Abstract: A satellite navigation receiver uses common dual-conversion superheterodyne and frequency synthesizer circuitry for receiving signals from both the GPS and the GLONASS satellite navigation systems. Successive first and second frequency down-converters in the receiver chain are fed by first and second local oscillator signals which are both variable in frequency such that the frequency of the first local oscillator signal is an integral multiple (preferably 8) of the second local oscillator signal. This relationship is provided by a binary divider (32) at least a portion of which may form part of a digital frequency synthesizer loop.

Abstract: A transmitter/receiver has a superheterodyne receiver, a transmitter, a local oscillation signal generating section for transmission, a first and a second local oscillation signal generating section for reception, and a fixed frequency divider. A reference signal fed from the outside of the transmitter/receiver is applied to the second reception local oscillation signal generating section having a low loop gain. The output of the second reception local oscillation signal generating section is applied to the fixed frequency divider as well as to the receiver. The resulting output of the fixed frequency divider is fed as a reference signal meant for the transmission local oscillation signal generating section and first reception local oscillation signal generating section. The transmitter/receiver prevents the modulation accuracy of a signal to be transmitted and reception sensitivity from being degraded even when the reference signal introduced from the outside involves noise.

Abstract: A GPS receiver downconverter combines on a single integrated circuit, a first super-heterodyne mixer, a voltage controlled oscillator, a phase locked loop, a pair of quadrature mixers and a pair of quantizers with in-phase and quadrature-phase sampler outputs operable at twenty-five MHz and 2.5 MHz. Emitter-coupled logic and special low-voltage bipolar semiconductor technology are combined for 3.3 volt operation at under one hundred milliwatts.

Abstract: A dual mode portable digital radio transceiver for communicating via a terrestrial network (first mode) and via a satellite network (second mode) synthesizes a modulation first frequency for modulation of signals transmitted in both modes and a conversion second frequency for demodulation of signals received in the two modes. It divides the conversion second frequency supplying a conversion third frequency for demodulation of signals received in one of the modes using a signal receive frequency band far away from the other frequency bands used. It is therefore possible, using a single synthesized pure carrier, to carry out direct conversion in a first mode and intermediate frequency conversion followed by the same direct conversion in the second mode.

Abstract: An FM receiver includes an RF section, a first mixer stage for converting a desired RF reception signal into a first IF signal having a carrier frequency located on average at a first intermediate frequency, a first IF section for selecting the first IF signal, and a second mixer stage for converting the first IF signal into a second IF signal having a carrier frequency located on average at a second intermediate frequency. The second intermediate frequency is below the first intermediate frequency. A second IF section selects the second IF signal and is coupled to an FM demodulator for demodulating the baseband modulation signal of the desired RF reception signal, followed by a low-pass filter for selecting the baseband modulation signal.

Abstract: A wideband RF-to-IF frequency converter providing multiple use of frequency conversion components for many different types of RF input signals. In specific examples, many different types of signals for communication, navigation, and for interrogation are processed through at least partly common frequency-conversion channels. Such RF input signals in the range from approximately 2 MHz to 2,000 MHz are converted to output IF frequencies, such as 1 MHz and 30 MHz, for further processing in the common receiver. Some narrow band signals, after conversion to IF, are subjected to off-center filtering in relatively broadband IF filters. Input RF filters are not used. Among several frequency conversion stages, only one of the local oscillator signals is tunable; but it is made tunable in relatively small, precise steps by using a double phase-locked loop arrangement in the frequency synthesizer.

Abstract: A method of receiving a data signal in a radio transceiver by passing an input receive signal through an input bandpass filter having a bandwidth sufficient to reject signals with frequencies equal to or greater than the receive signal frequency plus a first intermediate frequency (IF) signal frequency plus a first standard IF signal frequency and also to reject signals with frequencies less than the receive signal frequency minus twice the first IF frequency, and downconverting the input filter filtered input receive signal by the transmit frequency to produce the first IF signal. The first IF signal is filtered in an LC filter, and the filtered first IF signal is mixed with a local oscillator signal having a difference frequency therefrom which is equal to the first standard IF frequency to produce the first standard IF signal.

