Abstract: An oscillator 10 includes temperature compensation circuits 30 and 40, a frequency adjusting circuit 50, and an initial deviation correcting circuit 60. Switches SW 1 to 4 are controlled based on control data DC stored in a memory 90 so that a temperature compensation voltage V1, a temperature compensation voltage V2, a frequency adjusting voltage V3, and an initial deviation correcting voltage V4, output from the above circuits, are selectively added, supplying a sum to a voltage-controlled oscillation circuit 20 as a control voltage VA.

Abstract: Disclosed is an oscillator circuit (10) for use in a local oscillator of an RF communications device (100) that communicates over an RF channel. The oscillator circuit includes an oscillator transistor coupled to a power supply voltage (Vcc) through a buffer transistor, and a biasing network having bias voltage outputs coupled to a control input of the oscillator transistor and to a control input of the buffer transistor. In one embodiment the bias voltage network is coupled to Vcc, while in another embodiment the bias voltage network is coupled to a separate voltage (Vbias). Circuitry is provided for setting a magnitude of Vcc and/or Vbias as a function of at least one of RF channel conditions, such as channels conditions determined from a calculation of the (SNR), or an operational mode of the RF communications device. The magnitude of Vcc (and Vbias) may be set between about zero volts (i.e., turned off) and some maximum value.

Abstract: The frequency error of an oscillator is minimized by characterizing the operating environment of the oscillator. An electronic device monitors parameters that are determined to have an effect on the frequency accuracy of the internal frequency source. Temperature is one parameter known to have an effect on the frequency of the internal frequency source and a primary contributor to device temperature is the RF Power Amplifier (PA). The electronic device collects and stores the activity level of the PA. The effective PA duty cycle over a predetermined period of time is calculated. The LO operating environment is stabilized by operating the PA at the calculated duty cycle when the LO is required to operate in a high stability mode.

Abstract: Embodiments of the present invention relate generally to receivers. One embodiment relates to a digital FM receiver having multiple sensors (e.g. antennas). In one embodiment, the digital receiver includes a baseband unit having a channel processing unit. In one embodiment, the channel processing unit is capable of calculating or estimating a phase difference between the incoming signals prior to combining them. One embodiment uses phase estimation method for diversity combining the signals while another embodiment utlizes a hybrid phase lock loop method. Also, some embodiments of the present invention provide for echo-cancelling after diversity combining. An alternate embodiment of the channel processing unit utilizes a space-time unit to diversity combine and provide echo cancelling for the incoming signals.

Abstract: The present invention utilizes an even harmonic mixer for canceling a local oscillator (LO) leakage signal. The apparatus for canceling the LO leakage signal includes an in-phase divider, an intermediate frequency (IF) phase divider, an even harmonic mixers, an RF signal phase combiner and a band pass filter (BPF). The in-phase divider divides an LO signal into two in-phase LO signals, wherein the LO signal is inputted from an exterior LO. The IF phase divider divides an IF signal into two out-of-phase IF signals of which a phase difference is 90°, wherein the IF signal is inputted from an exterior means. The even harmonic mixer outputs two out-of phase RF signals of which the phase difference is 90°, after even-harmonic mixing of two in-phase LO signals divided by the in-phase divider and two out-of-phase IF signals divided by the IF phase divider.

Abstract: A circuit configuration for direction modulation contains an oscillator, whose output signal is split into quadrature components for modulation with a useful signal. A frequency shifting circuit has the effect that that the output frequency and the frequency of the oscillator are fractional rational multiples with respect to one another. The circuit contains a phase shifter for generating first further quadrature components and also a divider for generating second further quadrature components. The quadrature components are mixed with one another. As a result of the frequency offset, the oscillation frequency of the oscillator is shifted to outside the useful frequency band. Remodulation effects do not influence the adjacent channels. The circuit can be realized simply and cost-effectively and, in particular, requires only one oscillator.

