5000 results about "Center frequency" patented technology

A waveform adaptive transmitter that conditions and / or modulates the phase, frequency, bandwidth, amplitude and / or attenuation of ultra-wideband (UWB) pulses. The transmitter confines or band-limits UWB signals within spectral limits for use in communication, positioning, and / or radar applications. One embodiment comprises a low-level UWB source (e.g., an impulse generator or time-gated oscillator (fixed or voltage-controlled)), a waveform adapter (e.g., digital or analog filter, pulse shaper, and / or voltage variable attenuator), a power amplifier, and an antenna to radiate a band-limited and / or modulated UWB or wideband signals. In a special case where the oscillator has 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, a 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 UWB signal may be modulated to carry multi-megabit per second digital data, or may be used in object detection or for ranging applications. Activation of the power amplifier may be time-gated in cadence with the UWB source thereby to reduce inter-pulse power consumption. The UWB transmitter is capable of extremely high pulse repetition frequencies (PRFs) and data rates in the hundreds of megabits per second or more, frequency agility on a pulse-to-pulse basis allowing frequency hopping if desired, and extensibility from below HF to millimeter wave frequencies.

A system and method are disclosed for the management of WLANs in cases where unmanaged access points are present as well as with the addition or removal of access points. The disclosed system and method use signal data and network traffic statistics collected by mobile units to determine optimal configuration settings for the access points. The access point settings so managed can include the operating channel or center frequency, orthogonal signal coding used (optionally including the data rate), if any, and the transmission power. The solutions computed can account for the inherent trade-offs between wireless network coverage area and mutual interference that may arises when two or more access points use the same or overlapping frequency bands or channels and the same or similar signal coding.

A data-modulated ultra wideband transmitter that modulates the phase, frequency, bandwidth, amplitude and / or attenuation of ultra-wideband (UWB) pulses. The transmitter confines or band-limits UWB signals within spectral limits for use in communication, positioning, and / or radar applications. One embodiment comprises a low-level UWB source (e.g., an impulse generator or time-gated oscillator (fixed or voltage-controlled)), a waveform adapter (e.g., digital or analog filter, pulse shaper, and / or voltage variable attenuator), a power amplifier, and an antenna to radiate a band-limited and / or modulated UWB or wideband signals. In a special case where the oscillator has 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, a 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 UWB signal may be modulated to carry multi-megabit per second digital data, or may be used in object detection or for ranging applications. Activation of the power amplifier may be time-gated in cadence with the UWB source thereby to reduce inter-pulse power consumption. The UWB transmitter is capable of extremely high pulse repetition frequencies (PRFs) and data rates in the hundreds of megabits per second or more, frequency agility on a pulse-to-pulse basis allowing frequency hopping if desired, and extensibility from below HF to millimeter wave frequencies.

A millimeter-wave transmitter-receiver uses an NRD guide as a fundamental configuration and includes a millimeter-wave signal oscillator, a pulse modulator, a circulator, an antenna and a mixer. In the millimeter-wave transmitter-receiver, a line length of a third dielectric guide is set so that δ=±π in which δ is a phase difference at a center frequency between a portion of a transmission millimeter-wave signal, which is reflected via a third dielectric guide on the leading end portion of the third dielectric guide and returned to leak to a third connecting portion of the circulator, and another portion of the millimeter-wave signal, which leaks from a first connecting portion to the third connecting portion of the circulator. It is possible to reduce the change in the mixer output and enhance the millimeter-wave transmission / reception performance.

An LC parallel resonance circuit is connected in series with the power supply side of the antenna conductor portion. The antenna conductor portion is configured so as to resonate at a frequency slightly lower than the center frequency in the higher frequency band of two frequency bands for transmitting and receiving radio waves. The LC parallel resonance circuit is configured so as to resonate substantially at the center frequency in the lower frequency band for transmitting and receiving a radio wave and be capable of providing to the antenna conductor portion a capacitance for causing the antenna conductor portion to resonate at the center frequency in the higher frequency band. Thus, a circuit for changing the upper and lower frequency bands is not needed. Such a change-over circuit, which is complicated, causes problems in that the conduction loss increases, and the antenna sensitivity deteriorates. Without need of the change-over circuit, the conduction loss can be reduced, the antenna sensitivity can be enhanced and costs can be reduced.