Abstract: A method and device for canceling frequency offsets in received modulated signals. The frequency offset cancellation device includes a downconverter module, a channel unit and a control module. The downconverter module shifts received signals to a lower frequency. The channel unit searches the shifted received signals and demodulates them, and the control module adjusts the downconverter in accordance with frequency offset information generated by the channel unit, thereby continuously cancelling out any frequency offsets that may have occurred during frequency shifting.

Abstract: An FM receiver comprising a local oscillator (23), a heterodyning stage (24) and a demodulator stage (33). The heterodyning stage has a signal producing arrangement and a multiplier arrangement. The signal producing arrangement (25,26,27,29,30,31,32) produces n signals a.sub.1 . . . a.sub.n wherein each signal consists of a message signal modulated at the intermediate frequency of the receiver, and these signals a.sub.1 . . . a.sub.n are related by the expressiona.sub.i =cos [.omega..sub.IF t+k.sub.f .intg..sup.t A(t)*dt+.OMEGA.+.pi.*(.sup.i /n)]where .omega..sub.IF, k.sub.f and .OMEGA. are constants, n is a positive integer greater than or equal to 2 and i takes the values of all positive integers up to and including n. The multiplier arrangement (28) multiplies the n signals together and thus produces an output signal from the heterodyning stage, wherein the message signal is modulated at a frequency of n times the intermediate frequency.

Abstract: In an earth-based receiving station for receiving radio signals transmitted from a satellite relay station, a common first frequency converter and at least two receivers are provided. One of the receivers is used as a control receiver to receive a CSC carrier frequency transmitted from the satellite, to generate a first local oscillator frequency phase-locked to the CSC carrier frequency, and to supply the first local oscillator frequency to the common first frequency converter. Other receivers are used as channel receivers for receiving channel frequencies. In case when the control receiver is in trouble, any other receiver can be used as a control receiver.

Abstract: The invention provides a frequency offset dealing modulator and demodulator apparatus which modulates and demodulates transmission/reception data and is improved in that it can reproduce an accurate impulse when data are transmitted. The modulator and demodulator apparatus includes a modulator for modulating data, and a demodulator for demodulating a receive signal to reproduce such data. The demodulator includes a demodulation processing unit, a roll-off filter, a receive level adjustment unit, an equalizer, a carrier frequency offset removing correction signal generation unit, a normalizer, a multiplier and a sum calculation unit.

Abstract: A radio receiver front end having both feedforward and feedback mechanisms to suppress the amplitude of spurious signals so as to prevent those signals from flooding the dynamic range of the mixer of the front end. An illustrative embodiment of the present invention comprises splitting the input signal into a first signal and a second signal, creating a third signal based on the difference of the first signal and a difference signal, mixing down the third signal with a first oscillatory signal, isolating a feedback signal from the mixed down signal, mixing up the feedback signal with a second oscillatory signal and creating the difference signal based on the difference of the second signal and the mixed up signal.

Abstract: A radio frequency millimeter-wave signal antenna and mixer system includes a dielectric substrate having a generally planar upper surface, and a ground-plane layer of conductive material disposed below the upper surface. This ground plane layer includes a plurality of spaced-apart low conductivity sections or windows to allow passage therethrough of radio frequency signals received at a surface of the substrate. A plurality of antennae are disposed on the upper surface of the substrate, with each antenna being positioned over a respective one of the windows in the ground-plane layer. A plurality of mixers are also disposed on the upper surface of the substrate, each adjacent a respective antenna for receiving radio frequency signals therefrom and for producing intermediate frequency signals.

Abstract: A dual-mode radiotelephone terminal includes a .pi./4-shift DQPSK modulator (11). A dual-mode modulation is achieved by mixing an output of a transmitter oscillator (16) with an output of an offset oscillator (18) to form an injection signal (LO) at a final transmitter frequency, the injection signal being further modulated with a quadrature modulator in a digital mode of operation. In an analog mode of operation the transmitter oscillator or the offset oscillator is frequency modulated and the quadrature modulator is disabled, thereby passing the frequency modulated injection signal without substantial attenuation. The LO signal is regenerated and also phase shifted with a circuit (35) having a frequency multiplier (30) and a frequency divider (34). The circuit outputs two local oscillator (LO) signals (LOA and LOB), each of which directly drives an associated quadrature mixer (36, 38) of the modulator.

