Abstract: The present invention provides a method for determining nonlinear distortion of a transmitter. A test symbol sequence is transmitted from the transmitter under test as an analog output signal. The analog output signal is sampled to produce a first sequence which represents the test symbol sequence as distorted by a linear distortion sequence and a nonlinear distortion sequence. The test symbol sequence is filtered via an adaptive filter to produce a second sequence such that the second sequence is approximately equal to the test symbol sequence as distorted by the linear distortion sequence. The second sequence is subtracted from the first sequence to produce an output sequence substantially equal to the nonlinear distortion sequence.

Abstract: To ensure frequency stability of a radio frequency in a radio communication apparatus for generating the radio frequency synchronizing with a transmission path frequency of digital data transmitted from a wire digital transmission path and so on. Concerning influence of a difference of a transmission path frequency that obstructs stability of a radio carrier frequency, the difference of a transmission path frequency 12b is compared with a high-stability radio reference clock 22a, the difference frequency 17a is detected by a counter 71, and frequency offset of a radio-station-transmission signal of a local oscillator 61 is made on the basis of the differential frequency. By the operation, the influence of the difference of the transmission path frequency that obstructs the stability of the radio carrier frequency 63a can be compensated.

Abstract: A reference frequency generating section 10 capable of suitably changing frequency accuracy of an output signal in accordance with an input control voltage, and a high-accurate reference frequency generating section 13 having accuracy for a temperature change extremely higher than that of the reference frequency generating section 10 and in which output frequency accuracy thereof changes only within a range of prescribed values (frequency accuracy within a range where transmission and reception of a portable telephone can be conducted) are provided. A reference frequency after an AFC operation, which is output from the reference frequency generating section 10, is compared with an output signal from the high-accurate reference frequency generating section 13, and whether or not frequency accuracy of an output signal from the reference frequency generating section 10 meets a prescribed value is determined.

Abstract: An amplifier system for electrical or physical quantities such as voltage or sound converts the quantity in a transducer to a differential phase shift of a high carrier frequency which is an analog equivalent of the quantity and multiplies the differential phase shift by conversion to a low frequency and frequency doubling back to the carrier frequency in successive stages by means of digital logic circuits.

Abstract: This device includes a frequency synthesizer (12) comprising two phase-locked loops (L1 and L2). The one comprises a low-pass filter (68) and the other a high-pass filter (49). The loop with the low-pass filter fixes the basic frequency of the synthesizer and the other corrects the phase noise. With this arrangement it is easy to apply a modulation frequency to the terminal (11) that is not disturbed by said loops if this modulation frequency is found to be higher than the cut-off frequency of the low-pass filter.

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 wideband multiple channel frequency converter includes a mixer, a frequency generator for generating a local oscillator signal, a power divider for receiving the local oscillator signal and providing a portion of the signal to the mixer and a portion of the signal to a feed forward path which phase and amplitude adjusts the signal and a power combiner for receiving and combining a signal from the mixer and the phase and amplitude adjusted signal from the feed forward path. In addition, an attenuator may be implemented to reduce a power level of a signal to be converted and a band-pass filter may receive the signal from the power combiner. The converter compensates for local oscillator signal leakage and can reduce inter-modulation components.

Abstract: A method an apparatus for controlling frequency of a multi-channel transmitter. A reference frequency is generated and emitted to a thermally stable frequency discriminator. The thermally stable frequency discriminator emits a dc voltage to a plurality of individual oscillators. The individual oscillators in continuous wave mode or modulated by baseband signals are combined into a multi-channel signal at an intermediate range of frequencies. The multi-channel intermediate range of frequencies are preferably amplified and emitted as an output signal. At relatively lower frequencies, such as 4-6 GHz, up-conversion of the output signal is not necessary. At relatively higher frequencies, an up-converter can be used to employ a second thermally stable frequency discriminator.

Abstract: A transmitter system having an adjustable monolithic frequency stabilization and tuning internal capacitor circuit. The transmitter system has a transmitter for generating and transmitting a transmitter oscillator frequency signal. A data generating chip is coupled to the transmitter. The data generating chip is used for adjusting and controlling the transmitter oscillator frequency signal. A variable capacitor circuit is located internal to the data generating chip and is coupled to a ground pin and one of a plurality of function pins on the data generating chip. The variable capacitor circuit is used for adjusting and setting the centerpoint of the transmitter oscillator frequency signal.