Abstract: A system is disclosed for transmitting and receiving signals. The system includes the use of a frequency plan table a system for creating the frequency plan table. The frequency plan table relates carrier frequency channels to the operation of a synthesizer and a plurality of programmable frequency dividers in a locked loop. In a transmitter, a first programmable frequency divider accepts a reference signal and produces a comparison signal. A mixer accepts the reference signal and a transmission signal and produces a loop signal. A second programmable frequency divider accepts the loop signal and produces a loop signal having a divided intermediate frequency signal. A phase detector compares the comparison signal and the loop signal having a divided intermediate frequency and produces an output that controls a variable controlled oscillator. The variable controlled oscillator produces a modulated transmission signal.

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: A frequency scanning receiver not requiring the time for setting the frequency of the PLL of the first local oscillator and using a method capable of setting the receiving frequency in a simple circuit configuration, wherein the frequency scanning receiver is configured so that in the case where the reference frequency of the PLL of the first local oscillator has been set at a high frequency, when the frequency error is less than the second IF, it is configured so that the frequency error is controlled to be zero by the control circuit switching the frequency of the second local oscillator or the third local oscillator to an appropriate frequency using an output of the frequency discriminator.

Abstract: A quadrature demodulator applicable to digital communication and digital broadcast is provided, which simplifies the circuit configuration of a quadrature demodulator section and which reduces the labor or man-hours and the time required for adjusting the demodulation characteristic.

Abstract: Methods to generate a mobile time reference are provided. A representative method includes providing a high frequency clock, providing a low frequency clock, generating a mobile time reference using the high frequency clock, maintaining the mobile time reference using the low frequency clock when the high frequency clock is turned off, and continuing to generate the mobile time reference using the high frequency clock when the high frequency clock has been turned back on. Systems and other methods are also provided.

Abstract: A radio communication devices which transmits or receives a signal at a predetermined carrier frequency, The device includes a reference oscillator, which generates a clock frequency having a clock frequency error relative to a specified frequency thereof, a processor, which estimates the clock frequency error and parses the error to determine coarse and fine error correction components, at least one frequency synthesizer, which responsive to the clock frequency and to the coarse error correction component, generates a partially corrected frequency having a residual frequency error, which partially corrected frequency is applied to process the signal and baseband processing circuitry, which applies the fine error correction component to process the signal so as to correct the residual frequency error.

Abstract: Fast switching and fast settling is achieved in a phase locked loop (“PLL”) containing a bandwidth switched active loop filter (8) by feeding the phase error signal of the phase detector (1) of the PLL to the non-inverting input of the amplifier (7) within the loop filter and having the electronic switch (17) control the loop filter bandwidth through changing the resistance (9, 11) to ground at the inverting input of the amplifier between a high and low value associated respectively with broad bandwidth and narrow bandwidth to the loop filter. Switching is possible in as little as one microsecond, and is accompanied by fast settling of the loop with minimal generation of phase/frequency perturbation. The foregoing PLL is of particular benefit in fast switching frequency synthesizers, such as used in frequency hopping frequency synthesizers of frequency and time division multiplexing systems.

Abstract: To reduce the number of signal lines in the inside of a radio receiver which determines a reference voltage based on data supplied from an external CPU, the first and second reference value data from the external CPU (1) is supplied to an input section (20) of a PLL control circuit (19), and then latched by a latch circuit (21). The latched data is converted into an analogue reference voltage in D/A converters (23, 24). The reference voltage is transferred to a radio receiving circuit (2) to be supplied to comparison circuits (16, 18) via a single line, respectively, in the inside of the radio receiving circuit (2).

Abstract: A method and apparatus for generating digitally modulated signals in which a serial data stream of digital signals to be modulated (70) is provided, the serial data stream being converted into real and imaginary components (74) which are then converted into a complex polar signal (80) representing the serial data stream. A carrier of appropriate frequency is generated by an infinite impulse response filter (84,86) and the polar signal is mixed with the output of the infinite impulse response filter to provide a representation of the complex polar signal modulated at the frequency generated by the infinite impulse response filter (88). Subsequently the imaginary component of the resulting representation is stripped from the signal (90) and the real component of the resulting representation is applied to a digital to analog converter (92) to produce an analog version of the serial data stream.