Abstract: The present invention relates to a television tuner capable of receiving television broadcasting, CATV and satellite broadcasting. The television tuner includes a double superheterodyne tuner for receiving television signals, having an up-converter, a down-converter and a coupler for coupling the up-converter and down-converter, and the television tuner also includes a BS second mixer portion and a FM demodulator, for receiving signals from a broadcasting satellite. The double superheterodyne tuner, the BS second mixer portion and the FM demodulator are disposed in a housing, a combination of the up-converter and the BS second mixer portion is desiredly separated from the down-converter, the coupler is disposed in a space between the combination and the down-converter, and the FM demodulator is disposed in the remaining space of the housing.

Abstract: An embodiment of the present invention is a single-chip GPS receiver front-end comprising a radio frequency amplifier, a voltage-controlled oscillator operating at a first local oscillator frequency, a divide by seven and one-half counter for deriving a second local oscillator frequency from the first and a first and second mixer. The local oscillator frequency is mid-way between two carrier frequencies of interest that may be received by the radio frequency amplifier and the first mixer produces a first intermediate frequency. The second local oscillator frequency is then beat with the first intermediate frequency in the second mixer to produce a second intermediate frequency. A dual-conversion super heterodyne configuration is therefore employed in which the first and second local oscillator frequencies are derived from a single oscillator and the first local oscillator frequency is seven and one-half times the second local oscillator frequency.

Abstract: A mixer system for a direct conversion receiver, the receiver including an RF input path which is divided into I and Q paths for demodulating from the RF signals I and Q signals in phase quadrature with one another, the mixer system including first and second serially coupled mixer means in the I path, third and fourth serially coupled mixer means in the Q path, and a local oscillator providing a plurality of local oscillator signals in phase quadrature with one another to the mixer means, such that the first mixer means receives a local oscillator signal in phase quadrature to the local oscillator signal applied to the second mixer means, and the third mixer means receives a local oscillator in phase quadrature to that applied to the fourth mixer means.

Abstract: Two variable frequency, fixed bandwidth bandpass 10, 410 are cascaded to form a bandpass filter with variable center frequency and variable bandpass. Each filter 10, 410 includes first (16, 416) and second (24, 424) mixers separated by a fixed bandpass filter (20, 420). Each mixer includes a control input terminal 30, 32: 430, 432 which receives a control signal (f.sub.LO, f.sub.OFF). The center frequency of the filter arrangement is controlled by the frequency of control signal f.sub.LO, and the bandwidth is controlled by the difference frequency between f.sub.LO and f.sub.OFF. A tracking arrangement 456 allows direct control of the bandpass by control of the frequency of an offset oscillator 458.

Abstract: A receiver array in accordance with the reception principle of synchronous demodulation, in which a controllable oscillator array is pre-synchronized to a set value for the oscillator frequency by a digital first control circuit having a reference frequency source during a pre-synchronization phase, and a heterodyne signal derived from the oscillator frequency is then synchronized with phase locking to the received useful signal by switching the oscillator control input to an analog second control circuit.

Abstract: A method and apparatus for generation of high frequency pulses and for excitation of nuclear magnetic resonance of a sample generates a plurality of modurated high frequency waves having different frequencies from each other, and combines the generated these high frequency waves so as to generate high frequency pulses which provide a frequency spectrum having a predetermined band, thereby a shortening of the high frequency pulse width as well as a narrowing of the frequency band is achieved.

Abstract: A heterodyning lock-in amplifier in which the reference signal is shifted up in frequency (as in prior art designs), but then shifted back down in frequency prior to mixing with the input signal.

Abstract: This invention relates to an automatic tuning method and apparatus in which tuning voltage corresponding to picture/sound carrier wave difference of channel selected by double conversion tuner is transmitted to voltage control oscillator to thereby be re-tuned so that input filter inseting loss according to said picture/sound carrier wave is minimized, which is characterized by comprising automatic tuning device comprising, phase locked loop PLL circuit for controlling oscillation signal of local oscillator of tuning circuit, video intermediate frequency VIF producing circuit which receives output signal of said tuning circuit whereby outputting RF automatic gain control AGC signal and IF automatic gain control signal, and automatic tuning means which receives two output signals from said video intermediate frequency producing circuit whereby controlling band pass filter signal of the tuning circuit.

