65 results about "Constant envelope modulation" patented technology

Multiple radio channel frequency signals that are modulated with respective information modulation are transmitted from a common antenna at multiple radio frequencies. Multiple modulators are provided, a respective one of which corresponds to a respective one of the radio channel frequencies. Each modulator generates at least one constant amplitude, phase modulated drive signal at the corresponding radio channel frequency from the respective information modulation, such that the at least one constant amplitude, phase modulated drive signal corresponds to the information modulation for the corresponding radio frequency. At least one saturated power amplifier is provided for each of the at least one constant amplitude, phase modulated drive signals. A respective saturated power amplifier is responsive to the corresponding constant amplitude, phase modulated drive signal, to produce a corresponding amplified output signal at an output thereof. A coupling network connects the outputs of the saturated power amplifiers in series, to produce a combined signal that is applied to the common antenna, such that the common antenna radiates the radio channel frequency signals that are modulated with the respective information modulation. In first embodiments, the at least one constant amplitude, phase modulated drive signal is a single constant envelope modulation drive signal, wherein the information modulation is a constant envelope information modulation. In other embodiments, at least two constant amplitude phase modulated drive signals are provided at the corresponding radio channel frequency, such that the at least two constant amplitude, phase modulated drive signals correspond to the information modulation for the corresponding radio frequency.

A method (200) and circuit (100) for substantially maintaining an amplified constant envelope modulation signal at a constant pre-defined amplitude. The circuit (100) comprises a constant envelope modulation providing circuitry (104), a power amplifier (102), a power amplifier driver (106), a coupler (108) and a feedback circuit (110). In operation the sensor (110) has an output (120) that provides a radio frequency output signal proportional to an amplitude of an amplified constant envelope modulated radio frequency signal provided to the amplifier input (118) from the power amplifier driver (106). The feedback circuit (110) provides a gain control voltage a driver gain control input to maintain the constant envelope modulation signal at a constant pre-defined amplitude supplied to the amplifier input (118).

In a modulation system, in order to provide a two-level signal with a desired modulation which is suited to be amplified by a switching mode power amplifier, the modulation system may include a first constant envelope modulator modulating a signal according to a first control signal, a second constant envelope modulator modulating a signal according to a second control signal, and a combining portion combining the output signal of the first and said second constant envelope modulator to a single, two-level pulse-width-modulated signal. The information which is to be represented by the modulation of the single, two-level pulse-width-modulated signal is coded in the first and the second control signals. The invention relates equally to a corresponding method for generating a modulated signal.

A coherent adaptive subcarrier modulation system applies subcarrier modulation to quadrature modulated signals with constant envelope modulation suitable for efficient sinewave and squarewave subcarrier modulations. The quadrature subcarrier enables the addition of new signals to the in-phase and quadrature phase signals with spectral isolation in the Global Position System while maintaining a constant envelop amplitude.

Transmitter architectures designed to accommodate both constant and non-constant of envelope modulation schemes and capable of providing local oscillator carrier frequencies within any one of numerous desired frequency bands, thus allowing compliance with many different communication standards. One example of a programmable frequency synthesizer includes a plurality of transmitter components and a microcontroller coupled to the frequency synthesizer and to the plurality of transmitter components. The microcontroller is adapted to provide a frequency control signal to the frequency synthesizer to control a frequency of the local oscillator carrier frequency. In addition, the microcontroller is also adapted to provide digital control signals to at least some of the plurality of transmitter components to turn on and off different ones of the plurality of transmitter components based on an operating mode of the transmitter, such that the transmitter can accommodate both constant envelope modulation and non-constant envelope modulation schemes.

A system for a fast, closed power control loop that quickly adjusts the output power of a power amplifier in a non-constant amplitude modulation format. Embodiments of the invention allow fast and precise closed loop power control in a communication system that has a transmit signal that includes a phase modulated component and an amplitude modulated signal component. By detecting the level of the transmit signal before and after the power amplifier, the invention ignores changes in the amplitude of the transmit signal, resulting in an accurate measure of the power amplifier gain. The difference between the level of the transmit signal before and after the power amplifier provides a signal that represents the gain of the power amplifier. The gain signal is compared with a reference signal to develop an error signal. The error signal is used to control the output of the power amplifier.

Transmitter architectures designed to accommodate both constant and non-constant of envelope modulation schemes and capable of providing local oscillator carrier frequencies within any one of numerous desired frequency bands, thus allowing compliance with many different communication standards. One example of a programmable frequency synthesizer includes a plurality of transmitter components and a microcontroller coupled to the frequency synthesizer and to the plurality of transmitter components. The microcontroller is adapted to provide a frequency control signal to the frequency synthesizer to control a frequency of the local oscillator carrier frequency. In addition, the microcontroller is also adapted to provide digital control signals to at least some of the plurality of transmitter components to turn on and off different ones of the plurality of transmitter components based on an operating mode of the transmitter, such that the transmitter can accommodate both constant envelope modulation and non-constant envelope modulation schemes.