Abstract: A system, apparatus, and method for determining the distance between two objects using an indirect propagation delay measurement is disclosed. A frequency hopping scheme (such as the Bluetooth™ technology) is used to measure the relative phase offset of the received signal between the various frequencies. For a given distance between the objects, the phase offset vs. frequency curve is a straight line with the slope dependent upon the measured distance. After the phase of the received signals is detected, the data is plotted on a curve and the slope is calculated.

Abstract: Method and system for processing multicarrier radio communications applications, particularly in Global System for Mobile Communication (GSM). The invention is characterized by the transposition of a multicarrier spectrum (S) in a base-band, and the processing of each carrier (12; 14) independently using one single RF phase-locked loop (35) common in the present single-carrier terminals. According to an embodiment of the invention, the processing of each carrier independently comprises the transposition of each carrier (12; 14) in base band using the 200 kHz clock (36) generated by the RF PLL of a mobile phone set.

Abstract: A multi-band RF transceiver (100) includes a single dual band VCO (102) that is used in both transmit and receive modes of operation. The VCO's low band frequency output signal that is provided on output line (120) is multiplied by two by multiplier circuit (1302), when in the high band receive mode, as for example, when receiving a PCS or DCS signal. The VCO's high band frequency output signal provided on output line (120) is divided by two by divider circuit (130) when in the low band receive mode, as for example, when receiving a GSM signal. The single multi-band VCO (102) design provides for low susceptibility to both LO leakage and DC offset caused by radiation.

Abstract: A monolithic AM transmitter is disclosed. An external antenna forms part of a resonance network so that the antenna resonance point is automatically tuned to the transmit frequency. This provides flexibility with no added cost to the transmitter.

Abstract: There is disclosed a frequency synthesizer having an HF synthesizer for generating a first reference frequency signal having a variable frequency in a high-frequency band as a unit synthesizer, an LF synthesizer for generating a second reference frequency signal in a low-frequency band as another unit synthesizer, and an arithmetic circuit including a mixer for receiving the first and second reference frequency signals, a divider for receiving the second reference frequency signal, a mixer for receiving the first reference frequency signal and an output signal from the divider, a divider for receiving an output signal from the mixer, a divider for receiving an output signal from the mixer and capable of switching a division ratio, and a switch for switching and outputting output signals from the dividers, wherein an output signal of the switch is outputted as a first local signal, and an output signal from the divider is outputted as a second local signal.

Abstract: A local oscillation circuit comprising a crystal oscillating circuit for generating an output voltage having a constant frequency, and an interface part for converting the output voltage from the crystal oscillating circuit into a current signal, the current signal being used as a local oscillation signal to be mixed with the receiving signal from an antenna, whereby a receiving circuit, which can be made as a single semiconductor chip consuming little current, can be realized.

Abstract: An RF receiver, which is one of a network of receivers, is described which allows for a simple method of compensating for the group time delay asymmetry of an IF filter in the receiver. Compensation of the group time delay is important for time difference of arrival (TDOA) measurements for mobile location tracking applications, such as E-911 applications. The TDOA measurements are performed by the receiver network. The RF receiver includes a switch which alternately switches between two RF LO frequencies for consecutive pulse signals received from a mobile transmitter. One of the two RF LO frequencies is offset by the IF frequency on the positive side of the center frequency of the mobile transmitter signal received by the receiver. The other RF LO frequency is offset by the IF frequency on the negative side of the center frequency.

