Abstract: A levelling control arrangement for an RF transmitter circuit which additionally compensates for filter ripple, i.e. frequency dependant power variations caused by the filter disposed between a transmitter amplifier and an antenna. The forward and reflected power is sampled by a dual directional coupler between the amplifier and the filter. Signals V.sub.fwd and V.sub.rev are thus obtained indicative of the forward and reflected power levels respectively. The reflected signal V.sub.rev is subtracted from the forward signal V.sub.fwd at comparator and the difference signal V.sub.diff is compared with a reference signal Vref at comparator to produce a signal V.sub.c which is used to control the gain of the amplifier in such manner that the power developed by the amplifier increases as the signal V.sub.rev increases and vice versa. To protect against excessive reflected power levels a limiter may be included which causes the power developed by the amplifier to be reduced only if V.sub.

Abstract: A radiotelephone apparatus employed as a so-called portable telephone or a car telephone includes an outer casing, a chassis base plate provided in the outer casing and mounting an electronic circuit section containing above all a heated element or elements, and a fan containing section containing a heat sink and a fan device connected in a heat conductive relation with the chassis base plate. The electronic circuit section and the fan containing section within the outer casing are isolated from each other by an air current interrupting device for air cooling heated electronic components while preventing dust and dirt in the air from flowing into portions in the casing other than the fan containing section. An air intake window is provided in the vicinity of mechanically operating portion of the apparatus for self cleaning dust and dirt sucked by the air flow through the normal telephone operation.

Abstract: A radio communication apparatus has a modulating portion for modulating a carrier with a signal to be transmitting so as to produce a transmission signal. A signal transmitting portion causes the transmissible signal to be subjected to power amplification. The transmissible signal is transmitted after having been subjected to power amplification. A cooling device is provided for cooling by force a heat source contained in the signal transmitting portion in response to a condition detector for detecting a temperature condition or an operating condition of the signal transmitting portion. An operation control unit is operative to cause the cooling device to be in operation when a particular temperature condition in which temperature of the signal transmitting portion has exceeded a predetermined value or a particular operating condition in which the signal transmitting portion has been in a predetermined state is detected by the condition dectector.

Abstract: An instantaneous voltage drop detector includes a reset signal generating circuit which generates a low-level reset signal when a DC power voltage falls below a predetermined level. When the reset signal exists, an integrating circuit discharges the electric charge charged thereon in accordance with its time constant. If the reset signal disappears, i.e., the output of the reset signal generating circuit changes to a high level, a changing circuit rapidly charges the integrating circuit to avoid interference between instantaneous voltage drops which continuously occur at a short interval. The detector also includes a comparator which compares the output level of the integrating circuit with a reference level and a latch circuit (E/F) which latches the output of the comparator in response to the disappearance of the reset signal, i.e., in response to the positive-going edge of output of the reset signal generating circuit.

Abstract: An RF power supply serves to supply a regulated power amplified RF drive signal to an RF transmitter. The supply includes an RF oscillator for providing an RF input signal. A DC voltage source provides a DC voltage V. A plurality of power amplifiers are provided with each receiving the input RF signal and each having an input for receiving a DC voltage signal, and each serving to amplify the input RF signal by an amount dependent upon the magnitude of the DC voltage signal supplied to its input and thereby provide an amplified RF signal. The amplified RF signals are combined to provide an RF drive signal. The DC voltage V is directly supplied to the input of at least a first one of the power amplifiers.

Abstract: An adaptive thermal protection method and arrangement for a power amplifier by remote sense is disclosed which maximizes the amount of output power from electronic equipment such as a radio frequency (RF) power amplifier, having a finite heat sink and operating intermittently over a period of time. This method and apparatus utilizes a remote temperature sensor and knowledge of the on/off, or key/dekey times in conjunction with a stored, predetermined thermal model to adjust the operating power level to a maximum permissible point within a range of operating power levels such that the projected temperature of the power amplifier does not exceed a preset limit. In so doing, the apparatus and method combines the advantages of thermal protection and power maximazation and effects gradual changes in the operating power level by adapting to variable environmental and operational conditions.

