Abstract: Provided is a transmission modulation apparatus, using polar modulation of two-point modulation scheme, capable of completing a timing adjustment of a BB phase modulation signal and BB amplitude modulation signal in a short time. A phase modulation section (10) that performs two-point modulation with a PLL circuit is provided with a switch (17) to make the PLL circuit open loop, and when a first delay section (5) corrects the deviation in synchronization between the BB phase modulation signal and BB amplitude modulation signal, the switch (17) is turned off to make the PLL circuit open loop.

Abstract: A method for reducing out-of-band emission in an AM transmitter for digital transmission includes generating, from a digital modulation signal, an amplitude signal and a phase-modulated radio frequency signal configured to control the AM transmitter. A digital modulation process is used in which a hole is formed around a 0/0 point so that a zero crossing is avoided by a substantial margin in a vector diagram representation. Thereby a respective bandwidth of the amplitude signal and the phase-modulated radio frequency signal is limited so that the out-of-band emission decreases as a function of a shoulder distance achievable by the AM transmitter at a rate where a spectrum mask is not exceeded.

Abstract: Universal signal modulators structures are shown which are particularly useful for selectively generating polar-modulated digital sequences from input phase and amplitude symbols and for generating quadrature-modulated digital sequences from input first and second quadrature symbols. Significantly, the modulation structure (quadrature modulation or polar modulation) of these embodiments can selected by simply changing the state of a mode command.

Abstract: Envelope limiting for a polar modulator. A system is provided that intelligently compresses the amplitude modulation in a polar modulator so that it can be implemented with a single-stage variable gain amplifier. Limiting the amplitude modulation range on the low side prevents collapse of the transmit signal's time-varying envelope and eases circuit implementation. Limiting the amplitude modulation range on the high side reduces the peak-to-average ratio of the waveform and thereby improves the efficiency of the radio transmitter.

Abstract: A mobile communication system has a mobile phone in which a voltage is set corresponding to the characteristic variation of a PA even when a PA having characteristic variation is used. The mobile phone employs a polar loop method, which comprises an antenna (1) for transmission and reception of signal waves; an antenna switch (2) for switching the transmission mode and the reception mode; a BBLSI (3) having a function to control the transmission and reception; an RFIC (4) having a function for modulating and demodulating the transmitted and received signals; and a PA (5) for amplifying up to the target output power by means of the amplitude modulation at the time of the transmission.

Abstract: Polar modulators include a phase splitter, a controller, variable current sources, transistor circuits, and a combiner. The phase splitter splits a RF carrier signal into quadrature component signals that are 90 degrees out of phase with each other. The controller generates modulation control signals based on information that is to be transmitted. The variable current sources each generate a variable amplitude current signal based on a different one of the modulation control signals. Each of the transistor circuits amplify a different one of the quadrature component signals with a variable amplification based on the variable amplitude current signal from a different one of the variable current sources to generate an amplitude adjusted quadrature component signal. The combiner combines the amplitude adjusted quadrature component signals from each of the transistor circuits to generate a phase-modulated RF carrier output signal.

Abstract: A direct synthesis transmitter. A very efficient and highly linear direct synthesis transmitter is provided that can be used to directly synthesize and transmit any type of modulated signal. The direct synthesis transmitter includes a phase-locked loop (PLL) with controls phase modulation plus an accompanying variable gain amplifier for amplitude modulation. Also included is a system to align the phase and amplitude modulation signals. A transmitter constructed in accordance with the present invention is very efficient and suitable for use in portable radio equipment.

Abstract: An improved self-adjusting I-Q modulator system has a quadrature modulated carrier output that is input to a waveform acquisition circuit for obtaining a full waveform from which both amplitude and phase measurements are obtained. Calibration occurs by setting respective I and Q inputs to the multipliers to zero and adjusting corresponding variable offset voltages to null the modulated carrier output. Then a voltage reference is selected by each I and Q input path in turn, and the amplitude and phase of the modulated carrier output for each I and Q channel are measured. Respective phase shifters for a carrier signal are adjusted to move the outputs of the phase shifters toward a quadrature relationship in response to the measured amplitude and phase of the full waveform. These steps are repeated until the phases of the I and Q channels are in quadrature.

