Abstract: A reconfigurable quadrature coupler is disclosed. The reconfigurable quadrature coupler includes an input port transmission line connected to a first port, a coupled port transmission line and a coupled port transformer connected between the coupled port transmission line and a second port. The coupled port transformer is configured to have a selectable second port reflection coefficient. The reconfigurable quadrature coupler further includes an isolation port transmission line and an isolation port transformer connected between the isolation transmission line and a third port. The isolation port transformer is configured to have a selectable third port reflection coefficient. Also included is a through port transmission line and a through port transformer connected between the through port transmission line and a fourth port. The through port transformer is configured to have a selectable fourth port reflection coefficient.

Abstract: An electrical balance duplexer (EBD) may be used to isolate a transmitter and receiver that share a common antenna. By using impedance gradients to provide impedances that cause balance-unbalance transformers (balun) of the EBD to cut-off access to the common antenna rather than duplicate the antenna impedance, the EBD is balanced. Such cut-offs may have a lower insertion loss than an EBD that merely duplicates the antenna impedance to separate the differential signals of the receiver/transmitter from the common mode signal.

Abstract: A semiconductor device of an embodiment includes first and second couplers, an encoding circuit, and a demodulating circuit. The encoding circuit executes differential Manchester encoding on digital data based on a clock inputted thereto via the first coupler and outputs an encoded data. The demodulating circuit includes a first sampling circuit which samples the encoded data inputted via the second coupler based on a sampling frequency set to be two times higher than that of the encoded data and which outputs first sample data, a second sampling circuit which samples the encoded data at a timing earlier than that in the first sampling circuit and which outputs second sample data, a determination circuit which determines whether or not the first and the second sample data match each other, and a selection circuit which selects first phase data or second phase data from the first sample data.

Abstract: A multidimensional symbol encoder is coupled to a transmitter. Multidimensional symbols are encoded by concatenating two or more partial symbols, wherein individual intervals of up and down sections of the two or more partial symbols are independently controlled as to duration. A multidimensional symbol decoder is coupled to a receiver. Multidimensional symbols are decoded by measuring duration of individual intervals i) that are independently controlled as to duration and ii) that are up and down sections of two or more concatenated partial symbols.

Abstract: A method implemented in a device is disclosed for networking through signals transmitted across a shared medium network. The method starts with monitoring for a first signal on a shared medium of the shared medium network. The first signal is processed after it is received and while the first signal is being processed, a set of one or more signals is received on the shared medium. Then a set of one or more amplitude increases is determined, where each amplitude increase is from an earlier received signal to a later received signal. The set of one or more amplitude increases is compared to a threshold value and at least partially in response to the comparison, the device discards one or more signals from the first signal and the set of one or more signals.

Abstract: A method and an apparatus are provided. The apparatus may includes a clock recovery circuit having a comparator that provides a comparison signal indicating whether an input signal matches a level-latched instance of the input signal, a first set-reset latch that provides a filtered version of the comparison signal, where the first set-reset latch is set by a first-occurring active transition of the comparison signal and is unaffected by further transitions of the comparison signal that occur during a predefined period of time, delay circuitry that receives the filtered version of the comparison signal and outputs a first pulse on a first clock signal, and a second set-reset latch configured to provide a second pulse on an output clock signal when the first pulse is present on the first clock signal and the comparison signal indicates that the level-latched instance of the input signal does not match the input signal.

Abstract: Embodiments include systems and methods for increasing frequency offset tracking in clock data recovery (CDR) systems. For example, in asynchronous clocking environments, the receiver-side clock frequency can be offset from the transmitter-side clock. While traditional CDR systems can handle some amount of offset, they are typically ineffective at accurately adapting the receiver-side clocking to an optimal data sampling rate when the offset is excessive. Embodiments include a CDR frequency offset adaptation loop that generates an adaptation signal, which can be monitored to detect an adaptation error arising from excessive frequency offset. In response to the detecting, an offset seed can be selected and injected into the frequency offset adaptation loop, thereby reinitializing the frequency offset adaptation loop with a less stressful seed.

