Abstract: The present invention is directed toward an automatic frequency control system for compensating for frequency offset of received data signals in a radio frequency communication system. A reference sample index for the data to be compensated is first determined as a function of the transmission channel and known training data. A scaled phase error estimate is calculated along with a time-varying filter parameter. From the scaled phase error estimate and the filter parameter, a frequency offset estimate and a phase drift estimate are calculated. The system proceeds through the time-indexed, received data signals until the entire received batch of data signals has been processed, and the corresponding compensated soft data has been output.

Abstract: A wireless communication apparatus prevents desensitization in a line signal frequency caused by clock signal harmonic. The wireless communication apparatus is provided with a receiver/demodulator for receiving a line signal of a predetermined frequency and for demodulating the line signal, a control section decoding the demodulated line signal using an operation clock signal, and a clock signal generating circuit supplying a clock signal. The control section controls the clock signal generating circuit to change a frequency of the clock signal in response to the line signal frequency, therefore, harmonic of the clock signal do not enter into a desensitization range corresponding to the line signal frequency.

Abstract: A plurality of finger units despread a received signal with a first spread code to output pilot signals of a receiving channel which has been spread with the first spread code. An AFC unit despreads the received signal with a second spread code to output a pilot signal of an AFC channel which has been spread with the second spread code. An automatic frequency controller calculates a difference between an oscillating frequency of a oscillator and a frequency of the received signal for the channels based on the pilot signals of the receiving and AFC channels to supply a frequency control signal to the oscillator, whereby the oscillating frequency of the oscillator is controlled so that the oscillating frequency is substantially equal to the frequency of the received signal.

Abstract: Counter-clockwise and clockwise quadrant transitions are detected and accumulated with respect to a received complex signal over a certain time period. These transitions may then be compared in order to obtain information indicative of both a magnitude and phase of a frequency offset error. Additionally, zero-crossings of the received complex signal over the same certain time period are detected and accumulated. The accumulated crossings provide information indicative of frequency offset magnitude. The determined magnitude and phase of the frequency offset error may then be used to adjust a local oscillator frequency to provide for improved receiver performance.

Abstract: A receiver for broadcast signals, e.g. DAB, FM, DVB, and digital or analog short-wave RF broadcast signals according to the present invention includes a polyfunctional circuit (5) that can be switched into three modes and performs the digital frequency demodulation which is needed for the reception of a frequency modulated signal in a first mode A, a digital frequency adjustment of the receiver in case of the reception of a digital or analog modulated broadcast signal like DAB, DVB, DRM or AM in a second mode B and the digital frequency adjustment and the digital gain control of the receiver which is needed in case of the reception of a digitally modulated broadcast signal like DAB, DVB, DRM in a third mode C. Depending on the needed functionality not all of these modes need to be realized. Nevertheless, the same hardware will be used for different purposes although the circuit is realized with an optimized amount of hardware to realize an efficient receiver.

Abstract: A receiver (10) for a wireless telecommunications system that provides relatively wideband signal processing of received signals without increased signal distortion so that multiple received signals can be simultaneously processed. The receiver (10) includes a specialized LNA (16), frequency down-converter (18) and ADC (20) to perform the wideband signal processing while maintaining receiver performance. The frequency down-converter (18) employs a suitable mixer (28), BPA (32), attenuator (34), and transformer (36) that are tuned to provide the desired frequency down-conversion and amplitude control over the desired wideband. The down-converter devices are selected depending on the particular performance criteria of the ADC (20). A specialized digital channelizer (22) is included in the receiver (10) that receives the digital signal from the ADC (20), and separates the signals into the multiple channels.

Abstract: In an AFC ((Automatic Frequency Control) circuit, a frequency offset estimating circuit (11) produces a lock signal (102) if a calculated frequency error becomes smaller than a predetermined value. Then, a CPU (13) produces a control signal (104) to stop the operation of the frequency offset estimating circuit (11). A timing generating circuit (14) calculates a frequency error with reference to a frame timing correction amount from a delay profile/search circuit (12), and produces an unlock signal (103) if the frequency error becomes equal to or greater than the predetermined value. Then, the CPU (13) produces the control signal (104) to start the operation of the frequency offset estimating circuit (11). Thus, the frequency offset estimating circuit (11) stops its operation while the AFC operation is in the locked state.

Abstract: To provide a method and a circuit arrangement (100) for detecting synchronization patterns in a receiver, particularly in a UHF receiver or a VHF receiver, by which the average current consumption in a system with a receiver, particularly a UHF receiver or a VHF receiver, and with a subsequently arranged controller unit (200) can be clearly reduced,

Abstract: A digital communications radio receiver, as for television, digitizes a final intermediate-frequency signal offset from zero frequency no more than a few megahertz. This digitized final I-F signal is passed through an adaptive equalizer before being synchrodyned to baseband in the digital regime, which adaptive equalizer has its weighting coefficients determined by comparing I-F signal as received with possible multipath with ideal I-F signal free from multipath distortion. Decision feedback for adjusting the filtering coefficients of the equalizer is described, which is based on the ideal baseband signal being re-modulated onto final I-F carrier and compared to the received signal as translated in frequency to provide the final I-F signal.

