Abstract: A narrow bandwidth signal, such as a narrowband FM signal, is modulated in a modulator that modulates a wide bandwidth signal, such as a CDMA signal, by oversampling the narrow bandwidth signal and applying the oversampled narrow bandwidth signal to the modulator. By oversampling the narrow bandwidth signal, the same fixed low pass filter can be used for both the wide bandwidth signal and the oversampled narrow bandwidth signal. Accordingly, different low pass filters or switched low pass filters are not needed. The DC offset that is introduced by the digital-to-analog converter and/or the low pass filter of the modulator is compensated, preferably in the digital domain, to thereby reduce DC offset within acceptable limits for the modulation that is being used. More preferably, compensation is provided by subtracting from the sampled signal, a digital value representing the DC offset in the filtered analog signal that is introduced by the digital-to-analog converter and/or the low pass filter.

Abstract: Transceiver circuitry 1 comprises a first portion 10,20,30,41,50,100, having a first modulation means 41 operating at a first order of modulation, for transmitting and receiving voice signals; a second portion 20,30,42,50,100, having a second modulation means 42 operating at a second order of modulation, for transmitting and receiving digital signals at a higher data rate than is achievable by the first portion; and a data conversion means 20,30,100 operable to convert from or into voice signals intended for processing by the first portion into or from digital signals for processing by the second portion.

Abstract: A system to perform angle quantization includes a log ROM lookup table to provide a log of a real input (10) of a signal and a log of an imaginary input (20) of the signal. A subtractor (100) computes the difference between the log of the real input and the log of the imaginary input to provide a difference (102) equivalent to a division of the inputs, and a ROM lookup table (110) determines a phase from the difference.

Abstract: A method and system to create an ultra wideband (UWB) signal are disclosed. The UWB signal comprises a carrier frequency with each cycle reversing in phase. The UWB signal is generated from a limited number of high power narrow band amplifiers. Each amplifier's output signal is combined to produce the desired UWB signal. The combination may occur in a combiner network or in free space.

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: Compensating for non-linear distortion generated during non-linear high-power amplification in a transmitter after quadrature modulation of a baseband signalby extracting a non-linear distortion component from a non-linearly high-power amplified modulated signal; correcting a phase characteristic such that respective frequency signals in a frequency band of the non-linear distortion component have equal phase delays; quadrature-demodulating the corrected distortion component into a baseband distortion component; and overlapping a phase-inverted distortion component of the quadrature-demodulated baseband distortion component with the baseband signal.

Abstract: A signal source generates a phase-modulated output signal responsive to a phase-modulation signal. A phase splitter splits the phase-modulated output signal into two or more phase-offset output signals. A switch provides a selected one of the phase-offset output signals from the phase splitter to a transmit amplifier circuit. Large phase transitions in the phase-modulation signal are detected and reduced to decrease modulation bandwidth requirements at the signal source. When a phase transition in the phase-modulation signal is reduced, the switch is coherently switched from one phase-offset output signal to another to substantially restore the full phase transition in the output signal presented to the transmit amplifier circuit. In this manner, the transmit amplifier receives substantially the same phase transitions as are in the original phase-modulation signal.

Abstract: The invention reduces transient peaks in signals transmitted in CDMA communication systems. A plurality of spread spectrum data signals are combined into a combined signal having fluctuating power level corresponding to the combination of the data signals. The combined signal is modulated to produce an RF signal for transmission. The average power of the combined signal is measured over a selected time period. The combined signal power level is adaptively limited to a calculated power level based at least in part on the measured power.

Abstract: The present invention provides a method and apparatus for implementing a continuous phase modulation with an approximate phase constellation. The method reduces complexity by using fewer than all phase points of the nominal phase constellation. The method includes the steps of storing (502) an approximate phase constellation of phase points (100) selected from a nominal phase constellation of phase points, identifying (504) a next phase in the approximate phase constellation of phase points using an N-bit input word, and outputting (506) the next phase. In reducing the number of phase points used in the modulation, the method may store only unique phase points in said phase constellation, and may further reduce the number of phase points by storing only those phase points differing by at least a phase threshold.

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 transmitter has a phase modulator and a phase locked loop that has a relatively high powered voltage controlled oscillator. The phase locked loop has a phase sensitive detector for comparing a phase comparison frequency derived from the voltage controlled oscillator output with a phase modulated intermediate frequency carrier derived from the phase modulator. The phase modulator has a reference frequency source, means for deriving four quadrature phase components of the reference frequency produced by the source and phase selection means controlled by complex modulation means for deriving the phase modulated intermediate frequency carrier by random interpolation between the four quadrature components.