Abstract: A system for suppressing spurious product signals and radiation resulting from the leakage of local oscillator signal energy in superheterodyne radio receivers. The system includes a 0.degree. signal splitter, a 180.degree. signal splitter, a pair of mixers and a 180.degree. signal combiner. The splitters split the communications input signal and local oscillator signal into signal components which are mixed together in the mixers to form intermediate frequency components which are combined in the combiner.

Abstract: An apparatus for a transmission-reception simulation test between a transmitter and a receiver located in the same station includes a testing device coupled to the transmitter and the receiver. The testing device includes, a first frequency converter for microwave frequency to microwave frequency conversion for producing a mixed signal of the output signal of a transmitter having a frequency f.sub.rf1 and a second local oscillator signal having a frequency f.sub.l2, a low-pass filter, and a second frequency converter for intermediate frequency to microwave frequency conversion for producing a mixed signal of the output signal of the low-pass filter and a first local oscillator signal having a frequency f.sub.l1, the output signal of the second frequency converter having a frequency f.sub.rf2 being supplied to a receiver.

Abstract: An antenna is employed to receive a (1540 f0) L1 GPS-satellite signal. In addition, a filter, an (RF) amplifier, a harmonic mixer, and a (sole) local oscillator are employed, the combination configured to mix the seventh harmonic of a 192 f0 local oscillator generated signal with the receive satellite signal to down-convert the frequency of the received GPS-satellite signal to a 196 f0 IF frequency. Further, another filter, an (IP) amplifier, and a mixer are employed, the combination configured to mix the fundamental of the 192 f0 local oscillator generated signal with the 196 f0 GPS-satellite signal to down-convert the frequency of the satellite signal to four f0. Finally, yet another filter and an amplifier are employed, the combination configured to filter and amplify the four f0 GPS-satellite signal.

Abstract: An improved proximal cable-less communications system using at least two receivers is described. The system is significantly improved by eliminating the sidetone which can occur in full duplex systems. Components are placed in the receivers, between the mixer components and the components which detect the information encoded in the signal at the intermediate frequency, which function to cancel out the detrimental affect of those signals containing information derived from the modulation of the local oscillator of the receiver device.

Abstract: A method and circuit for automatically controlling the frequency of a radio telephone. According to this method, the frequency of the signal detected at the receiver of a radio telephone is mixed with the output frequency of a phase-locked loop in a first mixer. The output frequency of the first mixer is mixed in a second mixer with the frequency derived from a local oscillator. The frequency of the phase-locked loop is controlled on the basis of the frequency deviation of the output frequency of the second mixer. This frequency deviation can be determined by counting the pulses generated by the second mixer during a predetermined time interval, the time interval being equal to the amount of time which elapses when a specified number of pulses generated by the local oscillator is counted. The reference frequency of the phase-locked loop is derived from the frequency of the local oscillator.

Abstract: A balanced mixer and output filter for television receivers and the like is presented. The mixer is followed by a fairly selective bandpass filter to protect the IF amplifiers from first and second adjacent channel signals.

Abstract: A mobile communication transceiver includes a controller. The controller includes an A/D converter, a memory, and a CPU. The A/D converter converts an output voltage corresponding to a reception input voltage from the receiver into a digital signal. The memory stores a plurality of predetermined data for determining a speech enable electric field level and a plurality of predetermined data for determining a high electric field level. The CPU determines a speech enable electric field level by comparing the digital signal from the A/D converter with the data stored in the memory. The CPU compares the digital signal supplied from the A/D converter through an interface with the high electric field level determination data stored in the memory when the high electric field level is determined. The CPU selects a determination level of the speech enable electric field level from the plurality of data stored in the memory.

Abstract: A carrier is received containing a plurality of signals within a first frequency band, for example television signals within the cable television band. The signals are upconverted to a second frequency band above the first band wherein a selected one of the upconverted signals will reside at an intermediate frequency within the second band. The selected upconverted signal is input to a homodyne detector operating at or near intermediate frequency. In-phase and quadrature signals output from the homodyne detector are digitally processed to recover a baseband signal.