Abstract: A transmitter includes a phase-locked loop (PLL) circuit whose output is frequency modulated with a modulation signal. The modulated signal is amplified by an amplifier which is turned on only during a signal transmission of the transmitter. At a time when the amplifier is turned, the output frequency of PLL circuit fluctuates. To depress this frequency fluctuation, the transmitter includes a frequency fluctuation depressing (FFD) circuit. Upon the turning-on of the amplifier, FFD circuit applies a voltage change to the modulation signal so that the frequency fluctuation is depressed.

Abstract: An instantaneous voltage drop detector that comprises a power supply for a utilization circuit such as a mobile telephone. A first detector detects a drop in an output voltage of the power supply that falls below a first predetermined level. A second detector determines whether the first detection signal continues for more than a predetermined time. A control circuit responds to the first and second detection signals for controlling the utilization circuit.

Abstract: A radio-on timer and transmission-on timer of a cellular telephone (100) provide an accurate record of the total amount of time since manufacture that the cellular telephone (100) and its transmitter (160), respectively, have been turned on for the purpose of measuring the in-field reliability thereof. The cellular telephone (100) includes a processor (110) that is responsive an interrupt signal (117) for incrementing and storing an interrupt timer, the radio-on timer and the transmission-on timer in a volatile memory 114. When the processor (110) senses that power has been switched off, the processor (110) reads out from the volatile memory (114) the radio-on timer and transmission-on timer, reads out from the non-volatile memory (112) the previously stored radio-on timer and transmission-on timer, adds them together and stores the summed radio-on timer and transmission-on timer back in the non-volatile memory (112).

Abstract: A stabilized transmitter includes a gain converter that varies its gain according to an electrical signal; a power amplifier that amplifies a high-frequency signal passed through the gain converter; and a compensator having a temperature sensor which detects the temperature of the power amplifier for producing from a detection result of the temperature sensor the electrical signal applied to the gain converter so as to thereby to compensate for variations of the gain of the power amplifier caused by temperature variations. The compensator is adjusted in advance so that the gain of the power amplifier at a reference temperature becomes a predetermined value.

Abstract: An output power control circuit is provided in a casing of a mobile radio apparatus together with an automatic power control circuit and an RF signal amplifier. The output power control circuit applied level control signals to the automatic power control circuit for maintaining the power level of the output RF signal of the RF amplifier at one of a plurality of output power levels corresponding to the level control signals. The output power control circuit has a receiver, a temperature sensing circuit and a logic circuit. The receiver receives RF signals transmitted by a master station and detects power level setting command signals included in the received RF signal. The temperature sensing circuit detects an internal temperature of the casing and provides a power reduction signal upon detecting that the internal temperature has exceeded a predetermined temperature.

Abstract: An RF power amplifier is operated by supplying an RF signal to the amplifier for amplification and thereby providing an output RF signal to the amplifier's output circuit which has an impedance matching output network connected in series with a load. A detector serves to detect any reflected power in the output circuit. The RF power amplifier is turned off when the detected RF power exceeds a reference level. The amplifier is protected by discontinuing the supply of the RF signal to the amplifier while it is turned off and, instead, a frequency signal is supplied to the RF amplifier having a frequency that corresponds with that of any current flowing in the output circuit.

Abstract: An intermittently driven transmitter having high power output which is driven intermittently so as to transmit a signal via, for example, a satellite in which the voltage supplied to the transmitter is boosted and supplied to a capacitor. When the signal is to be transmitted, the voltage stored on the capacitor is supplied to a constant voltage circuit which generates a constant voltage which is higher than the voltage supplied to the transmitter and which is supplied to a power amplifier in the final stage of the transmitter and, thus, the intermittent type transmitter with a suitable battery drive system is obtained.

Abstract: The present invention relates to a device for use in an amplitude modulated RF transmitter. The device protects power transistors located in the RF transmitter particularly in the modulator and power amplifier portions of the transmitter. The device is comprised of a capacitor unit which is adpated to be charged in a first direction; a detector which detects an audio modulating signal; and a discharge unit which is connected to both the capacitor unit and the detector which selectively discharges the capacitor unit when the value of the audio modulating signal reaches a first preset level for a preset time duration during a portion of the audio modulating signal which causes positive modulation of the RF transmitter. The device also comprises a switch unit connected to the capacitor unit and which is activated when the capacitor unit discharges to a predetermined level. The switch unit is operable to remove, when activated, the audio modulating signal from the power transistors.

