Abstract: A polar-loop wireless communication apparatus includes, on a forward path between an amplitude detector and a power amplifier which constitute an amplitude control loop, a variable gain amplifier and a switch to change characteristics of a loop filter to output a frequency bandwidth of the amplitude control loop to an order less than an order for normal operation. The system is operated with the characteristics set to the lower order to measure outputs from the power amplifier to calibrate the output power of the power transmitter, and the register is operated with the characteristics set to the higher order to measure the open loop gain of the amplitude control. According to results of the calculation, data to correct gain characteristics of the variable gain amplifier with respect to an output control signal is stored in a nonvolatile memory of a baseband circuit.

Abstract: A transmitter comprises a device (20) for frequency up-conversion of a communication signal having at least two consecutive frequency conversion stages, a power amplifier (27) for amplifying the output signal therefrom for obtaining a transmission signal and means (29) for extracting the transmission signal. It also has a device for frequency down-conversion of said extracted transmission signal to the same frequency as the communication signal before said up-conversion for creating a feedback signal. Said two devices use the same local oscillators (25, 26). The transmitter also has means for signal parameter adaptation of the communication signal on basis of the feedback signal for obtaining a desired character of the transmission signal.

Abstract: In one aspect this invention provides a DC-DC converter that has a switch mode part for coupling between a DC source and a load, the switch mode part providing x amount of output power; and that further has a linear mode part coupled in parallel with the switch mode part between the DC source and the load, the linear mode part providing y amount of output power, where x is preferably greater than y, and the ratio of x to y may be optimized for particular application constraints. In a further aspect there is a radio frequency (RF) transmitter (TX) for coupling to an antenna, where the TX has a polar architecture having an amplitude modulation (AM) path coupled to a power supply of a power amplifier (PA) and a phase modulation (PM) path coupled to an input of the PA, where the power supply includes the switch mode part for coupling between a battery and the PA and the linear mode part coupled in parallel with the switch mode part between the battery and the PA.

Abstract: The invention relates to a transmitter which comprises a modulator providing a phase-modulated constant-envelope radio-frequency signal, and to a method of controlling the power level of a signal output by such a transmitter. In order to enable a power control over a large power range, it is proposed that a provided phase-modulated constant-envelope radio-frequency signal is divided into two identical signals for the power control. A first control arrangement then controls the output power for higher power levels by controlling amplifications applied to the two signals. A second control arrangement controls the output power for lower power levels by controlling phase shifts applied to the two signals. The processed signals are then combined and provided as a power controlled output signal.

Abstract: Phase modulation control techniques and supporting apparatus avoid phase discontinuity at the outset of RF signal generation. Such discontinuities might arise from phase control instabilities associated with transmit start up or from abrupt changes in phase at the beginning of transmit signal generation. A transmitter uses starting phase values in advance of transmit data phase values to initialize phase modulation control circuits or functions. Once phase control is stabilized, and possibly after other criteria are met, the transmitter transitions from using the starting phase values to using the transmit data phase values, so that a transmit signal begins carrying phase modulations associated with the desired transmit data.

Abstract: The present invention provides a unique feedback system in a wireless communication system wherein the transmission channel is always overloaded with data, which is configured and modulated at a select order of modulation. Based on the channel conditions, only a portion of the data can be successfully received. As such, the receiver will attempt to receive the data using demodulation techniques corresponding to the different levels of modulation used to encode the data transmitted. The receiver will determine the data that is recovered, or the highest order of modulation at which the data is recovered, and provide feedback to the transmitter. The transmitter will then retransmit the data that was not properly received. By overloading the channel at all times, the maximum amount of data capable of being transmitted over the channel is optimized without requiring or heavily relying on the receiver feeding back channel condition information to the transmitter.

