93 results about "Spurious emission" patented technology

A frequency-dependent phase pre-distortion technique is applied to an input signal in order to reduce spurious emissions resulting from subsequent amplification of the signal. In preferred embodiments, the frequency-dependent phase pre-distortion of the present invention is implemented in combination with the (frequency-independent) magnitude and phase pre-distortion technique described in U.S. patent application Ser. No. 09/395,490 (“the '490 application”), where one or more frequency-dependent phase pre-distortion signals are either advanced or delayed relative to the main pre-distorted signal generated in accordance with the '490 application. Each frequency-dependent phase pre-distortion signal is preferably based on a 180° phase difference between a pair of (critical) frequencies located outside (e.g., one on each side) of the signal channel. The magnitude of the frequency difference between the pair of critical frequencies dictates the magnitude of the desired advancement or delay in time of the frequency-dependent pre-distortion signal relative to the main pre-distorted signal. Embodiments of the present invention may be implemented in either the baseband domain or the RF domain. Implementations may also be based on look-up tables that are adaptively updated to ensure optimal performance over time.

A method and system (FIG. 2) for facilitating detection of intruders into a wireless network, through the use of physical layer anomalies. One or more monitoring stations (22, 24, 26) can be distributed across the potential intruder's sign transmission region. They process these transmissions and extract attributes of the signals, which can then transmit to one or more fusion stations (28), which correlate the calculated attributes with stored attributes of signals of known, authorized users of the network, and transmit alert messages in the case that these signal attributes do not match those of known, authorized users. Signal attributes in accordance with the instant invention include the carrier frequency, spurious emissions, and power-on and power-down transients. Also in accordance with the instant invention are methods and systems using both direct and multipath received signal strength, signal-to-noise ratio, and geometric characteristics such as direction/angle of arrival (AOA), time of arrival, position/range, time dispersion, Doppler shift and polarization.

A novel apparatus for and method of discrete spurious frequency leakage cancellation for use in a cable modem. The spurious leakage cancellation mechanism is particularly suitable for use in cable modem systems adapted to implement the DOCSIS 2.0 specification which specifies both downstream and upstream channels. In one embodiment, the spurious emission cancellation mechanism cancels the spurious emissions by first creating a replica of the aggressor clock signal having the same amplitude but 180 degree phase shift as the spurious signal. The phase shifted spurious replica is added to the original spurious signal thus cancelling the spurious signal. In another embodiment, an RF switch is used to couple the upstream path signal to the CATV cable only during transmission bursts. In between transmission bursts, the upstream signal is disconnected from the CATV cable. This embodiment takes advantage of the less stringent spurious requirements in the DOCSIS 2.0 specification for transmission bursts. In between transmission bursts, when stricter spurious requirements apply, the upstream signal is disconnected from the CATV cable.

Large signal peaks (for example, peaks 105 and 110) can dramatically increase the cost of a communications device by requiring high grade power amplifiers. Peak reduction can reduce the large peaks at a cost of increasing spurious emissions. A circuit (for example, circuit 500) combining a scaling window peak reducing unit (for example, unit 507) and a filter (for example, filter 509) can effectively reduce the signal peaks without significantly increasing spurious emissions.

Pre-distortion, whose magnitude—and preferably phase—are frequency-dependent, is applied to an input signal in order to reduce spurious emissions resulting from subsequent amplification of the signal. In preferred embodiments, the pre-distortion technique of the present invention is implemented in combination with the (frequency-independent) magnitude and phase pre-distortion technique described in U.S. patent application Ser. No. 09/395,490 (“the '490 application”), where the frequency-dependent pre-distortion corresponds to amplifier distortion that has a magnitude that is proportional to the frequency offset from the carrier frequency and a phase shift of ±90° on either side of the carrier frequency. Since these characteristics match those of a differentiator, a thorough correction of this part of the amplifier's distortion can be achieved using a differentiating filter. Embodiments of the present invention may be implemented in the baseband domain. Implementations may also be based on look-up tables that are adaptively updated to ensure optimal performance over time.

The embodiment of the invention discloses an antenna tuning circuit and a mobile terminal. The antenna tuning circuit comprises an antenna, a frequency band matching circuit and an antenna tuning switch, wherein the frequency band matching circuit is respectively connected with the antenna and the antenna tuning switch; the frequency band matching circuit comprises at least one frequency band matching sub circuit for selecting and matching corresponding frequency band signals from radio frequency signals transmitted by a radio frequency signal transmitter of the mobile terminal, and a low-pass filter serially connected between the frequency band matching sub circuit and the antenna tuning switch for retaining main frequency signals of a corresponding frequency band and filtering harmonics generated by the antenna tuning switch. Thus, the problem of radiated spurious emission brought by switch saturation as the antenna tuning switch generates harmonics can be avoided.

