Abstract: A Class AB voltage-to-current converter includes a plurality of DC coupled transconductance stages that produce a linearized output and a biasing circuit. The biasing circuit generates a primary bias voltage that is greater than a generated secondary bias voltage. As such, the first transconductance stage becomes active before the second transconductance stage with respect to the magnitude of a differential input voltage, thereby allowing the transconductance of the secondary transconductance stage to be added (or subtracted) from the transconductance of the primary stage to improve the overall transconductance of the Class AB voltage-to-current converter. As each of the plurality of transconductance stages is biased differently from the others, the various transconductance stages are biased on to differing amounts based upon the biasing signals as well as the input signal.

Abstract: A front end tuning system includes a tuning signal generator. The tuning signal generator includes a digital-to-analog converter (DAC) to receive a pre-conditioned tuning signal at a reference input, to receive a digital value at a digital control input, and to produce a modified tuning signal based on the digital value and the pre-conditioned signal. Preconditioning the tuning-voltage allows a simple current type DAC to be can be used, rather than an 8-bit ladder type DAC used by some other front end tuners. Significant cost savings can be achieved because less memory is required to store the digital values supplied to the DACs, and set up times can be reduced. An adjustable temperature compensation circuit provides additional adaptability.

Abstract: A single chip radio transceiver includes circuitry that enables received wideband RF signals to be down-converted to baseband frequencies and baseband signals to be up-converted to wideband RF signals prior to transmission without requiring conversion to an intermediate frequency. The circuitry includes a low noise amplifier, automatic frequency control circuitry for aligning a local oscillation frequency with the frequency of the received RF signals, signal power measuring circuitry for measuring the signal to signal and power ratio and for adjusting frontal and rear amplification stages accordingly, and finally, filtering circuitry to filter high and low frequency interfering signals including DC offset. The circuitry further includes a multi-stage mixer that produces current signal outputs from each mixing stage to a subsequent stage thereby avoiding a need for intermediate transconductance and output stages to convert between current signals and voltage signals.

Abstract: In order to always maintain a frequency of an oscillator within a proper range, the frequency chages due to temperature and a secular change, a method is disclosed in which the secular change is calculated from past control information, and the frequency of the oscillator is corrected according to the secular change. A storing unit records the past control information for the oscillator. A processing unit calculates the secular change of the frequency of the oscillator from the past control information. Thereafter, the processing unit gives the oscillator new control information for correcting the calculated secular change.

Abstract: A receiver including a frequency converter which converts a frequency of a received signal according to a control signal to obtain a frequency-converted received signal, and an AFC (automatic frequency controller) which converts the frequency-converted received signal into a data converted signal, which compares respective phases of the data converted signal and a previous data converted signal to generate a first phase difference value, which compares respective phases of the data converted signal and the previous data converted signal to generate a second phase difference value, which generates a loop gain value according to the first and second phase difference values, and which generates the control signal according to the first phase difference value and the loop gain value.

Abstract: A method of receiving an FM digital audio broadcasting signal including a first plurality of subcarriers in an upper sideband of a radio channel and a second plurality of subcarriers in a lower sideband of the radio channel comprises the steps of mixing the digital audio broadcasting signal with a local oscillator signal to produce an intermediate frequency signal, passing the intermediate frequency signal through a bandpass filter to produce a filtered signal, determining if one of the upper and lower sidebands of the digital audio broadcasting signal is corrupted, and adjusting the local frequency oscillator signal to change the frequency of the intermediate frequency signal such that the bandpass filter removes the subcarriers in the upper or lower sideband that has been corrupted. A receiver that processes a digital audio broadcasting signal in accordance with the method is also provided.

Abstract: An architecture for providing high-speed access over frequency-division multiplexed (FDM) channels allows transmission of ethernet frames and/or other data across a cable transmission network or other form of FDM transport. The architecture involves downstream and upstream FDM multiplexing techniques to allow contemporaneous, parallel communications across a plurality of frequency channels. Moreover, an automatic frequency control resolves some issues of a free-running clock in an upstream tuner of the central concentrator by performing adjustments based on the average frequency error of a number of active upstream tones. In the preferred embodiments of the present invention, the automatic frequency control (AFC) utilizes a feedback loop for at least each active upstream tone. Also, the average of the active upstream tones is determined and is utilized in providing feedback to adjust the automatic frequency control (AFC).