Abstract: A frequency diversity receiver system operating over a predetermined bandwidth comprising a first mixer receiving two identical information signals widely separated in frequency, a stepping oscillator with a predetermined number of steps controlling the output frequency of said mixer, two frequency channels at the output of said mixer, the first of said channels having a broad bandwidth filter and the second having a narrow bandwidth filter, a second mixer receiving simultaneously the output of said second filter and the output signal of a sweeping oscillator, said sweeping oscillator having a preselected sweep, means to synchronize said sweeping oscillator and said stepping oscillator, a multiplier simultaneously receiving the output signals from said first filter and said second mixer, a bank of parallel filters and associated detectors receiving the output signals from said multiplier, each of said filters of said bank having a predetermined bandwidth.

Abstract: A frequency difference detector (FDD) implemented as a balanced quadricorrelator has an automatic gain control system (68) having inputs capacitively coupled to the quadrature related, baseband frequency paths from the front end mixers (12,14). The a.g.c. system (68) has quadrature related mixers (78,80) coupled to said inputs for frequency up-converting the baseband signals to an intermediate frequency. The IF signals from the mixers are summed in a summing circuit (82) and subsequently squared in a squaring circuit (86). Any ripple in the output of the squaring circuit is removed by low pass filtering to produce a d.c. control signal which is applied to gain controlled amplifiers (22,24) present in said baseband frequency paths in order to render the output (V.sub.o) of the FDD less sensitive to variations in the input signal (V.sub.i).

Abstract: A divider circuit arrangement in which in order to avoid dividing by zero the divisor (V.sub.d) is modified by the addition of an extra signal (X.sub.a) to form a modified divisor V'.sub.d =V.sub.d +X.sub.a and the dividend (V.sub.i) is modified by the addition of the product of the quotient (V.sub.o) and the extra signal (X.sub.a) to form a modified dividend V'.sub.i =V.sub.i +V.sub.o X.sub.a. A particular but not exclusive application of this divider circuit arrangement is in normalizing an ouptut signal from a dual branch receiver (not shown).

Abstract: Local frequency which is subject to fluctuate in a mobile subscriber set is locked to stable transmit frequency of a base station. A mobile subscriber set (FIG. 3) for angle modulated signal has a frequency mixer (3.6, 3.9), for converting wireless receive frequency to an intermediate frequency by using local frequency (F.sub.L1, F.sub.L2), a limiter (3.11) for limiting amplitude of intermediate frequency signal, a discriminator (3.12) for demodulating angle modulated signal, a standard oscillator (3.1) by using a quartz crystal oscillator and a synthesizer (64) for providing local frequency for said mixer (3.6), a digital frequency counter (3.14) for measuring intermediate frequency, and control means (3.16) for adjusting said standard oscillator (3.1) depending upon error of intermediate frequency measured by said counter (3.14).

Abstract: A frequency dividing arrangement comprises an injection-locked divider arranged for receiving an incoming signal F.sub.in and for providing a frequency divided signal F.sub.out in response thereto, and a frequency divider coupled to the injection-locked divider. The frequency divider comprises logical circuits for providing a further frequency divided signalF".sub.out in response to the frequency divided signal F.sub.out provided by the injection-locked divider. The arrangement may be included in a frequency modulation receiver which comprises an FM detector. The injection-locked divider comprises a multiplier, and a tuning circuit.

Abstract: A frequency synthesizer has in series a digital synthesizer, mix and divide circuits, and a mix only circuit. Each mix and divide circuit includes a mixer having an IF input, a LO input and a RF output, a filter, and a frequency divider. A segment of a digital word selects a tone from a tone generator and also selects a passband of the filter. The selected tone is coupled to the LO input of the mixer. The frequency divider divides the filtered RF output of the mixer. The mix only circuit is at the output of the last of the series connected mix and divide circuits. The mix only circuit is similar to a mix and divide circuit, but does not have a frequency divider. The digital synthesizer provides a signal to the input of the first of the series connected mix and divide circuits, the frequency of which corresponds to a segment of a digital word. The filter is preferably a voltage tunable bandpass filter.