Abstract: A transceiver and transmitter are shown. A baseband processor receives a signal for transmission. It converts the signal into amplitude and phase polar components. Each component is then processed—the phase component through a wideband phase modulator and the amplitude component through a wideband amplitude modulator, and the components are then recombined for further processing or transmission.

Abstract: The invention is a combiner and a method for selectively combining modulated signals. The combiner includes a first modulator (12) with a selective input which receives at least one input signal and a first carrier signal and which outputs a first output modulated with the first carrier signal; a second modulator (14) with a selective input which receives at least one input signal and a second carrier signal and which outputs a second output modulated with the second carrier signal; means for combining (24?) the first and second amplified output signals to provide a combined output; and wherein the first and second carrier signals are selectably coherent or incoherent with the selection of first and second coherent carrier signals causing the combined output to comprise a single carrier of higher power and the selection of incoherent carrier signals causing the combined output to comprise two distinguishable carriers of lower power.

Abstract: An apparatus for generating a modulated signal which includes a modulator operative for receiving a first signal and input data signals, and modulating the first signal in accordance with the input data signals so as to produce a modulated reference signal; a first frequency divider coupled to the modulator output, operative to reduce the frequency of the modulated reference signal by a predetermined factor; a signal generator operative to produce a second signal; a first mixer having a first input coupled to an output of the first frequency divider and a second input coupled to the output of the signal generator. The first mixer operates to frequency translate the modulated reference signal by an amount equal to the frequency of the second signal. In addition, the signal generator of the present invention contains a direct digital synthesizer coupled to a second phase lock loop which operates to up-convert the output signal of the DDS to the microwave region.

Abstract: A phase-amplitude modulator for mobile communications employs a phase lock loop as an input to a nonlinear power amplifier providing phase information with amplitude information used to modulate the power amplifier output to synthesize phase-amplitude for the RF transmission signal.

Abstract: A system for using a translation loop upconverter and power amplifier including a secondary phase-error correction loop uses the output of the upconverter to lock a feedback loop during a time in which the output of the power amplifier is insufficient to provide feedback to the upconverter. After the power amplifier has developed sufficient power to provide feedback to the upconverter, the feedback to the upconverter is taken from the output of the power amplifier. By placing a phase detector and phase shifter in the secondary feedback path taken from the output of the power amplifier, any phase distortion present in the system can be detected and corrected.

Abstract: Power modulation systems and methods generate an amplitude waveform and phase waveform from data symbols. The amplitude waveform includes a low frequency portion and a high frequency portion. The phase waveform is phase modulated to produce a phase modulated waveform. A power amplifier, preferably a Class C power amplifier, includes a power supply input, a signal input and a power output. The phase modulated waveform is applied to the signal input. The low frequency portion of the amplitude waveform is amplified at high efficiency to produce an amplified low frequency portion. The high frequency portion is amplified at lower efficiency to produce an amplified high frequency portion. The amplified low frequency portion and the amplified high frequency portion are combined to produce a combined amplified amplitude waveform.

Abstract: A modulation system having in-phase and quadrature phase (IQ) calibration while on-line. The modulation system includes an on-line correction data state detector, an IQ correction code, and a scalar amplitude detector. The on-line correction state detector detects the presence of particular data states that are expected to result in particular modulation states or transition locations. When a particular data state is detected the IQ correction code compares the detected scalar magnitude with others that have been detected. The IQ correction code then uses the comparison to generate adjustments for I and Q offsets, I/Q phase, and I/Q gain. In a rotation embodiment, the modulation system further includes a rotation signal generator for generating rotation angles and an IQ rotator for applying the rotation angles for rotating the I and Q digital data streams.

Abstract: The modulator has an input (30) which receives data to be modulated. A plurality of memory regions acting as look-up tables (38-44) are arranged to contain information relating to the modulation method to be carried out by the modulator. At least one of the memory regions provides time independent modulation values and at least one of the memory regions provides time dependent modulation values. Values provided by the memory region is dependent on the data received via the input. Processing means provide a modulating signal based on the values provided by the memory regions.