Abstract: Apparatus for reducing DC offset in a signal path of a conversion system comprising a front end circuit for providing an input signal having an a DC offset; an amplifier system coupled to the front end circuit to receive and amplify the input signal; a multi-bit sigma delta modulator for receiving the input signal from the amplifier system and providing a first bit quantizer; a DC adapt circuit coupled to the sigma delta modulator for receiving the first bit quantizer from the sigma delta modulator and for providing an operation to reduce DC offset; a digital to analog converter (DAC) coupled to the digital DC adapt circuit to provide an analog signal representative of the DC offset correction to the input of the amplifier system, wherein the digital DC adapt circuit and the DAC form a feedback path originating at the first bit of the multi bit sigma delta modulator to the input of the amplifier system.

Abstract: A chopped intermediate frequency (IF) wireless receiver is disclosed. The wireless receiver includes a local oscillator (LO), a first and a second mixers, an LO frequency control module, an IF filter, a digital down converter and a down conversion controller. The LO provides a local oscillating signal to the first and second mixers. The first and second mixers converts a received radio frequency signal to an in-phase IF signal and a quadrature IF signal, respectively. The LO frequency control module alternately down converts a channel frequency by changing an oscillation frequency of the LO. Coupled to the digital down converter, the down conversion controller adjusts a complex sine wave within the digital down converter while the in-phase IF signal and the quadrature IF signal are being down-converted by the digital down converter to a baseband signal.

Abstract: A receiving unit in a communication system for receiving a communication signal. The receiving unit is preferably a wireless local area network (WLAN) receiver. The receiving unit comprises a synchronization data detection section and a frequency error correction section. The synchronization data detection section detects predefined synchronization data included in the received communication signal and computes an initial estimate of a frequency error of the received communication signal. The frequency error correction section corrects the frequency of the received communication signal based on frequency error estimates. An initial frequency error estimate used for a first frequency error correction is received from said synchronization data detection.

Abstract: A pole switch down-converter with symmetric resonator which reduce the non resonating phase to approximately half of the RF carrier period of the modulated signal is proposed. The down-converter comprises a first and second ?/2 resonator for collecting RF energy, wherein a differential RF signal is coupled to the first and second ?/2 resonator, a switching means coupled at one end of the first ?/2 resonator and one end of second ?/2 resonator for connecting the first and second ?/2 resonator, a control means for controlling the switching means, and a detecting means coupled to the first and second ?/2 resonator for detecting the down-converted signal, wherein the control means is adapted to initiate in a down-conversion cycle the switching means to connect the first and second ?/2 resonator for approximate half of the RF carrier period of the modulated signal. With this pole switch down-converter adjacent RF channels can be selected and down-converted by slightly varying the pole switch repetition rate.

Abstract: An automatic frequency control (AFC) system in an electronic device is operated by using an AFC-algorithm component to determine a frequency error corresponding to a difference between a frequency of a signal output from a signal generator and a received signal frequency. The frequency error determined by the AFC-algorithm component is multiplied by a scaling factor, which is set to zero after an adjustment has been made to change a frequency of the signal output from the signal generator. The scaling factor is increased from zero to one over time. The scaled frequency error is used to determine whether to adjust the frequency of the signal output from the signal generator.

Abstract: An automatic frequency tuning (AFT) system which can effect immediate and accurate automatic frequency tuning of the local oscillator (LO) of a receiver, in order to achieve a stable intermediate frequency (IF) signal while reducing the power consumption and the cost of the system. In the automatic frequency tuning (AFT) system, an analog-to-digital converter (ADC) converts the intermediate frequency (IF) to a digital value which is sent to a microcontroller. A signal sent from the microcontroller accurately and automatically tunes the local oscillator (LO).