A system and a method for medium wide band communications using impulse radio techniques. The method of transmitting medium wide band signals includes the steps of producing a sinusoidal signal and a train of preferably Gaussian shaped pulses. The method also includes the steps of multiplying the sinusoidal signal by the train of pulses to produce a train of sinusoidal bursts, and transmitting the train of sinusoidal bursts. The center frequency of the transmitted signal consisting of the train of sinusoidal bursts can be controlled by selecting an appropriate frequency of the sinusoidal signal. The bandwidth of the transmitted signal can be controlled by selecting an appropriate width of the pulses in the train of pulses. Information and / or coding modulation can be accomplished by adjusting the time position and / or phase of the sinusoidal bursts.

Multi-function transducers (130, 700) that are suitable for use in handheld devices such as cellular telephones (100, 900) and are capable of emitting audio, and generating accelerations of sufficient magnitude, and at frequencies that can be sensed by tactile sensation and which exhibit resonant modes that are characterized by center frequencies within a frequency range that can be sensed by tactile sensation, and specifically located between two musical notes on a musical scale are provided. Devices (100, 900) including such transducer are provided, and methods of operating such transducers are provided.

A dielectric resonator circuit is provided that is tunable over a broad frequency range and / or a broad bandwidth range. The center frequency is made tunable over a broad range by use of a dielectric tuning plug that is positioned in a through hole within the resonator. The bandwidth is made tunable over a broad range by tilting the resonators relative to the enclosure to increase the effective height of the cavity as seen by the resonator.

The invention relates to a device for guiding electromagnetic waves from a wave guide (10), in particular a multi-band wave guide, to a transmission line (20), in particular a micro strip line, arranged at one end of the wave guide (10), comprising coupling means (30-1, . . . , 30-7) for mechanical fixation and impedance matching between the wave guide (10) and the transmission line (20). It is the object of the invention to improve such a structure in the way that manufacturing is made easier and less expensive than according to prior art. According to the present invention that object is solved in the way that the coupling means comprises at least one dielectric layer (30) being mechanically connected with the main plane of the transmission line, the geometric dimension of that at least one dielectric layer extending along the propagation direction of the electromagnetic waves being correlated with the center frequency of electromagnetic waves in order to achieve optimised impedance matching.

A method is proposed for automatically adjusting the filter parameters—center frequency, quality and amplification or attenuation—of at least one digital equalizer which is a component of a reproduction device for audio signals in a vehicle passenger compartment. To that end, first of all, the acoustical frequency response of the passenger compartment is ascertained. The inadequacies in the acoustics of the passenger compartment in the form of local maxima and minima in the measured frequency response are then determined. On this basis, the filter parameters are adjusted automatically so that at least a portion of these inadequacies is compensated. A reproduction device for audio signals for implementing this method is also proposed.

The band-pass filter has a stacked pair of film bulk acoustic resonators (FBARs) and an acoustic decoupler between the FBARs. Each of the FBARs has opposed planar electrodes and a layer of piezoelectric material between the electrodes. The acoustic decoupler has a single layer of acoustic decoupling material having a nominal thickness equal to an odd integral multiple of one quarter of the wavelength in the acoustic decoupling material of an acoustic wave having a frequency equal to the center frequency. The acoustic decoupling material comprises plastic. The acoustic decoupler controls the coupling of acoustic energy between the FBARs. Specifically, the acoustic decoupler couples less acoustic energy between the FBARs than would be coupled by direct contact between the FBARs. The reduced acoustic coupling gives the band-pass filter desirable in-band and out-of-band properties.

