Abstract: A transmitting power control unit which generates and transmits a wideband transmission signal with a power level which does not differ by frequency. This transmitting power control unit includes means for generating voltage corresponding to a frequency of a transmission signal. The power of the transmission signal is controlled by added the voltage which is obtained by adding the generated voltage to a fixed voltage according to power control information. The power-controlled transmission signal is transmitted from an antenna with a frequency band thereof limited by a filter.

Abstract: An output level control circuit for radio-frequency transmitter which intermittently transmits radio-frequency carrier waves such as seen in the TDMA radio communication system and the digital cellular mobile telephone system. The variable gain amplifier unit of this transmitter amplifies the transmitting signal to a predetermined output power level in response to a control signal, the output power level is detected by a detecting diode which receives the application of a temperature-compensated bias voltage, and the sum of the detected output and the bias voltage becomes the detection output to the control loop.

Abstract: A noise adaptive automatic gain control circuit (100) includes an automatic gain control amplifier (105) for automatically adjusting the gain of the circuit (100) in response to an input signal applied to the input. A detector (135) is provided for detecting the presence of any background noise that may be present. Further, a voltage generator (126), a comparator (124), and a microcomputer (150) is provided for dynamically adjusting the gain of the AGC amplifier (105) to substantially prevent the amplification of the background noise. In other aspects of the present invention, a voice lull detector (140) detects voice lulls (402) in the input signal applied to the input. Further, a programmable amplifier (120) substantially maintains the gain of the AGC amplifier (105) to a constant level during voice lulls (402) to prevent excessive amplification.

Abstract: A voice communication apparatus in which voice and voiceless parts are detected from voice signal data which is derived from analog-to-digital converted input voice signal, the voice signal data is temporarily stored in a transmitting buffer in a time series manner so that, when a voice part is detected, transmission of the voice signal data stored in the transmitting buffer is started from a voice start point of the voice part preceding a voice detection point, whereby a head part truncation, which would occur at the time of shifting from the voiceless part to the voice part can be eliminated and thus a high quality of natural speech communication can be realized.

Abstract: A burst control circuit for use in a TDMA communications system comprises a power amplifier having two separate control terminals. A level control signal which is the difference between a reference signal and the level of the output burst signal of the amplifier, feedback-controls the level of the output burst signal through a first control terminal, and a waveform control signal having a predetermined waveform, controls the waveform of the output burst signal through a second control terminal. When the level of the reference signal is decreased, the amplitude of the waveform control signal is decreased as a function of the level of the reference signal.

Abstract: An automatic power control apparatus for use in a radio communication system employing a Time Division Multiplexing Access (TDMA) system according to the present invention has a level varying unit for amplifying a modulated wave that is output from a transmitter at an amplification factor specified by an external device, a level detecting unit for detecting a power level of a modulated wave, a computing unit for computing a power level of a non-modulated wave which is varied by a modulated wave obtained by linearly modulating a carrier wave in response to a modulation signal generated based on digital data, and a comparing unit that is used for comparing power levels. In the automatic power control apparatus, and amplification factor of the level varying unit is adjusted so that the power levels compared by the comparing unit become equal to each other during a transmission period of the non-modulated wave.

Abstract: A power booster (10) comprises a power amplifier (5) and is coupled to a portable radio telephone (20) which transmits an RF signal at one of a predetermined set of power levels. A first detector (6) generates an output signal C indicative of the power of the RF signal received by the booster. The signal C is used to generate a reference signal rf from a look up table (8) in which is stored a set of values corresponding with the respective power levels. The reference signal rf, which indicates the required power level, is applied to a power control circuit (7) which controls the gain of the amplifier (5) to maintain the power output substantially constant at the required power level as determined by the value of the reference signal rf.

Abstract: A radio-frequency amplifier (50) has an impedance transformation network (66) with a control input (70) for controlling the transformation characteristic of the transformation network (66). The radio-frequency amplifier (50) amplifies an input signal to produce an amplified radio-frequency output signal to a load (68). The control circuit selects a power level for the output signal, in response to a control signal, by transforming the impedance of the load to a transformed impedance at the output of the radio-frequency amplifier, so that the efficiency of the radio-frequency amplifier is not substantially degraded as the power level for the output signal is changed.