Abstract: An apparatus for demodulating a digital input signal having a pre-assigned symbol rate by using a single sample clock signal is disclosed. The pre-assigned symbol rate is selected from the group consisting of a plurality of symbol rates. The apparatus comprises: a Cascaded Integrated Comb (CIC) Decimator filter configured to perform a filtering-decimation operation to isolate the down converted digital signal having the pre-assigned symbol rate; a Shaper configured to restore an original spectrum of the I and Q components of the CIC output signal; and a CIC tuner loop filter configured to insert the estimated by the Coarse Frequency estimation block frequency offset into a carrier loop in order to complete a carrier recovery of the pre-assigned input digital signal.

Abstract: A frequency offset detector for AFC under Rayleigh fading. The AFC includes a variable phase generator, an exponential term ej ?107 t multiplied on an incoming signal, a low-pass filter, a gain amplifier, a multiplier, and an offset detector. The offset detector includes a filter, an amplifier, a delay block, three adders, and two blocks that output the absolute value of an inputted signal. The filter is a Finite Impulse Response (FIR) filter that produces a Hilbert Transformation of the inputted complex gain. The Hilbert FIR filter, together with the complex gain and two of the adders, generate two complex signals: Xp and Xn respectively representing the positive and negative frequency components of the inputted complex gain. The detector output is equal to the difference between the magnitudes of Xp and Xn.

Abstract: A method for correcting influence of frequency offset between a receiver and a transmitter by evaluating training symbols received during a preamble period. The method includes producing, based on at least one long training symbol, a first vector whose first vector angle is indicative of a fine offset between the receiver and the transmitter, producing a fine offset estimate based on the first vector angle, and multiplying, with a signal having a frequency based upon the fine offset estimate, data symbols that are received after the at least one long training symbol is received.

Abstract: A partial Fourier Transform is performed, using Goertzel's algorithm, to calculate two frequency bins. A phase variation is calculated for each bin, the phase variation preferably representing the phase difference between the bin calculated by a Fourier Transform performed on samples in a guard interval and the bin calculated by a Fourier Transform performed on matching samples within the useful part of the symbol. The local oscillator frequency offset is compensated by summing the phase variations, and the sampling frequency offset is compensated by taking the difference between the phase variations.

Abstract: An apparatus and method for compensating for the frequency offset of a received signal in a receiving apparatus of a mobile communication system. In the present invention, a sine component is calculated by adding I and Q channel signals resulting from downconverting a training sequence inserted between data symbols, and a cosine component is calculated by subtracting the Q channel signal from the I channel signal. Using the cosine and sine components at two time points, tangent components for the two time points are computed and thus first and second phase values are obtained. The frequency offset is estimated by determining the slope of a second-order line derived from the first and second phase values. The frequency offset of the received signal is compensated for based on the estimated frequency offset.

Abstract: An automatic frequency correction (AFC) apparatus used for CDMA multipath fading channels comprises a frequency-offset evaluator, an automatic frequency correction loop filter and a carrier frequency adjuster. The present invention provides a “multipath energy window” designing method for the non-determinacy of multipath signals in mobile communication environment. Frequency-offset information can be extracted from the multipath energy window by a simple calculation and evaluated by a maximal SNR weight process. This invention also provides a step-variable accumulation adjusting method and greatly improves the response speed of the AFC apparatus as compared with a conventional loop filter, whereby supplies better AFC required for CDMA mobile terminals.

Abstract: A mobile station is disclosed for performing an automatic frequency control based on a correspondence of a frequency error and TCXO control voltage to a base station. A plurality of frequency error measuring units each measure a frequency error between an internal clock signal and a clock signal in a specified base station. A plurality of control voltage calculators, each associated with a corresponding one of the plurality of frequency error measuring units, integrate a frequency error measured by the corresponding frequency error measuring unit to produce a control voltage. A control voltage selector selects a control voltage corresponding to a base station currently in communication with the mobile station from among control voltages calculated by the plurality of control voltage calculators. A clock signal generator generates an internal clock signal at a frequency in accordance with the selected control voltage.