Abstract: The invention relates to a transmitting device limiting the out-of-band interferences. The modulation is done with or without inversion of the spectrum. Next, frequency transposition is done in supradyne or infradyne fashion such that the parasitic effects originating from the modulation are always situated in the frequency band allocated for transmission. The invention relates to the transmission method, on the one hand, and to the transmission device, on the other hand.

Abstract: A system and method are provided for communicating a radio frequency (RF) signal. In use, a baseband signal is mixed with a plurality of oscillator signals with different phases in an interleaving manner. The mixed baseband signal is then communicated as an RF signal.

Abstract: The invention provides a method and a device for amplitude modulation of a radio frequency signal using a variable-gain radio frequency power amplifier, for automatic control of the amplifier output signal by generating an error signal between an amplitude modulation signal and a signal representing the power of the amplifier output signal, from which a gain control signal of the amplifier is generated, to monitor potential saturation of the amplifier by comparing the relative phases of the error signal and of the amplitude modulation signal, and, in case of saturation of the amplifier, to generate a correction signal for lowering the operating point of the amplifier. The invention is applicable to a transmitter of a mobile station or a fixed station of a radio communication system.

Abstract: Method and radiofrequency apparatus comprising at least one transmitter and/or one receiver of one or more useful signals comprising at least one device adapted to applying a coefficient to the useful signal or signals. Application to BPSK to QPSK type modulation.

Abstract: There is provided an antenna array apparatus using a GPS signal in a base station and a beamforming method thereof. In the antenna array apparatus, a GPS signal processor receives GPS position information from a mobile station and calculates the position information of the mobile station. A signal processor calculates a weight vector using the position information to form a transmission/reception beam. A transmission/reception beamformer forms the transmission/reception beam according to the weight vector.

Abstract: The present invention, generally speaking, provides methods and apparatus for producing an amplitude modulated communications signal, in which a constant-envelope carrier signal is modified in response to a power control signal to produce a modified constant-envelope carrier signal. The modified constant-envelope carrier signal is amplified in response to an amplitude modulation signal to produce a communications signal having amplitude modulation and having an average output power proportional to a signal level of the modified constant-envelope carrier signal. This manner of operation allows wide dynamic range of average output power to be achieved. Because amplitude modulation is applied after amplitude varying circuitry used to produce the modified constant-envelope carrier signal, the amplitude modulation is unaffected by possible non-linearities of such circuitry.

Abstract: The present invention provides a baseband RF clock synthesizer having particular use in a BLUETOOTH piconet device, which has the capability of providing simple and accurate calibration of modulation path gain (KMOD) by introducing a dual-loop phase locked loop (PLL) in the RF clock signal synthesizer. The disclosed technique and apparatus controls the maximum frequency deviation by the difference of two locked frequencies, one frequency in each path of the dual-path PLL. Once the PLL is locked within some frequency error, the present technique and apparatus calibrates for the deviation of amplitude of the modulation due to the modulation path. Accordingly, modulation gain (KMOD) calibration is provided by adding an auxiliary loop to a PLL in an RF frequency synthesizer.

Abstract: A transmitter and method is provided for digitally upconverting a baseband digital signal to a modulated intermediate frequency (IF) digital signal and sigma-delta modulating the IF digital signal. The baseband digital signal is split into N phases, as can be accomplished using a polyphase interpolation technique (polyphase filter), and modulated. The modulated N phases are not recombined and each phase is further modulated, as can be accomplished using a digital-to-digital sigma-delta modulator that generates digital output signals at the same rate. A high speed digital multiplexer multiplexes the digital output signals into a single bit stream at a higher rate for subsequent power amplification and RF transmission.

Abstract: A method (900) and a mobile station (160) for autonomously determining an angle of arrival (AOA) estimation are described herein. The mobile station (160) may receive information associated with a plurality of sectors (200) from a base station (140) having a plurality of antennas. Each of the plurality of antennas may provide communication service to one of the plurality of sectors (200). The information associated with the plurality of sectors (200) may be an antenna pattern, a boresight, a downtilt, and a signal strength value associated with each of the plurality of antennas. Based on the information associated with the plurality of sectors (200), the mobile station (160) may determine an antenna gain difference, which in turn, is used to determine the angle of arrival (AOA) estimation.