Abstract: In a method of calibration of a voltage controlled oscillator (VCO), the VCO (100) provides an output signal which is used to drive a dividing oscillator (10) such as a relaxation oscillator (RO). The RO has at least two states, one in which the RO provides an output signal which has a first frequency that is related to the VCO output signal by a first ratio (e.g. 1/N) and one in which the relaxation oscillator provides a RO output signal which has a second frequency that is related to the VCO output signal by a second ratio (e.g. 1/(N+1)). By measuring the first and second frequencies (and knowing the relationship between the first and second ratios), the VCO frequency is calculated and stored (110). Several VCO frequencies can be calculated and stored for several applied voltages. As a result the VCO can be driven to any selected frequency in the calibrated range and can be used to provide an injection frequency for a radio.

Abstract: A method and apparatus are provided for modulating a frequency synthesizer with an adjusted frequency control word determined by adjusting a carrier frequency control word based upon a bit content of a unsigned modulation control word. The method includes the steps of inverting a most significant bit of the unsigned modulation control word to produce an adjusted modulation control word and replicating the inverted most significant bit and appending the replicated bits to a most significant bit side of the adjusted modulation control word to increase a width of the adjusted modulation control word to a width of the carrier frequency control word. The method further includes the step of adjusting the carrier frequency control word by adding the replicated bits and the adjusted modulation control word to corresponding bits of the carrier frequency control word.

Abstract: A frequency generation device for a satellite communication system composed of a central hub station and a number of remote units. The remote units contain a single synthesizer located in an indoor unit. In this invention, the indoor-located synthesizer is a direct digital synthesizer which modulates the baseband signal and conveys the modulated signal to an outdoor unit for communication between the remote unit and the central hub. In the outdoor unit, the signal is converted directly by a fixed number to a Ku band frequency and transmitted to the central hub.

Abstract: A circuit for synchronizing transmission local oscillating frequency in a co-channel microwave system, with more reliability, synchronizes horizontal and vertical polarization waves phase locked dielectric resonators which generate transmission local oscillating frequencies in a digital co-channel microwave system.

Abstract: A circuit having a Cartesian amplifier is disclosed. The Cartesian amplifier includes a re-combining stage which re-combines an input signal from a signal source with a correction signal to output a result signal. A first mixer mixes the result signal with a first oscillating signal from a local oscillator. A power amplifier amplifies the mixed signal and a coupler couples part of the amplified signal to form an outcoupling signal. A feedback path has a second mixer for forming the correction signal by mixing the outcoupling signal with a second oscillating signal from the local oscillator. An envelope curve detector detects the envelope of the amplified signal to produce an envelope signal, and a phase adjustor adjusts the phase of the first or second oscillating signal. A control circuit is provided to control the phase errors in a phase locked loop of the Cartesian amplifier and to minimized the envelope signal.

Abstract: The present invention, generally speaking, provides an RF modulator that allows precise, stable phase shifts to be obtained. The modulator uses a PLL structure including an auxiliary feedforward path used to inject a baseband modulation signal into the PLL at a point past a loop filter of the PLL. A phase demodulator recovers phase information from the output signal of the PLL. The recovered phase information is compared to the phase information of the baseband modulation signal. A resulting error signal is used to control injection of the baseband modulation signal into the PLL, to automatically achieve the correct "dosage." A precise, adaptive, phase-stable modulator results. The adaptation of the modulator compensates for variability of the VCO and other components of the PLL.

Abstract: A method for synchronizing transmissions of mobile stations in a mobile radio system including a first and second mobile station and a radio unit all communicating on a direct mode channel. According to the method, the radio unit transmits synchronization information messages on the direct mode channel, which messages indicate the frequency used by the radio unit, and which messages include accuracy information, indicating that the accuracy of the transmit frequency used by the radio unit exceeds the accuracy normally employed on a direct mode channel. The mobile stations receive the synchronization information messages and tune respective receivers and transmitters to the frequencies indicated by the synchronization information message.

Abstract: A wireless communication system with one or more remote transceivers for transmitting a wireless data signal at an actual frequency that is different than the expected frequency and a base transceiver that can automatically adjust to receive the actual frequency. Each remote transceiver is adapted to initiate a wireless data signal at a selected time that is unique to that remote transceiver. The expected frequency is sequentially pre-determined in a pseudo-random sequence with each remote transceiver having a unique sequence. The base transceiver can respond to the remote transceiver at the actual frequency. Both the remote transceiver and the base transceiver can convert the wireless signals in a single step to baseband.