Abstract: A baseband signal modulator provides a phase and amplitude modulated carrier signal. First and second phase modulators each receive a common reference signal and derive therefrom a carrier signal frequency. The phase modulators each receive a respective pair of phase-encoded data signals so as to provide respective first and second phase-encoded carrier. The modulator outputs are summed to provide the phase and amplitude modulated carrier signal. Each phase modulator includes a respective phase locked loop incorporating an oscillator locked via the common reference signal to the carrier signal frequency, and a phase adder having a first input for receiving the carrier frequency signal and having second and third inputs for receiving the respective pair of data encoded signals.

Abstract: A method and apparatus for generating digitally modulated signals in which a serial data stream of digital signals to be modulated (70) is provided, the serial data stream being converted into real and imaginary components (74) which are then converted into a complex polar signal (80) representing the serial data stream. A carrier of appropriate frequency is generated by an infinite impulse response filter (84,86) and the polar signal is mixed with the output of the infinite impulse response filter to provide a representation of the complex polar signal modulated at the frequency generated by the infinite impulse response filter (88). Subsequently the imaginary component of the resulting representation is stripped from the signal (90) and the real component of the resulting representation is applied to a digital to analog converter (92) to produce an analog version of the serial data stream.

Abstract: The fundamental waves and 3rd harmonics waves of two local signals output from a 90° phase shifter are suppressed by use of low-pass filters. The local signals in which the fundamental waves and 3rd harmonics waves are suppressed are respectively supplied to two multipliers and respectively multiplied by Ich and Qch base-band signals. The results of multiplication in the two multipliers are added together in an adder to create a modulation signal.

Abstract: A radio receiver is adapted to receive radio signals in at least two frequency bands, in which the radio signals are modulated by information signals. The radio receiver includes a device for down-converting a received radio signal to an intermediate frequency signal by using a local oscillator, and a demodulating device for recovering the information signals from the intermediate frequency signal. The frequency of the local oscillator is selected so that the frequencies of at least one of the frequency bands are above the frequency of the local oscillator, and the frequencies of at least one of the frequency bands are below the frequency of the local oscillator.

Abstract: The circuit for combined operation of a mobile radio with GMSK and 8-PSK modulation includes a transmission PLL for GMSK operation, and a direct modulator for 8-PSK operation. A transmission oscillator in the transmission PLL is also used as a synthesizer oscillator for the direct modulator. The modulation in the transmission PLL is suppressed for this purpose. The circuit allows cost-effective implementation while retaining the advantages of a transmission PLL.

Abstract: A communication system (100) provides selecting a first modulation-coding scheme (111) based on a quality indicator of a communication between a source user and a first destination user, determining a first possible number of data bits (201) that can be modulated and encoded according to selected modulation-coding scheme (111) and spread according to one spreading code of a plurality of spreading codes (108-1 through 108-k) which results in fitting in a predetermined time frame, determining a first number of data bits (102) to be transmitted from the source user to the first destination user, determining a first load level based on comparing first number of data bits (102) and first possible number of data bits (201), and, if the first load level is unequal to a whole number, rounding to a next first whole number, selecting a first number of plurality of spreading codes (108-1 through 108-k) based on the first whole number of load level for spread coding of first number of data bits (102) after being modulate

Abstract: The invention relates, inter alia, to a transmitter device, in particular for a base transceiver station in a mobile radio system, which has a digital modulator for making available a signal containing a phase information, and a modulation closed loop having a digital phase comparator operating at baseband whose first input is connected to the output of the digital modulator. In addition, a controllable oscillator is provided for generating an RF transmission signal at a controllable transmission frequency, a device which is assigned to the controllable oscillator and has the purpose of converting the RF transmission signal into a baseband signal containing a phase information. The output of the converter device is connected to a second input of the digital phase comparator.

Abstract: A method and apparatus for predicting signal values for signals that have not yet been received wherein the information stream transmitted has been divided into a first stream and a second stream. A first Q component is predicted based on values stored in a state memory for the first bit stream. A first I component is predicted using the first predicted Q component and a previous bit from the state memory for the first bit stream. Then, a second Q component is predicted based on values in the state memory for the second bit stream. A second I component is then predicted using the second predicting Q component and the previous bit from the second bit stream. The first I component and the second Q component are added to obtain a combined I value and the first Q component and the second I component are added to obtain a combined Q value.