Abstract: The present invention relates to a method of regulating or adjusting the transmission power when transmitting signals between a mobile station and a base station in a digital mobile telephony system. The output power is regulated to maintain the transmission power at an optimum level to prevent unnecessary disturbance of neighboring channels transmitting information on the same frequency and to insure that the transmitted information is interpreted properly in the receiver. The measured values of signal strength and signal-transmission quality are collected, and their mean values are calculated. An anticipated value of signal strength and transmission quality is then calculated at a next time-point provided that the transmission power is maintained unchanged in relation to the transmission power at the present or instant time period (t.sub.0). The transmission power at the next time period (t.sub.1) is regulated on the basis of these anticipated signal strength and quality values.

Abstract: An automated voice operated transmitter control (VOX) arrangement devoid of any separate manual actuation requirement and adaptable to a dynamic acoustic environment is described. The VOX decides whether it should be operating, automatically selects a threshold condition (70) from a predetermined list according to a average acoustic signal level over a first time period, and provides a VOX PTT signal to activate a radio frequency transmitter (24) when the acoustic signal level, over a second time period that is less than the first time period and exceeds a debounce time (78), exceeds the threshold condition.

Abstract: A cellular telephone transmitter (100) includes a variable-gain power amplifier (102), the output of which is filtered and sampled by a filter (104) with an integral directional coupler. Filter (104) includes both a transmitter signal filter and a directional coupler on a ceramic block of one or more pieces. The directional coupler has been realized by two coupled transmission lines provided by the two holes (206 and 207) on the left side of the ceramic block, and the transmitter filter has been realized by five short-circuited coupled transmission lines provided by the five holes (201-205) on the right side of the ceramic block.

Abstract: An amplifier which contains two amplifier stages. Each amplifier stage (433,435) utilizes a diode (407) to attenuate the RF input signal (401) and to stabilize the bias current over temperature. The two amplifier stages (433, 435) are cascaded together. The control voltage inputs are serially coupled through a transistor (423). The transistor (423) shifts the voltage of the control signal (425) down, thereby, shifting the control characteristics and AM characteristics of the first amplifier stage (435) relative to the second amplifier stage (433).

Abstract: In a radio transmitter, a part of an output of a transmission output amplifying circuit is supplied to a variable attenuating circuit and an output of the variable attenuating circuit is supplied to a detecting circuit. An output of the detecting circuit and a reference voltage are compared and a control voltage is given to the transmission power amplifying circuit in accordance with the result of the comparison, thereby controlling the transmission output. By controlling the attenuation amount of the variable attenuating circuit, the transmission output can be controlled over a wide dynamic range with a high reproducing fidelity.

Abstract: A TDMA cellular telephone (600) includes in its transmit signal path, microphone (608), vocoder (612), data format circuitry (601), quadrature modulator (602), 90 MHz local oscillator (606), transmitter with mixer (604), transmitter filter (618), and antenna (620). In its receive signal path, the TDMA cellular telephone (600) includes receiver filter (622) coupled to antenna (620), quadrature demodulator (624), and data deformat circuitry (625). The channel frequency of TDMA cellular telephone (600) is loaded into synthesizer (616) by microcomputer (614) and applied to transmitter (604) and demodulator (624). TDMA cellular telephone (600) is controlled by microcomputer (614) which includes a memory with a control and signaling computer program stored therein.

Abstract: In a transmitter, a modulator switchably operates on one of two modes of operations, that is, in a first mode of the operation, such as an offset QPSK, FSK or .pi./4 shift QPSK, an amplitude of an output signal of the modulator does not become zero at any instant, and in a second mode of the operation, such as two-phase FSK or four-phase PSK, the output signal of the modulator is 100% amplitude-modulated or 180 phase-modulated. Second mode operation. The operation mode is switched by changing the mode of the parallel input signals to the modulator, where the parallel signals have been converted from a serial input data signal to be transmitted.

Abstract: A power control circuit used for both analog/digital dual mode is disclosed which comprises a switching circuit (17) for applying the feedback signal to the gain control terminal (40) of the power amplifier (2) and applying a fixed bias voltage to the attenuation control terminal (30) of the attenuator (10) so that the amplifier operates as a C class amplifier in the case of analog mode, and for applying the feedback signal to the attenuation control terminal (30) of the variable attenuator (10) and applying the predetermined bias voltage to the gain control terminal (40) of the power amplifier (2) so that the amplifier operates as an A class amplifier in the case of digital mode. In the present invention, as a single amplifier operates for both analog mode and digital mode, the configuration is simplified and assembled cheaply.