Abstract: A digital communication system and method is provided for increasing bit-rates while maintaining the reliability of transmitted digital information and avoiding increased power demands. The communication system includes a transmitter that modulates one or more bits onto a carrier signal to generate and transmit a first transmission signal during the first part of a pulse time TB, receives an additional bit, and based on the value of the additional bit, either transmits the first transmission signal again during the second part of the pulse time TB or transmits a second transmission signal during the second part of the pulse time TB.

Abstract: A modulator and a method of modulating utilizes phase or frequency modulation and amplitude modulation. A delay circuit or synchronization circuit is utilized to coordinate the performance of amplitude modulation and phase modulation. The amplitude modulation can be provided after phase modulation is provided to the signal. The modulation circuit can be utilized in any frequency range including high frequency and low frequency circuits.

Abstract: A modulation system having in-phase and quadrature phase (IQ) calibration while on-line. The modulation system includes digital filters for converting I and Q data bit streams into filtered multilevel I and Q digital data streams, digital-to-analog converters, and an IQ modulator for converting the analog I and Q data streams into a modulated output signal having a representative IQ diagram having modulation states and transition locations between the modulation states. The system also includes an on-line correction data state detector, an IQ correction code, and a scalar amplitude detector. The on-line correction state detector monitors the data states in memories of the digital filters and detects the presence of particular data states that are expected to result in particular modulation states or transition locations. The amplitude detector monitors the modulated output signal and provides representative detected magnitudes.

Abstract: A modulation system having in-phase and quadrature phase (IQ) calibration while on-line. The modulation system includes digital filters for converting I and Q data bit streams into filtered multilevel I and Q digital data streams, digital-to-analog converters for converting the digital data streams from digital to analog form, and an IQ modulator for converting the analog I and Q data streams into a modulated output signal having a representative IQ diagram having modulation states and transition locations between the modulation states. The digital filters include forward shifting memories having several samples of the data bit streams for each data bit time. The system also includes an on-line correction data state detector, an IQ correction code, and a scalar amplitude detector. The on-line correction state detector monitors the data states in the memory and detects the presence of particular data states that are expected to result in particular modulation states or transition locations.

Abstract: A VSAT system for generating and transmitting a modulated data signal to a satellite. The VSAT system includes an indoor unit for generating a modulated data signal having an envelope of constant amplitude, and an outdoor unit including a transmitter module operative to receive the modulated data signal and to frequency multiply and amplify the modulated data signal so as to produce a modulated carrier signal having an envelope of constant amplitude. The transmitter module includes a multiplier operative to frequency multiply the modulated data signal to the frequency of the modulated carrier signal, and a power amplifier operated in the saturation mode, which amplifies the modulated carrier signal to the desired power level. The components constituting the transmitter module are formed on a single integrated circuit.

Abstract: An apparatus for generating a modulated signal which includes a modulator operative for receiving a first signal and input data signals, and modulating the first signal in accordance with the input data signals so as to produce a modulated reference signal; a first frequency divider coupled to the modulator output, operative to reduce the frequency of the modulated reference signal by a predetermined factor; a signal generator operative to produce a second signal; a first mixer having a first input coupled to an output of the first frequency divider and a second input coupled to the output of the signal generator. The first mixer operates to frequency translate the modulated reference signal by an amount equal to the frequency of the second signal. In addition, the signal generator of the present invention contains a direct digital synthesizer coupled to a second phase lock loop which operates to up-convert the output signal of the DDS to the microwave region.

Abstract: Modulation systems and methods can modulate a stream of complex numbers representing a desired modulation of a radio signal by representing a real part of each of the complex numbers in a stream of complex numbers representing a desired modulation of a radio signal, as a plurality of first digits of decreasing numerical significance and representing an imaginary part of each of the complex numbers as a plurality of second digits of decreasing numerical significance. A respective one of the first digits and a respective one of the second digits of like numerical significance are grouped to form a plurality of phase control symbols. A respective phase control symbol is then used to control the phase of an output signal at the radio carrier frequency from a respective one of the plurality of power amplifiers. Each of the power amplifiers provides an output power level that is related to the numerical significance of the first and second digits that form the associated phase control symbol.