Abstract: The invention relates to a transmitter and a method of generating a transmission signal, which transmitter includes a modulation device (110) for generating two uncompensated transmission signals Y, Z by respective modulation of at least one baseband signal I, Q with an oscillation signal XLOQ, XLOI, the two uncompensated transmission signals Y, Z containing at least one respective interference component, which interference components are phase shifted by a given amount relative to one another.

Abstract: A power amplifier for use in a wireless communication system operates like a quadrature mixer with conversion gain. The amplifier includes a local oscillator that generates two reference signals 90° out of phase with respect to each other. Four quadrature mixer elements receive signals representing the in-phase and quadrature components of a baseband signal. Each quadrature mixer amplifies the in-phase or the quadrature component of the baseband signal while upconverting with the corresponding reference signal.

Abstract: Apparatus for phase/frequency digital modulation includes a digital circuit receiving and processing a digital modulation input signal to generate a digital modulation control signal, a digital-to-analog converter coupled to the digital circuit converts the digital modulation control signal into an analog modulation control signal, and an RF/analog circuit is coupled to the digital-to-analog converter. The RF/analog circuit includes a voltage controlled oscillator to generate a modulated output signal in response to the analog modulation control signal, and a quadrature tuner coupled to the voltage controlled oscillator generates an in-phase tuner output and a quadrature tuner output in response to the modulated output signal. An analog-to-digital converter is coupled to the quadrature tuner and converts the in-phase tuner output and the quadrature tuner output to digital in-phase and quadrature tuner outputs.

Abstract: In the phase modulation multiplexing transmission unit of FIG. 2, a digital input signal is divided by a signal division unit 1, each of the resultant division signals is output to multiplication units 3a and 3b, respectively. The multiplication units 3a and 3b multiply the division signals by spread code signals output from spread code generators 2a and 2b, respectively. A multiplication signal Sb output from the multiplication unit 3b is shifted by &pgr;/2 radian through a phase shifter 4, which is added to a multiplication signal Sa output from the multiplication unit 3a through an adder 5. A synthetic signal Se(n) output from the adder 5 is BPSK modulated through a modulator 6, which is transmitted through a transmission amplifier 7 and an antenna 8.

Abstract: A power amplifier for use in a wireless communication system operates like a quadrature mixer with conversion gain. The amplifier includes a local oscillator that generates two reference signals 90° out of phase with respect to each other. Four quadrature mixer elements receive signals representing the in-phase and quadrature components of a baseband signal. Each quadrature mixer amplifies the in-phase or the quadrature component of the baseband signal while upconverting with the corresponding reference signal.

Abstract: A quadrature modulator includes a local oscillator oscillating at an oscillation frequency equal to 4/(2N+1) times a carrier frequency where N is a natural number, a frequency conversion block for multiplying the oscillation frequency by a factor of (2N+1)/2, a divider for dividing the multiplied oscillation frequency to output a pair of orthogonal carrier waves, first and second multipliers for modulating the carrier waves with a digital baseband signal, and an adder for adding the modulated carrier waves to output a carrier signal having the carrier frequency. The frequency conversion block includes a divider for dividing the oscillation frequency, N frequency mixers cascaded from one another and a band-pass-filter, which are cascaded in this order.

Abstract: A modulator is configured with a first multiplexer having a first data signal input coupled to receive the first digital baseband signal and a second data signal input coupled to receive the second digital baseband signal. The first multiplexer provides a multiplexed output signal including components of the first and second digital baseband signals. The modulator also includes a source of alternating samples of first and second carrier signals and a multiplier having a first input coupled to the output of the first multiplexer and a second input coupled to the source of carrier signal samples. The multiplier is thereby coupled to provide a digital modulated output signal. The source of alternating samples of first and second baseband signals may include a second multiplexer having a first signal input coupled to receive a first carrier signal and a second signal input coupled to receive a second carrier signal.

Abstract: A method has the steps of generating a first control message having a plurality of message symbols and a first audio message to be transmitted from a first radio-communications device to a second radio-communications device. The first audio message is sampled to obtain a first plurality of audio samples, each with an instantaneous signal valve, and a first radio frequency signal which varies in frequency from a first predetermined radio frequency dependent on the instantaneous signal valves of the first plurality of samples is generated. The first radio frequency signal is formatted into a first pulsed radio frequency signal, each pulse having a time duration representative of one of the plurality of message symbols of the first control message, which is transmitted from the first radio-communication device to the second radio-communication device.