Abstract: A radio communication apparatus comprising a modulating portion for modulating a carrier with a signal to transmit so as to produce a transmissible signal; a signal transmitting portion for transmitting the transmissible signal; a level adjusting portion for adjusting a level of the signal to transmit or a level of a control signal used for controlling the transmissible signal in accordance with digital control data supplied to the level adjusting portions; a memory for storing digital adjusting data; and a control unit for reading the digital adjusting data from the memory and supplying the level adjusting portion with the digital adjusting data read from the memory or modified digital adjusting data obtained based on the digital adjusting data read from the memory as the digital control data.

Abstract: An amplifier circuit for providing precise linear control over the output of a nonlinear amplifier, including a nonlinear gain controllable amplifier and an output control circuit. The output control circuit is connected to sample the signal output by the nonlinear amplifier. The amplifier output signal may be a continuous or a discontinuous signal. The output control circuit also receives a baseband signal. The sampled amplifier output signal and the baseband signal are alternatively transmitted to a detector. The detector produces a signal representative of the power level of either the sampled amplifier output signal or the baseband signal. The signals produced by the detector are stored separately in a pair of sample-and-hold circuits. A difference amplifier determines the difference between the stored signals and transmits this difference signal to the gain control input of the amplifier. The output signal from the amplifier is thereby adjusted to linearly track the baseband signal.

Abstract: In a QAM microwave radio communications system an IF (intermediate frequency) input signal is amplified and predistorted, and the amplified IF signal is mixed with a local oscillator signal to produce an RF (radio frequency) signal which is amplified in a power amplifier for transmission, the predistortion compensating for non-linear gain of the power amplifier. Clipping in the power amplifier is controlled by down-converting part of the RF signal to produce an IF output signal, monitoring amplitude distortion of the RF signal by comparing the IF output signal with the IF input signal, and controlling the IF amplifier gain in dependence upon the monitored amplitude distortion.

Abstract: A method of generating a first signal (115) in a radiotelephone (101) representing the detection of speech on a second signal having background noise, a magnitude, a zero crossing rate and divided in time by frames having a predetermined time period. In absence of speech, the method characterizes the background noise (209) and computes background noise thresholds (211). The method computes an average of the magnitude of the second signal and a zero crossing rate of the second signal for a given frame (215). Then, compares said average of the magnitude (217) and said zero crossing rate (221) of the second signal to said background noise threshold. Upon one of said average of the magnitude and said zero crossing rate consecutively exceeding said background noise thresholds for a first predetermined number of frames, the transceiver(107) is turned on.

Abstract: A closed loop amplifier circuit (100) having an on state (202) and an off state (204) is disclosed. The amplifier circuit (100) includes an Automatic Gain Control (AGC) circuit (116). The AGC circuit (116) controls the rate of change in the output power (120) of the amplifier circuit (100) when it changes from the off state (204) to the on state (202) or vice versa. The amplifier circuit (100) also includes a programming circuit (114) that is coupled to the AGC circuit (116). The programming circuit (114) is used to program a desired rate of change into the AGC circuit (116).

Abstract: A control circuit for a radio frequency (rf) amplifier having multiple selectable power output levels in response to a plurality of input control signals is presented. The rf amplifier includes a variable gain input which is responsive to the control circuit. The control circuit includes an attenuator coupled to the output of the rf amplifier for providing an attenuated rf signal and an detector coupled to the output of the attenuator for generating a DC output signal which is substantially linearly related to the magnitude of the rf signal output by the rf amplifier. The control circuit also includes a means coupled to the input control signals for selecting one of a plurality of amplification factors. An amplifier is used to amplify the DC output signal generated by the detector using the selected amplification factors. The amplified output is coupled to the variable gain input of the rf amplifier.

Abstract: RF power is sampled and measured at the input and output of a solid state power amplifier using directional couplers and matched square law detectors. Outputs from the detectors are applied to differential inputs of a DC operational amplifier. Outputs from the detectors are compared and filtered in the operational amplifier and the resulting difference signal is applied to a control input on a switching type power supply. The power supply converts a DC input voltage to the various positive and negative voltages required to operate the RF devices in the solid state power amplifier. When the control loop is closed, the supply voltage varies to maintain a constant operating point resulting in constant gain, efficiency, and linearity for the overall solid state power amplifier despite variations in signal levels and signal composition. In another embodiment, the solid state power amplifier has a series of single-ended low power amplifiers terminating in an output high power module.

Abstract: A linearity correction circuit for television transmission operates at intermediate frequency to introduce appropriate pre-distortion into the amplitude envelope to compensate for non-linearity in the power amplifier states. An array of parallel current sources (11), each of which is independently adjustable in response to the perceived requirement for pre-distortion over a corresponding amplitude band, to inject a current sufficient to introduce an appropriate differential voltage at the output. The circuit provides for the independent correction of each amplitude band, so that it is capable of operation under microprocessor control in real time.