A microwave tunable filter having some advantages as follows: a) the integration of MEMS tunable filter and MMIC; b) the very low signal transmission loss and low dispersion; and c) the drastic variation and linear characteristic of frequency by means of MEMS capacitor and an external control signal. The microwave tunable MEMS filter includes a plurality of unit resonant cells, each unit resonant cell being formed by various serial and parallel combination of an inductor, a capacitor, a transmission line, and a variable MEMS capacitor, whereby capacitance variation of the variable MEMS capacitor in the unit resonant cell converts a resonant frequency of the unit resonant cell to thereby convert a center frequency of the filter.

Field effect transistors having a power density of greater than 25 W / mm when operated at a frequency of at least 4 GHz are provided. The power density may be at least 30 W / mm when operated at 4 GHz. The power density of at least 30 W / mm may be provided at a drain voltage of 120 V. Transistors with a power density of at least 30 W / mm when operated at 8 GHz are also provided. The power density of at least 30 W / mm may be provided at a drain voltage of 120 V. Field effect transistors having a power density of greater than 20 W / mm when operated at a frequency of at least 10 GHz are also provided. Field effect transistors having a power density of at least 2.5 W / mm and a two tone linearity of at least −30 dBc of third order intermodulation distortion at a center frequency of at least 4 GHz and a power added efficiency (PAE) of at least 40% are also provided.

In one embodiment, the present invention includes a test signal generator capable of producing an impedance test signal comprising of a sine wave having a known frequency. The test signal generator may include a crystal oscillator, a counter, and a lookup table. The lookup table output is applied to a digital to analog converter and is then low pass filtered using a conventional analog filter to produce a sine wave of a known frequency and voltage amplitude. The test signal flows through the electrode and combines with an electrophysiological signal to form a combined signal. A signal processor is used to isolate the combined signal into the test signal component and the electrophysiological component. The signal processor digitally low pass filters the combined signal and the output of the low pass filter is the electrophysiological signal. The signal processor then digitally bandpass filters the combined signal using a filter with a center frequency which is the same as the test frequency. The output of this filter is then used to calculate the electrode impedance.

Full duplex radio wireless systems and methods and especially transceivers for full duplex radio wireless systems with reduction of self-interference are described. MIMO (=multiple input multiple output several antennas for output and input) is used within one device with multiple antennas to remove self-interference in a proactive way. For example, a transceiver is described having self-interference suppression, comprising, within one transceiver device: two or more transmitters comprising one or more signal generators for transmitting transmit signals having transmit center frequencies in a selected first subchannel; and one or more receivers having receiver inputs for simultaneously receiving a desired receive signal in a second subchannel and an undesired accumulated interference signal due to said transmitted signals; and at least one of said transmitters also comprising a precompensation circuit that modifies the transmit signals such that said accumulated interference signal at the receiver(s) inputs is reduced.

A medical lead system includes at least one bandstop filter for attenuating current flow through the lead across a range of frequencies. The bandstop filter has an overall circuit Q wherein the resultant 3 dB bandwidth is at least 10 kHz. The values of capacitance and inductance of the bandstop filter are selected such that the bandstop filter is resonant at a selected center frequency or range of frequencies. Preferably, the bandstop filter has an overall circuit Q wherein the resultant 10 dB bandwidth is at least 10 kHz. Such bandstop filters are backwards compatible with known implantable deployment systems and extraction systems.

An optical transmission system has a directly modulated laser for modulating data directly on an optical signal, and a narrow band optical filter having a band center frequency offset from a central optical frequency of the optical signal, to reduce the phase difference between FM and AM of the modulated optical signal, the filter having a bandwidth sufficiently narrow to substantially remove frequencies outside a spectrum of adiabatic frequency chirp resulting from the modulation, combined with Fourier broadening caused by the data modulation. This is a cost effective way of improving the dispersion tolerance to give greatly improved system reach and to make it practical to use directly modulated lasers with existing NDSF. The narrow band filter can be located at the transmitter or the receiver, and can have a center frequency locked to a feature in the frequency spectrum of the laser.