Abstract: A method and apparatus for synthesizing high-frequency signals, such as wireless communication signals, includes a phase-locked loop (PLL) frequency synthesizer with a variable capacitance voltage controlled oscillator (VCO) that has a discretely variable capacitance in conjunction with a continuously variable capacitance. The discretely variable capacitance may provide coarse tuning adjustment of the variable capacitance to compensate for capacitor and inductor tolerances and to adjust the output frequency to be near the desired frequency output. The continuously variable capacitance may provide a fine tuning adjustment of the variable capacitance to focus the output frequency to match precisely the desired frequency output. During fine tuning adjustment, the PLL may be controlled by a plurality of analog control signals. The analog control signals may be derived by first generating a plurality of phase shifted signals from a divided version of the VCO output clock.

Abstract: Baseband processor and communication overloading can be relieved in a portable wireless communication terminal by decentralizing power control (38, 39) and frequency shift control (75) functions that are conventionally concentrated in the baseband processor. A timing sequencer (31) for power control can be integrated into a transceiver of the portable wireless communications terminal, thereby advantageously permitting power control signals to be generated on the transceiver side (27, 29) rather than the baseband processor side. Shadow registers (74) containing information indicative of commonly used or repeated frequencies can be integrated into the transceiver side, thereby advantageously relieving the baseband processor of corresponding frequency shift control responsibilities.

Abstract: A selective-calling radio receiver using the direct conversion method is provided, which commonly uses a VCO and its neighboring component for different frequency bands.

Abstract: Only a first radio station is equipped with a local oscillation signal source. A signal transmitted to a second radio station includes local oscilaation signal components used to up-convert a modulated intermediate frequency band signal in addition to intermediate frequency band signal components. The second radio station that receives the signal from the first radio station extracts and regenerated the local oscillation signal used at the first radio station using a local oscillation signal regenerator. The extracted and regenerated local oscillation signal is used to down-convert modulated radio signal components to the intermediate frequency band and simultaneously up-convert to the radio frequency band the modulated intermediate frequency band signal to be transmitted to the first radio station.

Abstract: A microwave oscillator for inducing parallel feedback from collector to base and obtaining a stabilized oscillation output is realized by connecting MSL A with released end to a base terminal of a transistor, connecting MSL B to its collector terminal, and disposing a DR closely to the MSL A and B to couple them electromagnetically. The length between the released end and the position of MSL A which is closest to the center of DR is set to &lgr;g¼ (&lgr;g1 is the guide wavelength in the MSL A), and HIL is merely connected to this position as a bias supply line to the base terminal. This structure does not require the choke circuits which occupied a relatively wide area on the conventional circuit board, and a small and stable microwave oscillator having excellent phase noise characteristics, and a low-noise converter for receiving satellite signal by using the same are realized.

Abstract: A multi-channel system is provided for both wide-band and narrow band low frequency transmission/reception of digital telemetry. The multi-channel system uses coherent detection having a high selectivity, and a quadrature detector having a high sensitivity. A filter is provided to average out noise. The multi-channel system oscillator is software controlled for scanning/multiplexing. The multi-channel system is used for data transmission over inductive, infrared, sonic and cable links.

Abstract: An AM receiver with at least one IF filter with a fixed IF bandwidth comprises at least one downconversion stage (3, 4, 5) to shift the signal input thereto into an IF range (IF1) having a variable oszillation frequency (fLO1) which is adjustable to detune a wanted center frequency (fC1) of a wanted signal part (30) from a center frequency (fIF1) of said at least one IF filter so that an unwanted signal part (31b) adjacent to said wanted signal part (30) lies outside said fixed IF bandwidth.

Abstract: A locator using Navstar constellation signals for determining geographical location of a mobile receiver. The locator is integrated with a mobile unit of a cellular network, which derives its reference frequency from a local oscillator (26). A frequency measuring module (28) counts the number of digital numbers derived from the local oscillator passing between two consecutive time-tagged indicators of the cellular network. The estimated frequency is calculated by dividing the number of digital numbers by the nominal time interval (T0) between the indicators.