Abstract: A modulated signal is translated to a broadcast frequency by a translation phase lock loop. In the translation phase lock loop the output frequency, which is the broadcast frequency, is mixed with a translation frequency, and the resulting translated frequency is compared to the modulated signal. If an amplitude modulator is inserted into the translation loop, the phase comparison/feedback nature of the phase lock loop will tend to cancel the phase noise introduced in the amplitude modulation process. Any other circuits placed within the loop will tend to have any phase noise they introduce, which is in the phase lock loop bandwidth, canceled by the loop.

Abstract: A digital filter and modulator provides programmable distinctive modulation on a programmable frequency selective basis with channelization. The digital channelization processor includes a plurality of channels. Each channel includes a filter and transform circuit that convert a real input signal to a quadrature signal that has a magnitude signal and a phase signal. The quadrature signal is offset and converted back to a real signal that is temporarily held and phase shifted. The digital filter and modulator minimize throughput delay and eliminate analog tolerance and inflexibility problems while eliminating digital processing overflow difficulties.

Abstract: The present invention provides a method for transmission of serial information over a wireless channel. The method includes modulating bits of information at selected parts of each cycle of a carrier waveform. At the receiving side, the selected parts of each cycle of the modulated waveform are integrated to produce an integrated value and compared with stored value to recover transmitted bits.

Abstract: A circuit arrangement with a data sequence generator for the generation of an oscillator signal as a sequence of digital data, and having the following circuit parts: a first multiplication unit driven by a first auxiliary signal and a first control signal, where the first control signal corresponds to the sine of a manipulated variable that determines the frequency of the oscillator signal; a second multiplication unit driven by a second auxiliary signal, where the second control signal corresponds to the cosine of the manipulated variable; a third multiplication unit driven by a third auxiliary signal and a third control signal, where the third control signal corresponds to the sum of the first and second control signal; a first adding unit driven by the first multiplication unit and third multiplication unit; a second adding unit driven by the first multiplication unit and the second multiplication unit; a first time-delay unit driven by the first adding unit, where the oscillator signal is provided as a t

Abstract: A variable rate modulator for selectively encoding a variable rate data stream according to one of a plurality of modulation formats. A timing and control circuit locks the variable rate data to a master clock, an encoder selectively encodes the data according to one of a plurality of modulation formats, and a polyphase filter performs pulse shaping and interpolation functions using only shift and add functions to produce a DAC-ready output signal.

Abstract: A transmitting circuit comprises a QPSK modulator, a voltage controlled oscillator used as a frequency modulator, and a PLL circuit for controlling the oscillation frequency of the voltage controlled oscillator. The frequency of a reference signal supplied to the PLL circuit is used as a first reference frequency in the event of performing the QPSK modulation by the QPSK modulator and is used as a second reference frequency lower than the first reference frequency in the event of performing the frequency modulation by the voltage controlled oscillator.

Abstract: A transmitter in which a complex low IF digitised signal is applied in quadrature to a complex phase comparator together with a digitised frequency down-converted version of an analogue signal produced by a transmitter VCO. The low IF digitised signal serves as a reference against which the digitised frequency down-converted version of the transmitter VCO is compared. The output of the complex phase comparator is converted to an analogue signal which is applied as a control signal to the transmitter VCO. An analogue embodiment of the transmitter which uses zero-IF signals is also disclosed.

Abstract: A method and device are adapted to perform digital frequency modulation. First, an input frequency modulation signal is converted into a digital signal via an A/D (Analog/Digit) adapter, then a varied carrier frequency parameter "a" for each different system is added to the digital signal by an adder; next, the digital signal is multiplied by a various frequency variation parameter "b" assigned to each different system accordingly, and is further multiplied by another number 2.sup.-U, U=10 for SVHS system and U=11 for VHS system, by a multiplier; afterwards, the digital signal is processed by a digital integrator; then corresponding amplitudes in mapping with all angles .theta. and .theta.' within 360 degrees are obtained by sin.theta. ROM and Cos.theta.' ROM, wherein Z.sup.-1 is a flip-flop, the parameters "a", "b" are variable corresponding to specifications of PAL, NTSC, VHS, SVHS systems and the interlace scanning so as to make the design applicable to various systems.

