Abstract: A communication system which includes a receiving section having a frequency convertor for converting a received signal into an intermediate frequency signal by mixing with a local oscillation signal, and a demodulator for demodulating the received signal converted into the intermediate frequency signal, a transmission section for modulating a transmission signal received thereby, to transmit the so modulated signal, and an input/output section for receiving the demodulated signal from the receiving section and outputting it externally and receiving the transmission signal externally and outputting it to the transmission section.

Abstract: For starting a registration operation of location information of movable radio telephone sets into a subscriber's file in a line connection unit connected to radio connection devices in a mobile telephone network system after travel of each of the radio telephone sets, each radio telephone set is provided with a unit for measuring a travel amount. The radio telephone set produces a request signal for the location information registration when the travel amount measured exceeds a first threshold value. Alternatively, the radio telephone set reset the measuring unit when the travel amount measured exceeds a first threshold value and thereafter produces a request signal for the location information registration when the travel amount measured does not exceed a second threshold value smaller that the first threshold value. Radio connection devices announce location information signals and each radio telephone set holds, as a held location information, the location information registered in the subscriber's file.

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: A circuit for alternately providing a first frequency to a receiver stage (20) and a second frequency to a transmitter stage (25) of a transmitter and receive circuit (11). The circuit comprises an oscillator (38), a first switch (33), a second switch (42), and a control circuit (29). The first switch (33) couples information to the oscillator (38) to be transposed on the second frequency during transmission. The second switch (42) couples the oscillator (38) to either the transmitter stage (25) or the receiver stage (20). Prior to changing oscillator frequency the control circuit (29) disables both outputs of the second switch (42). The control circuit (29) alternately tunes the oscillator (38) to the first frequency and enables the second switch (42) such that the oscillator (38) is coupled to the receiver stage (20) and tunes the oscillator (38) to the second frequency, enables the first switch (33), and enables the second switch (42 ) such that the oscillator (38) is coupled to the transmitter stage (25).

Abstract: A new digital oscillator is described that can be synchronized with a broadcast digital input signal by iteratively rotating the phase of the complex oscillator signal by increasing or decreasing the components, depending upon the phase difference between the broadcast signal and the oscillator output signal.

Abstract: A wireless transmission system includes a plurality of terminal units, a specific one of which is provided with a transmission/receiving circuit that transmits a reference signal of a local oscillation frequency, while all others of which are provided respectively with a transmission/receiving circuit that prepares, on the basis of the reference signal received, a local oscillation frequency signal for frequency conversion of transmitting/receiving frequency signal and intermediate frequency signal, to thereby realize the system at lower costs even when a high local oscillation frequency is employed.

Abstract: A time-division duplex radio transceiver is disclosed which can avoid the deterioration of reception sensitivity and interferences in other radio communication equipments of the same kind which may be caused in the conventional transceiver by generation in the transceiver of an interfering signal of a transmission frequency or a frequency in the vicinity thereof, even upon reception. In the time-division duplex radio transceiver according to the present invention, in order to generate a carrier frequency signal in the transmission state or an intermediate frequency in a transceiver portion, there are provided an oscillator for oscillation at a frequency higher than the carrier frequency and the intermediate frequency, and frequency dividers for frequency-dividing an output of the oscillator, where the operation of the frequency dividers is stopped in the reception state.

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.

Abstract: The synchronization process of the present invention filters the received signal with an adaptive band-pass filter (101) while buffering the received signal in memory (108). The energies of the input signal and the filtered signal are estimated (103 and 104) and the gain of the filter is adapted (105) based on the difference between the energies. The pole of the filter is adapted (102) to center the frequency of the input signal in the filter's pass-band. If a tone is detected (106), the length of the tone is determined (107) to ascertain if it is a frequency correction burst (FCB). If the tone detected is an FCB, the signal in the memory is also the FCB that is then filtered in the band-pass filter (101) and the difference between the frequency of this signal and 67.5 kHz is determined (109). This difference represents the frequency offset between the base station carrier frequency and that of the mobile radiotelephone, and can be fed into the local oscillating means to compensate for the frequency offset.

Abstract: A transmitting and multiple line superheterodyne receiving device and transmitting device for the communications, particularly telecommunications field is disclosed. To suppress the modulation signal components otherwise generated by the transmitting device, a compensation device is provided which includes a frequency control circuit with a voltage controlled oscillator, whose nominal frequency corresponds to the sum or difference of the first and second intermediate frequencies and which is connected to a second receiving mixer.

