RF front end (10 to 28) for receiving a wanted data signal modulated on a carrier signal and for producing quadrature related low IF signals, an image rejection filter formed by a polyphase filter (30) for filtering the quadrature related low IF signals, soft limiting means (36,38) for compressing the dynamic range of the filtered quadrature related IF signals and a signal demodulator (41) for recovering the data signal. The soft limiting means (36,38) has a characteristic which is substantially linear at signal levels 10 dB below a predetermined minimum wanted signal level, moves into compression for higher signal levels and hard limits at substantially 10 dB above the desired receiver sensitivity which avoids degrading the sensitivity of the receiver.

Abstract: In multi-path regions of high wave strength, noise in produced sounds of a vehicle audio system is reduced due to controlling of amplification of radio waves received by an on-glass antenna on the basis of wave strength at a running position of a vehicle and its change rate.

Abstract: This invention relates to a method for determining a modulation method comprising demodulating said method comprising demodulating said received signal using at least two different modulation methods, determining for each demodulated signal an estimate of said channel, said estimate of said channel comprising m taps, selecting n of said taps for each channel estimate, a being less than m, estimating a variance for each demodulated signal based on said n taps, and comparing the estimated variances and based on said comparison making a determination as to the modulation method applied to the received signal.

Abstract: Various mixer topologies, configured to cancel various low order spurs. The mixer topologies each include a pair of mixers and a plurality of couplers. The couplers are configured to cancel specific spurs. As such, the mixer topology eliminates the need for band splitting thus allowing larger input frequency ranges and allows for simpler and less expensive filtering.

Abstract: A differential FM detection of signals uses in-phase and quadrature phase signal components of a received signal in the detection process, wherein the in-phase and quadrature phase signal components are at a low intermediate frequency (IF). The in-phase and quadrature phase signal components are each amplitude limited, sampled at a prescribed sampling rate and filtered in a prescribed manner. Delayed versions of the filtered in-phase and quadrature phase signal components are generated and, then, signal products are generated of the delayed in-phase signal component and quadrature phase signal component, and the delayed quadrature phase signal component and in-phase signal component. The algebraic difference of the generated signal products is obtained to yield the desired data signal, e.g., symbols.

Abstract: The present invention includes backscatter communication systems, interrogators, methods of communicating in a backscatter system, and backscatter communication methods. According to one aspect of the present invention, a backscatter communication system includes an interrogator including a transmitter configured to output a forward link communication and a receiver configured to receive a return link communication having a carrier signal, the receiver being configured to reduce the amplitude of the carrier signal of the return link communication; and a communication device configured to modulate the carrier signal to communicate the return link communication responsive to reception of the forward link communication.

Abstract: An FM demodulation circuit includes a phase conversion circuit which converts a frequency variation of an input signal into a phase variation and has a variable conversion characteristic, and a control current source circuit which outputs, when the level of the input signal drops lower than a predetermined level, control current to vary the conversion characteristic of the phase conversion circuit so that the demodulation sensitivity may be raised.

Abstract: For a possible simple structure, dispensing with ceramic filters, an FM demodulator for demodulating sound-FM signals comprises a controllable amplifier (1) which receives the sound signals converted to intermediate frequencies, said amplifier having a gain which is adjusted by means of an amplitude control circuit (4) and whose output signal is applied to the amplitude control circuit and to the phase-locked loop which supplies a demodulated sound signal in the locked-in state from its output, said phase-locked loop including a loop filter (7) which comprises a filter (8, 9, 10) of at least the second order with a pole at the frequency f=0, and a limit-detection circuit (13) which feeds back the operating frequency of the phase-locked loop to a predetermined frequency range when said phase-locked loop leaves this frequency range around a predeterminable nominal demodulation frequency, the amplitude control circuit (4) controlling the controllable amplifier (1) in dependence upon its output signal and a signa

Abstract: A relay-race FLL/PLL high-speed timing acquisition device according to the invention comprises a transition detector, a voltage controlled oscillator, a loop filter of PLL, a first lowpass filter, a 90.degree. phase shifter, a second lowpass filter, and a plurality of multipliers. In addition, this relay-race FLL/PLL high-speed timing acquisition device is characterized by further comprising a frequency delimiter which includes a highpass filter coupled to a first circuit, a second circuit coupled to the highpass filter, a third lowpass filter coupled to the second circuit, a Schmitt inverter coupled to the third lowpass filter, and a switch member coupled to the Schmitt inverter. The relay-race FLL/PLL high-speed timing acquisition device can obtain stable and high speed timing acquisition by means of the frequency delimiter.

Abstract: Co-channel interference of a frequency modulated signal represented by complex signal samples is reduced by amplitude limiting each sample and non-linearly filtering the limited samples. The non-linear filter low pass filters the limited samples, multiplies the filtered samples by their complex conjugates, and high pass filters the products to produce resultant signal samples. It also squares the filtered samples, low pass filters the squared samples, multiplies the filtered squared signals by the complex conjugates of the filtered samples, combines the result with said resultant signal samples and the filtered samples, and low pass filters the combined signal to produce samples having reduced co-channel interference. The limiter and non-linear filter can be constituted by a digital signal processor.