Abstract: A system and method for implementing a cellular radio transmitter device comprises a first oscillator device for generating a first oscillator output signal, a second oscillator device for generating a second oscillator output signal, a power amplifier for amplifying the second oscillator output signal to obtain a transmit signal, a mixer device for combining the first oscillator output signal and the transmit signal to produce a mixer output signal, a phase comparator for comparing the mixer output signal and a transmitter input signal and responsively generating a control signal to control the transmit oscillator, and a feedback path for adding the mixer output signal to the transmitter input signal to compensate for distortion present in the transmit signal.

Abstract: The present invention teaches a paging transmitter that has an exciter that upconverts a modulated signal to an intermediate frequency (IF) above that of the transmit frequency. By so doing, the paging transmitter can broadcast a large range of transmit frequencies. Additionally, filtering of unwanted byproducts during the upconversion process is significantly simplified.

Abstract: An RF module for a radio control transmitter capable of detecting detaching of the RF module from a transmitter body while keeping the transmitter body turned on. The RF module includes a monitor circuit, which judges whether or not a modulation signal is outputted from the transmitter body within 1 second after the RF module is turned on and further judges, when it is judged that the modulation signal has been fed within 1 second, whether the modulation signal is a PCM signal or a PPM signal. When it is a PCM signal, an RV output is rendered "on"; whereas when it is a PPM signal, the RF output is rendered "off".

Abstract: When starting a radio transmitter, a transmission frequency is generated by a phase/frequency-locked loop which includes a phase/frequency comparator, a loop filter and a voltage-controlled oscillator. The start-up is performed by switching on an operating voltage to the voltage-controlled oscillator. To minimize the frequency error of the transmitter at start-up, measuring data about relationship between the control voltage of the oscillator and the output frequency of the oscillator at a specified calibration temperature are pre-stored in connection with the oscillator, and immediately before switching on the operating voltage, the control voltage needed for locking onto the selected output frequency at the prevailing temperature is estimated and the estimated control voltage is set as the control voltage of the oscillator.

Abstract: An apparatus and a method for improving the stability of the transmitting frequency by using a costas loop section in a communication system of a half duplex transmitting method is disclosed, in which a receiving terminal is provided with an A/D converter, a D/A converter, a switching circuit, and a central processing unit, and thus, during a data transmission, a reference frequency is extracted through the costas loop section without installing a separate reference frequency extracting facility, thereby improving the stability of the transmitting frequency. In the conventional technique, in forming a reference frequency for a transmitting frequency, additional devices such as a pilot signal detector, a transmission reference frequency oscillator and the like are required, with the result that the cost for establishing the system becomes high, and that too much man hours and too many additional components are required.

Abstract: A frequency converter capable of providing a highly stable frequency by frequency feedback using a phase locked loop circuit. The frequency converter includes a local oscillator; a frequency converter for mixing an output of the local oscillator and a feedback frequency therefrom to generate a mixed frequency; a first filter for filtering the mixed frequency; a phase comparator for generating a voltage signal corresponding to a phase difference in between an input frequency to the frequency convertor and the output frequency of the first filter; a second filter for converting the voltage signal of the phase comparator to a constant polarity voltage and eliminating any noise component of the converted voltage signal; and a voltage controlled oscillator receiving the output of the second filter as a control voltage so as to provide a stable output frequency by generating the feedback frequency responsive to the control voltage.

Abstract: A circuit for measuring output powers of channels and stabilizing RF output in a system using a linear power amplifier, includes a channel portion in which each of channels is made up with an RF control board and frequency increasing board; a base station output portion for combining and outputting the respective channel signals via an antenna; and an output stabilizing portion for mixing the RF output signal of the base station output portion with a selected second local signal among the second local signals by the frequency increasing boards to make a low intermediate frequency, filtering it, and converting it into a direct current, and comparing the current with the output of a base station so as to control a selection channel frequency of channel portion and stabilize the output, whereby the variation of output power possibly occurring by an RF stage and the output power of the base station are stabilized.

Abstract: Within a communication system, driving a numerically controlled oscillator with a frequency of a precision frequency oscillator and adjusting the frequency of the numerically controlled oscillator by a calculated number to be equal to that of a frequency signal derived from an external source. The calculated number utilized to adjust the numerically controlled oscillator is then transmitted to each of a number of subunits. Each subunit has another numerically controlled oscillator that is driven by a frequency derived from an internal communication link connecting the subunit to the communication system; and the other numerically controlled oscillator is controlled by the calculated number so that its frequency matches the frequency of the precision oscillator. The frequency of the internal communication link is controlled by the precision oscillator.

