6406 results about "Phase modulation" patented technology

An exemplary embodiment provides a current regulator for controlling variable brightness levels for solid state lighting. The current regulator is couplable to a phase-modulating switch, such as a dimmer switch, which is coupled to an AC line voltage. An exemplary current regulator includes a rectifier; a switching power supply providing a first current; an impedance matching circuit; and a controller. The impedance matching circuit is adapted to provide a second current through the phase-modulating switch when a magnitude of the first current is below a first predetermined threshold, such as a holding current of a triac of the phase-modulating switch. The controller is adapted to determine a root-mean-square (RMS) voltage level provided by the phase-modulating switch from the AC line voltage and to determine a duty cycle for pulse-width current modulation by the switching power supply in response to the comparison of the RMS voltage level to a nominal voltage level.

A method for tomographic imaging comprises the steps of providing a source of at least partially coherent radiation and a frequency-swept laser source through an interferometer; phase modulating the radiation in the interferometer at a modulation frequency for elimination of DC and autocorrelation noises as well as the mirror image; detecting interference fringes of the radiation backscattered from the sample into the interferometer to obtain a spectral signal; transforming the spectral signal of the detected backscattered interference fringes to obtain a time and location dependent signal, including the Doppler shift and variance, at each pixel location in a data window; and generating a tomographic image of the fluid flow in the data window and of the structure of the scanned fluid flow sample in the data window from the time and location dependent signal. The apparatus comprises a system for tomographic imaging operating according to the above method.

A light emitting diode (LED) lighting system includes a power factor correction (PFC) controller that determines at least one power factor correction control parameter from phase delays of a phase modulated signal. In at least one embodiment, a peak voltage of the phase modulated signal is a PFC control parameter used bit the PFC controller to control power factor correction and generation of a link voltage by a PFC LED driver circuit. The phase delays are related to a peak voltage of the phase modulated signal. Thus, in at least one embodiment, detecting the phase delay in one or more cycles of the phase modulated signal allows the PFC controller to determine the peak voltage of the phase modulated signal.

A method is provided for communicating signals at a low power level in an electromagnetic interference (EMI) environment. A first device transmits a modulated signal having a first carrier frequency, including the encoded information via a hardwire transmission medium. In one aspect, the power level of the modulated signal can be adjusted to minimize power consumption or reduce the generation of EMI. The modulated signal may be in one of the following formats: frequency modulation (FM) or phase modulation (PM) to name a few examples. A second device including a logarithmic detector amplifier (LDA) demodulator circuit receives the signal, which may be mixed with EMI. The LDA demodulator circuit amplifies the modulated signal, without amplifying the EMI, to supply a demodulated baseband signal, which may be an n-ary digital signal, or an audio signal. A low-power, noise insensitive communication channel is also provided.

Methods, systems, and apparatuses for down-converting an electromagnetic (EM) signal by aliasing the EM signal are described herein. Briefly stated, such methods, systems, and apparatuses operate by receiving an EM signal and an aliasing signal having an aliasing rate. The EM signal is aliased according to the aliasing signal to down-convert the EM signal. The term aliasing, as used herein, refers to both down-converting an EM signal by under-sampling the EM signal at an aliasing rate, and down-converting an EM signal by transferring energy from the EM signal at the aliasing rate. In an embodiment, the EM signal is down-converted to an intermediate frequency (IF) signal. In another embodiment, the EM signal is down-converted to a demodulated baseband information signal. In another embodiment, the EM signal is a frequency modulated (FM) signal, which is down-converted to a non-FM signal, such as a phase modulated (PM) signal or an amplitude modulated (AM) signal.