Abstract: An emergency locating transmitting (ELT) system comprising a legislated ELT modified with an interface unit and connected by a multiwire cable to a remote control monitor (RCM), typically located at the pilot position. The RCM can remotely (1) test the ELT by disabling the legislated swept tone and allowing transmission of a single tone, (2) turn the ELT "on" for legislated ELT transmission, and (3) reset the ELT to an "armed" condition. The RCM also provides visual and audio indications of transmitter operating condition as well as ELT battery condition. Removing the RCM or shorting or opening the interface input connections will not affect traditional ELT operation.

Abstract: A battery-powered mobile communications unit for reception and transmission of signals in which the continued transmitter operation, following activation, is controlled in response to accurate detection of battery deterioration. The battery voltage is monitored by a reset circuit to detect any voltage drop that exceeds a predetermined threshold and a command unit responds to the reset circuit to turn the transmitter off as long as the battery voltage is below threshold and to turn the transmitter on when the battery voltage rises above threshold. The duration of the voltage drop is also measured to determine if the drop is instantaneous, due to interferences or extended due to a battery deterioration. If extended, the command unit will not turn the transmitter on, even though the reset circuit indicates a rise in battery voltage above threshold.

Abstract: An improved platform transmitter terminal (PTT) is disclosed for use in an ARGOS type satellite system. The PTT has reduced size, weight and extended life due to a solar array/rechargeable battery power source operating under the supervision of a unique power supply control and protection means. The invented PTT, when used in an ARGOS type system, opens the possibility of tracking, on a global basis, wild animals weighing as little as a few kilograms.

Abstract: An improved power controller and protection circuit to regulate the RF output power of a radio transmitter and to protect its RF amplifier from overload damage. The controller features a floating input, voltage controlled current source with high common-mode rejection to provide feedback of the DC input current drawn by the RF power amplifier. The controller can use an arbitrary reference voltage, which allows its application universally with power amplifiers designed for different rated output powers and frequency ranges.

Abstract: An apparatus for controlling the output power of a transmitter that is installed in a vehicle or used in a mobile radio communication equipment has a power amplifier, a coupler for delivering an output corresponding to the output power from the power amplifier, a detector disposed after the coupler, a comparator for delivering an output proportional to the difference between the output voltage from the demodulator and a reference voltage, and a voltage control circuit for controlling the output power of the power amplifier in response to the output from the comparator. An RF variable attenuator is disposed before the comparator to compress the dynamic range of the signal applied to the voltage control circuit.

Abstract: An output transistor of an RF power amplifier remains stable so that it does not generate subharmonic spurious outputs. An adaptive stabilization network maintains the stability of the output by decreasing the impedance presented to the output transistor when voltage levels at the output transistor exceed a predetermined level. A combination consisting of a peak detector coupled to a Zener diode senses the predetermined level. A PIN diode couples to the Zener diode and to the output transistor so that the PIN diode becomes forward biased when the predetermined level is exceeded.

Abstract: A radio communication device comprises a portable communication device and a power amplifier device adapted to accommodating the portable communication device thereinto for amplifying a transmitter output therefrom. The radio communication device further comprises a detector circuit for detecting that an electrical coupling between the portable communication device and the power amplifier device, thereby effecting a control such that the transmitter output power level is kept at a minimum input level required for the power amplifier device. Thus, this can suppress exceesive heat generation in the communication device when the portable communication device is used by being accomodated in the power amplifier device.

Abstract: An adaptive impedance mismatch detector system is provided for determining whether or not a particular load impedance is matched or mismatched to the characteristic impedance of a transmission line. The detector system is capable of determining if a particular load impedance has a value outside of an impedance threshold circle having a center at a location other than at the center of the Smith Chart. The system changes the radius and/or center of the threshold circle in response to changes in circuit operating conditions or parameters. This flexibility enables the detector to be more selective in determining improper load conditions.

Abstract: An overload protector, using a power-dissipating element for receiving and dissipating excessive radio-frequency power, can safely transfer a signal from an input to an output. The protector also has a detector coupled to the input for providing a bias current in response to an input signal in excess of a predetermined magnitude. Also included in a diverter coupled to the input, the output, the power-dissipating element and the detector. This diverter can receive the bias current and can, in response, redirect power at the input from the output to the power-dissipating element.