Millimeter wave imaging apparatus for use, in articular, as an indoor security system to identify objects concealed under the clothing of a person in a background scene, including means for generating a millimetric temperature contrast between the person to be imaged and the surroundings in scene. This may be a "hot" or "cold" source for producing a flux, and a relatively smaller flux respectively, of incoherent millimeter wavelength radiation. The apparatus may also include at least one partial ellipsoid reflective enclosure for reflecting millimeter wavelength radiation emitted from the "hot" and "cold" source so as to generate non-localized and uniform illumination of the person. The enclosure may have a metallic inner surface on which a dimpled pattern may be embossed to diffuse the millimeter wavelength radiation reflected from the metallic inner surface. The apparatus also includes one or more millimeter wavelength imaging cameras for detecting the millimeter wavelength radiation at one or more millimeter wave center frequencies, which may be mounted inside or outside the reflective enclosure. An image of the objects may be generated on a television monitor from the detected radiation.

The present invention provides a method and apparatus for optical feedback control for an illumination device, wherein the control signal for each array of one or more light-emitting elements corresponding to a particular color, is independently configured using a modification signal whose frequency is different for each color. Electronic filters whose center frequencies are substantially equal to the modification signal frequencies of the drive currents for the light-emitting elements are used to discriminate between the radiant flux corresponding to each of the different colors of light-emitting elements, from a sample of the mixed radiant flux output collected by one or more optical sensors. The output of an individual electronic filter is substantially directly proportional to the radiant flux output of the light-emitting elements of the associated color, which together with the desired luminous flux and chromaticity of the output light, the controller can use to adjust the control signals.

An audio loudness compensation system includes a level sensor receiving an audio input signal and operable to estimate a level of the audio input signal over a first predetermined time period, and a level mapper receiving the estimated level and operable to map the estimated level to a raw audio gain in response to a slope setting and an offset setting. The system further includes an attack and decay filter receiving the raw audio gain and operable to smooth out increasing and decreasing changes in the raw audio gain in response to a second and, possibly a third predetermined time period, and a compensation filter receiving the smoothed raw audio gain and operable to modify the audio input signal in response to the smoothed raw audio gain, a center frequency setting and a bandwidth setting, and generate a loudness compensated audio output signal.

An AFC circuit for controlling an oscillation frequency of a local oscillator is disclosed. An f / V converter converts a frequency of an FSK signal to a received signal voltage varying depending on the frequency of the FSK signal. A window generator generates a voltage window including a reference voltage corresponding to a center frequency of the FSK signal. The oscillation frequency of the local oscillator is controlled depending on a deviation of the received signal voltage from the voltage window so that the received signal voltage falls into the voltage window.

A method of radar-imaging a scene in the far-field of a one-dimensional radar array, comprises providing an array of backscatter data D(fm, x′n) of the scene, these backscatter data being associated to a plurality of positions x′n, n=0 . . . N−1, N>1, that are regularly spaced along an axis of the radar array. The backscatter data for each radar array position x′n are sampled in frequency domain, at different frequencies fm, m=0 . . . M−1, M>1, defined by fm=fc−B / 2+m−Δf, where fc represents the center frequency, B the bandwidth and Δf the frequency step of the sampling. A radar reflectivity image 1(αm′, βn′) is computed in a pseudo-polar coordinate system based upon the formula (2) with formula (3) where j represents the imaginary unit, formula (A) is the baseband frequency, FFT2D denotes the 2D Fast Fourier Transform operator, αm′, m′=0 . . . M−1, and βn′, n′=0 . . . N−1 represent a regular grid in the pseudo-polar coordinate system, and Pmax is chosen >0 depending on a predefined accuracy to be achieved. A corresponding method of radar-imaging a scene in the far-field of a two-dimensional radar array is also proposed.I(αm′,βn′)=∑p=0PmaxIp(αm′,βn′),Formula(2)I(αm′,βn′)=1p![-j2πβn′fc]pFFT2D[D(fm,xn′)(f^m,xn′)p],Formula(3)f^m=-B / 2+m·ΔfFormula(A)