A cashless business transaction system (e.g., a vending system, a material tracking system, or a highway toll system) incorporates a method and apparatus for transmitting a digital information signal. A signal generator (311) generates a constant frequency signal. A phase modulator (305) varies the instantaneous phase of the constant frequency signal to represent digital information, thereby producing a phase modulated signal (325). A tuned resonant circuit (307) filters and averages the phase modulated signal to produce a simulated FM signal, and transmits the simulated FM signal via its antenna (309). One such business transaction system (e.g., a vending system) incorporates such a transmitter to facilitate transmission of billing information from a device located within a substantially electrically shielded environment. Another such business transaction system preferably incorporates such a transmitter to facilitate half-duplex transmission of digital information regardless of whether or not the digital information is transmitted from a device located within a substantially electrically shielded environment.

An amplifier system is provided that switches between a linear mode of operation, an envelope tracking mode of operation and a polar mode of operation. The amplifier system switches between modes of operation based upon a characteristic of an input signal relative to a first threshold level and a second threshold level. A mode selector selects the operation mode by transmitting an amplitude modulated signal plus a variable headroom voltage to a supply terminal of a power amplifier during the envelope tracking mode, an amplitude modulated signal to the supply terminal and phase modulated input signal during the polar mode and a substantially constant amplitude signal to the supply terminal during the linear mode.

A high power light source is provided. The light source includes one or more diodes that may produce relatively coherent light of a desired intensity. The diodes may be pulsed to provide light as desired. The light projected by the diodes passes through a combiner, which combines the light from the different diodes and passes the combined light to an incoherence apparatus. The incoherence apparatus may include a rotating surface relief phase device such as an optical hologram, a computer generated hologram, or a diffractive optical element with random phase modulation. The incoherence apparatus may include a rotating fiber conduit comprising a plurality of multifiber cores. The incoherence apparatus renders the combined light incoherent and passes it to an illuminator apparatus that focuses the incoherent combined light onto an image plane.

A ultra high speed photonic Analog to Digital Converted (ADC) for sampling and quantizing an electrical voltage signal, internally enabled by photonics uses coherent optical detection architectures for photonic quantization. Coherent light is phase modulated by the test signal. Using an interferometer, or an array of interferometers the phase of modulated light is compared with a reference light. Flash ADC, successive approximation ADC and delta-sigma ADC configurations are presented.

A system for transmitting digital programming includes a program source providing digital information, circuitry for modulating the digital information onto a visual carrier modulated with analog television programming, and a visual transmitter coupled to the modulating circuitry. Using a phase modulation method, the system phase modulates the digital information onto a visual carrier, reduces the baseband frequencies of the phase modulated visual carrier, and amplitude modulates the phase-modulated video carrier onto a video signal. The amplified and encoded video signal are combined with an amplified sound signal and transmitted. Using an additive method, the system modulates the sidebands of the video carrier with the digital information and amplitude modulates the video signal onto the video carrier. The data-modulated sidebands are phase-shifted such that they will be in quadrature with the amplitude-modulated video signal. The system combines the amplitude-modulated video carrier and the data-modulated quadrature sidebands. With a blended multiplicative/additive method, the system provides phase modulation and quadrature sideband addition to provide an optimized result. Process, systems, circuits and devices for abating or otherwise correcting effects of the information on the analog television signal are also disclosed.

Multiple radio channel frequency signals that are modulated with respective information modulation are transmitted from a common antenna at multiple radio frequencies. Multiple modulators are provided, a respective one of which corresponds to a respective one of the radio channel frequencies. Each modulator generates at least one constant amplitude, phase modulated drive signal at the corresponding radio channel frequency from the respective information modulation, such that the at least one constant amplitude, phase modulated drive signal corresponds to the information modulation for the corresponding radio frequency. At least one saturated power amplifier is provided for each of the at least one constant amplitude, phase modulated drive signals. A respective saturated power amplifier is responsive to the corresponding constant amplitude, phase modulated drive signal, to produce a corresponding amplified output signal at an output thereof. A coupling network connects the outputs of the saturated power amplifiers in series, to produce a combined signal that is applied to the common antenna, such that the common antenna radiates the radio channel frequency signals that are modulated with the respective information modulation. In first embodiments, the at least one constant amplitude, phase modulated drive signal is a single constant envelope modulation drive signal, wherein the information modulation is a constant envelope information modulation. In other embodiments, at least two constant amplitude phase modulated drive signals are provided at the corresponding radio channel frequency, such that the at least two constant amplitude, phase modulated drive signals correspond to the information modulation for the corresponding radio frequency.