Abstract: Subscribers participating in a call may communicate information un-impeded until the occurrence of an event (such as the expiration of a time interval). After detecting this event, the quality or intelligibility of the communicated information is repeatedly reduced to encourage the subscribers to voluntarily conclude the call.

Abstract: A variable attenuating circuit is provided between a control circuit of a radio telephone and a transmitter to control the level of the control signal to either terminate or hold the speech when either the speech terminating or the holding operation is performed. When the control signal for either speech termination or speech holding is transmitted from the radio telephone to a base unit, the degree of attenuation by the attenuating circuit is controlled so as to be reduced. Thus, the level of the control signal in the transmitter is controlled to thereby reduce the level of the control signal leaking possibly to the cable telephone line. When the base unit cannot receive the control signal to either terminate or hold the speech, it restores the original degree of attenuation of the attenuating circuit and again sends the control signal to either terminate or hold the speech.

Abstract: An amplifier drive control circuit having a power combiner for combining an RF input signal with a feedback signal to provide a composite RF signal, a power control circuit for providing a selectively attenuated replica of the composite RF signal to the input of the amplifier, and feedback circuitry connected between the output of the amplifier and the power combiner for providing a level controlled portion of the output of the amplifier as the feedback signal. The power control circuit selectively attenuates the replica of the composite RF signal when the power of the composite RF signal exceeds a predetermined threshold, while the feedback circuitry controls the level of the feedback signal as a function of the gain of the amplifier as determined by the level of the composite RF signal and the level of the amplifier output. The feedback circuitry includes a feedback phase control circuit for controlling the phase of the feedback signal relative to the input to the amplifier.

Abstract: An automatic power control system compensates for temperature variable components in a broadband signal generator by providing a reference signal generating circuit that is temperature matched with an automatic level control feedback circuit. The temperature matched components are either monolithic or placed in substantial thermal contact with one another. The signals from the matched signal paths are input to a summing circuit such that the effect of any temperature variation in one path is exactly offset by the corresponding temperature variation in the other path.

Abstract: A power amplifier is provided for amplifying a radio frequency signal such as in a burst modulation manner for use in GSM cellular radio. The amplifier has means, such as a ROM (16), for producing a predetermined sequence of values in response to a control pulse. Means (21) are provided for converting each value into a power control signal, and control means (9) are provided for controlling the amplifier output power in accordance with said power control signal. In this manner, the power/time characteristic can be made to take the form of a raised cosine. The invention also provides power selection means for selecting a nominal output level from a plurality of discrete levels and for selecting power sub-levels offset from said selected level. An indication is recorded as to which sub-level best represents the nominal power level.

Abstract: An improved PSK transmitter such as may be used in a CATV system in the up-link from terminal units to a center having a simple arrangement for switching ON and OFF the PSK carrier signal. An oscillator produces a oscillation output signal at a frequency twice that of the desired carrier frequency. The output of the oscillator is then frequency divided by an element such as a T-type flip-flop, the operation of which is switched ON and OFF by a control signal.

Abstract: In an AM broadcast transmitter having a switching amplifier as main modulator (12), an additional modulator (18) is used in the radio frequency circuit in order to achieve a steady 100% modulation at the modulation minima, with the aid of which additional modulator the carrier signal is also modulated at the modulation minima. The LF signal needed for controlling the additional modulator (18) passes through a delay circuit (16) and a correction circuit (17).

Abstract: The power transmitted by an r.f. transmitting and receiving station, such as a mobile station, to a fixed base station, is controlled as a function of power received by the mobile station to obtain a constant receiving power level in the fixed station despite variations in the relative location of the stations. The power received by the mobile station is measured and sampled at predetermined instants. At each predetermined instant, the power to be received by the mobile station at a following predetermined instant is estimated as a function of the measured power, to derive an estimated power. R.f. signal power transmitted by the mobile station is reduced between the successive instants in proportion to the estimated power.

Abstract: A modulation limiter that eliminates over-deviation otherwise caused by asymmetrical modulation signals in a frequency modulated (FM) transmitter. The output signal from a conventional modulation clipper is integrated, multiplied by a gain constant, and subtracted from the input, which causes the clipper output to have zero average and a high-pass frequency response with a time constant determined by the feedback gain. The zero average value allows the clipped modulation signal to be coupled to a modulator without over-deviation caused by shifts in the average value of the clipped signal, and the high-pass response can be used to give the modulation signal pre-emphasis.