Abstract: An RF amplifier includes a phase modulator developing a phase modulated RF input signal to be transmitted. A power amplifier receives the RF input signal and amplifies the RF input signal to develop an RF output signal. An amplifier control is operatively associated with the phase modulator and the power amplifier. The amplifier control includes a memory for storing correction information correlating desired amplitude of the RF output signal relative to actual amplifier amplitude, and a control varies power amplifier supply voltage responsive to the correction information to linearize amplitude modulation in the power amplifier.

Abstract: An apparatus and method generate a linearly modulated signal in a polar modulation system. A signal for transmission is separated into a phase component and an amplitude component, and a carrier signal is modulated with the phase component in a phase modulator, creating a phase distortion. A compensator compensates for the phase distortion created by the phase modulator by modifying the amplitude component. The phase modulated carrier signal is amplitude modulated by the compensated amplitude component to produce a linearly modulated signal.

Abstract: A transmitter and a phase locked loop (30) for a transmitter are disclosed. The phase locked loop (30) upconverts the frequency of a baseband signal to a frequency for radio transmission. As well as the usual components, the phase locked loop (30) comprises a modulator (39) for modulating a baseband signal (f.sub.bb) onto a carrier (f.sub.ref /R) and forwarding the resultant modulated signal (f.sub.c) to one of the inputs of the phase detector (33). It also comprises a low pass filter (38) in its forward path between the phase detector (33) and the voltage controlled oscillator (34) for passing signals having baseband signal frequencies. A mixer (35) and main frequency divider (36) are provided in the feedback path to downconvert the transmit signal (f.sub.tx). This low division eliminates large amounts of multiplicative noise within the loop bandwidth, and therefore enables a large loop bandwidth to be used. Consequently, the settling time of the phase locked loop is improved.

Abstract: A transmitter subsystem is disclosed whereby the output frequency spectrum of a DDS device, for use in the transmitter subsystem, is frequency multiplied to achieve greater frequency coverage at the RF bands. In one embodiment of the present invention, a DDS device is structured in such a way that the DDS output signal spectra can be multiplied directly for direct conversion to RF or IF bands. As such, the requirements placed on the DACs in the DDS device are lessened, because the DACs require much lower sampling frequencies than those used in the existing technology. Also, the requirements placed on the implemented bandpass filters used for image rejection in the applied upconverters are lessened, because of the larger frequency difference created between the desired output and the image frequency band. In a second embodiment of the present invention, a DDS device is also structured in such a way that multiplication of the baseband spectra can be accomplished at the IF.

Abstract: An apparatus for implementing post-detection dispersion compensation on a minimum-phase optical single sideband signal propagating along an optical fiber, in which the optical fiber induces phase distortion on the minimum-phase optical single sideband signal.

Abstract: A multi-channel modulator for the transmission of telephony signals within a broadband communication system. An interpolation module generates processed I and Q signal components by upsampling filtered I and Q signal components. In turn, these processed I and Q signal components output by a filter are passed to a set of channel modulators. Each channel modulator accepts a pair of processed I and Q signal components and, in response, modulates a selected carrier signal with one of the telephony signals to produce a complex modulated signal. An adder module responds to the complex modulated signals by summing the real signal components to produce a real resultant signal, and to sum the imaginary components to produce an imaginary resultant signal. A digital-to-analog converter (DAC) module coverts the real resultant signal and the imaginary resultant signal, which are represented by digital data streams, to analog signals.