Abstract: A translation loop signal upconverter is disclosed. Embodiments of the invention minimize nth order harmonics and spurious tones in the radio frequency output spectrum of a portable transceiver. In one embodiment, the invention is a signal upconverter, comprising a modulator configured to develop a modulated intermediate frequency (IF) signal at a fundamental frequency, the modulated IF signal also including a plurality of nth order components, a synchronous oscillator configured to receive the modulated IF signal, the synchronous oscillator also configured to operate at the fundamental frequency of the modulated IF signal, thereby providing an IF signal substantially free of the nth order components, and a translation loop having a phase locked loop, the translation loop configured to receive the IF signal output of the synchronous oscillator, and supply a radio frequency (RF) output signal to a power amplifier.

Abstract: An electronically programmable multimode circuit is described. More particularly, the present invention is an electronically programmable multimode circuit that includes a first path and a second path wherein a mode and a signal directional flow direction is controlled through the selective biasing of the first path and the second path. A multimode circuit is produced that contains modes such as a phase shifter mode, an IQ modulation mode, an amplifier mode, a mixer mode, and a multiplier mode.

Abstract: Embodiments of methods, transmitters, and computer program products are provided for transmitting a signal by adjusting a delay between an amplitude component of the signal and a phase component of the signal based on the transmission power. Error vector magnitude and adjacent channel power ratio are two common criteria used in evaluating transmitter performance. By adjusting the delay between the amplitude component of the transmitted signal and the phase component of the transmitted signal, the error vector magnitude and/or the adjacent channel power ratio may be reduced. The particular delay value that provides the best error vector magnitude performance and/or adjacent channel power ratio performance may differ based on the transmission power level. Therefore, the delay value is adjusted based on the transmission power.

Abstract: The present invention is directed towards a data detector for deriving a data signal from an incoming radio frequency input. The data detector comprises a delay logic which receives an unfiltered signal in quadrature and in-phase components, and applies a delay to each of the in-phase and quadrature phase components of the unfiltered input signal. The detector further comprises a first multiplication logic that multiplies the delayed in-phase component of the unfiltered signal by the quadrature phase component of the unfiltered signal to obtain a first result, and a second multiplication logic that multiplies the delayed quadrature phase component of the unfiltered signal by the in-phase component of the unfiltered signal to obtain a second result. Finally, an adder adds the first result with the second result to generate a data signal. In alternative embodiments a post detection correction algorithm may be added to improve performance.

Abstract: The invention relates to a transmitter which comprises a modulator providing a phase-modulated constant-envelope radio-frequency signal, and to a method of controlling the power level of a signal output by such a transmitter. In order to enable a power control over a large power range, it is proposed that a provided phase-modulated constant-envelope radio-frequency signal is divided into two identical signals for the power control. A first control arrangement then controls the output power for higher power levels by controlling amplifications applied to the two signals. A second control arrangement controls the output power for lower power levels by controlling phase shifts applied to the two signals. The processed signals are then combined and provided as a power controlled output signal.

Abstract: A closed power control feedback loop system allows a single portable transceiver architecture to be used for systems in which a transmit signal including both a phase modulated (PM) component and an amplitude modulated (AM) component are supplied to a power amplifier and in systems in which the transmit signal has only a PM component supplied to a power amplifier. By injecting the inverse of the AM portion of the desired transmit signal into the closed power control feedback loop, the feedback loop will not cancel the AM portion of the signal, thus allowing a system where both a PM component and an AM component of the transmit signal are present at the output of the power amplifier to function using a closed power control feedback loop.

