1334 results about "Noise (radio)" patented technology

A gravity gradiometer is combined with a two-stage actively controlled isolation system. The gravity gradiometer and two stage isolation system may then be mounted within (or on) a mobile vehicle such as, for example, an aircraft. It has been recognized by the inventors herein that the accelerations imparted to an aircraft during normal operations can be separated through system design into two relatively distinct regimes within the frequency domain. The invention provides a first isolation mount, which forms part of the isolation system, to isolate accelerations (and resulting translations) falling within a first of the two frequency regimes. The second isolation mount, which is mounted to the first isolation mount, isolates accelerations falling within the second of the two frequency regimes. A gravity gradiometer can then be mounted to the second isolation mount. As a result of housing the gravity gradiometer within the nested isolation system (a combination of the first and second isolation mounts), the gravity gradiometer is substantially isolated from the accelerations experienced by the mobile vehicle. Consequently, gravity gradients measured by the gravity gradiometer are relatively noise free and provide heretofore-unobtainable accuracy.

A Radio Frequency (RF) receiver includes a low noise amplifier (LNA) and a mixer coupled to the output of the LNA. The gain of the LNA is adjusted to maximize signal-to-noise ratio of the mixer and to force the mixer to operate well within its linear region when an intermodulation interference component is present. The RF receiver includes a first received signal strength indicator (RSSI_A) coupled to the output of the mixer that measures the strength of the wideband signal at that point. A second received signal strength indicator (RSSI_B) couples after the BPF and measures the strength of the narrowband signal. The LNA gain is set based upon these signal strengths. LNA gain is determined during a guard period preceding an intended time slot of a current frame and during a guard period following an intended time slot of a prior frame. The lesser of these two LNA gains is used for the intended time slot of the current frame.

A wireless air tube headset that includes a wireless transceiver operating in a radio frequency band, which wireless receives audio signals. The headset includes an acoustic chamber with an acoustic port through to the exterior thereof, and an acoustic transducer that is electrically coupled to the transceiver, and that operates to generate acoustic signals. The acoustic transducer is aligned with the acoustic chamber to emit the acoustic signals through the acoustic port. There is an acoustic isolator disposed to attenuate extraneous acoustic signals emitted from the acoustic transducer and also to attenuate ambient noise entry into the acoustic chamber. An acoustic conduit is formed from an electrically non-conductive material, and has a first opening engaged with the acoustic port and a second opening engaged with an acoustic coupler, which has a first earpiece engagement means. An earpiece is engaged to the first earpiece engagement means, and thereby forms an electrically non-conductive acoustic path from the acoustic transducer to the earpiece. The acoustic path has a length to enable displacement of the transceiver and the acoustic transducer from the earpiece at a distance sufficient to yield at least a six decibel radio signal propagation power loss at the radio frequency band.

A method is disclosed for processing all types of received, interfering radio frequency signals corrupted by noise to extract the individual signals without having any a priori knowledge about them. Received signals are converted for eigenspace processing and are subjected to repeated non-linear time domain and fast Fourier transform frequency domain processing that calculates eigenstream beam forming weights U. By performing calculations in eigenspace, the number of independent weights U that must be calculated is generally reduced, minimizing calculating time. Once the weights U have been calculated in eigenspace they are transformed into antenna beam forming weights W that are used to extract the individual signals and to determine the angle of arrival of each of the individual signals. Further time is saved because the weights W do not have to be updated for every time slice of the received signals.

The invention relates to a measurement method and device of a Bell-Bloom self-modulation three-axis magnetic field. A conventional Bell-Bloom magnetometer utilizes a single beam to measure a scalar magnetic field, is simple in structure, is high in measurement accuracy and is widely applied to measurement of various scalar magnetic fields. The single-beam Bell-Bloom magnetometer can only measure the scalar magnetic fields, but three-axis magnetic field information is needed in many places in scientific researches and production life, and then a vector magnetometer is needed. Based on the single-beam Bell-Bloom magnetometer, the measurement method and device of the Bell-Bloom self-modulation three-axis magnetic field realize measurement of the three-axis magnetic field by utilizing the self-modulating action on detection light of atomic procession. Compared with the common vector magnetometer, the measurement device of the Bell-Bloom self-modulation three-axis magnetic field is not provided with a radio frequency coil or a magnetic shielding barrel, thereby having a simple light path, being compact in structure and achieving miniaturization and integration easily; the measurement device is low in heating temperature and needs fewer electric elements, so that systematic power consumption is lowered and operation conditions are met more easily; the measurement device utilizes the self-modulating action on detection light of the atomic procession, is lower in noise and is high in detection accuracy.