Abstract: A code multiplexing transmitting apparatus spread-spectrum modulates transmission data of a plurality of channels by spreading codes that differ from one another, combines the spread-spectrum signals of each of the channels and transmits the resultant spread-spectrum modulated signal. A spread-spectrum modulating unit for each channel includes a phase shifter for shifting, by a predetermined angle channel by channel, the phase of a position vector of the spread-spectrum modulated signal of each channel. As the result of such phase control, the phases of pilot signal portions of the spread-spectrum modulated signals of the respective channels are shifted relative to one another so that the peak values of the code-multiplexed signal can be suppressed.

Abstract: A modulator and modulation method for orthogonally modulating digital baseband signals include interpolation filters that frequency convert the frequencies of an in-phase component and a quadrature phase component of a digital baseband signal to four times the frequency of an intermediate frequency. .DELTA..SIGMA. modulation circuits are provided and .DELTA..SIGMA. modulate the frequency converted signals. A low pass filter is provided to remove unnecessary components from the .DELTA..SIGMA. modulated signals. A switching circuit selects a signal that has passed through the low pass filter according to an order of an in-phase component, a code inverted component of a quadrature phase component, a code inverted component of the in-phase component and the quadrature phase component, and outputs these signals as a digital orthogonal signal. An N bit D/A converter converts the digital orthogonal signals into analog orthogonal signals.

Abstract: A novel and improved method and apparatus for generating a reduced peak amplitude high data rate channel comprised of a set of lower rate channels is described. The set of lower rate channels are phase rotated before being summed and transmitted. The amount of phase rotation is dependent on the number of channels used to form the higher rate channel. In an embodiment where two lower rate channels are used, the in-phase and quadrature-phase components of the two channels are complex multiplied before upconversion with an in-phase and quadrature-phase sinusoids. For a high rate channel comprised of more than two lower rate channels, the in-phase and quadrature-phase component of each channel is upconverted with a set of sinusoids that are phase offset from one another.

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 programmable apparatus is disclosed for generating a frequency modulated signal at a selected center frequency in accordance with digital data of at least first and second data levels. The modulating apparatus comprises a modulator having an input and an output and is responsive to an input modulation signal applied to its input for generating at its output the frequency modulated signal at a center frequency dependent on a quiescent voltage appearing at its input. A circuit is provided for sampling and storing a value of the quiescent voltage. An addressable memory stores a plurality of offsets. A programmable adding circuit adds a downloaded offset voltage to the stored value of the quiescent voltage to output a high modulation voltage. A programmable subtracting circuit subtracts a downloaded offset voltage from the stored value of the quiescent voltage to provide a low modulation voltage.

Abstract: A communication system supports multiple modulation schemes having differing symbol rates. The system supports two modulation schemes that have the same symbol rate and at least one modulation scheme that does not have the same symbol rate. For as long as communication can be carried out using the modulation schemes with the same symbol rate, the system avoids using the modulation scheme with different symbol rate, even if communication can be carried out using this scheme.

Abstract: Method and apparatus for recovering in a receiver of a wireless communications system independent bit streams from each of two co-channel frequency modulated carriers. In the transmitter, timing for the two independent bit streams is derived from a common clock. One bit stream is placed directly on the carrier of greater power. An XOR circuit maps the two bit streams into one bit stream which is placed on the carrier of lesser power. In the receiver, an ordinary frequency demodulator provides an output consisting of the bit stream of the dominant carrier having superimposed voltage spikes. A limiter removes the spikes and provides as output the bit stream on the carrier of greater power. The peak value and the rate of occurrence of the spikes each contain information about the bit stream on the carrier of lesser power. A peak voltage detector provides an output signal which indicates the differences in the peak value of the spikes.

Abstract: A phase modulator having a Gilbert cell mixer can be used in frequency ranges from a microwave frequency band of several GHz to a millimeter wave band of several 10 GHz. Two output signals Vout1, Vout2 from the Gilbert cell mixer are supplied to balanced input terminals of a balanced-to-unbalanced converter, which produces a phase-modulated output signal Vout from an unbalanced output terminal thereof. Even when a differential amplifier comprising FETs Q1, Q3 and a differential amplifier comprising FETs Q2, Q4 do not operate symmetrically, the phase modulator generates phase-modulated output signals that have the same amplitude as each other and are in opposite phase to each other. With the Gilbert cell mixer comprising FETs, the phase modulator can be used in the frequency ranges described above. If the balanced-to-unbalanced converter is in the form of a planar circuit, then the phase modulator may be implemented by an MMIC.