Abstract: Techniques to acquire and track pilots in a CDMA system. In an aspect, frequency acquisition of a number of signal instances (i.e., multipaths) in a received signal may be achieved concurrently based on a frequency control loop (RAFC) maintained for each finger processor of a rake receiver. Upon successful acquisition, frequency tracking of acquired multipaths may be achieved based on a combination of a frequency control loop (VAFC) maintained for an oscillator used for downconverting the received signal and the RAFCs for the finger processors. In a tracking mode, the VAFC tracks the average frequency of the acquired multipaths by adjusting the frequency of the oscillator. The RAFC of each finger processor tracks the residual frequency error (e.g., due to Doppler frequency shift) of the individual acquired multipath by adjusting the frequency of a complex sinusoidal signal used in a rotator within the finger processor.

Abstract: A mobile communication terminal includes (a) a first unit for calibrating a frequency, (b) a global positioning system (GPS) module, and (c) a processor which electrically connects the first unit and the global positioning system module to each other. The first unit counts the number of an intermediate frequency (IF) signal generated by converting a frequency of a signal transmitted from a base station, the processor coverts a count of the intermediate signal obtained while the first unit is in lock-up condition, into a real count offset, and the global positioning system module counts the number of a signal transmitted from a circuit which generates an operational frequency of the mobile communication terminal, and calibrates the number of the signal with the real count offset.

Abstract: A wireless communication device (WCD) estimates frequency error by averaging frequency error estimates over multiple integration lengths to generate short-term and long-term averages. The WCD compares the short-term and long-term averages with short-term and long-term thresholds. The long-term thresholds are lower than the short-term threshold. If the average for any integration length exceeds its respective threshold, a frequency offset is determined and an oscillator frequency is adjusted based on that frequency offset. The use of both short-term and long-term thresholds facilitates responding quickly to relatively large changes in the frequency error, while ignoring smaller changes that may be indicative of noise in the system rather than actual changes in the frequency error.

Abstract: A multiple channel receiver (200) includes a communications receiver synthesizer (204) and at least one numerically controlled oscillator (NCO) (406) that produce local oscillator signals that are derived from a common reference oscillator (202). A DSP (212) and CPU (214) perform automatic frequency control (AFC) by adjustment of the reference oscillator (202) based upon a signal received by a receive channel using the local oscillator signal produced by the communications receiver synthesizer (204). The CPU (214) also provides a synchronous indication of adjustments to the reference oscillator (202) to control circuitry for the at least one NCO (406) so that the configuration of the NCO (406) can be altered so as to maintain a substantially constant frequency output during the adjustment of the reference oscillator (202).

Abstract: The present invention is related to a method and apparatus for automatic frequency correction of a local oscillator. The apparatus receives a carrier signal. The carrier signal includes a code sequence known to the apparatus. The apparatus downconverts the carrier signal to a baseband signal using the local oscillator. The apparatus performs a block correlation of the samples of the baseband signal with the known code sequence to generate a frequency error signal. The frequency error signal is fed back to the local oscillator to correct the frequency error.

Abstract: When a cellular phone terminal is powered on, it immediately receives a reference signal (non-modulated reference frequency signal for correcting a crystal oscillation circuit) for correcting the reception frequency of a radio signal transmitted from a base station at all times, and corrects the error of the reception frequency on the basis of the reference signal received. After the error of the reception frequency is corrected, the cellular phone terminal makes normal communications with the base station.

Abstract: A portable radio terminal for realizing automatic frequency control (AFC) for automatically controlling the oscillation frequency of an oscillator includes a unit for intermittently performing AFC operation, and a unit for shortening an AFC operation stop period when the frequency shift of the oscillation frequency is large. An AFC control method is also disclosed.

Abstract: A method for controlling frequency of a local oscillator in a DS-CDMA type receiver includes transforming a known spread spectrum signal into a sampled digital signal formed of symbols with a despreaded frequency spectrum, and determining a residual frequency error fe for each symbol including a first residual frequency error fe1. The method further includes correcting the frequency of the local oscillator with the residual frequency errors, and determining an average of absolute values of a predetermined number of successive residual frequency errors. The average is compared with a threshold, and if the average is greater than or equal to the threshold, the local oscillator frequency is corrected using an error equal to ?sgn(fe1) (1/T?|fe1|), where sgn is the sign function, | | is the absolute value function and T is duration of a symbol before determining the next residual frequency error associated with the next symbol.

