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7557671 |
Real time VCO gain non linearity calibration
A method of determining a gain nonlinearity receives a phase difference and generates an output frequency based on the received phase difference. The method reconstructs a waveform by using the...
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7343139 |
Device for converting frequencies, method of calibrating said device and system for transmitting/receiving electromagnetic signals comprising such a device
The invention relates to a device for converting frequencies comprising a local oscillator of fixed frequency and a first mixer with two inputs and an output, a first input receiving the signal to...
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7230981 |
Integrated data jitter generator for the testing of high-speed serial interfaces
An integrated data jitter generator for the testing of high speed serial interfaces is provided. A transmit timing generator for use in a transmit data path includes a high frequency clock...
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6970052 |
Modulator immune from temperature variation-induced change in modulation factor
A modulation factor is kept immune from the influence of temperature variation. A modulator is provided with an operational amplifier to one of whose input ends are inputted video signals and to...
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6907085 |
Activation method of communications apparatus with a non-linear distortion compensation device
First, a digital section constituting a linearizer is activated. Then, a feedback loop for updating a distortion compensation coefficient is opened. Then, the analog section on the antenna side is...
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6879218 |
Frequency modulation corrector keeping a good oscillating signal quality and suppressing dependability of a modulation degree
A correction circuit for a voltage-controlled oscillator (VCO) is arranged outwardly of the voltage-controlled oscillator. The oscillation of the selected frequency and the frequency modulation are...
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6771708 |
Nonlinear compensator
A nonlinear compensator comprising a signal processing section, a distortion detecting section, and a distortion correcting section. The signal processing section detects the time difference and...
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6400415 |
System and method for predistorting signals to be amplified
A system and method for predistorting a signal which is to be amplified by a non-linear amplifier. The system and method uses additional predistortion circuits to eliminate the predistortion caused...
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6373902 |
Device and method for linearizing transmitter in digital communication system
A device for linearizing a transmitter in a digital radio communication system. In the device, a predistortion lookup table stores predistortion data determined by measuring in advance distortion...
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6353370 |
Method and apparatus for modulation of a voltage controlled oscillator
A method and apparatus for modulation of a voltage-controlled oscillator (VCO). The VCO receives a tuning control voltage for adjusting a center frequency of an output periodic signal formed by the...
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6034573 |
Method and apparatus for calibrating modulation sensitivity
A method and apparatus for continuously calibrating the modulation sensitivity of a voltage controlled oscillator (VCO) within a modulator of a transmitter. In accordance with the present...
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5796782 |
Digital modulator with Root-Nyquist filter
A digital modulator having a pulse shaping filter which generates and accumulates impulse responses including prior impulse responses and posterior impulse responses to perform a Root-Nyquist...
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5638404 |
Pre-compensated frequency modulation (PFM)
A system for transmitting FM signals comprised of apparatus for receiving an input data signal, apparatus for precompensating the received data signal, apparatus for applying the precompensated...
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5633893 |
Digital modulation method with controlled envelope variation
Continuous phase modulated (CPM) signals, such as quaternary CPFSK signals, are filtered to limit their bandwidth while simultaneously minimizing the amount of amplitude modulation and intersymbol...
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5600279 |
VCO having adjustment for fluctuations in relation between control voltage and output frequency
A VCO circuit has a voltage variable capacitance CVD2 connected in series with or in parallel to a condenser C3 connected in series with an inductance L1, which constitutes a resonator of the VCO...
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5592132 |
Frequency modulator comprising an adjusting circuit
In a frequency modulator (1) having an adjusting circuit by which frequency modulator an applied luminance signal of a color video signal that contains synchronization pulses is frequency...
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5535247 |
Frequency modifier for a transmitter
A transmitter has an oscillator (101, 201, 303, 401, 501) that operates at frequency k multiplied by f c , thus the oscillator (101, 201, 303, 401, 501) outputs a signal at an output frequency, kf...
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5515013 |
Fixed compromise equalization for a dual port FM modulator
A dual port frequency modulator and method for eliminating the undesired affects caused by high port/low port phase differences in a standard dual port frequency modulator. The frequency modulator...
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5404378 |
Distortion compensating circuit
In a distortion compensating circuit, an initial value sufficient to provide a distortion compensating effect is previously set in a memory storage for storing distortion compensating data, whereby...
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5357222 |
Voltage controlled component including a capacitive diode biased to operate in the linear region
The invention relates to a biased electronic circuit in which a voltage-controlled component has a characteristic with a non-linear portion and a substantially linear portion. The circuit is biased...
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5339054 |
Modulated signal transmission system compensated for nonlinear and linear distortion
In a modulated signal transmission system operable in response to an input digital signal of a baseband to produce a modulated signal through a nonlinear amplifier, a nonlinear converter is...
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5151668 |
FM modulator for compensating modulation characteristics on each channel
A frequency-modulation modulator in a cellular wireless telephone for modulating frequency after uniformly and linearly compensating for frequency characteristics to be suitable for each engaged...
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5126699 |
Digitally compensated modulation system for frequency synthesizers
A digitally compensated modulation system for frequency synthesizers has a single modulation input line with flat frequency response to zero hertz. The above is accomplished while eliminating...
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5107520 |
Adaptive predistortion circuit for a digital transmission system
An adaptive predistortion circuit for a digital transmission system includes a predistortion circuit (52 1 , 52 2 , 52 3 ) for predistorting the input data before they pass through a modulator (56)...
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5091705 |
FM modulator
A modulation signal is digitally integrated by an integration circuit and then phase-modulated by a phase modulating circuit. The integrated modulation signal is converted in phase modulating...