Abstract: To minimize the overall circuitry necessary in a multiband-frequency generator, output terminals of a voltage-controlled multiband oscillator (22-1, . . . , 22-N) are coupled to a frequency synthesis unit (10) via a frequency selective coupling unit (24). The frequency synthesis unit (10) derives a phase difference between a frequency control input signal and the output signal of the frequency selective coupling unit (24) to control the voltage-controlled multiband oscillator (22-1, . . . , 22-N).

Abstract: Methods and systems are provided for frequency generation suitable for use in wireless devices capable of operating at multiple frequencies. Such systems may change the loop gain of an automatic frequency control loop based on the operating frequency of the wireless device. Furthermore, such a frequency dependent loop gain may be carried out by the selection of subroutines with differing loop gains associated with the subroutines. Furthermore, the loop gain may also be temperature compensated based on the temperature of the wireless device and/or the operating frequency of the device.

Abstract: A frequency correction apparatus for a radio calling system includes reception antennas, local oscillation sections, demodulation sections, and a correction control section. The reception antennas receive call signals constituted by frames as units, each constituted by a frame synchronization portion and a data portion. The local oscillation sections generate local oscillation frequencies. The demodulation sections demodulate the received call signals after the call signals are converted into reception intermediate frequencies by using the local oscillation frequencies from the local oscillation section. The correction control section corrects the local oscillation frequency of the local oscillation section on the basis of frequencies of the frame synchronization portions of demodulated signals output from the demodulation section.

Abstract: A method and apparatus for improving the sensitivity of a radio frequency (RF) receiver at certain frequencies suffering from co-channel interference. In the preferred embodiment, when a reference frequency, FREF, generates significant harmonics for a received RF signal in a selected channel, the reference frequency is varied or offset by a small amount, &Dgr;F. The harmonics of the offset reference frequency, F′REF=FREF±&Dgr;F, are thereby shifted away from the frequency of the received RF signal, thus reducing co-channel interference. The offset amount &Dgr;F is chosen such that the same injection frequency synthesized from FREF can still be synthesized from FREF±&Dgr;F by shifting N by an integer amount, preferably to N+1 or N−1. However, the invention encompasses shifting N by other integer amounts.

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.

Abstract: This invention provides a method of generating multiple frequencies for use in a digital data transmission system including a remote transmitter and receiver. The reference frequency used in the transmitter is replicated in a remote receiver. A single crystal oscillator is used to generate a reference frequency similar to that used in the transmitter. The receiver reference frequency is manipulated by dividing the frequency into required multiple frequencies for use within the receiver. A constant comparison is made between the clock signal received in the transmitted data stream with the receiver reference frequency and the divisors are adjusted accordingly to maintain the clock frequency in the receiver within a predetermined tolerance range. This allows the output signal for display from the receiver to match the quality of the input display provided to the transmitter.

Abstract: An electronic system, such as a wireless telephone handset (10), having multiple voltage-controlled oscillators (26, 28) so that the system can operate in a selected one of multiple frequency bands, is disclosed. Each of the voltage-controlled oscillators (26, 28) is associated with one of multiple loop filters (32, 34), which filter the control voltage (CP1, CP2) responsive to which the frequency of oscillation of the voltage-controlled oscillators (26, 28) controlled. Only one of the voltage-controlled oscillators (26, 28) is enabled at any one time, responsive to a control signal (VCOSEL). Synthesizer circuitry (30) includes a phase detector (44) which is coupled to a common node (VCOCLK) at which outputs of the voltage-controlled oscillators (26, 28) are coupled; the phase detector (44) compares the phase of this signal (VCODIV) to a reference signal (REFDIV) based on a reference clock (REFCLK), and controls a charge pump (46) accordingly.

Abstract: Parasitic feedback is prevented in a transmitter, a modulator, or a demodulator from having an interfering influence on the circuit section that generates the mixed frequency. The circuit has a main oscillator and a subordinate oscillator connected downstream of the main oscillator. The main oscillator generates a signal having an x.sup.th harmonic that serves to excite the subordinate oscillator. Furthermore, a frequency divider is connected downstream of the subordinate oscillator. The frequency divider divides the frequency of an output signal of the subordinate oscillator by an integer divider value. The divider value differs from the value x.