Abstract: In a mobile communication device, communication can be resumed upon next communication without causing problem even when an AFC control signal becomes abnormal upon interruption of communication. Locked state and unlocked state of an AFC portion is monitored by an AFC monitoring portion 5. Upon interruption of communication, if in unlocked state, a TCXO 1 is controlled by the AFC portion using a TCXO control signal upon preceding locked state. By this, when communication failure is caused by influence of building, tunnel or the like or when communication is terminated, a reference frequency of the mobile communication device does not significantly offset from the reference frequency of a base station to facilitate communication upon next communication.

Abstract: A device and a method for automatic frequency correction are used in mobile radio receivers. After channel estimation has been performed, the phases of the received data symbols are analyzed in order to determine the frequency shift. Following the phase analysis, a phase correction of the received data symbols is performed.

Abstract: A cross product is determined for a received signal. A dot product is also determined for the received signal. If the cross product is greater than a predetermined threshold, the cross product is decremented by the product of the dot product multiplied by a constant value. If the cross product is less than or equal to the predetermined threshold, the cross product is incremented by the product of the dot product multiplied by the constant value. The incrementing or decrementing is continued until the frequency error approaches a minimum value.

Abstract: The demodulator of the invention includes a DSP. The DSP determines the distortion amount of the transmission channel based on known signals included in a radio receiving signal, and estimates the frequency of the direct wave based on the distortion amount. Furthermore, the DSP rotates the phase of the distortion amount based on the phase amount corresponding to the estimated frequency of the direct wave. Next, the DSP estimates the center frequency of the Doppler spread based on the distortion amount after the phase is rotated. Furthermore, the DSP synthesizes the phase amount corresponding to the estimated center frequency of the Doppler spread and the phase amount corresponding to the frequency of the direct wave to estimate the last frequency offset. Thereafter, the DSP eliminates frequency offset of the radio receiving signal based on the estimated frequency offset. Thereby, a sufficient frequency offset compensating range can be secured, and excellent BER characteristics can be realized.

Abstract: A radio device requires a tunable transceiver such that the transceiver can be accurately set to a desired frequency. When a signal with known frequency accuracy is being received, an offset detector can determine the frequency offset generated by the transceiver due to improper tuning. An automatic frequency control (AFC) system (100) is comprised of a tunable transceiver, an adaptive detector (102) for comparing an incoming sample from the tunable transceiver to an adaptive maximum deviation threshold for determining if a sample from the tunable transceiver should be used for the direct current (DC) component of the AFC, an offset detector (103) and an AFC control processor (105) for utilizing information from the offset detector to reduce the inaccuracy in frequency by tuning the transceiver towards the received signal frequency. The AFC control processor (105) utilizes one of more threshold levels for defining a maximum correction threshold (311) based upon the desired maximum offset correction.

Abstract: A tuner comprises a first frequency changer with a mixer and local oscillator. The output of the frequency changer is connected to a first intermediate frequency filter, whose output is connected to a second frequency changer. The output of the frequency changer is connected to the usual second intermediate frequency filter and to an amplitude detector. A reference oscillator is connectable under control of a controller via a multiplexer to the input of the mixer. During an alignment mode of the tuner, the reference signal from the oscillator is supplied to the mixer and the local oscillators and are controlled by the controller to sweep across a frequency range encompassing all possible pass frequencies of the filter. The controller monitors the output of the detector so as to establish the frequency response of the filter. Frequency offsets are then stored in the synthesizers and so as to center each channel during a reception mode on the actual center frequency of the filter.