Abstract: A radio frequency modulator/demodulator (modem) and method for receiving and transmitting data over a radio frequency data link. The modem has a transmitting section which includes a modulator which modulates a radio frequency signal in response to data provided by, for example, an associated processor. The transmitting section further includes a watchdog or enable circuit which monitors a request-to-send signal produced by the associated processor, with the request-to-send signal being present when the processor is generating data to be transmitted over the data link. The enable circuit will disable the modulator should a transmission exceed a maximum predetermined time period, thereby preventing the associated processor from monopolizing the data link in the event of a processor failure.

Abstract: An RF-AM transmitter includes a pulse amplifier responsive to a pulse width modulated (PWM) signal derived in response to an information signal. A low pass filter converts pulses derived by the power amplifier into a variable amplitude signal that is DC coupled to a power supply for an RF amplifier. An amplifier system including the pulse and RF amplifiers has stray capacitance coupled to a modulator which derives the PWM signal; the stray capacitance lengthens narrow modulator output pulses so they are excessively long. The amplitude of only the narrow pulses is reduced by a resistor-capacitor timing circuit in series with a switch to substantially preserve the narrow pulse area. The switch provides a low impedance path from the timing circuit to a reference potential terminal when current initially flows in the circuit during pulse transitions and throughout the length of each of the short duration pulses.

Abstract: An arrow that accepts standard target or hunting tips includes a radio signalling transmitter which emits a carrier signal that is receivable by a directional receiver for tracking and locating the arrow when released from a bow. The transmitter includes a carrier interrupting circuit operating at a rate that is inversely proportional to battery voltage which permits dynamically testing the battery prior to releasing the arrow. This provides reliable operation of the transmitter by insuring an adequate minimum charge in the battery. An electrical switch embodying the arrow tip as an actuator permits selectively connecting or disconnecting the battery from the transmitter to conserve the battery charge.

Abstract: An RF modulator is characterized by a gain adjusting circuit for gain adjustment incorporated with an RF amplifier for amplifying a carrier wave provided from a carrier oscillator and applying the same to a video signal modulator and to an audio signal mixer so that the gain of the RF amplifier is adjustable so as to adjust a difference in level of the carrier wave provided differently depending upon a resonance element being connected to the carrier oscillator.

Abstract: A target tracking transmitter has an internal voltage supply which may be operated at a first operative level and a second reduced operative level. A switch is provided for cycling the voltage supply between the first and second operative levels, which are both sufficient to ensure generation by the transmitter of radio frequency signals for detection by a remote receiver. The switch is arranged to control the time for which the transmitter is cycled at the first and second levels whereby the operating life of the internal voltage supply is maximized while enabling continuous generation of the radio frequency signals.

Abstract: A single-channel-per-carrier multiple-access communication system including a voice-activated transmission power controller operable in the absence of voice signal input to attenuate the transmission power or modulator output signal to a predetermined level under the control of voice detector output, facilitating carrier sync recovery at the receive end and simplifying design and structure of the demodulator.

Abstract: A burst signal generating apparatus and related method includes a modulator circuit for modulating a carrier wave of an intermediate frequency signal with a modulating signal. The output of the modulator having a carrier wave frequency is converted to a radio frequency which is amplitude controlled in response to a burst control signal. The carrier wave of the intermediate frequency is switched in response to a burst control signal. Thus, a carrier wave of the radio frequency signal has a desired envelope, permitting ready suppression of the carrier wave during pauses between burst signals.

Abstract: A pulse repetition modulator apparatus having a pulse width modulator to supply a series of maximum transmitter power output bursts that have been generated with a pulse time correlation to the sampled amplitude of the voice signal input to the link. The output bursts would therefore be of variable length with the durations proportional to the amplitude of the voice input signal.

Abstract: A method for controlling the carrier of an amplitude-modulated transmitter, wherein a saving in carrier power with simultaneous minimum dynamic distortions is achieved by digitizing the useful signal and digitally processing all control signals. The circuit for carrying out the method contains a digital computing circuit which calculates from the digital amplitude values of the useful signal a carrier-control value which controls the carrier level via a digital switching amplifier.