Abstract: The present invention relates to a wireless communication system having improved PLL circuits in the RF transmitter and receiver sections. The PLL circuits in the wireless communication system according to the present invention include time constant controllable filters. A series circuit of capacitor and resistor detects turn-on of the power switch for the PLL circuits to generate an output signal to be applied to the filters, thereby controlling the time constant of the filters in the PLL circuits to a lower value than normal for a given time after power-on of the PLL circuits.

Abstract: A first phase-locked loop (PLL) includes a first integrated voltage-controlled oscillator (VCO) whose output signal has a frequency modulated by an input signal of the device about a multiple of a reference frequency. A second PLL includes a second integrated VCO and frequency transposition means. The transposition circuit receive the output signal of the second VCO and a transposition signal having a non-modulated frequency. The second PLL addresses to the second VCO a control signal capable of aligning the frequency of the output signal of the transposition circuit with the frequency of the first VCO. The output signal of the second VCO forms the frequency modulation transmission signal produced by the device.

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: In multiple-channel microwave transmitters and communications systems, such as multi-point video distribution systems operating at frequencies of around 29 GHz or 40 GHz, good frequency stability for each of the channel frequencies is achieved with a feed-back loop including an error detector circuit. The error detector circuit (39,29) is coupled between a sampler and an input circuit of the source. This detector circuit detects any drift or other error in the carrier frequency of the sample from the desired microwave frequency for that channel signal and provides a corrective signal to the input circuit. The part of the feed-back loop comprising at least a part of the detector circuit is common to a group of the channels. Switch means couple the common part of the feed-back loop between the sampler and the source input circuit of each channel, and so permit this common part to be time multiplexed between the respective feed-back loops of the group of channels.

Abstract: A two-way medical telemetry system is provided for displaying and monitoring, at a central location, physiologic and other patient data of multiple, remotely-located patients. The system comprises multiple battery-powered remote telemeters, each of which is worn by a respective patient, and a central station which receives, displays and monitors the patient data received (via RF) from the remote telemeters. The telemeters communicate with the central station using a two-way TDMA protocol which permits the time sharing of timeslots, and which uses a contention slot to permit telemeters to transmit service requests to the central station. Two-way spacial diversity is provided using only one antenna and one transceiver on each remote telemeter. The remote telemeters include circuitry for turning off the active transceiver components thereof when not in use (to conserve battery power), and include circuitry for performing a rapid, low-power frequency lock cycle upon power-up.

Abstract: Reduction of transmitter exciter chain generated noise from the receive bank of a portable/hand-held duplex transceiver is achieved using a high output power, low-noise voltage-controlled-oscillator (VCO) in the transmitter exciter chain. Using this high-power, low-noise oscillator as the RF source in the transmitter exciter chain precludes the need for the conventional buffer/driver amlplifier stage and an associated inter-stage noise filter. Elimination of buffer/driver stage components and bulky inter-stage noise filter components allows complete integration of transmitter exciter chain components resulting in reduced size and cost.

Abstract: A DC frequency modulation circuit for modulating audio signals wherein the high frequencies of the audio signals are modulated by a first phase locked loop and the low frequencies of the audio signals, along with the DC signals, are filtered by a low pass filter, applied through an A/D converter, and modulated by a direct digital frequency synthesizer. The two modulated signals are then mixed by a second phase locked loop.

Abstract: A wireless communication system with one or more remote transceivers for transmitting a wireless data signal at an actual frequency that is different than the expected frequency and a base transceiver that can automatically adjust to receive the actual frequency. Each remote transceiver is adapted to initiate a wireless data signal at a selected time that is unique to that remote transceiver. The expected frequency is sequentially pre-determined in a pseudo-random sequence with each remote transceiver having a unique sequence. The base transceiver can respond to the remote transceiver at the actual frequency. Both the remote transceiver and the base transceiver can convert the wireless signals in a single step to baseband.

Abstract: The effects of long-term drift in a local reference oscillator are compensated by dividing the local reference oscillator frequency by one of three divider patterns (nominal ratio, add a cycle, delete a cycle) so that the symbol clock of the remote terminal is equal to the outroute symbol rate. The number of add a cycle and delete a cycle divider patterns are counted and stored. The average of the number of add a cycle and delete a cycle patterns is used to control the transmit frequency of the remote terminal to correspond to the outroute symbol rate. Thus, the clock recovery process generates a frequency calibration number used to track the frequency of the remote terminal local reference oscillator and to adjust the transmit frequency of the remote terminal accordingly.