An acoustic wave device includes a piezoelectric substrate, an interdigital transducer (IDT) electrode provided on an upper surface of the piezoelectric substrate, a first dielectric film covering the upper surface of the piezoelectric substrate to cover the IDT electrode, and a second dielectric film covering an upper surface of the first dielectric film. The second dielectric film includes a thin portion positioned in a tip region of electrode fingers of the IDT electrode and a thick portion which is positioned in a middle region of the IDT electrode and is thicker than the thin portion. The acoustic wave device suppresses spurious emission and has superior passband characteristics.

An input signal is pre-distorted to reduce spurious emissions resulting from subsequent signal amplification. Frequency-dependent pre-distortion is preferably implemented in combination with frequency-independent pre-distortion, where the frequency-dependent pre-distortion corresponds to amplifier distortion that has a magnitude that is proportional to the frequency offset from the carrier frequency and a ±90° phase shift on either side of the carrier frequency. The frequency-dependent pre-distortion is generated by differentiating waveforms corresponding to two different sets of pre-distortion parameters with respect to time. In one embodiment, one of the differentiated waveforms is applied to a positive-frequency filter and the other to a negative-frequency filter to generate positive- and negative-frequency pre-distortion signals, respectively, to account for asymmetries in the amplifier characteristics. In another embodiment, only one of the differentiated waveforms is applied to an asymmetric filter (i.e., either a positive-frequency filter or a negative-frequency filter).

An exemplary apparatus includes a modulator configured to modulate a data signal onto a carrier signal to generate a modulated signal having a transmit frequency within a predefined frequency range adjacent to and within a boundary of an uplink frequency band, a filter configured to at least partially remove a carrier frequency component from the modulated signal to produce a filtered modulated signal, and an antenna configured to transmit the filtered modulated signal.

A phase shift is defined as a point in frequency at which the phase is changed from 0 degrees to 180 degrees. A device is provided for combining analog and digital in-band-on-channel (IBOC) signals to feed a common antenna utilizing phase shifting allpass filter modules to provide a 180 degree phase shift to specific IBOC channels within a constant impedance dual-hybrid circuit. The IBOC Allpass combiner includes one input 90 degree 3 dB quadrature hybrid coupler, one output 90 degree 3 dB quadrature hybrid coupler, a load resistor, and two phase shifting allpass filter modules. Each phase shifting allpass filter module is comprised of a two coaxial cavity resonators coupled to a 90 degree 3 dB quadrature hybrid coupler. Components and modules are coupled using mating transmission lines. The four coaxial cavity resonators are used as devices to produce two distinct phase shifts at isolated upper and lower IBOC side band frequencies. The circuit is designed for one center analog frequency and two sideband IBOC OFDM carrier frequencies, such that all frequencies will combine in phase at the common antenna input with minimal loss and minimal group delay. Out of phase and spurious emissions are ported to the load resistor.

Pre-distortion, whose magnitude—and preferably phase—are frequency-dependent, is applied to a non-baseband input signal in order to reduce spurious emissions resulting from subsequent amplification of the signal. In preferred embodiments, the pre-distortion technique of the present invention is implemented in combination with the (frequency-independent) magnitude and phase pre-distortion technique described in U.S. patent application Ser. No. 09/395,490 (“the '490 application”), where the frequency-dependent pre-distortion corresponds to amplifier distortion that has a magnitude that is proportional to the frequency offset from the carrier frequency and a phase shift of ±90° on either side of the carrier frequency. Since these characteristics match those of a differentiator, a thorough correction of this part of the amplifier's distortion can be achieved using a differentiating circuit. Embodiments of the present invention may be implemented in the RF domain. Implementations may also be based on look-up tables that are adaptively updated to ensure optimal performance over time.

The application discloses an antenna tuning circuit and a mobile terminal. The antenna tuning circuit includes an antenna, a first matching circuit, a second matching circuit, a first switch, a secondswitch, and a radio frequency signal transceiver. The antenna includes a first feed point, a second feed point, and a third feed point that are arranged in sequence. The first matching circuit and the first switch are connected in series between the first feed point and the ground. The second matching circuit and the second switch are connected in series between the second feed point and the ground. When the operating frequency band is at a low frequency, a radio frequency signal transmitted by the radio frequency signal transceiver is transmitted to an antenna radiator through the third feedpoint. Both the first switch and the second switch are turned on. The frequency band in the third frequency range is smaller than the frequency band in the second frequency range. With the embodiments of the application, the radiation spurious emission can be suppressed.