Abstract: A modulation amplifier includes a signal converter, a summator and a plurality of high frequency stages (3.sub.1-m or 4.sub.1-n). The high frequency stages (3.sub.1-m) are driven by equiphased control signals (s.sub.1-m); the high frequency stages (4.sub.1-n) are driven by control signals (t.sub.1-n) of different phase .PHI..sub.1-n. The high frequency stages (3.sub.1-m or 4.sub.1-n) can be selected in an arbitrary manner by the control signals (s.sub.1-m or t.sub.1-n). The summator adds the high frequency output signals (x.sub.1-m or y.sub.1-n) of the high frequency stages (3.sub.1-m or 4.sub.1-n). The output signal can be conveyed, for example, to a low pass and a subsequent load. The phases (.PHI..sub.1-n) of the output signals (y.sub.1-n) of the high frequency stages (4.sub.1-n) correspond to those of the control signals (t.sub.1-m). So many high frequency stages (3.sub.

Abstract: A numerically controlled oscillator (10) includes a difference engine (12) that receives a numerator signal (14) and a numerator minus denominator signal (16). The numerator signal (14) and the numerator minus denominator signal (16) represent constant input values for a desired fractional relationship between a sine wave output signal (34) and a sample clock input signal (20) of numerically controlled oscillator (10). The difference engine (12) generates a difference output signal (18) that is received by a phase adder (22) for adding either a one or a zero to a combination of the delta phase input signal (24) and a phase accumulator output signal (26). The difference engine (12) optimally distributes ones and zeros so as to minimize phase jitter in the output signal (34).

Abstract: In a signal point arranging method for use with a quadrature amplitude modulator/demodulator device in which a desired number of signal points are arranged on a rectangular plane, a plurality of grid points are first set such that they are symmetrical with respect to the rectangular coordinate axes of the rectangular plane and arranged at intervals of a unit distance. Next, a plurality of concentric circles with their center at the coordinate origin of the rectangular plane are set, each of the concentric circles having a radius equal to a distance between the coordinate origin and a grid point. Then, a desired number of signal points are arranged on points of intersection of the grid points, the concentric circles beginning with the circle smallest in radius and continuing with circles of increasing radius. As a result, each of the signal points can be arranged as close to the coordinate origin as possible, thus enabling the peak power of modulated signals to be minimized.

Abstract: A multifunction microwave modulator circuit has an input signal splitter to provide two equal amplitude signal components. A phase quadrature relationship between the two signal components is obtained by constructing the splitter as a Lange coupler. There is pair of circuit cells, each of which operates separately on one of the two signal components to electronically adjust a vector representation of the signal to provide a vector having a desired amplitude, ranging over both positive and negative values of amplitude, including zero amplitude. The signal vectors of the two cells are combined by means of a Wilkinson combiner to provide an output signal represented by a resultant vector which may have any direction within 360 degrees, and an amplitude scale factor which varies from unity to zero.

Abstract: A wide-band microwave modulator arrangement for an information transmission system, such as a video signal distribution system, in which signals from a microwave carrier signal source are split and directed over a first path comprising an attenuator and a second path comprising phase shift means and a balanced modulator, the output signals from the two paths being combined for transmission. Signals from the carrier signal source may also be directed over a third path including phase shift means and a second balanced modulator, amplified output signals from the first two paths being combined with output signals from this third path before transmission.

Abstract: Transmitting signals containing amplitude modulated (AM) and phase modulation (PM) components requires a transmitter having AM and PM control loops. The PM control loop provides phase modulation, frequency translation and phase predistortion for the transmitter. The phase predistortion/correction is accomplished by using an oscillator, thus, the amount of PA phase correction is essentially unlimited. Additionally, the PM control loop is nested about a power amplifier (PA), allowing the PM control loop to correct for any distortion introduced by the PA.

Abstract: An automatic gain calibration system for a phase modulator for forcing a predetermined phase shift amplitude includes a phase modulator responsive to an applied voltage for modulating the phase of a radiation beam. The frequency spectrum of the modulated radiation beam is converted to the electrical domain where a selected even harmonic of the spectrum is nulled. The scaling circuit then responds to the amplitude of voltage applied to the phase modulator that obtains the phase shift which produced the nulling of the selected even harmonic and scales that voltage to generate the predetermined phase shift amplitude which is desired.