Abstract: A machine-implemented system and method are described for removing interference between adjacent distributed-input-distributed-output (DIDO) clusters comprising. For example, a method according to one embodiment comprises: detecting signal strength at a first client from a main DIDO cluster; detecting interference signal strength at the first client from an interfering DIDO cluster; if the signal strength from the main DIDO cluster reaches a specified value relative to the value of the interference signal strength from the interfering DIDO cluster, then generating channel state information (CSI) defining channel state between one or more antennas of the first client and one or more antennas of the interfering DIDO cluster; transmitting the CSI from the first client to a base transceiver station (BTS) in the interfering DIDO cluster; and implementing DIDO precoding with inter-DIDO-cluster interference (IDCI) cancellation at the BTS in the interfering DIDO cluster to avoid RF interference at the first client.

Abstract: A wireless charging in-band communication system includes a transmitter module that formats a message using CRC calculation and attaches the results of the CRC calculation to the message for message error detection. The transmitter includes channel encoding for message error correction. A modulation module performs biphase modulation for DC balanced signals and impedance switching to change reflected impedance seen by the source. A synchronization module prepending the message with a synchronization sequence having Golay complementary codes. Moreover, the in-band communication includes a receiver module that receives the message from the transmitter module. The receiver module includes an impedance sensing circuit to detect changes in the reflected impedance of the transmitter module. The receiver module includes a front end filter used for pulse shaping and noise rejection.

Abstract: In a control unit for passenger protection and a method for triggering passenger protection devices, a Manchester-coded signal is supplied by an interface and the Manchester-coded signal is decoded by a coding unit, so that an analyzer unit performs the triggering of passenger protection devices as a function of the decoded signal. The decoding unit uses a shift register structure for decoding and oversampling for the Manchester-coded signal.

Abstract: A comparator circuit compares a test pattern generated by a test pattern generator circuit, with a test pattern transmitted to a memory card and returned from the memory card. A control circuit determines a bandwidth corresponding to frequency components correctly transmitted between a host apparatus and the memory card, based on the returned test pattern, and selects an encoding method requiring a maximum available bandwidth. The control circuit generates a notification message indicating the selected encoding method, and encodes the notification message using the selected encoding method, and transmit the encoded notification message to the memory card. The control circuit establishes communication between the host apparatus and the memory card, when receiving a response message including an acknowledgement to the notification message, from the memory card.

Abstract: A communication receiver and a receiving method are disclosed. An analog front-end device samples a receiving signal and generates a sampled signal. A signal detector detects presence of the receiving signal according to the sampled signal. A symbol timing recovery (STR) unit determines an optimal symbol sampling point according to a zero-crossing point of the sampled signal when the receiving signal is present, and then generates a recovered symbol based on an optimally chosen sampled value according to the optimal symbol sampling point.

Abstract: An improved RFID Tag, Interrogator, and system wherein at least one tag modulates a radio frequency signal by modulated backscatter operations.

Abstract: Decoder circuits and methods down-sample the samples that oversample an input signal having a differential Manchester encoding. A first input port receives first, second, and third samples. A second input port receives a state indicating whether a clock transition or a data transition precedes the first, second, and third samples. A third input port receives first, second, and third down-sampled bits. A detector circuit is configured to generate a detection signal indicating a presence of a short pulse within the samples when the state indicates the clock transition and the second and third down-sampled bits are equal and differ from the first down-sampled bit and the third sample. A generator circuit is configured to generate a fourth down-sampled bit that equals the third sample when the detection signal indicates the presence of the short pulse, and that equals the second sample when the detection signal does not indicate the presence.

Abstract: A video signal and an audio signal are TMDS transmitted from a source device to a sink device. Through a reserved line and a HPD line provided separately from a TMDS transmission line, an Ethernet™ signal is bidirectionally transmitted, and also, a SPDIF signal is transmitted from the sink device to the source device. The Ethernet™ signal bidirectionally transmitted between Ethernet™ transmitter/receiver circuits is differentially transmitted by an amplifier and is received by the amplifier. The SPDIF signal from a SPDIF transmitter circuit is common-mode transmitted from an adder and is received by the adder to be supplied to the SPDIF receiver circuit.

Abstract: Digital data encoding and decoding method and system is provided. The data encoding includes encoding a frame signal into a bit stream, including detecting a specific bit pattern in the bit stream when the frame signal is present, generating a control signal in respect to the specific bit pattern, and encoding the bit stream into one or more marks and one or more spaces so that encoded data include a unique encoding pattern for the frame signal. The data decoding includes detecting at least one of mark and space from encoded data, recovering a bit stream from the encoded data when the at least one of mark and space is present, detecting a specific bit pattern associating with a frame signal from the encoded data when the at least one of mark and space is present, and recovering the frame signal from the encoded data.