The present invention provides a method and apparatus for optical feedback control for an illumination device, wherein the control signal for each array of one or more light-emitting elements corresponding to a particular colour, is independently configured using a modification signal whose frequency is different for each colour. Electronic filters whose center frequencies are substantially equal to the modification signal frequencies of the drive currents for the light-emitting elements are used to discriminate between the radiant flux corresponding to each of the different colours of light-emitting elements, from a sample of the mixed radiant flux output collected by one or more optical sensors. The output of an individual electronic filter is substantially directly proportional to the radiant flux output of the light-emitting elements of the associated colour, which together with the desired luminous flux and chromaticity of the output light, the controller can use to adjust the control signals.

A wireless communication apparatus receives an quadrature modulated signal, generate a local signal having a frequency different from a center frequency of the quadrature modulated signal, performs quadrature demodulation on the quadrature modulated signal by using the local signal, to obtain an I channel signal and a Q channel signal, performs Fourier transform on the I channel signal and the Q channel signal, to obtain signals in a frequency domain, and calculates a first correction coefficient for correcting phase distortion and amplitude distortion caused by the quadrature demodulation by using pairs of signals among the signals, each of the pairs are located at symmetrical frequency positions with respect to the frequency of the local signal.

An equalizer bank with interference reduction is disclosed. The equalizer bank with interference reduction comprises a front-shelving filter, a plurality of peak filters, a rear-shelving filter and a plurality of compensators. The center frequency and the quality factor of each compensator are designed intentionally to be identical to those of the corresponding peak filter. When a user selects a specific gain level, the corresponding parameters that determine the peak filter and the compensator are retrieved directly and a complex calculation is skipped. Therefore, an audio signal can be equalized more efficiently with lower hardware cost.

A coding section 101 turbo-codes transmit data and outputs parity bit data, and systematic bit data for which good quality is required. A modulation section 102 modulates the parity bit data and systematic bit data. A subcarrier allocation section 103 rearranges the transmit data so that systematic bit data is allocated to subcarriers in the vicinity of the center frequency and parity bit data is allocated to subcarriers in the vicinity of both ends. An OFDM section 104 performs orthogonal frequency division multiplexing of the transmit data, and allocates parity bit data and systematic bit data to respective subcarriers. By this means, it is possible to improve significantly the error rate characteristics of transmit data for which good quality is required, and prevent degradation of the quality of transmit data for which good quality is required.

The present invention provides methods and apparatus for integrating the operation of a plurality of radio networks. The plurality of radio networks may utilize a common frequency spectrum. The radio center frequencies are adjusted so that frequency drift in relation to each radio network is reduced. Also, system information about the plurality of radio networks may be sent on a radio channel that is associated with one of the radio networks. An oscillator synchronizer synchronizes a first reference oscillator that is associated with a first radio network and a second reference oscillator that is associated with a second radio network in order to adjust radio center frequencies. With a variation of the embodiment, a reference oscillator of one of the radio network adjusts center frequencies for radios that are associated with the other radio network.

An analog signal processing circuit including: a frequency conversion unit for receiving a plurality of radio frequency signals having different center frequencies or a plurality of radio frequency signals having the same center frequencies but different amplitude-characteristics or phase-characteristics and converting the frequencies of the signals; a frequency selection unit for selecting a signal output from the frequency conversion unit at a predetermined band width; and an addition unit for adding a plurality of signals output from the frequency selection unit is provided.

A method and apparatus for operating in a new radio access technology (NR) carrier in a wireless communication system is provided. A user equipment (UE) receives an indication of a system bandwidth and a center frequency of the system bandwidth from a network, and operates subbands in the NR carrier according to the indication. The center frequency of the system bandwidth corresponds to a direct current (DC) subcarrier.