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.

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.

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.

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 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 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 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.

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 V_α and V_β would result in a larger angle of separation between the calculated phase of V_α (for phasor A) for the current time sample (N) and the phase of V_A for the previous time sample (N−1) than the angle of separation between the calculated phase of V_β (for phasor B) for the current time sample (N) and the phase of V_A for the previous time sample (N−1), the phase values for the phasor fragments V_α and V_β are swapped so that the phase of V_A is that of V_β (i.e. V_A=V_β) and the phase of V_B is that of V_α (i.e. V_B=V_α).