Abstract: A galvanic isolator having a transmitting section and a receiving section is disclosed. The transmitting section includes a frame input circuit, a data encoder, and a data transmitter. The frame input circuit receives an input data frame that includes a plurality of input binary bits. The data encoder encodes the input binary bits to generate an encoded data frame that includes a sequence of encoded binary bits in which two successive encoded binary bits represent each input binary bit. The successive encoded binary bits representing a 1 are 01 or 10, and the successive encoded binary bits representing a 0 are 00 or 11. The sequences are chosen to maximize the number of transitions in the encoded data frame. A data receiver recovers the encoded data frame by examining successive pairs of encoded data bits using a clock that is reset on the edges in the encoded data frame.

Abstract: A differential receiver which provides for estimation and tracking of frequency offset, together with compensation for the frequency offset. Estimation and tracking of the frequency offset is undertaken in the phase domain, which reduces computational complexity and allows frequency offset estimation and tracking to be accomplished by sharing already-existing components in the receiver. Compensation for the frequency offset can be performed either in the time domain, before differential detection, or in the phase domain, after demodulation, or can be made programmably selectable, for flexibility.

Abstract: A system and method for controlling modulation. The system includes a plurality of modulators and a transmitting unit. The plurality of modulators decodes data from a data signal and also encodes the data into a clock signal. The transmitting unit transmits the encoded clock signal. According to the system and method disclosed herein, the present invention provides optimized coding efficiency while minimizing overall power consumption.

Abstract: An improved RFID Tag, Interrogator, and system wherein at least one tag modulates a radio frequency signal by modulated backscatter operations.

Abstract: A novel and useful apparatus for and method of nonlinear adaptive phase domain equalization for multilevel phase coded demodulators. The invention improves the immunity of phase-modulated signals (PSK) to intersymbol interference (ISI) such as caused by transmitter or receiver impairments, frequency selective channel response filtering, timing offset or carrier frequency offset. The invention uses phase domain signals (r, ?) rather than the classical Cartesian quadrature components (I, Q) and employs a nonlinear adaptive equalizer on the phase domain signal. This results in significantly improved ISI performance which simplifies the design of a digital receiver.

Abstract: The present invention relates to a method for configuring a physical layer of a low frequency band based on wireless magnetic field communication, and a computer-readable recording medium including a program for executing the method. The method supports the proper packet format, coding mode, and modulation mode between a master and a slave in order to enable wireless communication in variable data rate or coding modes depending on a peripheral environment in a low frequency band based on wireless magnetic field communication which is applied to a difficult environment. The method of the invention is characterized by changing the data rate and the coding mode of a payload field within a preset range depending on the peripheral communication environment, wherein the payload field is included in the request and response frames between the master and the slave.

Abstract: An ASK modulator for reducing the difference in the On/Off ratio due to the difference in the envelope frequency components without deteriorating an adjacent wave leakage power is disclosed. The ASK modulator includes a Manchester encoder that generates Manchester-encoded signals by applying Manchester encoding to an input signal sequence, a waveform shaping unit that generates band-limited encoded signals from the Manchester-encoded signals, and detects and limits minimum values of waveforms of the band-limited encoded signals to generates shaped signals, and a modulating unit that modulates carrier waves based on the shaped signals.

Abstract: A receiver includes a signal input for receiving a differentially-encoded quadrature phase-shift keyed (DEQPSK) communication signal. A demodulator performs bit decisions on a received coherent symbol and bit decisions on a received differential symbol. A processor is operative with the demodulator and scales a soft decision by a factor from 0 to 1 when the results of the bit decisions on the received coherent branch and differential branch are different.

Abstract: To provide a code amount estimating device which can perform, at high speed and with high precision, estimation of code amount obtained after arithmetic coding. The code amount estimating device includes a context index calculation unit which calculates a context index of a binary symbol included in binary data, and an estimate code amount calculation unit which calculates an estimate code amount for the binary data based on symbol occurrence probability information stored in association with the calculated context index and on a held probability interval range. The estimate code amount calculation unit estimates the code amount for the binary data according to code amount information indicating an association between (i) a combination of a binary symbol string including one or more binary symbols, symbol occurrence probability information, and a probability interval range and (ii) an estimate code amount for the binary symbol string.