Abstract: The invention provides an apparatus and procedure for radio transmission of information using a middle channel, a first side channel and a second side channel. The transmitted middle channel is FM-modulated by a suitable frequency. A signal symmetrically amplitude-modulated with respect to the center frequency of the middle channel is generated, and a first amplitude-modulated single side band (LSB) and a second amplitude-modulated single side band (USB) are formed from the amplitude-modulated signal. The first single side band (LSB) is modulated by the information in the first side channel to form two side bands for the first single side band, and the second single side band (USB) is modulated by the information in the second side channel to form two side bands for the second single side band. The middle channel FM signal, the modulated first single side band (SSB) and the second modulated single side band (SSB) are then combined in a combiner for simultaneous transmission of all three channels.

Abstract: The invention relates to a method for modulating an output voltage of a transmitter circuit comprising a voltage controlled oscillator, a digital/analog converter and an antenna circuit, the method comprising the method comprising sending an output signal of sufficient power from the voltage controlled oscillator directly to the antenna circuit and directly modulating a frequency of the output signal of the voltage controlled oscillator. The invention furthermore relates to a transmitter circuit comprising a voltage controlled oscillator having a tank circuit, a digital/analog converter and an antenna circuit, wherein the voltage controlled oscillator is adapted to send an output signal of sufficient power directly to the antenna circuit and wherein the digital/analog converter is arranged to modulate an output frequency of the voltage controlled oscillator.

Abstract: A shaped-wave application section inputs a first pulse signal corresponding to transmission data output from a transmission data output section, and applies, to a modulation and amplification section, a signal wave corresponding to a second pulse signal such that the waveform of the first pulse signal is shaped. The pulse signal applied to the base of the transistor of the modulation and amplification section is amplitude-modulated into an amplitude-modulated wave in which the amplitude-modulated portion is strengthened, in accordance with the signal wave corresponding to the second pulse signal applied to the emitter thereof. The amplitude-modulated wave is supplied to an antenna section including a resonance circuit via the collector thereof, and is transmitted as an electromagnetic wave from the antenna section.

Abstract: A phase error detector that detects phase error between differential signals. A quadrature oscillator provides in-phase (I) and quadrature phase (Q) differential carrier signals and receives a phase error signal from the phase error detector. The oscillator maintains a quarter cycle phase delay between the I and Q carrier signals based on the phase error signal. The phase error detector includes a summing network and first and second bipolar transistor mixer circuits. The summing network develops four sum signals by summing respective pairs of the differential components of the I and Q carrier signals. A bias circuit biases the transistors to turn on at positive base voltages. The mixer circuits may include filter capacitors so that the transistors are responsive to positive base voltages. The mixer circuits develop polarity signals based on the sum signals, and the resulting phase error signal is the differential of the polarity signals.

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: A modulator, and an associated method, are described for use by a sending station, operable in a communication system, to communicate data to a receiving station upon a communication channel susceptible to fading. The modulator includes a mapper for mapping modulator output symbols to a set of antennas. The modulator ensures that an Orthogonality Condition is satisfied to impart maximum transmission diversity upon the data sent over the fading communication channel.

Abstract: A method and system is described wherein a signal with a lower frequency is up-converted to a higher frequency. In one embodiment, the higher frequency signal is used as a stable frequency and phase reference. In another embodiment, the invention is used as a transmitter. The up-conversion is accomplished by controlling a switch with an oscillating signal, the frequency of the oscillating signal being selected as a sub-harmonic of the desired output frequency. When the invention is being used as a frequency or phase reference, the oscillating signal is not modulated, and controls a switch that is connected to a bias signal. When the invention is being used in the frequency modulation (FM) or phase modulation (PM) implementations, the oscillating signal is modulated by an information signal before it causes the switch to gate the bias signal.

Abstract: Phase modulation control techniques and supporting apparatus avoid phase discontinuity at the outset of RF signal generation. Such discontinuities might arise from phase control instabilities associated with transmit start up or from abrupt changes in phase at the beginning of transmit signal generation. A transmitter uses starting phase values in advance of transmit data phase values to initialize phase modulation control circuits or functions. Once phase control is stabilized, and possibly after other criteria are met, the transmitter transitions from using the starting phase values to using the transmit data phase values, so that a transmit signal begins carrying phase modulations associated with the desired transmit data.