Abstract: An information transmission arrangement comprising transceiver units (1, 2) located in a propagation medium (10) whose attentuation varies as a function of frequency. At least one unit (1) comprise a meter (67) for measuring the level of the received signal in order to influence the frequency variation control (32) of the control oscillator (28) in the send circuit (26, 28) of the other unit (2). This arrangement profits from a monotonic attenuation gradient of the propagation medium (10) having a zone (Z1) in the 50-60 GHz band to control the send level in a simple and effective manner.

Abstract: A frequency modulated radio frequency broadcast network in which re-transmitting stations employ a synchronous frequency modulated booster system. Included in the frequency modulated booster system is a synchronous frequency modulated exciter for converting a frequency modulated intermediate frequency into a frequency modulated broadcast signal. The synchronous frequency modulated exciter includes phase locked loop circuits for synchronizing the re-transmitted frequency modulated broadcast signal with the frequency modulated intermediate frequency signal by detecting reference signals in the composite baseband of the intermediate frequency signal and in the composite signal frequency modulated broadcast signal.

Abstract: A high stability oscillator circuit 100 having an output 150 and a multiple of reference oscillators 102, 104, and 106 for enhanced stability and reliability is disclosed. The output signals of these oscillators 108, 110, and 112 are mixed and analyzed for determination of excessive frequency shift including component failure. Additionally a switch 148 decouples the shifted oscillator signal from the output of the circuit 150 and couples another one of the oscillators in its place.

Abstract: A frequency modulated radio frequency broadcast network in which re-transmitting stations employ a synchronous frequency modulated booster system. Included in the frequency modulated booster system is a synchronous frequency modualted exciter for converting a frequency modulated intermediate frequency into a frequency modulated broadcast signal. The synchronous frequency modulated exicter includes phase locked loop circuits for synchronizing the re-transmitted frequency modulated broadcast signal with the frequency modulated intermediate frequency signal by detecting reference signals in the composite baseband of the intermediate frequency signal and in the composite signal frequency modulated broadcast signal.

Abstract: A diode tuned resonant circuit (42) with an inductor (L1) a first variable reactance diode (VAR1) connected in parallel with the inductor (L1), and a second variable reactance diode (VAR2) connected in series with the parallel combination of the inductor (L1) and first diode (VAR1) is used in an oscillator circuit. The resonant frequency of the circuit may be adjusted over a relatively broad frequency range while maintaining a relatively constant Q-factor by applying a biasing voltage to the first and second diodes (VAR1, VAR2).

Abstract: A field telephone system having a widely dispersed set of telephone lines including a page line pair and a party line pair, audio processing equipment including telephone handsets, handset amplifiers, receiver amplifiers and paging speaker amplifiers is designed to have improved voice transmission by provision of a narrow band FM carrier system. The FM carrier system includes a device for generating a carrier frequency signal, a modulator for modulating the carrier frequency with an audio signal derived from one of the handsets at a transmitting station and circuitry for transmitting the modulated signal over a line pair to a receiving station. The receiving station includes circuitry responsive to the transmitted signal and the carrier frequency signal for extracting the audio component of the transmitted signal and for processing the extracted audio signal and for providing the processed audio signal to a handset at the receiving station.

Abstract: A narrow band relatively ultra stable radio apparatus for communicating alarm or data signals from a radio transmitter device to a radio receiver device, which receiver or transmitter may be carried by individuals, or may be battery operated or fixed to other devices, such as smoke detectors or burglary sensors, or the like, wherein the transmitting device and the receiving device are both phase locked to a 60 Hertz power line signal either by direct connection or via a 60 Hertz voltage induced into said radio devices from nearby power lines to thereby provide a means to precisely synchronize the transmitting device radio carrier signal and/or digital clock stream with the receiving device to achieve very high signal transmission reliability is disclosed.

Abstract: An automatic frequency control (AFC) circuit is disclosed for use in an SSB radio transceiver having the capability of transmitting and receiving SSB and FM data signals over any one of a number of communication channels having equal bandwidths. The dual-mode AFC circuit includes AFC circuitry which is capable of tracking the frequency of either: (a) a first radio frequency (RF) carrier having voice signals modulated via a signal sideband amplitude modulation within a first channel bandwidth by locking to the reduced pilot carrier transmitter with the SSB signals; or of (b) a second RF carrier having high speed data signals modulated by narrowband frequency modulation within the designated channel bandwidth. The AFC circuit also includes control circuitry to memorize the AFC control voltage during the time the mobile is transmitting, and to assist the acquisition of the FM data carrier by varying the AFC sweep rate on the signalling channel.

Abstract: A method for operating a transmitting/receiving circuit for ultrasonic signals includes the steps of producing a carrier frequency by a voltage-controlled oscillator having an output frequency controlled in accordance with a temperature dependency of an inherent frequency of the transducer, modulating the carrier frequency, applying the modulated carrier frequency in a transmitting mode to energize an ultrasonic transducer to produce ultrasonic transmission signals, switching from the transmitting mode to a receiving mode, applying output signals from the transducer representative of received ultrasonic signals to a phase-locked-loop circuit using the voltage-controlled oscillator whereby the phase-lock-loop circuit is automatically matched to a frequency of the received signals.