Abstract: A method is disclosed for continuous analysis of the transmission quality in fieldbus networks in automation systems with a plurality of fieldbus participants, which communicate with one another over the fieldbus network. Directly measurable logical and physical bus parameters are recorded from the line signal transmitted over the fieldbus network, and are stored with a predefinable retrospectivity. Operational parameters are derived from the measured bus parameters, these being weighted and the weighted bus parameters being linked together to form the operational parameter. The quantitative weighting of a bus parameter is functionally determined by at least one other bus parameter.

Abstract: A bi-phase modulator including a driver and a mixer. The driver includes a prescaler having an input for receiving a signal and an output for outputting a baseband signal. The mixer includes a mixer having an input coupled to the output of the prescaler for receiving the baseband signal output by the prescaler. The baseband signal output by the prescaler drives the mixer so as to output a modulated waveform from an output of the mixer.

Abstract: A mixer circuit accumulates I signal (digital signal of first channel) having its band limited by low-pass filter and first carrier signal to perform two-phase shift keying modulation thereon. An adder adds fundamental-wave component of bit clock signal BCK into Q signal (digital signal of second channel) having its band limited by the another low-pass filter to obtain a resultant added-up signal. Another mixer circuit accumulates the added-up signal and second carrier signal to perform two-phase shift keying modulation thereon. Output signals of the mixer circuits are input to another adder so that they may be added up to obtain a QPSK signal as a modulated quadrature signal. The QPSK signal contains frequency signals whose frequencies are a sum of bit clock frequency and carrier frequency and a difference between them. When demodulating, the carrier signal and the bit clock signal are reproduced using the frequency signals.

Abstract: A receiver including first circuitry configured to combine corresponding soft decision values from at least two groups of RDS/RBDS data transmitted as part of a broadcast channel to generate a set of combined values and second circuitry configured to identify a subset of the combined values that indicate a relatively constant subset of the received values from the at least two groups of the RDS/RBDS data is provided.

Abstract: An apparatus and method for improving a symbol error rate of an M-ary phase shift keying (M-PSK) system having a quadrature error are provided. The apparatus includes: a conversion parameter detector that detects a conversion parameter and converts a symbol decision region using the quadrature error and at least one pair of first received symbols; and a converter & determiner converting a pair of second received symbols using the detected conversion parameter, and determining a transmission symbol according to a symbol of the converted pair of second received symbols. An increase in a symbol error rate due to the quadrature error can be prevented and the quadrature error can be easily estimated.

Abstract: An apparatus for demodulating an analogue input signal comprises a hard limiter stage (4) for converting the signal to a two level signal. A digital down converter/low pass filter stage (6) converts the signal to a base band signal, and a symbol synchronization stage (8) extracts symbol timing. An instantaneous phase detector (10) calculates the instantaneous phase of the one or more symbols associated with the input signal. If the input signal has been modulated according to a pi/4DQPSK, pi/2DBPSK, GMSK, or a GFSK modulation scheme, a differential detector (12) determines a difference in the phase between adjacent symbols, a coarse frequency offset compensation stage (14) applies a compensation signal to compensate for frequency offset, and a frequency offset estimation stage (16) updates this compensation signal. A demapper (18) generates a demodulated output signal after compensation by the frequency offset compensation stage.

Abstract: A differential receiver which provides for estimation and tracking of frequency offset, together with compensation for the frequency offset. Estimation and tracking of the frequency offset is undertaken in the phase domain, which reduces computational complexity and allows frequency offset estimation and tracking to be accomplished by sharing already-existing components in the receiver. Compensation for the frequency offset can be performed either in the time domain, before differential detection, or in the phase domain, after demodulation, or can be made programmably selectable, for flexibility.

Abstract: A method and circuit are shown for decoding a Manchester encoded data input signal, wherein preamble found, data input, and recovered clock signals are received and a phase of the data input signal stored responsive thereto. A decision time signal alternates state responsive to the recovered clock signal. A switch pulse signal asserts when the decision time signal is active and the stored phase and current phase of the data signal have the same logic value, which is stored and cleared responsive to the recovered clock signal. A data output is decoded from a decision pair of phases responsive to the recovered clock, preamble found and decision time signals. The stored and current phases of the data input signal are selected to be the decision pair when neither the switch pulse signal or stored switch pulse signal are asserted and, otherwise, the stored phase and inverted stored phase are selected.