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4952888 |
Phase locked loop for direct modulation
A PLL for direct modulation having a flat modulation characteristic in the audio frequency range is described. The PLL for the direct modulation comprises a voltage controlled oscillator whose...
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4942374 |
Phase-locked loop type synthesizer having modulation function
In a phase-locked loop type synthesizer comprising a phase-locked loop which comprises a phase comparator, a loop filter, a voltage controlled oscillator having a gain Kv, and a circuit for feeding...
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4926144 |
Multi-function modulation and center frequency control port for voltage controlled oscillator
A circuit for use in conjunction with a voltage controlled oscillator (VCO). The circuit introduces modulation into a radio system (to create a substantially flat frequency response) at the same...
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4816781 |
FM modulator
Circuitry for producing an extremely linear frequency modulated audio carrier for use in the head end of a video signal distribution system, such as a cable television system. A reference...
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4675618 |
Linearizer circuit for frequency modulation oscillator
A system for frequency modulation by a signal, the system including an oscillator having a known linearity distortion, a circuit for selecting one from a plurality of predetermined constants, a...
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4633197 |
Single resonant tank modulated oscillator
A modulatable oscillator for radio frequencies is disclosed in which the single resonant tank includes a tightly coupled varactor diode for wideband modulation and frequency control. Nonlinearities...
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4630008 |
Direct FM crystal-controlled oscillator
A direct frequency modulation crystal-controlled oscillator circuit is provided having a configuration which minimizes the number of parts required for modulation while maintaining a linear...
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4595888 |
Pre-distortion shaping network
A pre-distortion shaping network employing a field effect transistor as one leg of a resistive voltage divider for shaping the modulating signal of a voltage controlled oscillator is described.
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4573026 |
FM Modulator phase-locked loop with FM calibration
Apparatus to provide calibrated frequency modulation (FM) of frequencies generated in a phase-locked loop is disclosed. A phase-locked loop (PLL) includes a voltage-controlled oscillator (VCO)...
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4554517 |
Device for the automatic linearization of the control signal-frequency characteristic of a frequency-modulated variable frequency oscillator
A phase lock loop having an instruction input to which is applied the output signal of the frequency-modulated variable frequency oscillator. The pass band of the loop is regulated in order to...
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4528522 |
FM Transceiver frequency synthesizer
A frequency synthesizer used for a frequency modulation (FM) transceiver which uses negative feedback to make the modulation characteristics linear and stable over a wide frequency range. The...
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4510465 |
Linear gain voltage controlled oscillator with modulation compensation
In a compensated VCO circuit arrangement for providing constant modulation level over a wide frequency band a VCO is disclosed having a linear VCO gain factor vs. control voltage curve over the...
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4501019 |
Frequency modulation transmitter
A frequency modulation transmitter has a frequency synthesizer comprised of a voltage controlled oscillator for operating a transmitter section of the modulation transmitter. The output center...
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4494090 |
Frequency modulation system for a frequency synthesizer
A voltage controlled oscillator includes a main varactor diode coupled to a frequency resonating circuit to produce an output frequency in response to a control voltage. A secondary varactor diode...
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4378534 |
Wideband modulation sensitivity compensated voltage controlled oscillator
A wideband, modulation sensitivity compensated, voltage controlled oscillator which automatically and continuously compensates over a wide bandwidth for modulation sensitivity variations resulting...
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4375621 |
Circuit for linearizing frequency modulated oscillators on microstrip
In a microstrip frequency modulated oscillator, the linearity of the modulating circuit incorporating a varactor diode is adjusted by using a microstrip transmission line as a secondary resonator...
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4309674 |
Frequency modulators with compensation for variations in modulation sensitivity
In a frequency modulation system, the frequency modulation sensitivity of an oscillator is itself a function of the carrier frequency of the oscillator. The frequency modulation sensitivity is...
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4282497 |
Frequency modulator having linearized operation
A frequency modulator comprising an oscillator the output frequency of which is dependent upon the amplitude of a modulating signal, modulating signal control means via which the modulating signal...
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4189689 |
Automatic leveling stabilized VHF-FM frequency synthesizer
An automatic modulation leveling circuit gain controlled by the tuning voltage level into the voltage controlled oscillator of an FM frequency synthesizer providing a normalized modulation gain....
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4140981 |
Linearizing network
A linearizing circuit is described which gives a nonlinear relation between an input and an output signal of the circuit. Such a circuit can be used to compensate for the nonlinearity in, for...
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4117422 |
Circuit for compensating VCO nonlinearities in frequency modulated phase-locked loops and method thereof
The nonlinear characteristics of a voltage controlled oscillator (VCO) in a phase-locked loop are approximately matched by a single diode in the audio circuitry to provide an essentially constant...
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4088968 |
Frequency linearization and sensitivity equalization of a frequency modulated crystal oscillator
A direct FM modulator includes an oscillator comprising a current conducting device providing amplification to sustain oscillations and a frequency determining circuit connected thereto for...
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4003004 |
Frequency modulated oscillator
A frequency modulated push-pull oscillator in which the non-linear characteristic of varactors producing frequency modulation is compensated for by an opposite non-linear characteristic of a field...
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3789323 |
MULTIPLE INPUT SIGNAL MODULATOR AND METHOD THEREFOR
A frequency modulator for either stereo or quadraphonic FM which in addition to summing the sampled audio inputs, also sums continuous fractions of the audio inputs to form the composite signal...
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3735288 |
PHASE MODULATOR
A phase or frequency modulator having an operational amplifier with inverting and noninverting terminals, an RC network wherein R is light responsive, a control signal for controlling the light...
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