A disk drive is disclosed comprising a spindle motor comprising a plurality of windings for rotating a disk. The spindle motor is rotated by commutating the windings over a plurality of commutation states, wherein audible noise generated by the disk drive is reduced by phase modulating the commutation interval. Further audible noise reduction is achieved by modulating a current applied to the windings which substantially reduces discontinuities in the torque output of the spindle motor caused by phase modulation of the commutation intervals.

A test signal comprising a periodic waveform, such as a triangular waveform and sawtooth waveform, is used for propagation delay matching in a transceiver front-end. The test signal is separately fed to the envelope path and the RF path. At the power amplifier stage, a phase modulator is used to obtain the envelope signal and the phase modulated RF signal for demodulation by an IQ demodulator. At the output end of the IQ demodulator, the I-signal is measured while the delay block is adjusted in order to vary the propagation delay. When the propagation delay matching is correct, the peak-to-peak value of the I-signal is a minimum. Preferably, during calibration using the test signal, the transmitter RF power amplifier is disabled so that no spurious signals will be sent. The transmitter can be an EDGE polar transmitter, a non-EDGE transmitter or a EER polar transmitter.

A power amplifier controller controls a power amplifier and is coupled to a polar modulator. The polar modulator generates an amplitude component and a phase-modulated component of the desired RF modulated signal, and outputs to the power amplifier controller. The power amplifier controller regenerates a combined phase and amplitude modulated RF signal to generate an input signal to a power amplifier by adjusting the gain of a VGA based on the amplitude component of the desired RF modulated signal. Concurrently, the power amplifier controller both controls an adjusted supply voltage to the PA and adjusts the gain of the VGA based upon an amplitude correction signal or amplitude error signal.

The transmission system includes a first electro-optical modulator adapted to supply in response to an input electrical signal a controlled phase optical signal having an optical power modulated between low levels and high levels and a phase shift within each time cell that contains a low power level. To make it more flexible to use, the system includes a second electro-optical modulator controlled by the input signal and optically coupled to the first electro-optical modulator to apply to said controlled phase optical signal complementary power and/or phase modulation so as respectively to modify its extinction ratio and/or to apply a transient "chirp" to it.

A polar modulation transmitter circuit provides reduced ACPR in its output signal by controlling the relative delay between its envelope and phase modulation operations based on direct or indirect feedback measurement the output signal's ACPR. Such measurement and associated control may be based on a delay controller that includes an ACPR measurement circuit and a delay control circuit. Additionally, or alternatively, the polar modulation transmitter circuit provides a greatly extended transmit power control range by using a staged amplifier circuit that includes a driver amplifier circuit operating in combination with a power amplifier circuit to impart desired envelope modulation. In an exemplary embodiment, the driver amplifier circuit is implemented as differential transistor pairs responsive to tail current modulation. As such, the driver amplifier circuit is suited in particular for economical and space saving integration within a transmitter or transceiver integrated circuit (IC).

In phased array antennas, multiple signals that perform different functions, such as radar, electronic warfare (EW) and telecommunications, can each be simultaneously transmitted only through a different sub-aperture of the array. For maximum power and efficiency, the power amplifiers operate on one signal at a time. This patent provides the technique of forming a common waveform from multiple signals for transmission through a common aperture. To practically implement this technique in wideband operations, processes performing the required waveform-shaping and amplitude-to-phase-modulation are devised that can transmit the high-power diverse waveforms without serious intermodulations and spectral distortion through every element of the array.