Abstract: A technique which enables the use of a low cost linear power amplifier to generate a wideband composite signal, such as in cellular mobile telephone (CMT), personal communication system (PCS), or other multi-channel wireless systems. A composite signal is generated by a wideband digital combiner as a frequency multiplexed combination of many narrowband modulated digital carrier signals. The technique involves introducing predetermined phase shifts into each of the digital channel signals after a baseband modulation step. The wideband composite signal thus exhibits a reduced peak-to-average signal power, despite the fact that the phases of the digital carrier signals cannot be directly controlled. This permits the use of a power amplifier, which may have a much smaller peak-to-average rating.

Abstract: Disclosed is a digital multiplication circuit to multiply a digital signal SN by a periodic waveform that is, in principle, a sine waveform. This circuit uses a phase digital generator .phi. varying in saw-toothed form and it uses an approximation of the samples of a function K sine .phi. by algebraic sums of positive integer values of two for each phase value, K being a coefficient identical for all the phase values. The product of SN by these sums is rapid and easy to obtain and does not require a sine table. A decoder receiving the phase .phi. defines the powers of two to be set up, and a routing circuit carries out the operation of multiplication by powers of two under the control of the decoder. One or two adders obtain the sums of powers of two. The result is an approximate result of the product SN.K. sine .phi..

Abstract: A transmitter which can easily suppress diffusion of a spurious signal with a simple constitution, wherein the on/off operations of the transmitting circuit and the carrier signal generating circuit are controlled by the first control signal which rises at the predetermined timing and falls at the predetermined timing, and the on/off operation of the modulator is controlled by the second control signal which gently rises at the same or later timing than the rise timing of the first control signal and gently falls at the same or earlier timing than the fall timing of the first control signal, so that a phenomenon which is similar to pulse modulation of the leaked carrier signal fc becomes hard to be generated, therefore diffusion of the spurious signal can be suppressed.

Abstract: A remote ground terminal transmitter for transmitting a modulated data signal having a constant envelope amplitude. The remote ground terminal transmitter comprises a source of data signals, a modulator for providing a carrier signal, receiving a data signal from the source of data signals, and modulating the carrier signal with the received data signal so as to produce a constant envelope minimum shift key modulation signal. The transmitter further comprises a power amplifier which operates in the saturation mode to amplify the modulated carrier signal produced by the modulator to the desired power level.

Abstract: A base band waveform generation circuit 10 calculates the equations: I.sub.1 ={I+Q.multidot.SQRT(4/a.sup.2 -1)}/2; Q.sub.1 ={Q-I.multidot.SQRT(4/a.sup.2 -1)}/2; I.sub.2 ={I-Q.multidot.SQRT(4/a.sup.2 -1)}/2; and Q.sub.2 ={Q+I.multidot.SQRT(4/a.sup.2 -1)}/2, based on I and Q of a modulating signal. Where, SQRT(x) refers to a square root of x, that is, a.sup.2 =(I.sub.2).sup.2 +(Q.sub.2).sup.2. A quadrature modulator 12 quadrature modulates a carrier with the I.sub.1 and Q.sub.1. A quadrature modulator 22 quadrature modulates a carrier with the I.sub.2 and Q.sub.2. The output signals of the quadrature modulators 12 and 13 are amplified with a transmission power amplifiers 13 and 23, then composed.

Abstract: An improved quadrature phase shift key modulator circuit of the type which includes a non-linear amplifier in the transmitter and includes a frequency select logic circuit for receiving the in phase and quadrature phase digital data to be modulated onto a carrier frequency signal. The output of the frequency select circuit produces select signals that are coupled to the input of a digital carrier frequency generator. The digital carrier frequency generator synthesizes and increases, decreases, or leaves unchanged the carrier frequency as a representation of the data occurring on the in phase and quadrature phase input lines. The output of the digital carrier frequency generator is smoothed and converted to an analog signal which has a constant vector power magnitude during phase change.

Abstract: A communications reduced instruction processor forming a simple programmable digital signal processing architecture (10) for processing analog waveforms. The architecture (10) includes a main DSP core that includes a tightly coupled CORDIC co-processing element (26). The CORDIC co-processing element (26) performs trigonometric operations for converting polar coordinates to rectangular coordinates and rectangular coordinates to polar coordinates. These trigonometric functions include an angle accumulate operation for calculating the magnitude and angle of a vector given in X-Y cartesian coordinates, and a vector rotate operation for calculating a sine and a cosine of a given phase angle.