Abstract: A system for transmission of combined, multi-carrier signals wherein combiner/filters, commonly called combiners, have been eliminated. A cartesian feedback loop linearizes the system and thereby suppresses carrier frequency intermodulation by feeding back a portion of the combined multi-carrier signal to each channel device.

Abstract: A full duplex data transceiver for transmitting and receiving trinary frequency-modulated ("FM") signals representing binary data includes separate transmit and receive antennas, and a single oscillator which serves as both the radio frequency ("RF") signal source for the transmitter and the local oscillator "LO") signal source for the receiver. During signal transmission, the oscillator output is frequency-modulated to provide a FM transmit signal to the transmit antenna. The oscillator output is frequency-modulated with binary transmit data by modulating an error feedback signal which serves as the control voltage for a voltage-controlled oscillator in a phase-lock-loop, thereby producing the FM transmit signal. During signal reception, the oscillator output, in the form of the transmitted FM signal, is received via the receive antenna along with a FM receive signal for mixing therewith to down-convert the FM receive signal.

Abstract: A method and apparatus in a radio communication transmitter (600) stabilizes a carrier frequency locked to a reference oscillator (102). The reference oscillator (102) is controlled by a control signal and generates a first signal at a reference frequency. The first signal is coupled to a frequency multiplier (212) for multiplying the reference frequency by a predetermined factor to generate a second signal at the carrier frequency. Cycles of the carrier frequency are counted (508, 514) during a predetermined interval to determine (516, 518) a measured cycle count. The measured cycle count is compared (520) with an expected cycle count corresponding to a predetermined carrier frequency to determine a drift error. From the drift error a control signal adjustment required to correct the drift error is computed (522). The control signal of the reference oscillator (102) is adjusted (524) by the control signal adjustment to correct the drift error.

Abstract: A transmitter has an oscillator (101, 201, 303, 401, 501) that operates at frequency k multiplied by f.sub.c, thus the oscillator (101, 201, 303, 401, 501) outputs a signal at an output frequency, kf.sub.c. Coupled to the oscillator (101, 201, 303, 401, 501) is a frequency modifier (103, 205, 307, 405, 505), for modifying the oscillator output frequency by factor 1/k, thereby producing a signal at frequency f.sub.c at the frequency modifier output. Coupled to the frequency modifier output is a modulator (105, 215, 301, 407-417, 507-517) for producing a modulated output signal substantially centered at frequency f.sub.c.

Abstract: A radio transmitter includes a power amplifier (12); a linearizer (10) for maintaining linearity in the power amplifier; and a feedback path (13) for feeding a signal from an output of the power amplifier to the linearizer. The amplifier, linearizer and feedback path cooperate to form a feedback loop having adjustable loop linearization parameters (for example phase and gain). Further, a look-up table (19) is used to store predetermined loop linearization parameters and cooperates with a microprocessor having an operating condition input.

Abstract: A frequency modulating system for frequency-modulating an input signal with a predetermined carrier frequency comprising a controller circuit and a frequency modulator is provided. The controller circuit includes an automatic frequency detecting circuit, a voltage controlled oscillator, an error current generator, a feedback clamping circuit, a deviation current generator, and an adder circuit generating a frequency deviation/carrier frequency correction signal provided to the frequency modulator. The frequency modulator modulates the frequency in response to an output of the controller circuit and includes an oscillator having the same structure as that of the voltage controlled oscillator.

Abstract: A frequency modulating system for frequency-modulating an input signal with a predetermined carrier frequency comprising a controller circuit and a frequency modulator is provided. The controller circuit includes an automatic frequency detecting circuit, a voltage controlled oscillator, an error current generator, a feedback clamping circuit, a deviation current generator, and an adder circuit generating a frequency deviation/carrier frequency correction signal provided to the frequency modulator. The frequency modulator modulates the frequency in response to an output of the controller circuit and includes an oscillator having the same structure as that of the voltage controlled oscillator.