Abstract: A dual band radio receiver is provided. The dual band radio receiver includes a local oscillator configured to generate a local oscillator (LO) signal. The dual band radio receiver also includes first and second mixer devices. The first mixer device is configured to receive the LO signal and an RF signal included within a first band. Responsive to these signals, the first mixer device outputs a first IF signal. The second mixer device is configured to receive the LO signal and a second RF signal included within a second band. In response to these signals the second mixer device outputs a second IF signal. The local oscillator is configured to operate within a third band located between the first and second bands.

Abstract: A stabilized oscillator circuit is provided with a differential amplifier type oscillator circuit for generating an oscillation signal, and a differential amplifier type buffer output circuit for amplifying and outputting the oscillation signal. The stabilized oscillator is also provided with a frequency variation stabilizing circuit. This circuit controls the amount of current of the constant current source I2 of the buffer output circuit, in accordance with fluctuations of the power supply voltage applied to the oscillator circuit. Accordingly, the collector-base capacitance of the transistors of the buffer output circuit is controlled, and the oscillation frequency variations are suppressed in spite of fluctuations of the power supply voltage.

Abstract: A receiver, especially useful for MMIC semiconductor communications circuits, in which plural mixers replace LRC filter networks to produce notched bandwidth filters. In a preferred embodiment, the input signal and a the output of a variable oscillator are mixed to produce a beat frequency. As an operator changes the desired frequency notch of the receiver, the output frequency of variable oscillator similarly changes to ensure that the beat frequency is the same regardless of desired frequency. Circuity downstream may be thus fixed, eliminating the need for large variable capacitors, which MMIC technology cannot fabricate in desirably small sizes.

Abstract: A communication system is provided for increasing communication range between at least two radio communication devices without increasing the output power of transmitted radio signals from the devices, and without increasing the antenna gain of the received signals. Each radio device includes an oscillator for generating a carrier reference signal, and an SATPS receiver which receives at least one standard timing reference signal from at least one SATPS satellite. The received standard timing reference signal is used to continuously adjust the timing and synchronization of the oscillator to improve the accuracy of the carrier frequency signal. The improved accuracy in the carrier frequency signal may then be used to reduce the bandwidth of the modulated carrier frequency signals generated by the radio device to thereby increase the effective communication range and sensitivity of the device.

Abstract: A method and apparatus for controlling frequency synchronization in a frequency correction feedback loop of a radio telephone. A processor in a frequency update controller ascertains increment/decrement values pro-proportionally related to confidence levels representing a ratio that a likelihood probability of estimated offset frequecies of an input carrier signal are accurate in proportion to a likelihood probability that the estimated offset frequencies are inaccurate. The processor adds or subtracts the value to a counter depending on its sign. When the counter reaches a certain predefined positive number, the counter is decremented by this number and the processor increases the frequency of a reference oscillator frequency. When the counter reaches a certain predefined negative number, the counter is incremented by the absolute value of the negative number and the processor decreases the frequency of the reference oscillator frequency.

Abstract: Disclosed is a channelized multi-carrier signal processor capable of equalizing power levels of individual carriers of a multi-carrier signal to within a predetermined dynamic range. In one embodiment, the signal processor includes a power splitter for splitting a multi-carrier input signal into a plurality of electrical paths. In each electrical path there resides a signal modifier that is operable to isolate signal energy associated with a given carrier of the multi-carrier signal. Each signal modifier includes an automatic gain control (AGC) circuit to control the power level of the carrier isolated therein to within a predetermined power level window so that the isolated carriers of each signal modifier are equalized in power. A power combiner then combines the equalized carriers to produce a multi-carrier output signal, which can be applied to a limited dynamic range device such as an A/D converter.