A high performance radio frequency receiver includes a low noise amplifier with large binary and stepped gain control range, controlled impedance, and enhanced blocker immunity, for amplifying and converting a radio frequency signal to a current; a pulse generator for generating in-phase and quadrature pulses; a crossover correction circuit and pulse shaper for controlling a crossover threshold of the pulses and interaction between in-phase and quadrature mixers; and a double balanced mixer for combining the RF signal with the pulses to generate an intermediate frequency or baseband zero intermediate frequency current-mode signal. The in-phase and quadrature pulses have a duty cycle of 20-35%. The intermediate frequency signal and second order harmonics may be filtered with a high frequency low pass filter and a current injected complex direct-coupled filter. Decreased die size, current drain, cost, and complexity, as well as improvements in gain, 1 / f noise, noise figure, sensitivity, and linearity may result.

A demodulator can include first data and clock pads to couple the demodulator to a host device via a first bus, and second data and clock pads to couple the demodulator to a radio frequency (RF) tuner via a second bus. The device may further include passthrough logic to couple host data and a host clock from the first bus to the second bus and to couple tuner data from the second bus to the first bus during a passthrough mode. During this mode, however, the two buses may remain electrically decoupled. When the passthrough mode is disabled, the RF tuner is thus shielded from noise present on the first bus.

A method of operation of a filter (12) of a receiver (10) of a mobile station or a base station of a radio access network and corresponding equipment, the method for use in suppressing co-channel interference and based on separating the in-phase (I) and quadrature phase (Q) components of the received signal and then performing whitening on a symbol-by-symbol basis, i.e. the whitening operation is done within one symbol. The invention provides a filter (12) including a module (12b) for performing IQ whitening (either according to the invention or otherwise), and also provides a switch (12a) that can be used to enable or disable IQ whitening, depending on the character of the received signal, and in particular based on the noise plus interference correlation matrix ({tilde over (R)}ii)

The present invention provides an apparatus for portable through-the-earth radio (PTTER). The PTTER provides bidirectional voice and / or data communication between a surface radio and a portable radio. The PTTER also provides a transmit antenna having a primary loop and one or more secondary loops configured to increase the magnetic field produced by the primary loop. The PTTER also provides a transportable loop antenna that can be wound around a form for transportation. The PTTER also provides a receive antenna optimal for implementing noise cancellation. The PTTER also provides a navigation subsystem for detecting distance and direction to increase the effective range of the PTTER. The PTTER can be implemented in a backpack form factor.

A charge pump replica bias detector is disclosed which provides a charge pump with a greater working output voltage range or larger output compliance. A larger working range will provide a charge pump with more symmetric source and sink currents than prior designs with a reduction of the multiple frequency sideband levels that occur in a voltage controlled oscillator of a phase-locked loop synthesizer. Further improvements are the prevention of disturbances of the loop filter voltage level due to unwanted leakage currents in a charge pump that are dependent on the value of loop filter voltage. Finally, by providing improved output voltage compliance and limiting loop filter voltage disturbances there are improvements in the reduction in reference frequency feed-through, charge sharing and noise transient coupling and phase noise in the phase-locked loop. Possible applications include but are not limited to charge pump phase-locked loop designs for single chip CMOS multi-band and multi-standard radio frequency transceiver integrated circuits.

The invention provides a circuit for providing a low-noise band-gap reference voltage source. The band-gap reference voltage source provides multiple circuits of current with temperature coefficients, and the temperature coefficient of the current can just counteract the temperature coefficient of a resistance adopted in the reference voltage source. The band-gap reference voltage source with zero temperature is generated when the current flows by the resistance, and a low-pass filter with low cut-off frequency is connected behind the band-gap reference voltage source to filter the noise of the band-gap reference voltage source, so that different current can be supplied to different modules in a radio frequency (RF) chip on a subscriber identity module (SIM) card of a mobile phone.