A driver circuit for an electroluminescent (EL) lamp that consumes less power and reduces electromagnetic interference (EMI). Electrical charge is stored during a discharge cycle of an AC signal employed to illuminate an EL lamp, and subsequently reused during the AC signal's charging cycle. The reuse of electrical charge enables the driver circuitry to illuminate the EL lamp while drawing the least amount of power from a power supply, such as a battery. Also, multiple charge pumps can be sequentially/serially turned off during the discharge cycles of the AC signal driving the EL Lamp. By sequentially discharging the EL lamp, a waveform for the AC signal can be synthesized that more closely resembles a relatively symmetrical sinusoidal shape. The relatively symmetrical shape of the synthesized AC waveform serves at least in part to reduce spurious emissions of electromagnetic interference (EMI), audio noise, and improve the efficiency of the driver circuitry.

A technique for agile region and band conscious frequency planning for wireless transceivers in which a comparison frequency is selected for generating a local oscillator signal. The comparison frequency (F_comp) is selected for a frequency band of a particular communication standard or protocol, in order not to introduce harmonic components of the selected comparison frequency in a transmitted signal from the wireless device that generates spurious emissions restricted by the particular communication protocol or another protocol. The F_comp selection may also take into consideration restrictive region-specific criteria for out-of band spurious emissions.

In accordance with some embodiments of the present disclosure, a method may include digitally pre-distorting a digital baseband signal with an opposite phase of a C-IM3 distortion term such that the pre-distortion and C-IM3 distortion cancel each other out in a transmitter. The method may also include digitally conditioning the pre-distorted digital signal in order to provide a flat amplitude response of a composite filter comprising a baseband filter and a digital half-band filter of the transmitter, and to provide a linear phase response for the composite filter.

A direct digital synthesizer (DDS) (300) that uses a system for reducing spurious emissions in a digital-to-time converter (DTC) (317). The DDS (300) includes one or more dither sources (307) and a random access memory (RAM) (305). The RAM (305) utilizes a look-up table for storing delay error values by using an output of the look-up table which is combined with the dither source (307) to compensate unequal unit delay values in the DTC (317).

The embodiments of the invention disclose a method for controlling radiated spurious emission standard exceeding, a device for controlling radiated spurious emission standard exceeding and a mobile device. The method includes the following steps that: radiated spurious emissions generated by each antenna in a plurality of antennas is measured respectively under maximum transmitting power when the plurality of antennas are adopted as the transmitting antenna of the mobile device; when an antenna of which the radiated spurious emissions exceed standards exists in the plurality of antennas, the maximum transmitting power calibration value of the antenna of which the radiated spurious emissions exceed standards can be obtained through calculation according to the difference value of the measurement value of the radiated spurious emissions of the antenna adopted as the transmitting antenna and a standard value; and the maximum transmitting power calibration value of the antenna of which the radiated spurious emissions exceed standards is stored in the mobile device. With the method and device provide by the embodiments of the invention adopted, the radiated spurious emissions of the antenna can satisfy the requirements of RSE (radiated spurious emission) standards, and user experience can be enhanced.

The invention provides a radiation spurious emission (RSE) auxiliary test circuit which is applied to an electronic device. The auxiliary test circuit comprises a power amplifier, a first match circuit, a radio frequency switch, an antenna, a second match circuit, a change-over switch, a detecting circuit and a control unit, which are connected electrically in sequence. The second match circuit is electrically connected to the change-over switch; the change-over switch is electrically connected to a node between the power amplifier and the first match circuit; the detecting circuit is electrically connected between the radio frequency switch and the antenna; the control unit is electrically connected between the change-over switch and the detecting circuit; the detecting circuit is used for judging whether the electronic device is subjected to the RSE test and outputting the corresponding detecting result; and the control unit controls the change-over switch to establish or disconnect the electrical connection between the second match circuit and the node according to the detecting result, so that when the electronic device is subjected to the RSE test, the power amplifier and the antenna reach impedance matching therebetween.

An antenna assembly generally includes an antenna element, an amplifier, and an electronics protection system coupled generally between the antenna element and the amplifier for filtering cross-talk and/or for protecting against electrostatic discharge and/or for suppressing radiated spurious emissions. The electronics protection system generally includes first and second inductors disposed in series generally between the antenna element and the amplifier, and first and second diodes coupled in shunt and disposed generally between the first and second inductors.