Abstract: The system and method enable simpler analog processing in a transmitter by reducing the number of bits in a digital signal through delta sigma modulation. Selection of current sources in a digital to analog converter of the transmitter is done using a randomization circuit.

Abstract: A mixer circuit accumulates I signal (digital signal of first channel) having its band limited by low-pass filter and first carrier signal to perform two-phase shift keying modulation thereon. An adder adds fundamental-wave component of bit clock signal BCK into Q signal (digital signal of second channel) having its band limited by the another low-pass filter to obtain a resultant added-up signal. Another mixer circuit accumulates the added-up signal and second carrier signal to perform two-phase shift keying modulation thereon. Output signals of the mixer circuits are input to another adder so that they may be added up to obtain a QPSK signal as a modulated quadrature signal. The QPSK signal contains frequency signals whose frequencies are a sum of bit clock frequency and carrier frequency and a difference between them. When demodulating, the carrier signal and the bit clock signal are reproduced using the frequency signals.

Abstract: An ASK modulator for reducing the difference in the On/Off ratio due to the difference in the envelope frequency components without deteriorating an adjacent wave leakage power is disclosed. The ASK modulator includes a Manchester encoder that generates Manchester-encoded signals by applying Manchester encoding to an input signal sequence, a waveform shaping unit that generates band-limited encoded signals from the Manchester-encoded signals, and detects and limits minimum values of waveforms of the band-limited encoded signals to generates shaped signals, and a modulating unit that modulates carrier waves based on the shaped signals.

Abstract: Provided is a direct-conversion frequency mixer for down converting a radio frequency (RF) signal into a baseband signal, in which a single phase RF signal and a quadrature location oscillation (quadrature LO) signal are used to generate the baseband signal, the frequency mixer comprising a first frequency mixing unit that uses quadrature LO signals having respective phases of 0 degrees and 180 degrees to directly down-convert the single phase RF signal into the in-phase baseband signal, and a second frequency mixing unit that uses quadrature LO signals having respective phases of 90 degrees and 270 degrees to directly down-convert the single phase RF signal into the quadrature-phase baseband signal, whereby drains and sources of the transistor for receiving the quadrature LO signal and the transistor for receiving the RF signal are connected in common, thus enabling low power source voltage driving.

Abstract: Nuclear spectroscopy systems have improved over the course of time especially with the advent of digital pulse processing. One disadvantage of digital processing, however, is that it has eliminated the older, universally compatible interface standard of analog signals. Digital component interfaces are often defined by computer software, protected by copyright and unique to a single manufacturer. Consequently, all components of an entire spectroscopy system must be from a single manufacturer. This not only dictates system wide component replacement, but also impedes optimization that would otherwise occur were component compatibility the rule rather than the exception. The present innovation describes a method and apparatus to relieve the present incompatibility between digital components of a nuclear spectroscopy system that are supplied by more than one manufacturer.

Abstract: A spread spectrum coding method. First, a data signal containing a DC component is encoded into an encoded data signal without any DC component. The encoded data signal excluding any DC component is then spread with a spreading code to generate a transmission signal, wherein the transmission signal does not contain any DC component. Furthermore, an alternative method is to spread a data signal with a spreading code to generate a transmission signal, wherein the data signals, spreading codes, and transmission signals all contain a DC component. The transmission signal is then encoded to remove the DC component.

Abstract: A data communication device configured to communicate with a link partner is provided. The data communication device comprises a port coupled to link partner and an auto-negotiation system configured to generate a first differential Manchester signal that comprises information that identifies at least one mode of operation of the data communication device and configured to transmit the first differential Manchester signal to the link partner using the port.

Abstract: A waveform-adaptive ultra-wideband (UWB) transmitter and noise-tracking UWB receiver for use in communications, object detection and radar applications. In one embodiment, the output of an oscillator is gated by a low-level impulse generator either directly or through an optional filter. In a special case of that embodiment wherein the oscillator is zero frequency and outputs a DC bias, a low-level impulse generator impulse-excites a bandpass filter to produce an UWB signal having an adjustable center frequency and desired bandwidth based on a characteristic of the filter. In another embodiment, the low-level impulse signal is approximated by a time-gated continuous-wave oscillator to produce an extremely wide bandwidth pulse with deterministic center frequency and bandwidth characteristics. The low-level impulse signal can be generated digitally. The UWB signal may be modulated to carry data, or may be used in object detection or ranging applications.