Abstract: A radio-frequency (RF) apparatus capable of transmitting RF signals includes transmitter path circuitry. The transmitter path circuitry includes a voltage-controlled oscillator (VCO) that generates an output signal. The frequency of the output signal of the VCO circuitry is adjustable in response to a first control signal and a second control signal. The transmitter path circuitry also includes a first feedback circuitry and a second feedback circuitry that are responsive to the output signal of the VCO circuitry. The first feedback circuitry provides the first control signal to the VCO circuitry. The first control signal coarsely adjusts the frequency of the output signal of the VCO circuitry to a desired frequency. The second feedback circuitry supplies the second control signal to the VCO circuitry. The second control signal fine tunes the frequency of the output signal of the voltage-controlled oscillator circuitry to the desired frequency.

Abstract: A vehicle radio includes a microprocessor-controlled tuner having a seek function. The tuner generates a station detect signal when a sufficiently strong signal is received, and the tuner also generates a multipath detect signal when a received signal exhibits undesirable multipath or adjacent channel conditions. To avoid ending the seek function when a relatively strong but poor-quality sideband signal is received, the microprocessor waits about 200 milliseconds after the station detect signal is generated, then determines whether the multipath detect signal is present, and if so, allows the seek to continue. On the other hand, the multipath detect signal can be expected to indicate that no multipath conditions exist (and, hence, that a good station signal exists) about 200 milliseconds after receipt of a good station signal, in which case the seek is terminated.

Abstract: The present invention intends to provide a receiver which receives a signal by switching a plurality of communication systems, wherein a circuit scale is reduced to intend to the miniaturization of a device. The receiver converts a received signal to a base band signal by a local oscillation frequency based on the selected communication system by a mixer, limits a band by an LPF through which signals of all communication systems can pass, performs a band limitation based on the communication system by weighting with a tap coefficient based on the selected communication system to synthesis by a transversal filter, and demodulates a signal by a demodulation system based on the selected communication system by a demodulating unit.

Abstract: The timing of a carrier signal is tracked in a receiver. The receiver receives a signal produced by a transmitter having a single frequency source which is used to generate a reference clock frequency and a carrier signal frequency, there being a fixed, predetermined relationship between the reference and carrier frequencies. In the receiver there is a single frequency source which is used to generate a reference clock frequency and a carrier reference signal frequency, there being a fixed, predetermined relationship between the reference and carrier reference frequencies. The fixed, predetermined relationship in the transmitter and the receiver is the same.

Abstract: A reference frequency generating section 10 capable of suitably changing frequency accuracy of an output signal in accordance with an input control voltage, and a high-accurate reference frequency generating section 13 having accuracy for a temperature change extremely higher than that of the reference frequency generating section 10 and in which output frequency accuracy thereof changes only within a range of prescribed values (frequency accuracy within a range where transmission and reception of a portable telephone can be conducted) are provided. A reference frequency after an AFC operation, which is output from the reference frequency generating section 10, is compared with an output signal from the high-accurate reference frequency generating section 13, and whether or not frequency accuracy of an output signal from the reference frequency generating section 10 meets a prescribed value is determined.

Abstract: In a mobile communication terminal, a switch 10 is initially set to an initial setting mode at time of turning on a power supply. A reference oscillator control circuit is initialized, and in this state, the output frequency of a reference oscillator is usually greatly shifted. The base station search is first conducted, and as a result, if the base station cannot be grasped, an offset signal is generated by a frequency offset generating circuit 12, to shift the output frequency of a reference oscillator 6 through a reference oscillator control circuit 5. This operation is repeated until the base station is grasped so that the base station search is continued while the output frequency of the reference oscillator 6 is being shifted. When a grasp of the base station succeeds, the switch 10 is switched to an AFC side to conduct automatic frequency adjustment.

Abstract: Upon installation of a broadcast receiver, for example, a television receiver, the different tuning frequencies/channel numbers are to be stored in a memory of the broadcast receiver. To facilitate the installation, the network provider transmits a list of nominal tuning frequencies, for example, as a teletext page, together with at least one of the broadcast television programs. To further improve installation, also the RF frequency of a so-called subscription channel is also inserted in the list. As the RF frequency of the set-top box may differ from the nominal value in the list, a fine-tuning is performed to modify the stored tuning frequency/frequencies.

Abstract: A digital carrier recovery system includes at least two modes of operation, namely, an acquisition mode and a tracking mode. The bandwidth of the carrier recovery loop filter is different for the acquisition mode and the tracking mode. In the acquisition mode, the digital phase-locked loop seeks and locks to the long term frequency offset of the received carrier signal. In the tracking mode, the digital phase-locked loop tracks the instantaneous variations in the carrier phase. Switching between the acquisition mode and the tracking mode is realized digitally, and includes programmable hysteresis, resulting in optimal performance in the presence of signals having high levels of phase noise (jitter). More specifically, the carrier recovery loop filter “locks” to the pilot signal of an incoming signal, e.g., a vestigial side band (VSB) video signal, by employing a so-called digital vector tracking phase-locked loop that demodulates the VSB signal.

Abstract: The present invention relates to the automatic frequency control circuit and the method of automatic frequency control. The automatic frequency control circuit for processing frequency control of a received signal frequency based on an incoming received signal comprises a first control circuit for processing frequency control based on a precision counter by using the incoming received signal and a second control circuit for processing frequency control based on a coarse counter by using the incoming received signal, wherein the first control circuit and the second control circuit are configured to be used interchangeably in response to the incoming received signal. By employing the circuit which directly counts the received signal and the circuit which counts the regenerative carrier signal in combination, the follow up range of the automatic frequency control circuit is thus expanded.