Abstract: The present invention minimizes noise pops due to Rayleigh fades by controlling receiver gain relative to the average received signal strength so that only a predetermined level of limiting occurs prior to the recovery of the audio information. The amount of limiting is selected so that a significant Rayleigh fade will cause the amplified IF signal to drop below the limiting level and enter the linear amplification region. During the fade the magnitude of the signal provided to the discriminator decreases thereby decreasing the discriminator's output and minimizing the magnitude of the audio pop. Additional minimization of the subject noise pops is achieved by utilizing a discriminator which has a square law transfer characteristic so that the recovered audio level will decrease 2 dB for every 1 dB decrease in input signal level.

Abstract: An improved FM receiver is disclosed incorporating improved oscillating limiter circuitry having an electrically tunable bandpass filter which is phase modulated by the baseband signal the phase of which has been advanced in accordance with the formula: ##EQU1## wherein td.sub.1 equals the time delay through the limiter, td.sub.2 equals the time delay through the feedback filter, td.sub.3 equals the time delay through the demodulator and f.sub.n equals the frequency of the respective baseband components.

Abstract: An improved FM receiver is disclosed incorporating improved oscillating limiter circuitry having an electrically tunable bandpass filter and variable attenuator in regenerative feedback relationship around the limiter. The electrically tunable bandpass filter is responsive to DC components and high frequency noise components of the demodulated video baseband signal. The variable attenuator is responsive to the carrier-to-noise ratio of the received FM signal whereby the amount of regenerative feedback around the limiter will vary inversely proportional to charges in the carrier-to-noise ratio.

Abstract: An arrangement for suppressing amplitude variation in FM signals comprises a frequency divider which frequency divides an incoming FM signal to provide frequency divided signals having two discrete levels dependent upon the amplitude of the incoming FM signal in relation to a threshold value, and a frequency multiplier which combines the frequency divided signal to provide an output signal of substantially constant amplitude and having a frequency equal to that of the incoming signal.

Abstract: An FM-receiver having an FM-channel successively comprising an RF-input stage and mixer stage (B), an IF-circuit (A) and a ratio detector (R). The ratio detector incorporates silicon detector diodes and a smoothing capacitor conductively connected to the detector diodes for a dynamic amplitude limitation of the ratio detector output signal in dependence on the amplitude of the ratio detector input signal. A bias voltage is applied to the silicon diodes to prevent the silicon diodes from being blocked at signals lower than the threshold voltage of the diodes. The bias voltage comprises an average noise voltage that is generated by amplifying a noise component of the FM signal, the noise component being present in the IF bandwidth. The average noise voltage is predominantly obtained by amplifying the noise produced within the IF-passband of the IF-input stage.

Abstract: A circuit is described for maintaining an input signal to a limiter used to limit amplitude excursions of a signal to be angle demodulated. Means are provided for detecting a temporary loss in signal to said limiter resulting from the loss of signal due to large negative amplitude modulation or other factors. When the amplitude of the angle modulated wave falls below a predetermined minimum, a substitute intermediate frequency signal is generated to maintain the limiter in a limiting condition during the temporary loss in broadcast signal. The substitute intermediate frequency signal has a frequency substantially equivalent to the intermediate frequency signal developed from the broadcast signal during periods when the amplitude of the broadcast signal is adequate. The substitute signal prevents the occurrence of noise generated from an angle demodulator due to a temporary loss in signal.

Abstract: A demodulator for PSK-FM double modulated carrier signals in which the carrier signal is 2.sup.N phase modulated by a main signal and frequency modulated by a sub-signal. A clock component is extracted from the received double-modulated carrier signal and the carrier signal sampled in accordance therewith. The amplitude of the output of the sampling gate is limited prior to frequency multiplication by 2.sup.N. A frequency modulated component is then demodulated from the multiplied signal.

Abstract: The present invention includes backscatter communication systems, interrogators, methods of communicating in a backscatter system, and backscatter communication methods. According to one aspect of the present invention, a backscatter communication system includes an interrogator including a transmitter configured to output a forward link communication and a receiver configured to receive a return link communication having a carrier signal, the receiver being configured to reduce the amplitude of the carrier signal of the return link communication; and a communication device configured to modulate the carrier signal to communicate the return link communication responsive to reception of the forward link communication.

Abstract: The present invention includes backscatter communication systems, interrogators, methods of communicating in a backscatter system, and backscatter communication methods. According to one aspect of the present invention, a backscatter communication system includes an interrogator including a transmitter configured to output a forward link communication and a receiver configured to receive a return link communication having a carrier signal, the receiver being configured to reduce the amplitude of the carrier signal of the return link communication; and a communication device configured to modulate the carrier signal to communicate the return link communication responsive to reception of the forward link communication.