Abstract: The present invention achieves constant voltage at radio frequencies to drive a constant voltage to constant current converter, by employing a tightly coupled d.c. feedback loop to control the voltage via a transformer to the drain of a FET operated as a Class C amplifier in the saturated mode whereby among other advantages, the amplifier can withstand, without damage, very high VSWRs. Control is affected by a high gain differential amplifier which compares a d.c. voltage derived from the r.f. output of the system against a highly stable d.c. voltage reference. A controller, responding to the output of the differential amplifier causes a first level of voltage to be applied to the drain of the FET when the system is not loaded and causes a second voltage varying between said first level and a higher level when the system is loaded.

Abstract: A warning and protection circuit arrangement suitable for use in conjunction with a two-way portable transceiver having a removable battery pack/antenna includes a battery enclosure containing an antenna structure. A circuit is enclosed inside the battery enclosure for providing information indicative of certain predetermined parameters of the antenna or the battery. This information may be used by the transceiver to provide the user with an alert in the event an inappropriate battery pack/antenna is being used. The information may also be used to modify the normal operation of the transceiver to avoid possible damage.

Abstract: A circuit for providing a constant current to an output stage of a cordless telephone transmitter using AC power lines as a transmission medium to maintain the RF component on the AC lines to within regulated limits. The RF component is sensed to provide a control signal to a voltage-responsive capacitor in a tuned circuit connected to a tuned coupling transformer between a modulating circuit and the transmitter output amplifier. When the RF component exceeds the current limit of 90 mA, the coupling transformer is detuned to maintain the RF current in the power lines to within the regulated limits.

Abstract: A power source device for a portable type radio apparatus having a transmitting circuit wherein the transmitting circuit is connected to the power source through a time constant circuit and a tone signal generating circuit is connected to the time constant circuit through a delay timing circuit. The tone signal generating circuit is operated at a required time before the operation of the transmitting circuit is terminated by the time constant circuit to inform a user of the fact that the transmitting circuit is about to be stopped in operation.

Abstract: Disclosed is a regulator circuitry (stabilizer) for controlling the output of an RF generator according to a programmable input signal. A power stage is responsive to the selected value of the programmable input signal to drive the RF generator at the desired power level. A forward power feedback control circuit monitors and controls the power output stage so that the desired RF output level is maintained at a constant level. In this particular mode of operation, RF output power is maintained constant and therefore independent of variations in gain due to temperature changes and other parameters which could effect the overall transfer function of said generator (and including mismatch of the generator into the load).

Abstract: A radio transmitter has an output power control circuit including a power amplifier, a directional coupler coupled to the power amplifier, a detector of the forward power of the directional coupler, a generator of a difference voltage between the output voltage of the detector means and a reference voltage. A power regulator varys the output power of the power amplifier in response to the output of the difference voltage. The power applied from the power amplifier through the directional coupler to the detector is controlled by a control signal.The control circuit electrically varies the coupling coefficient of the directional coupler for attenuating the power applied from the directional coupler to the detector means to extend the controllable range of the transmitter output power.

Abstract: An intermodulation distortion limiter controls the ratio of average power to peak envelope power in the output of a linear power amplifier and this protects against excess non-linearity by reducing the drive power when the ratio exceeds a similar ratio associated with the incoming RF signal.

Abstract: A radio transmitter is protected against the possibility of initiating transmission without the radio being connected to a load by having a switch that controls a push-to-talk key line that is only enabled when the antenna load is connected to the transmitter.

Abstract: A camera has an image pick-up device for taking out image signals, and a setting circuit having a first setting mode for bringing the image pick-up device into a non-excited state, a second setting mode for bringing the image pick-up device into a first excited state, and a third setting mode for bringing the image pick-up device into a second excited state and making it possible to take out the image signals from the image pick-up device.

Abstract: A protection circuit for a transmitter amplifier which provides power leveling and controls transmitter output power as a function of the ratio of reflected power to forward power. The circuit senses forward power level and develops a first voltage which is compared with the reference voltage to provide a control voltage which controls the power developed by the transmitter amplifier. Reflected power is sensed and a second voltage is developed which is compared to a portion of the first voltage and causes a reduction in the reference voltage when the reflected power to forward power ratio exceeds a predetermined level.