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: Amplitudes of signals produced by a digital modulator can be clipped so that instead of processing the output vector of the digital modulator or it's component vectors, processing is applied to the base band I and Q signals prior to modulation. The I- and Q signals are applied to an input of a clipping circuit. Predetermined limit values are also applied to another input of the clipping circuit. The clipping circuit rotates on the I-Q vector towards the limit vector. At the same time the limit vector is rotated towards the I-Q vector. Rotations are performed by using Cordic algorithm. After rotations have been completed, the rotated I-Q vector is aligned with the original limit vector, and the rotated limit is aligned with the original I-Q vector. Then the length of the rotated I-Q vector will be compared with the original limit vector. If the rotated I-Q vector is shorter than the limit vector, then the original I-Q signals are output signals from the clipping circuit.

Abstract: Device for estimating the frequency offset in a signal received by a differential demodulator of a mobile-telephone set, intended for implementing the method according to one of claims 1 to 3, characterized in that it has means (1) for calculating an error signal &egr; on the basis of the phase &phgr; of the output signal of the demodulator and the ideal phase &phgr;o of this signal, means (4) for establishing the absolute value (ABS) of the error signal &egr;, means (2, 5, 7) for calculating an estimate of the average of the error signal &egr; calculated over a certain number of samples, from which estimate nFO-RAW bits are taken, means (3, 6, 8) for calculating an estimate of the average of the absolute value of the error signal &egr; over a certain number of samples, from which estimate nQ-RAW bits are taken, and means (10) for modelling a frequency-offset function &OHgr;(FO-RAW, Q-RAW) on the basis of the said estimates.

Abstract: An amplifier system to increase the efficiency of amplification systems that employ linear modulation schemes. The amplifier system has a signal amplifier for receiving a constant amplitude input signal and producing an amplified version of the input signal. A variable impedance network presents various impedances to an output of the signal amplifier responsive to a load control signal. An envelope mapping circuit coupled to the variable impedance network produces the load control signal responsive to a desired amplitude modulation (AM) envelope. The various impedances causes the desired AM envelope to be impressed upon the amplified version of the input signal.

Abstract: The present invention, generally speaking, provides for high-efficiency power control of a high-efficiency (e.g., hard-limiting or switch-mode) power amplifier in such a manner as to achieve a desired modulation. In one embodiment, the spread between a maximum frequency of the desired modulation and the operating frequency of a switch-mode DC-DC converter is reduced by following the switch-mode converter with an active linear regulator. The linear regulator is designed so as to control the operating voltage of the power amplifier with sufficient bandwidth to faithfully reproduce the desired amplitude modulation wave-form. The linear regulator is further designed to reject variations on its input voltage even while the output voltage is changed in response to an applied control signal. This rejection will occur even though the variations on the input voltage are of commensurate or even lower frequency than that of the controlled output variation.

Abstract: A method 1100 and apparatus 1200 utilizing unbalanced modulation for providing users in a communication system with different amounts of effective communication energy according to their individual communication environments. A user's communication energy needs are determined based on conditions such as weather, signal-to-noise ratio, and cell location. Signals destined for a user are modulated according to the determined needs of the user. A signal destined for a user operating in a relatively friendly communication environment is modulated with less effective energy than a signal destined for a user operating in a relatively hostile communication environment.

Abstract: A hardware-efficient transceiver. The transceiver includes a digital circuit for converting baseband signals to intermediate frequency signals. A signal source provides a first periodic signal of a first frequency. A direct digital synthesizer provides a second periodic signal of a second frequency from the first periodic reference signal. An upconverter circuit digitally upconverts the baseband signals to digital intermediate frequency signals using the second periodic signal A digital-to-analog converter converts the digital intermediate frequency signals to analog intermediate frequency signals using the first periodic signal. In the transceiver implementation, the digital circuit upconverts a first transmit signal from a first frequency to a second frequency in response to the second periodic signal and provides a digital transmit signal in response thereto. A second circuit is provided for converting the digital transmit signal to an analog transmit signal.