Abstract: A data collision detection device that includes a means for de-modulating at least one carrier signal corresponding to a received modulated subcarrier signal from at least one data transmitter to recover the subcarrier signal from the carrier signal. A microcontroller is operatively connected with the means for recovering a subcarrier signal. The microcontroller includes a means for decoding a recovered subcarrier signal. The means for decoding the recovered subcarrier signal is capable of interpreting signal transitions in the recovered subcarrier signal, and is capable of detecting data collisions in the recovered subcarrier signal when in the presence of a plurality of modulated subcarrier signals.

Abstract: A decoding circuit and associated method are provided for decoding a biphase signal. The decoding circuit may include a precharging register to precharge a pair of states of the biphase signal, where a state of the pair of states is precharged at each pulse of a periodic precharging signal. The decoding circuit may further include a verification circuit to compare the two states of the pair of states and give an active error signal if the two states are equal.

Abstract: A hard disk drive (HDD) holds data using a biphase scheme. A plurality of matched filters are used to detect binary data represented by the biphase pattern without the need for synchronous sampling or equalization.

Abstract: Techniques for an electronic shelf label (ESL) system which uses a digital modulation technique for a modulated backscatter uplink from an ESL to a communication base station (CBS) which utilizes pseudo-random sequences instead of a single continuous wave frequency. The CBS transmits a message to an ESL using a Manchester coded amplitude modulated carrier. After receiving the message, the ESL responds by reflectively modulating a continuous wave (CW) signal with a pseudo-random code sequence. Multiple pseudo-random code sequences may be chosen, with each code sequence corresponding to a particular response. The code sequence is modulated onto a kHz carrier which is used to reflectively modulate the CW signal received from the CBS. The CBS then receives the reflectively modulated signal and correlates the received signal to determine message transmitted.

Abstract: A method of transmitting and rapidly recovering a burst of data without first having to establish a timing or phase lock. The signals are transmitted as modified Manchester coded signals having pulse transitions at a clocking pulse rate which is a multiple of the clocking pulse rate at which the signals are originally generated, and wherein the MOOSE coded signal is modified by ON-OFF keying.

Abstract: Method and apparatus for time aligning first and second signals. The second signal is modulated by the first signal to provide a third signal. Frequency components of the third signal are then determined, the frequency components being indicative of time alignment between the first and second signals. The method and apparatus is particularly suitable for converting a Non-Return-to-Zero data signal to a Return-to-Zero data signal by modulating the Non-Return-to-Zero data signal with a Return-to-Zero pulse signal. The method and apparatus provides for the Non-Return-to-Zero data signal and the Return-to-Zero pulse signal being correctly time aligned in an automated manner without human intervention.

Abstract: A system provides two distinct solutions for encoding and decoding servo positioning data for a hard disk drive. A first solution includes: encoding each group of four bits of a pattern signal in a Matched Spectral Null (MSN) format through an intermediate rate 4/6 code; providing a duplicated bit for each bit of the six bit code word obtained with the previous step. A second solution includes: encoding each group of four bit of the pattern signal adding a parity check bit as an intermediate rate ? code; encoding each of the five bits using the biphase map. Both solutions include subsequently: reading a servo wedge information signal using a read and write channel of the hard disk drive; and using a trellis Partial Response decoding scheme matched to the encoded word for obtaining angular and radial information for the head positioning.

Abstract: A method of determining a transfer speed of an encoded data signal including a clock signal and a data signal is provided. First, the encoded data signal is decoded to generate a decoded clock signal. Then, a data transfer speed of the encoded data signal is determined using the decoded clock signal.

Abstract: A waveform-adaptive ultra-wideband (UWB) transmitter and noise-tracking UWB receiver for use in communications, object detection and radar applications. In one embodiment, the output of an oscillator is gated by a low-level impulse generator either directly or through an optional filter. In a special case of that embodiment wherein the oscillator is zero frequency and outputs a DC bias, a low-level impulse generator impulse-excites a bandpass filter to produce an UWB signal having an adjustable center frequency and desired bandwidth based on a characteristic of the filter. In another embodiment, the low-level impulse signal is approximated by a time-gated continuous-wave oscillator to produce an extremely wide bandwidth pulse with deterministic center frequency and bandwidth characteristics. The low-level impulse signal can be generated digitally. The UWB signal may be modulated to carry data, or may be used in object detection or ranging applications.