Abstract: A high efficiency amplitude/phase modulation amplifier circuit (100) includes a first (102) and a second (106) high efficiency amplifier. These amplifiers (102 and 106) amplify two constant amplitude/phase modulated signals. A combiner (104) combines the output signals from the amplifiers (102) and (106) to produce a combined signal to a load (108). Two shunt elements (202 and 204) are included to prevent the reactive components of the combined signal from reaching the amplifiers (102) and (106). With no reactive components reflected back, the amplifiers (102 and 106) can remain non-linear even though they are used to amplify an amplitude/phase modulated signal which includes Amplitude Modulation (AM) components.

Abstract: A numerically-controlled modulated oscillator and modulation method which selectively provides frequency modulation, phase modulation or amplitude modulation with minimal circuitry. A numerically-controlled modulated oscillator is provided having a tuning register for receiving a center frequency parameter, an adder for receiving at one input the frequency parameter, a phase accumulator for receiving a phase increment number from the adder and producing a waveform phase number, a waveform memory for producing a waveform amplitude number in response to the phase number, and a digital-to-analog converter for producing an analog signal in response to the waveform amplitude number. Another input is provided to the adder from an angle modulation register which provides an angle modulation parameter. This parameter can perform either phase or frequency modulation.

Abstract: A vector locked loop is disclosed having a topology somewhat similar to two cross coupled phase locked loops, but wherein both magnitude and phase are used as feedback signals. The output signal is generated by combining the outputs of two VCOs in a combiner network. This output signal is fed back to the input, where phase and magnitude detectors are used to generate error signals. These error signals are processed to yield control signals for controlling the frequencies of the two VCOs. The vector locked loop can be adapted for a number of applications, including frequency translation, modulation (phase, amplitude or arbitrary), and high efficiency linear power amplification.

Abstract: Transmitter for transmitting communication traffic via phase modulated carrier signals. The device provides for an efficient amplification of a phase modulated carrier signal using Class C amplifier technology. An envelope function is applied to the carrier signal by modulating the Class C amplifier with a related spectrum-suppressing amplitude envelope signal. Phase distortion accompanying the amplitude modulation of the Class C amplifier is compensated by generating a phase offset for the carrier signal. As each envelope function for suppressing the spectrum is generated, a corresponding phase offset may be applied to the carrier signal, avoiding the consequences of phase shift resulting from amplitude modulating the carrier signal in the Class C amplifier.

Abstract: Apparatus, and a method for its use, for linearly phase-modulating a microwave signal with only minimal accompanying amplitude modulation. An incoming signal is divided into two components, one of which is shifted by ninety degrees from the other, plus or minus a small offset phase angle selected to minimize amplitude variations in an output signal. The component with the offset phase angle is amplitude modulated, then recombined with the other component to provide the desired phase-modulated output signal. When the offset phase angle and the nominal amplitude of the amplitude-modulated component are appropriately selected, phase modulation of the output signal is substantially linearly related to the amplitude modulation of the offset input signal, and amplitude modulation of the output signal is minimized.

Abstract: A magnetic induction modulation and frequency multiplication system includes three toroidal coils physically mounted close to one another to provide magnetic flux coupling between them. One of the coils is supplied with a relatively high frequency carrier signal which has been shaped to eliminate one or the other of the positive or negative excursions thereof. A second coil is provided with an audio signal or other suitable input signal. The third coil constitutes the output coil and is utilized to provide signals to a transmitting circuit coupled to a transmitting antenna. The output signal from the third coil constitutes an amplitude modulated and phase/frequency modulated signal directly produced through the mutual inductive coupling of the three coils.

Abstract: A system is described for using the modulation of the phase of a RF carrier as means of transmitting information. The RF input is split into four quadrature components each of which is passed through individual amplitude control attenuators and then summed in a combiner to create the required phase-controlled RF signal. The resultant signal is then amplified in an RF signal amplifier chain as required to achieve the desired output level. The RF output level is sampled and routed back to an in-phase splitter the output of which is compared to the corresponding individual quadrature components of the unmodulated RF signal to generate a signal which is compared with a processor generated modulation reference signal in a control loop amplifier and the resulting error signal is applied to the individual attenuators to adjust the output amplitude of each quadrature component. The quadrature components are then combined to obtain the desired phase-modulated RF output signal.