Abstract: In accordance with a specific embodiment of the present invention, a system is disclosed having an analog to digital converter and control module. The analog-to-digital converter includes an analog input, digital output, and control input. The control input of the analog-to-digital converter is connected to a pulse width modulated output of the control module which provides an offset pulse width modulated signal. During a first portion of the offset pulse width modulated signal a sampling capacitor is charged. During a second portion of the offset pulse width modulated signal an integration capacitor is charged.

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: The present invention, generally speaking, provides for high-efficiency power control of a high-efficiency (e.g., hard-limiting or switch-mode) power amplifier in such a manner as to achieve a desired modulation. In one embodiment, the spread between a maximum frequency of the desired modulation and the operating frequency of a switch-mode DC-DC converter is reduced by following the switch-mode converter with an active linear regulator. The linear regulator is designed so as to control the operating voltage of the power amplifier with sufficient bandwidth to faithfully reproduce the desired amplitude modulation waveform. The linear regulator is further designed to reject variations on its input voltage even while the output voltage is changed in response to an applied control signal. This rejection will occur even though the variations on the input voltage are of commensurate or even lower frequency than that of the controlled output variation.

Abstract: A wireless microphone use UHF band carrier FM transmitter adopting a PLL system, which has a voltage controlled crystal oscillation type modulator (VCXO) for performing FM modulation on an oscillation frequency of a crystal oscillation circuit by an input of a modulation signal AF of an acoustic signal and which uses an FM modulated signal fr obtained from the VCXO as a reference signal Vr to be input to an analog phase comparator (PC) of a PLL circuit 60. The PC performs a phase comparison operation at a high speed (10 MHz or more), therefore a cutoff frequency of a loop filter (62) may be a high band frequency of about 100 KHz to 1 MHz so that the cutoff frequency considerably higher than the highest audible frequency 20 KHz can be selected. The filter output moves at an inaudible frequency and therefore there is no audible noise generated even due to vibration, feedback, etc.

Abstract: An antenna compensation system and method equalizes transmission link efficiency in sectors having unequal antenna or path gain while maintaining an equalized power spectral density. Areas of a sector having lower gains receive broadcasts with more robust coding to equalize their transmission link performance with areas of a sector having higher gains. The robustness of coding is controlled through setting of different forward error code rates, setting of different modulation types, or a combination of both. In analog systems it is controlled through variation of a signal-to-noise sensitive transmission parameter. Sectors may be divided azimuthally with areas at or near the boresight receiving less robust coding and areas nearer the sector edges receiving more robust coding. Similarly, sectors may be divided into radial areas with the more distant areas receiving more robust coding.

Abstract: A system and a method for transfer of a digital information carrying signal 51 between an input of a transmitter and an output of a receiver. The information carrying signal is modulated in a modulator included in the transmitter 12, and the modulated signal is transmitted via a transmission medium 13 by transmission means 25 connected to the modulator. The transmitted signal is received by receiving means 41 included in the receiver, and the received signal is demodulated in a demodulator. The information carrying signal is modulated in the modulator with a predetermined first modulation index h0, adapted for efficient use of an available bandwidth of said transmission medium. In the receiver 14 a frequency signal 63 is created from the received signal. Further, the frequency signal 63 is amplified with a factor A, for creating a scaled frequency signal 64, from which a scaled phase signal 65 is created.

Abstract: A low frequency signal generating portion 1 generates a first discrete signal (a signal sampled at a first sampling rate f1). A band pass portion 2 operates at a second sampling rate f2, performs a frequency selecting operation to a second discrete signal generated when the first discrete signal generated by the low frequency signal generating portion 1 is inputted, and generates a modulated signal with a prescribed center frequency.