Abstract: A method of calibrating a radio receiver (100) which has a desired IF center frequency (fo) includes generating and applying to the receiver's demodulator (126) a plurality of reference signals. The demodulated reference signals are used to generate, for the demodulator, a transfer function that is predictive of amplitude versus frequency characteristics of signals to be demodulated by the demodulator (126). The transfer function (202) is used to determine a frequency offset between a received signal's intermediate frequency and the desired frequency fo. The determined frequency offset is used to adjust the IF frequency of the received signal towards the desired frequency fo. The adjustment process preferably continues until the frequency offset is below a desired threshold. A receiver using the disclosed method is also described.

Abstract: In a selective radio paging receiver, power supply for a local oscillator portion which has the longest period to take up to normal operation from on-set of power supply is performed with an elevated voltage higher than the battery voltage in the normal operation to shorten the take-up period. Subsequently, the battery voltage is supplied to the local oscillator portion together with the radio reception portion, wave shaper circuit and so forth. Therefore, power supply for the radio reception portion and the wave shaper circuit can be delayed to shorten the overall power supply period to improve battery saving effect.

Abstract: A first AFC apparatus receives and detects I and Q signals from a received first FSK signal with a local osc signal; demodulates the I and Q signals; F/V-converts I or/and Q signals into a voltage; compares it with a reference; and detects a frequency deviation direction of the local osc signal from the carrier signal according to the results of comparing and the demodulating. The local osc frequency is controlled by a given amount according to the result of the frequency deviation direction detection. A second AFC apparatus receives and detects I and Q signals using a first osc signal; FSK-modulates the I and Q signals with a second local osc signal having a lower frequency than the first local osc signal; and compares the frequency of the second FSK signal and the second local osc signal to supply a demodulation result. A frequency control for the first local osc signal is obtained by an averaging circuit averaging the modulation result.

Abstract: A wide-band receiving apparatus used in an FM-FDM type optical image distributing system for transmitting multi-wave and multiple TV signals comprises a circuit for receiving a wide-band input signal containing modified RF signals of two or more different frequency bands and separating the RF signals by the bands; respectively, a first circuit for selecting one of the separated RF signals; a local oscillating circuit for generating a first oscillating signal of a fundamental frequency which is determined based on the frequency range of the selected RF signal; a circuit for producing at least one oscillating signal of a frequency having a predetermined ratio to the fundamental frequency; a second selecting circuit for selecting one of the first oscillating signal and at least one second oscillating signal; a circuit for mixing the selected RF signal with the selected oscillating signal thereby producing an intermediate-frequency signal; and a circuit for demodulating the intermediate-frequency signal.

Abstract: An improved synchronous tracking AM receiver having low power requirements and a small size. The synchronous tracking AM receiver provides signal tracking capability and sensitivity approaching a conventional superhetrodyne receiver. The synchronous tracking AM receiver includes an RF amplifier synchronous input section which couples input signals to a synchronization filter circuit, including a modified Colpitts oscillator. The Colpitts oscillator recycles the signal to generate a high Q output signal. The output signal of the synchronization circuit is coupled to a low pass filter, then amplified by a low frequency amplifier and triggered to produce a digital output signal.

Abstract: A current controlled variable frequency oscillator (260) operates at a characteristic frequency that is determined primarily by a scaled current. A filter cascade (320) receives the scaled current for setting a filter cascade frequency substantially equal to the characteristic frequency. Additionally, the filter cascade (320) receives a triangular signal at a non-inverting input, the filter cascade (320) converting the triangular signal into a sinewave signal. A lowpass filter (330) receives the scaled current for setting a lowpass filter frequency to a frequency substantially less than the characteristic frequency. The lowpass filter (330) also receives the sinewave signal and provides an average signal therefrom. A comparator (340) receives the scaled current, wherein the comparator (340) compares the sinewave signal and the average signal for providing a substantially squarewave signal therefrom.