Abstract: Sense voltages representative of transmitter power and the temperature of the transmitter output stage are summed and fed to the input of a high gain amplifier. The output of the amplifier provides bias to the transmitter driver stage and, thus, controls the total transmitter developed power. The resulting overall feedback system provides precise transmitter power control and output stage thermal protection.

Abstract: A frequency modulated stereo transmitter in the preferred embodiment has a stereo generator which receives audio sterero signals directly. The stereo generator includes gain control circuitry which acts directly on the sum and difference signals generated in the stereo generator.The stereo generator then directly modulates a modulation protion of an RF transmitter unit thereby maintaining a very high index of modulation. Audio gain control and audio limiting are thus eliminated. In alternative embodiments the stereo generator unit gain control circuitry is adapted to existing FM stereo transmitters.

Abstract: Circuitry for controlling the power output of an R.F. generator for regulating the forward power transmitted into a load of varying impedance, such as an R.F. sputtering target, and for limiting reflected power to a safe predetermined level. Forward power is controlled by circuitry that compares the voltage across the target with a predetermined reference voltage and the amplified output is applied to the signal generator control circuitry. Reflected power is measured by a sensor that outputs a proportional D.C. signal that is compared with a predetermined threshold voltage. Whenever the reflected power signal exceeds this threshold, it removes the effect of the target voltage input signal so that the amplified control signal to the R.F. generator is a function only of the reflected power.

Abstract: A device for monitoring the performance of a transmitter, comprising a first input connected to receive a signal representative of transmitter output current, a second input connected to receive a signal representative of transmitter output voltage, a multiplier, a comparator connected to the output of the multiplier, and a switch controllable either to connect the first and second inputs to the multiplier such that the multiplier output is representative of the transmitter output power, or to connect one of the two inputs to the multiplier and the other to the comparator and to connect the comparator output to the multiplier such that the comparator remains in balance and the comparator output is representative of the transmitter output impedance. The first input may be connected directly to the multiplier and the second input can be selectively connected to either the multiplier or the comparator by the switching means.

Abstract: An automatic modulation control in a transmitter, comprising an alternating modulation signal source, a modulation signal amplifier, a carrier generator, a modulator for modulating the carrier signal as a function of the output of the modulation signal amplifier, a threshold detector coupled in a direct current manner to the output of the modulation signal amplifier for threshold detecting the modulation signal output, a smoothing circuit for smoothing the threshold detected output, an amplifier for the threshold detected and smoothed output, and a control circuit for controlling the input of the modulation signal to the modulation signal amplifier as a function of the output of the threshold detected output amplifier.

Abstract: A mobile data terminal system is capable of voice or microprocessor controlled data transmission over a keyed transmitter. The improved timer apparatus disables further transmission if the transmission duration or the average duty cycle over a predetermined time period of repeated transmitter keying exceed predetermined limits. Where the disable mode resulted from a microprocessor fault, the transmitter continues to be disabled until the microprocessor is reset.

Abstract: A compatible AM stereo system including a modified quadrature modulation scheme. Two stereo modulators are described which each generate composite modulated signals including a carrier component and two phase-shifted components. The two phase-shifted components, corresponding to the left (L) and right (R) source signals, are phase shifted by equal phase angles .theta. on either side of the carrier, where .theta. is between 10.degree. and 20.degree.. A limiter is included which operates to limit the magnitude of the source signals supplied by the stereo modulator. The limiter allows each source signal to contribute up to 80% of the total modulation, as long as total modulation constraints are not exceeded due to the combined amplitudes of the two source signals. A receiver is described for demodulating the composite modulated signal.

Abstract: An optical signal transmitter for use by priority vehicles for remotely controlling traffic signals, including a light source which is flashed at a controlled repetition rate to transmit an optical signal to a receiver located at the traffic intersection. Circuitry associated with the light source includes a comparator network for disabling an electrical energy supply in the event of certain predetermined operating conditions.

Abstract: A method and apparatus for monitoring and controlling the anode power dissipation of transmitters. First and second signals proportional to the anode power input and anode power output are produced and subtracted from each other, thus resulting in a third signal proportional to anode power dissipation. The third signal is applied to a pair of threshold value actuators, with one threshold value actuator actuating transmitter tuning elements when an initial threshold level is exceeded, and the second threshold actuator switching the transmitter off when a second threshold is exceeded.