Certain aspects of the present disclosure relate to a method for demodulating CPM modulated signals transmitted in a wired or wireless communication system using a linear modulation model consisting of a linear superposition of time pulses modulated using pseudo-PSK pulses.

The invention discloses an envelope tracked Doherty power amplifier. Particularly, a radio-frequency signal input end is respectively connected with the input end of a power distributor and the input end of an envelope detector through a coupler; the output end of the power distributor is respectively connected with the input end of a main power amplifier and a phase compensation line; the phase compensation line is connected between the output end of the power distributor and the input end of an auxiliary power amplifier; the output end of the main power amplifier and the output end of the auxiliary power amplifier are coupled to a second impedance conversion line through a first impedance conversion line, and then connected to a load; the other end of the load is grounded; the output end of the envelope detector is respectively connected with the input end of a drain envelope amplifier and the input end of a grid envelope amplifier; the output end of the drain envelope amplifier is connected to the drain end of the main power amplifier; and the output end of the grid envelope amplifier is connected to the grid end of the auxiliary power amplifier. The envelope tracked Doherty power amplifier disclosed by the invention is capable of effectively amplifying a non-constant envelope modulation signal having a high peak-to-average ratio, and can be used for modern wireless communication terminal equipment or base station equipment.

Circuits for reducing the signal peaks in telecommunications signals are described. The circuits and methods are preferably adapted for reducing the peak to average power ratio of non-constant envelope modulation signals. In one example the circuit includes a band-limiting filter for limiting the bandwidth of a data bearing signal and a predictive filter for predicting peaks in the data bearing signal at the output of the pulse-shaping filter. The circuit also includes a clipping processor for generating a compensation signal in response to one or more signal peaks predicted by the predictive filter and a signal combining device for applying the compensation signal to the data bearing signal prior to amplification of the data bearing signal.

A transmitter includes a dual mode modulator and an amplifier coupled to the dual mode modulator. The dual mode modulator implements a linear modulation scheme during a first mode of the modulator to produce a variable envelope modulated signal. The dual mode modulator implements a non-linear modulation scheme during a second mode of the modulator to produce a constant envelope modulated signal. The amplifier is biased as a linear amplifier during the first mode of the modulator and is biased as a non-linear amplifier during the second mode of the modulator. A feed-forward connection between the dual mode modulator and the amplifier is used to indicate a change in modulation mode and to adjust the bias of the amplifier. A power of the constant envelope modulated signal is increased such that an operating point of the amplifier remains substantially constant during the first and second modes of the modulator.

The invention discloses a multicarrier signal constant envelope modulation method. By using the method, technical problems that simultaneous emission of a plurality of carrier wave signals of a radar, communication, electronic interference and high-efficiency and undistorted power amplification are solved. The method can be widely used for signal modulation and power amplification of a radar, communication and electron interference integration system, and modulation and amplification of the plurality of carrier wave signals of a digital array module. A CORDIC algorithm and a multiphase processing technology are used. Base-band modulation of each carrier wave signal and synthesis of the plurality of carrier wave signals are completed. Amplitude-phase conversion and digital carrier wave modulation are performed. Constant envelope modulation and power amplification of the plurality of carrier wave signals of the radar, the communication, electronic interference and the like are realized. A sampling frequency of a signal is effectively increased and a bandwidth of signal processing is increased too. Through an amplitude phase conversion modulation technology, constant envelope modulation of the plurality of carrier wave signals of the radar and the communication is completed and the undistorted and high-efficiency power amplification of the plurality of carrier wave signals is realized.

A method for designing a constant envelope PSK modulator-demodulator comprises the steps of S1 signal processing of a constant envelope PSK modulator and S2 signal processing of a constant envelope PSK demodulator. According to the step S1, at a transmitting terminal, binary bit streams output by a channel encoder are grouped according to a modulation parameter M; a differential phase sequence is obtained; a minimum additive group is generated by the differential phase; digital signals are subjected to digital-to-analogue conversion, and the modulation process is completed. According to the step S2, at a receiving terminal, first, received FSK signals are sampled, frequency modulation signals are subjected to phase integration; correlation operation is conducted on the signals of a synchronization sequence and all sampling points to obtain the best sampling point; the phase of the PSK signal at the best sampling point is used for extracting soft information, making hard decisions and achieving digital demodulation. According to the method, the NPSK modulation signals are subjected to constant envelope conversion to be used as modulation output, so that the power efficiency of power amplification of the transmitting terminal of a communication system is improved; the receiving terminal enables the signals to be sampled, and the PSK modulation signals can be restored and acquired through a phase integrator and a matched filter.