Abstract: A split band filtering scheme to reduce adjacent band interference in a communications network, such as a cellular mobile radio system, is disclosed. A repeater, interposed between a base or cell site and a mobile/portable radio, includes a down converter for converting a system operating frequency to a lower frequency signal. The lower frequency signal represents a communications band. The signal is presented to a split band filter having a narrow passband with steep skirts. The processed signal is coupled to an up converter where it is restored to the system operating frequency. In this way, the passband of the repeater is restricted to that of the desired communications band and adjacent band interference is reduced or eliminated.

Abstract: An IF system that makes satisfactory use of a first IF stage frequency selected from between 108 MHz and 132 MHz to thereby provide an IF system that can be utilized in radios intended for reception in all land mobile frequency bands. The first IF stage (17) includes a high tolerance crystal filter (24) that contributes to the satisfactory reception performance of a radio so equipped.

Abstract: A working on the zero IF principle is disclosed which contains a feedback circuit instead of a preselector for suppressing interfering signals. The interfering signals contained in the incoming signal (F.sub.E) are separated from the useful signal by filters in the baseband. They are then reconverted to the RF value, amplified, and substracted from the incoming signal (F.sub.E) by a subtracter (S1). In the steady state, the output of the subtracter (S1) provides the useful signal, which is converted into the baseband and then fed to a signal processor (SV).

Abstract: A TVRO receiver for receiving frequency-modulated video signals, the receiver comprising a tuner including a superheterodyne circuit having a voltage-controlled oscillator (VCO), means for supplying a controlling input voltage to the VCO, and a mixer for combining incoming 1st IF signals with the output of the VCO to reduce the frequency of the 1st IF signals to a 2nd IF frequency which is sufficiently high to permit the output frequency of the VCO to be above the frequency range of the 1st IF signals, and a linear phase passband filter for passing a single video channel in the 2nd IF output from the mixer, the filter producing an output which is at least about 10 dB down from its peak at both +10 MHz and -10 MHz from the center of the passband of the filter.

Abstract: A digital television signal deghosting system includes an IIR filter responsive to the in-phase and quadrature-phase components of modulated television signals for cancelling ghost signals irrespective of their phase. A double-conversion tuner develops modulated composite video signals having a 3f.sub.c carrier frequency. An analog-to-digital converter responsive to a two-phase 3f.sub.c clock signal develops digital samples which alternately represent the baseband in-phase and quadrature-phase components of the modulated video signals. These samples are separated to develop digital signals representing the in-phase and quadrature-phase components of the modulated television signals.

Abstract: A radio receiver from antenna to detector designed to be realized substantially on an integrated-circuit chip comprises a single tunable oscillator and a plurality of mixers. An input signal from an antenna is connected as an input to a first mixer and mixed with a signal derived from the oscillator. The signal may be taken directly, may be multiplied to a desired level or may be divided to a desired level. A particular output from the first mixer is selected by a first tunable filter. The output of the first tunable filter is taken as an input to a second mixer where it is mixed with a second signal derived from the oscillator. The process of mixing and application of the mixed signal to a tunable filter to select a desired frequency is continued as needed until the signal is reduced to a desired intermediate frequency range where it is amplified as needed to a level sufficient to drive a discriminator.

Abstract: A radio receiver is disclosed in which a received signal is amplified, filtered, and then sampled at a rate determined by a clock signal produced by a selectable-rate, digital oscillator. In sampling the received signal, a family of harmonics are generated which are distributed in a pattern determined by the sampling rate. One harmonic is selected as an intermediate frequency signal and, like the received signal, it is amplified, filtered, and sampled. The second sampling process is driven by a second clock signal produced by a variable-rate, digital oscillator. This produces a second family of harmonics which are derived from the intermediate frequency signal. The second clock signal rate is selected to produce one harmonic which has a carrier component centered on zero frequency. This harmonic, which is the desired baseband signal, is separated from the other harmonics by means of a low-pass filter.

Abstract: A frequency standard is operable to provide an output signal at a frequency which is directly proportional to the frequency of a received radio frequency signal. The frequency standard circuit contains a mixer which generates an intermediate frequency signal from the radio frequency signal and a local oscillator signal. The frequencies of the local oscillator and the amplified intermediate frequency signals are multiplied or divided by the same factor and then combined in another mixer to obtain an output signal having a frequency directly proportional to that of the received radio frequency signal.