Abstract: A frequency modulating system for frequency-modulating an input signal with a predetermined carrier frequency comprising a controller circuit and a frequency modulator is provided. The controller circuit includes an automatic frequency detecting circuit, a voltage controlled oscillator, an error current generator, a feedback clamping circuit, a deviation current generator, and an adder circuit generating a frequency deviation/carrier frequency correction signal provided to the frequency modulator. The frequency modulator modulates the frequency in response to an output of the controller circuit and includes an oscillator having the same structure as that of the voltage controlled oscillator.

Abstract: A method of compensating the dependence of the useful transmitter signal on the transfer function of a combiner filter in a mobile radio communication system includes filtering the useful transmitter signal in the base band before it is fed to the combiner filter. This is done in connection with carrier frequency modulation with a filter, the total transfer function of which at least approximately comprises the inverted value of the transfer function of the combiner filter transformed to the base band.

Abstract: In a data transmitter (200), a precision timing signal receiver (201) provides a precise timing signal (203) to an informationally responsive comparator (205). The informationally responsive comparator compares an output (211) of a controllable oscillator (209) to the precise timing signal to produce a comparison metric. An output of the informationally responsive comparator, comprising a combination of an information signal (207) and the comparison metric, is then used to control the controllable oscillator.

Abstract: A frequency synthesizer 10 having a digital to analog converter (DAC) 40 and a feedback system which detects the deviation of a frequency modulated signal and aligns the detected deviation. DAC 40 provides a presteering stimulus for alignment purposes. After presteering alignment, the gain of DAC 40 is accurately set for frequency deviation because modulation is sourced from the same digital to analog converter that performs presteering.

Abstract: A PLL circuit modulatable by a modulation signal having a direct current component has a voltage-controlled main oscillator, a loop divider, a phase comparator and a loop filter. The reference frequency signal for the phase comparator is derived from the modulation signal by a first compensation filter, a voltage-controlled reference oscillator and a reference divider being connected downstream of said first compensation filter. The voltage-controlled main oscillator is controlled by the modulation signal via a second compensation filter followed by a downstream data lowpass.

Abstract: A transmitter using a dual conversion system which effects frequency conversion twice has a local oscillator (113) for generating a first local oscillation signal, a multiplier (118) for multiplying the frequency of the first local oscillation signal to produce a second local oscillation signal, a first mixer (115) for mixing the first local oscillation signal and first IF signal to produce a second IF signal, and a second mixer (120) for mixing the second local oscillation signal and second IF signal to produce a signal to be transmitted. A voltage controlled filter (116) whose center frequency varies with the frequency of the first local oscillation signal is connected to the output of the first mixer (115).

Abstract: A digital frequency synthesizer circuit with spur compensation includes a demodulator circuit (118) for demodulating the output signal (116) of the synthesizer's accumulator (108). Demodulator (118) also inverts the signal, and provides an inverted demodulated output signal (142) which is then coupled to the synthesizer clock (124) after passing through a gain stage (122) in order to modulate the synthesizer clock (124) with a compensation signal (146). The compensated clock signal (140) is then sent to accumulator (108) in order to substantially cancel out any jitter in the accumulator's output signal (116). The modulation signal (MOD IN) which is digitally applied to accumulator (108) is applied in analog fashion to the gain stage (122) in order to prevent the desired modulation signal (MOD IN) from being canceled in the output signal (116).

Abstract: A method for providing a positive transmitter power switch-on in a dual-mode mobile phone is disclosed. According to the invention the transmitter is switched on in two or more phases, controlled by the mobile phone microprocessor program. Preferably the power amplifier sections are switched on in a sequence, so that the output power amplifier sections (3 and 4) are first switched on by enabling the transmit enable signal (TXE). Then the input power amplifier sections (1 and 2) are switched on by enabling ramp-up signal (RAMP-UP) Transmission is thereafter enabled by the transmit power control signal (TXC) being switched on, the amplifiers then output the amplified radio frequency input signal (RFIN) to the duplex circuit (10) transmit terminal (TX).

Abstract: For use in a spread spectrum communication system there is provided in an embodiment of the invention a spread spectrum transmitter which uses a voltage controlled oscillator (VCO) for generating a carrier signal wherein the frequency of the oscillator is controlled by the output of a correlation code generator and data generator coupled to a varactor in the oscillator. The use of a VCO eliminates the need for sidelobes associated with mixers. In another embodiment the separation of the output of the correlation code generator and data generator coupled to the varactor and the output of a phase detector coupled to the varactor simplifies tuning of the transmitter and in another embodiment the use of a high gain differential amplifier to couple the output of the correlation code generator and data generator to the varactor eliminates tuning the transmitter.