The invention discloses an OFDM system frequency offset synchronization method based on constant envelope modulation, and belongs to the technical field of wireless communication. According to the OFDM system frequency offset synchronization method based on constant envelope modulation, a transmitter carries out constant envelope transformation on a signal processed through constellation diagram mapping again, so that data have the constant modulus characteristic before being processed through IFFT, and channels obey quasi-static fading; a receiver synchronizes frequency offset through the energy difference between a minimized receipt signal and a known channel frequency response. The OFDM system frequency offset synchronization method has the advantages of being applicable to frequency offset blind synchronization of an MIMO-OFDM system of any constellation diagram, and applicable to the situation that null carrier waves exist in the OFDM system.

A transmitter has a power amplifier amplifying a radio frequency transmit signal. The radio frequency transmit signal is a non-constant envelope modulated signal. The power amplifier has a first compression point. In a method for sliding a compression point in the transmitter, the power amplifier is operated at a first backoff from the first compression point such that a given adjacent channel power ratio requirement is met for a first peak-to-average ratio of the radio frequency transmit signal. The first compression point is slide to a second compression point for a second peak-to-average ratio of the radio frequency transmit signal, the second compression point being lower than the first compression point. The first and second peak-to-average ratios are dependent on information content of the non-constant envelope modulated signal.

A baseband circuit for a communications transmitter includes a baseband modulator, a pulse-shaping filter, and an AMPR reduction circuit. The baseband modulator is configured to generate a sequence of symbols formatted in accordance with a non-constant envelope modulation scheme. The pulse-shaping filter is configured to band-limit the sequence of samples to provide a sequence of samples. The AMPR reduction circuit is configured to analyze and modify one or more samples in the sequence of samples, if a sample in the sequence of samples that has been previously analyzed by the AMPR reduction circuit is determined to have a magnitude less than a predetermined low-magnitude threshold.

A burst transmitter is obtained which, when a constant envelope modulation is used, can control the envelope of a transmission output power by controlling a baseband signal without causing the spreading of the spectrum. A transmission output power control device includes: an I / Q signal amplitude control unit (101) for variably controlling the shape of a rise and a fall of the waveform of a baseband signal and its burst transmission time from the end of the rise to the beginning of the fall in accordance with a modulation system signal; a modulating unit (2003) for modulating the baseband signal controlled in the I / Q signal amplitude control unit (101) into a high-frequency signal for transmission in accordance with the modulation system signal; an amplifier (2004) for amplifying the transmission high-frequency signal modulated in the modulating unit (2003); and a control voltage signal selecting unit (102) for outputting a predetermined constant voltage which is determined by the modulation system signal and a transmission power level signal, so as to control the output power of the amplifier.

A multi-mode communication device (100) uses a quadrature transmitter (102) for transmitting both amplitude and constant envelope angle-modulated signals. For angle modulation, a separate feedback path is used from that used for amplitude modulated signal transmission. An FM receiver (136) is used to produce error signals (214, 216) used in correcting the I and Q quadrature signals (206, 208).

A power amplification apparatus and method provide for controlling envelope modulation of a Radio Frequency (RF) signal. The power amplification apparatus includes a linear amplifier configured to receive an input signal to be amplified, and generate a linear output signal for compensating for a current ripple of an amplified signal and a switch control signal having a current obtained by dividing the linear output signal by a predetermined ratio. The power amplification apparatus also includes a switching amplifier configured to receive the switch control signal through a multi-mode resistor having a variable resistance, and generate the amplified signal. The variable resistance of the multi-mode resistor determines a switching frequency representing an operating speed of the switching amplifier, and is adjusted according to a communication mode of the input signal.

There is disclosed a method and apparatus for control of a power control loop. The method comprises the steps of: amplifying a non-constant envelope modulation signal to thereby produce an output signal; combining a power level control signal with a signal representing the envelop of modulation; comparing the combined signal to a signal representing the power level of the output signal to thereby produce a comparison signal; and attenuating the amplified signal in dependence on said comparison signal.