Abstract: Measuring gate pulse is generated that rises in synchronism with one of first and second clock signals and falls in synchronism with the other of the first and second clock signals. Then, a pulse width of the generated measuring gate pulse is measured by counting clock pulses higher in frequency than the first and second clock signals. When counted values indicative of respective pulse widths of an adjacent pair of the measuring gate pulses generated in succession coincide with each other, it is determined that the frequencies of the first and second signal are the same, but when the counted values of the adjacent pair of the measuring gate pulses do not coincide with each other, it is determined that the frequencies of the first and second signal are not the same.

Abstract: A receiver uses an adaptive algorithm to tune a low-cost crystal oscillator according to a temperature compensation profile so as to produce a precision master reference frequency despite temperature, initial tolerance, and aging effects. An automatic frequency control system also tunes the crystal oscillator. The adaptive algorithm adjusts the temperature compensation profile for the crystal oscillator according to the adjustments made by the automatic frequency control should a received signal's quality factor exceed that associated with the temperature compensation profile.

Abstract: Frequency correction of a radio module. Multiple samples of frequency data are taken during a quiescent portion of the base station transmission, to estimate the amount of frequency correction needed. An embodiment applies the frequency data to a median filter to eliminate invalid data. Next, a new reference frequency is applied to a radio transceiver in the radio module to provide the frequency correction. If the frequency was corrected by greater than a pre-determined amount, the process performs a large shift frequency correction, including verifying that the first frequency correction was satisfactory and verifying that the radio transceiver is able to receive data after the frequency correction has been performed. If the frequency was corrected by smaller than a pre-determined amount, the process performs a small shift frequency correction, including updating a total of all frequency corrections made since a stored reference frequency was updated.

Abstract: A receiver (22) includes an IF filter (44) and a nearby process-variant circuit (80) formed on a common semiconductor substrate (24). The actual center frequency of the IF filter (44) is determined by resistors (70, 74) and capacitors (72, 76) exhibiting imprecise values and is unlikely to equal a nominal center frequency. The process-variant circuit (80) includes a test resistor (102) and test capacitor (104) formed using the same resistor-forming and capacitor-forming processes used to form the IF filter resistors (70, 74) and capacitors (72, 76). In response a test signal (88) from the process-variant circuit (80) and a reference signal (84) from a process-invariant circuit (82), a tuning parameter for a tunable local oscillator (90) is determined so that a local oscillation signal (94) will exhibit a frequency which, when mixed with an RF signal (38) yields an IF signal (42) at the actual center frequency of the IF filter (44).

Abstract: A frequency extractor extracts an input frequency of an input signal. The frequency extractor includes a frequency multiplier, first and second filters, a binary circuit and a frequency divider. The frequency multiplier obtains a signal of a multiplied frequency, the multiplied frequency being N times the input frequency, N being an integer greater than 1. The first filter, having a first bandwidth, filters the signal of the multiplied frequency to provide a first filtered signal. The binary circuit binarizes the first filtered signal to a binary signal. The frequency divider divides the binary signal by a factor of N to provide a divided signal. The second filter, having a second bandwidth, filters the divided signal to generate the input frequency in a form of a continuous wave, wherein the second bandwidth is about 1/N times the first bandwidth.

Abstract: A method and apparatus are provided that performs timing acquisition for multiple radio terminals. According to one aspect of the present invention the invention includes receiving a sequence of symbols modulated onto a carrier frequency over a channel and demodulating the symbols using a clock frequency. The invention further includes determining a frequency offset of the received symbols with respect to the clock frequency and applying the determined frequency offset to adjust the clock frequency.

Abstract: An amount-of-correction extracting unit detects a deviation angle from a phase of a reference signal point of phase information contained in a received signal, and determines an amount of correction based on the deviation angle. On a transmission side, transmission data is converted into a pair of amplitude data corresponding to a signal point of the transmission data. The amount of correction is added to the phase of the signal point indicated by the pair of amplitude data. A carrier wave for transmission is modulated by the pair of amplitude data after correction, and is then transmitted. Thus, it is possible to transmit the modulated wave which varies in accordance with the frequency precision of the other communication party.

