131results about "Automatic scanning with simultaneous frequency display" patented technology

A system and method for generating a local oscillator (LO) frequency in a zero intermediate frequency (IF) receiver or transmitter is presented. A signal is received from a voltage controlled oscillator (VCO). The signal has a VCO frequency. The VCO frequency is divided by a number N to produce a signal having a divided-down frequency. The signal having the VCO frequency is then mixed with the signal having the divided-down frequency to produce an output signal having an output frequency. Local oscillator leakage is reduced. Thus, the receiver or transmitter may operate in multiple wireless communication bands and modes and meet the associated specifications.

Frequency modification circuitry may be employed as part of a crystal oscillator circuit to generate a reference signal with adjustable frequency. The frequency modification circuitry may be implemented as part of a crystal oscillator circuit that includes digitally controlled crystal oscillator (“DCXO”) circuitry and a crystal. The frequency modification circuitry may adjust the frequency of the reference signal in response to one or more frequency control signals. In one example, the frequency modification circuitry may include variable capacitors such as one or more continuously variable and/or discretely variable capacitors for providing coarse and/or fine adjustment of the reference signal frequency.

A technique to share a local oscillator signal between two radio frequency integrated circuits (RFICs). The local oscillator signal generated internally by one RFIC is ported to the other RFIC for use in transmit and/or receive operation. The local oscillator signal that is ported may be an RF local oscillator signal. Each RFIC may include a bi-directional port circuit that can be operated to make the RFIC a master, slave or may be totally disabled to disable the porting feature. This is particularly useful in RFICs that are used to communicate using MIMO radio algorithms which rely for optimum performance on phase and frequency coherency among a plurality of transmitters and a plurality of receivers.

An analog open-loop voltage controlled oscillator (VCO) calibration circuit and method for selecting the frequency of the VCO for a phase locked loop (PLL).

A frequency divider module produces a 50% duty cycle divided local oscillation and a 50% duty cycle divided reference signal, wherein the divided signals are substantially equal. A period-to-voltage conversion module converts the divided local oscillation signal and the divided reference signal to voltages proportional to the divided signals. A comparator module produces a frequency adjustment signal based on a comparison of the proportional voltages and couples the frequency adjustment signal to a logic module which produces a frequency compensation signal based on the frequency adjustment signal. The frequency compensation signal functions to adjust the configuration of switched capacitors in a capacitor bank, coupled to the VCO tuned circuit, until the divided local oscillation signal is substantially equal to the divided reference signal.

The embodiments of the present invention provide a configurable homodyne/heterodyne RF receiver including first and second mixers. The configurable homodyne/heterodyne RF receiver functions as a homodyne receiver when the first and second mixers are configured to operate in parallel, and as a heterodyne receiver when the first and second mixers are configured to operate in series. The embodiments of the present invention further provides an RFID reader employing the configurable homodyne/heterodyne RF receiver to facilitate a listen-before-talk function.

The present invention relates generally to communications, and more specifically to a method and apparatus for generating local oscillator signals used for up- and down-conversion of RF (radio frequency) signals. A major problem in the design of modulators and demodulators, if the leakage of local oscillator (LO) signals into the received signal path. The invention presents a number of highly integratable circuits which resolve the LO leakage problem, using regenerative divider circuits acting on oscillator signals which are running at a multiple or fraction of the frequency of the desired LO signal, to generate in-phase (I) and quadrature (Q) mixing signals. Embodiments of these circuits also use harmonic subtraction and polyphase mixers, as well as virtual local oscillator TM (VLO) mixing signals. VLO mixing signals are signal pairs which emulate local oscillator signals by means of complementary mono-tonal and multi-tonal mixing signals.

Systems and methods are disclosed to maintain synchronous communications that uses a global positioning system satellite, a primary communication unit, and a secondary communication unit. The satellite based time reference broadcasts a reference signal to the primary communication unit and the secondary communication unit. The primary communication unit contains a high quality oscillator, and operates a virtual model of a secondary oscillator which is located in the secondary communication unit. The primary and secondary units have synchronous communications with each other by using a global positioning system satellite broadcast as a reference signal. If the secondary unit loses its signal from the global positioning system, the secondary oscillator enters a holdover state and transmits a notification of the holdover state to the primary communications unit. The primary communication unit then transmits time insensitive synchronization data based upon the virtual model through the packet switched network to the secondary communications unit to maintain synchronization.

A network search method of a user equipment (UE) for a wireless communication system that improves network search speed for acquiring Public Land Mobile Network (PLMN) available list available where the user equipment is located. A network search method measures powers of all the frequency bands supported by a UE in response to a network search request, generates a scan list as a result of measurement of the powers, searches networks listed in the scan list for available channels; acquires neighbor cell information from a system information message of one of the available channels. In addition, the method skips the networks indicated by the neighbor cell information in search of networks by removing the networks from the scan list.