The invention discloses a method and a device for dual-frequency constant envelope modulation of a navigation signal. Through the modulation method, service signals at any way and any power ratio on two sidebands are combined to one constant envelope signal to be transmitted. The modulation device comprises a single-frequency constant envelope modulator, a dual-frequency constant envelope modulator and a quadrature modulator. The single-frequency constant envelope modulator respectively modulates the service signals on the upper and lower sidebands to one constant envelope baseband signal and outputs real-part signals and imaginary-part signals of the constant envelope baseband signals of the upper and lower sidebands to the dual-frequency constant envelope modulator; the dual-frequency constant envelope modulator combines the constant envelope baseband signals of the upper and lower sidebands into one constant envelope baseband signal and outputs the real-part signal and the imaginary-part signal of the constant envelope baseband signal to the quadrature modulator, and the quadrature modulator outputs the input signal after quadrature modulation. According to the scheme, a dual-frequency signal can be transmitted through a set of transmission chains, a set of additional independent modulators and transmission chains are not needed, and any power ratio and any signal way can be achieved.

The present invention discloses a double TRU (Transceiver Unit) ( 45 ). The output signals from the power amplifiers ( 64, 84 ) are combined to one common output signal provided to an antenna arrangement ( 91 ). A DSP (Digital Signal Processor) ( 52, 72 ) of each TRU ( 50, 70 ) comprises means for a constant-envelope modulation scheme ( 54, 74 ) and a non-constant envelope scheme ( 53, 73 ). The DSP:s ( 52, 72 ) select the modulation scheme according to modulation information ( 49, 69 ). In such a way, a switching between different modulation schemes can be performed even on a time-slot basis. For non-constant-envelope modulation, the modulated signal is separated into two component signals. Each TRU ( 50, 70 ) takes care of the amplification of one component. A phase compensation of at least one of the TRU:s ( 50, 70 ) is performed in order to correct for different paths of phases of the power amplifiers ( 64, 84 ). The non-constant envelope modulated signal can also be a multi-carrier signal, e.g. of two or more constant-envelope signals. Also a TCC (Transmitter Coherent Combining) operation is achievable.

A quadrature modulated transceiver (102) is used to generate a constant envelope angle modulated signal for communications. To produce the required feedback when operating in the constant envelope mode, an orthogonal frequency division multiplexed receiver (136) is used.

A waveform generator for use in IQ modulation in a wireless cellular device having an FM waveform generator (104) that is programmable to generate a desired FM frequency deviation; a digital accumulator (108, 110, 112) to provide phase generation.First and second look-up tables 114 and 116 use the 6 MSBs and the 6 LSBs of 12-bit digital accumulator values to look up phase-space values that are combined in complex multipliers (130, 140), which are re-used from other parts of the circuit.This provides the following advantage(s):Support of both FM and I / Q modulation techniques for constant envelope modulation; low cost implementation; and flexibility to address multimode systems.

A direct-conversion receiver includes an analog stage for receiving an incident signal from a transmission channel, mixers and programmable-gain amplifiers. The receiver further includes at least one compensation module having input and output terminals respectively connected between the output of the mixers and the input of the programmable-gain amplifiers. The compensation module compensates for both a static DC voltage offset and a possible dynamic DC voltage offset of the analog stage.

The invention relates to the field of wireless communication, and discloses a method and a device for recognizing modulation modes on the basis of peak-to-average ratios. The method includes computing the peak-to-average ratios according to constellation diagram symbols of received signals; comparing each peak-to-average ratio to a preset threshold so as to determine the modulation modes of the received signals are constant-envelope modulation modes or amplitude modulation modes. The method and the device have the advantages that the number of operation is low, and the constant-envelope modulation modes and the amplitude modulation modes can be effectively distinguished.

A system and method of the present invention forms a hybrid encoded signal. A signal generator generates a coded waveform having a trellis structure, such as a continuous phase modulated signal. A modulator is operative with the signal generator and adds at least one orthogonal or amplitude modulated waveform to a trellis structure of the coded waveform to create a non-constant envelope modulated signal that has at least one of increased bandwidth, improved bit error rate, or an increased number of bits encoded into a single symbol.

An improvement for a phasor fragmentation engine and method, whereby a phasor flipping algorithm is applied when determining fragment phasors for a non-constant envelope modulation signal (e.g. OFDM). The phasor flipping algorithm avoids sharp phase transitions for the fragment phasors, which cause an increase in bandwidth, by performing a comparison of the phasor angle separation between the prior and current time samples. This comparison corresponds to a determination of whether the modulation signal V has passed near or through zero. When it is determined that the calculated phases of Vα and Vβ would result in a larger angle of separation between the calculated phase of Vα (for phasor A) for the current time sample (N) and the phase of VA for the previous time sample (N−1) than the angle of separation between the calculated phase of Vβ (for phasor B) for the current time sample (N) and the phase of VA for the previous time sample (N−1), the phase values for the phasor fragments Vα and Vβ are swapped so that the phase of VA is that of Vβ (i.e. VA=Vβ) and the phase of VB is that of Vα (i.e. VB=Vα).