Abstract: An amplitude-modulated transmitter wherein the carrier value (T) is controlled in accordance with an improved HAPUG (controlled-carrier) method. Increased energy saving with simultaneous increase of the signal-to-noise ratio at the reception site is achieved by controlling the carrier along a static characteristic (SK) which begins, with a decreasing modulation level (P), with a residual carrier value (R), drops with increasing modulation levels to a minimum carrier value (T.sub.min) and passes into an ideal carrier-control characteristic only above a first level value (P.sub.1). Additional dynamic control results in a reduction in cross-over distortions.

Abstract: A compressed single side band communication system and method in which the audio signal is compressed prior to pre-emphasis and thereafter summed with a pilot tone for further compression prior to transmission. Initally, only the pilot tone is transmitted at full rated power to aid in acquisition of the signal by the receiver. Thereafter, the transmitter ALC is disabled and the pilot tone is attenuated. The receiver adjusts the frequency characteristics of the pilot tone filter and phase lock loop filter in the detector as a function of lock-on. The delay after loss of lock-on in reverting to wide band pilot tone and wideband loop filters is varied as a function of signal strength. The pilot tone may be modulated for tone coded squelch. The modulating source is located in the return end of the phase lock loop filter. A unique filter is provided to insure acquisition of the pilot tone.

Abstract: A rectifier, preferably a bridge rectifier, is connected in series between a radio frequency (RF) signal generator and audio signal generator, and an antenna included in an RF signal transmitting circuit for rectifying the signal generated by the transmitting circuit before transmission. In the case of an amplitude modulation (AM) transmitting circuit, relatively low percentage modulation causes the rectifier to operate in a linear range and results in relative intensification of the power in the sidebands of the AM signal, whereby the ratio of the sideband power to the carrier power is increased which means that a relatively greater amount of power is applied to transmission of the message-bearing sidebands as compared to the carrier than in conventional AM transmitting circuits.

Abstract: In a transceiver, a multiple function switch decoder includes means for detecting actuation of the switch and means for monitoring the status of the receiver. A timer responsive to the monitoring means and detecting means establishes a predetermined time interval following each switch actuation or each received message of predetermined type. When the switch is actuated during the time interval the transmitter is enabled. When the switch is activated outside the time interval the receiver audio is activated so the user may monitor the channel. During the first switch actuation in any given time interval an encoder is enabled. On subsequent switch actuations during the same time interval the encoder is inhibited. This allows a single switch to perform a plurality of transmitter and receiver functions.

Abstract: Improved radio transmitter modulation control circuitry is described which significantly increases the average power of the modulating signal, resulting in enhanced audio signal quality since the signal-to-noise ratio is likewise increased. The inventive modulation control circuitry includes a microphone 110, audio amplifier 120, splatter filter 130, modulator 150, potentiometer 140, oscillator and transmitter 180, and antenna 190. The audio amplifier 120 further includes an operational amplifier 160 having an input resistor 162 coupled via capacitor 168 to microphone 110, a phase-lag filter 170 coupled to the output of the operational amplifier 160, and a feedback resistor 161 coupled between the filter 170 and the input resistor 162. When driven into amplitude limiting, the phase and amplitude of harmonic signals from the operational amplifier 160 are altered by phase-lag filter 170 to produce a waveform similar to that shown in FIG. 2.

Abstract: In a system for transmitting a charging signal from an exchange to a telephone system together with a voice signal, radio equipment in the exchange side detects the charging signal sent from the exchange and encodes it into a pulse code signal comprising a plurality of continuous pulses. Thereafter, this pulse signal is modulated into a frequency signal outside the voice transmitting frequency band and then transmitted as a radio signal after it is superimposed on the voice signal. Radio equipment on the telephone side detects this charging signal carrier and demodulates it into the pulse code signal, then counts it and transfers the charging signal when the counted value reaches a specified value.

Abstract: A portable frequency modulation transmitter (1) for voice or data is disclosed for operation at infrared frequencies. The transmitter comprises keyboard (200) or microphone (402) input capability and dual modes of use. In the data mode, carrier is generated when the keyboard is operated and is not generated when the keyboard is idle in order to conserve power. In the voice mode, either voice or data may be transmitted, data having priority over voice. A series connection of two variable modulus counters (302, 303) and other counters (304, 305, 306) provide a frequency shift keyed data signal, marker data signal, marker data frames between data frames, parity insertion and other features. In the event that the local battery power level falls below a particular level, a particular word is inserted in the applied binary data input.

Abstract: Peak-limiting AGC for increased average power SSB transmission is improved by deriving a gain-control signal using Hilbert transform detection techniques to obtain a modulated envelope signal which is compared with a peak clipping reference to form the limiting gain-control signal.