The present invention provides reduces the number of required synthesizers thereby reducing the area and power concerns to extract/insert a signal from/to a multi-channel communication system and is also known as frequency planning. The highest frequency of operation required for the synthesizers or oscillators is approximately the midpoint of the entire signal frequency range. Two superimposed Weaver architectures are used to form the architecture. The receiver extracts the baseband I and Q signals from the multi-channel communication system, while the transmitter upconverts the baseband I and Q signals to the multi-channel communication system. The Weaver architecture, depending on the select bit, can enhance the image signal and reduce the desired signal or the image signal can be reduced while the desired signal is enhanced. Because the image and signal components are symmetrically displaced from the RF LO, less IF LO frequencies or synthesizers are required to operate the system.

The invention discloses a dual frequency multiplexer by which a first and second coaxial harmonic oscillator type band pass filters are disposed in a box. The box includes a base body, a cover plate and a cover body. The two coaxial harmonic oscillator type hand pass filters are located on the base body and spaced each other by a metal plate; the multiplexer port, first and second ports are positioned on lateral side of the base body. The blocking capacitors are contained in the coaxial chamber of the two coaxial harmonic oscillator type band pass filters. The cover plate is secured on the base body; the first and second direct current circuits are placed on the cover plate; the low pass filters of the first and second direct current circuits are fixed on an edge of a top surface of the coaxial chamber by means of a support member; the cover body and the base body are fastened with each other. The blocking capacitors each are of distributed parameter capacitor. Utilization of distributed blocking capacitors makes the product of the invention small. Moreover, improvement of the structure of the invention brings effect such as less differential loss, large power capacity, as well as high isolation degree between circuits.

The present invention provides a method of processing signal data comprising generating a first clock signal and a second clock signal and processing the signal data using the first clock signal and the second clock signal. While processing the signal data, the phase difference between the first clock signal and the second clock signal is measured and corrected for so that a target phase difference between the first clock signal and the second clock signal is maintained.

Methods and systems for vector combining power amplification are disclosed herein. In one embodiment, a plurality of signals are individually amplified, then summed to form a desired time-varying complex envelope signal. Phase and/or frequency characteristics of one or more of the signals are controlled to provide the desired phase, frequency, and/or amplitude characteristics of the desired time-varying complex envelope signal. In another embodiment, a time-varying complex envelope signal is decomposed into a plurality of constant envelope constituent signals. The constituent signals are amplified equally or substantially equally, and then summed to construct an amplified version of the original time-varying envelope signal. Embodiments also perform frequency up-conversion.

The present invention provides a baseband RF clock synthesizer having particular use in a BLUETOOTH piconet device, which has the capability of providing simple and accurate calibration of modulation path gain (KMOD) by introducing a dual-loop phase locked loop (PLL) in the RF clock signal synthesizer. The disclosed technique and apparatus controls the maximum frequency deviation by the difference of two locked frequencies, one frequency in each path of the dual-path PLL. Once the PLL is locked within some frequency error, the present technique and apparatus calibrates for the deviation of amplitude of the modulation due to the modulation path. Accordingly, modulation gain (KMOD) calibration is provided by adding an auxiliary loop to a PLL in an RF frequency synthesizer.

A multi-mode PLL frequency synthesizer of a wireless multi-mode transceiver is provided which includes a reference frequency source providing an oscillator signal with a constant reference frequency, a first frequency synthesizer subunit for converting the signal into carrier signals with frequencies in the range of a first frequency band, a second frequency synthesizer subunit for transforming the oscillator signal into carrier signals having frequencies in the range of a second frequency band, and a third frequency synthesizer subunit for converting the oscillator signal into an auxiliary signal with a fixed frequency. The auxiliary signal is used together with the carrier signals of the second frequency band to generate carrier signals with frequencies in the range of a third and fourth frequency band. A frequency divider derives a signal in the range of a fifth frequency band from further intermediate frequency signals supplied by the third frequency synthesizer subunit by dividing the frequency of the auxiliary signal by an integer value.

A mobile wireless communication device has a speaker that functions as a vibration alert in addition to an audio output device. The speaker is selected from a group of speakers having variation in mechanical vibration resonant frequency. A drive signal sweeps back and forth across a sweep frequency range including the varient speaker mechanical vibration resonant frequencies. The drive signal drives the speaker causing it to vibrate at the mechanical vibration resonant frequency and in turn causing the mobile wireless communication device to vibrate, thereby alerting the user. In this manner, the same drive signal can be used to vibrate each speaker at the speaker's mechanical vibration resonant frequency despite the variation in mechanical vibration resonant frequencies among the group of speakers.

Provided is a display system for transmitting FM signals to an external audio system having an FM reception function. The display system includes: a tuner for receiving an RF signal and dividing the RF signal into a video signal and an audio signal; an audio processor for receiving the audio signal from the tuner; an FM detector for searching usable channels or unused channels among FM frequency bands of a reception area and transmitting information on the unused channels; a microprocessor for setting at least one of the unused channels as an available channel, the unused channels being provided from the FM detector; a memory for storing the available channel under control of the microprocessor; and an FM transmitter for receiving the audio signal from the audio processor and transmitting the audio signal over at least one channel selected among the channels stored in the memory under control of the microprocessor.