Abstract: A symbol independent automatic frequency controller (100) includes a symbol correlator (110) for receiving a complex digital signal generated within a selective call receiver wherein the symbol correlator provides a real signal (114), an imaginary signal (116), and a magnitude signal (112), a discriminator (140) coupled to the symbol correlator for receiving and processing the real signal and the imaginary signal to provide a frequency error signal, a low pass filter (120) and comparison element (130) for filtering the magnitude signal and comparing the magnitude signal to a predetermined lock threshold signal that controls the bandwidth of the symbol correlator in the event the magnitude signal exceeds the lock threshold signal, and a feedback loop providing the imaginary signal (116) to an accumulator (170) and back to the symbol correlator wherein the accumulator provides the symbol correlator with an apriori-symbol phase feedback (172).

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 receiver having a phase-locked loop (PLL) for synchronizing its oscillator with a carrier (CA). A calibration circuit (CAL) calibrates the phase-locked loop's oscillator (OSC) in the following manner. It measures (FMC) the frequency difference (dF) between a nominal frequency (Fnom) of the carrier (CA) and a frequency (Fosc) of the phase-locked loop's oscillator (OSC). Furthermore, it adjusts the frequency (Fosc) of the PLL oscillator in accordance with the measured frequency difference (dF). As a result, the phase-locked loop's oscillator will be substantially tuned to the nominal frequency of the carrier. The actual frequency of the carrier may differ from the nominal frequency. In general, such a difference will be sufficiently small for the phase-locked loop (PLL) to capture the carrier (CA).

Abstract: A circuit configuration has a radio-frequency section with a receiving mixing stage, and has a signal processing circuit with an A/D converter, a digital filter and a frequency estimator. The frequency estimator continuously determines a first frequency correction control signal, which is representative of a frequency offset between the frequency of an IF received signal and a frequency which is characteristic of a pass band of the filter. The first frequency correction control signal is used for readjustment of the mixing frequency.

Abstract: A mobile communications device using a common oscillator for communication and global positioning system (GPS) functions. In one embodiment, a communications unit receives a precision carrier frequency signal from a source and generates a reference signal that is used to calibrate a common oscillator.

Abstract: Techniques for inner/outer loop tracking that is stable and provides desirable loop convergence characteristics are disclosed. In one aspect, the contribution from any one inner loop to the tracking function of the outer loop is limited, to prohibit any one received signal component from dominating the outer loop. In another aspect, the rate of outer loop tracking variation is controlled to provide inner and outer loop stability. Various other aspects are also presented. These aspects have the benefit of providing stable inner and outer loop control, as well as efficient convergence and tracking by the various loops, resulting in reduced frequency error and improved communication performance.

Abstract: A front end tuning system includes a tuning signal generator. The tuning signal generator includes a digital-to-analog converter (DAC) to receive a pre-conditioned tuning signal at a reference input, to receive a digital value at a digital control input, and to produce a modified tuning signal based on the digital value and the pre-conditioned signal. Preconditioning the tuning-voltage allows a simple current type DAC to be can be used, rather than an 8-bit ladder type DAC used by some other front end tuners. Significant cost savings can be achieved because less memory is required to store the digital values supplied to the DACs, and set up times can be reduced. An adjustable temperature compensation circuit provides additional adaptability.

Abstract: A portable telephone apparatus includes a reference frequency generating section 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 having accuracy for a temperature change extremely higher than that of the reference frequency generating section and in which output frequency accuracy thereof changes only within a range of prescribed values. A determination device determines whether or not frequency accuracy of an output signal from the reference frequency generating section meets the prescribed value. A selector selects an output signal from the reference frequency generating section in a case that a determination result of the determination device meets the prescribed value, and selects an output signal from the high-accurate reference frequency generating section in a case that a determination result of the determination device does not meet the prescribed value.

Abstract: The invention provides a radio receiving method and apparatus by which adjustment of a reception frequency when a radio modulation signal of a PSK system is received is realized by simple processing. Phase data is sampled out in a predetermined cycle from a random received modulation signal and cumulatively added for a predetermined period, and the reception frequency is adjusted so that a calculation result of the cumulative addition may satisfy a predetermined allowance range. Consequently, the reception frequency can be adjusted by simple processing without detecting a phase error from the modulation signal.