Abstract: A method and system for rejecting interfering signals in a wireless communication system employing antenna diversity. According to the method, the angle between an interfering signal and a desired carrier signal is determined and used to estimate an offset angle. The offset angle is incrementally adjusted such that, when added to the received signal, the carrier-to-interference (C/I) ratio of the received signal is substantially maximized.

Abstract: A multichannel television access control system is disclosed wherein processing of the broadband signal is performed by gated coherent RF injection on a plurality of channels, thereby effecting selective descrambling of an arbitrary subset of channels in a channel group. The system provides for a closed loop injection signal phasor control so as to maintain substantially constant relationship between the television signals and the injected signals. The combined signals are supplied to subscribers enabling the use of their cable ready equipment.

Abstract: A circuit for generating a modulated signal contains a reference oscillator for generating a reference signal, a digital synthesis circuit having a clock input and an addition value input for generating a synthesis signal, and a phase comparator for generating a tuning signal depending on the result of a comparison of the phase of the reference signal with the phase of the synthesis signal. An oscillator is provided, which is controlled in a manner dependent on the tuning signal and serves for generating the modulated signal and a further oscillator signal, from which a clock signal present at the clock input of the digital synthesis circuit can be derived. The circuit has a drive device, which generates a digital drive signal from carrier frequency and modulation signals. The drive signal being present at the addition value input of the digital synthesis circuit.

Abstract: An RF direct down-conversion topology that is insensitive to leakage and device mismatching is presented. According to the system the RF signal is split into two arms with each arm having a mixer. Each mixer has two inputs namely a phase modulated local oscillator signal and the RF information signal. The phase modulated local oscillator signal between each arm differs by a 90 degrees phase shift. The output of the mixers is subtracted and the output of the subtractor is mixed with the phase modulation signal. The output of the third mixer represents the base band. A low pass filter then removes the unwanted signals.

Abstract: The invention provides a FM modulation system using a quadrature modulator, wherein a circuit for exclusive use in FM modulation and a change-over means can be dispensed with. In this system, modulating signals are inputted to a baseband signal processing circuit, converted into digital signals after integration, and turned into an analog signal by reading out a sine wave signal pre-stored in a sin ROM, thereby generating a baseband signal I for an equi-phase signal and a baseband signal Q for a quadrature signal. By adding together results of multiplication of the baseband signal I for the equi-phase signal and the baseband signal Q for the quadrature signal by a local signal of cosine and a sine wave signal obtained by phase shifting the local signal through 90 degrees, respectively, a quadrature modulation signal containing a FM modulated signal and the maximum frequency deviation can be generated.

Abstract: A double mode modulator, particularly, for a portable telephone, which is adapted to realize both digital and analog modulations and have a low phase noise and a reduced locking time with a device readily integrated in an integrated circuit, including: a frequency synthesizer for synthesizing a particular frequency from an external reference clock signal; a digital modulator for performing a quadrature modulation for an output signal of the frequency synthesizer; and an analog modulator for performing a frequency modulation for the output signal of the frequency synthesizer.

Abstract: An FM transmitter includes I and Q channels, each deriving a baseband sinusoidal wave having a frequency determined by speech and/or music broadcast information amplitude and nominally having the same maximum amplitude. Each wave drives a different balanced mixer, each responsive to orthogonally phased carrier waves. Outputs of the mixers are added to derive a frequency modulated output wave. The channels, mixers, and circuitry associated with them tend to introduce unwanted components in the output wave. Offset, peak amplitude, phase and relative delay of the added mixed outputs are such that the unwanted components are substantially eliminated from the output wave. The sinusoidal waves are derived by DACs responsive to signals derived by a digital processor having a memory storing amplitude vs. phase position values and slope vs. phase position values that are combined in response to samples of the broadcast information.