Abstract: In a TV answer back system where many receiver stations communicate with a TV transmitter station by means of rf pulses generated by rf oscillators at the receiver station, the requirement for keeping all oscillators on frequency is achieved without crystal temperature control by automatically controlling the rf oscillator frequency using synchronization signals carried in the video signal received from the TV studio. By this invention it has been possible to control the frequency of multiple megahertz oscillator as accurately as desired from relatively low frequency synchronizing signals such as the vertical and horizontal video sync pulses. Thus an oscillations counter is gated for a very accurate time period by the sync pulses, and the oscillation count is compared with a datum count representing the desired oscillation frequency.

Abstract: Apparatus to provide calibrated frequency modulation (FM) of frequencies generated in a phase-locked loop is disclosed. A phase-locked loop (PLL) includes a voltage-controlled oscillator (VCO) which is locked to a loop frequence signal frequency. A modulo-10 divider is included which adds integral multiples of two pi radians of phase to the output signal of the VCO whenever the modulus of the divider is reduced by an integer. This forces the PLL to step change the loop frequency by an integral multiple of the reference frequency. A sampling circuit senses and measures the change in the VCO control voltage resulting from the step change in the loop frequency. The change in the control voltage is a measure of the VCO gain at that frequency. The change in the control voltage is converted to a digital number which is loaded into a multiplying digital-to-analog converter (DAC) to adjust the gain of the DAC.

Abstract: A millimeter wave measurement apparatus utilizing a phase-locked transmitter to generate a millimeter wave-signal and a phase-locked local oscillator receiver to receive the transmitted millimeter wave signal. A conventional microwave receiver unit receives the IF signal from the millimeter wave receiver and downconverts the IF signal for detection and measurement.

Abstract: A frequency converter for use in a receive-transmit ground station in a satellite communication system, having improved frequency control characteristics and reduced cost. The converter utilizes three local oscillators, one of which is a voltage controlled oscillator. In the transmit channel, an output signal for transmission is obtained which is derived from the sum signals from each of three serially connected mixers, each receiving one of the local oscillator signals. In the receive channel, the receive signal is subtracted from the third local oscillator signal, the second local oscillator signal is subtracted from the result, and the final local oscillator signal is added to the result. A pilot tone is extracted from the resulting baseband signal, which is used to control the voltage controlled oscillator. The voltage controlled oscillator can be used either as the first or third local oscillator.

Abstract: A frequency control system with a phase-locked loop for automatically adjusting the frequency of an alternating signal and an external signal derived coherently therefrom to the variant zero phase-shift frequency of a phase shifter adapted to receive the external signal, the control system comprising: a phase shifter responsive to the external signal for introducing a frequency sensitive bipolar phase-shift to the external signal to produce a phase shifted external signal thereat, the phase shifter introducing zero phase-shift at a drift-prone frequency, f.sub.o ; an alternating signal source for generating the alternating signal of adjustable frequency covering a range of frequencies including frequency, f.sub.

Abstract: A single channel, or push-to-talk transceiver includes a switch-controlled Gunn oscillator for generating the carrier frequency during transmission and a continuously operating local oscillator for demodulation of a received signal in the receive mode. When the push-to-talk switch is depressed, the transmit oscillator is energized and leakage signals cross the circulator to the receiver portion of the transceiver. An RF AFC loop between the transmitter and receiver portions includes a low-pass filter at the preamplifier output which serves as a simple slope discriminator. This output is detected and used to close an electronic servo loop. Once closed, this servo loop locks the transmit oscillator frequency relative to the local oscillator thereby preventing frequency drift during warm-up.

Abstract: An AFC loop for controlling the frequency of a VCO including an A to D converter and divider for providing pulses at some frequency equal to or lower than the output of the VCO, a source of stable reference pulses and a counter constructed to count to a predetermined number and count the reference pulses in synchronism with the divided pulses, a second divider connected to divide the reference pulses by the predetermined number and means for subtracting the output of the second divider from the counter to provide a control voltage for the VCO which is proportional to the drift in frequency of the VCO from a mean frequency.

Abstract: To maintain a cophasal relationship between two concurrently transmitted waves of the same high frequency derived from a common pilot oscillator, one of these waves being modulated by a low-frequency signal, a phase shifter in cascade with the modulator is controlled by a phase discriminator including a comparator with inputs receiving the two high-frequency waves. An analog multiplier driven by the low-frequency modulating signal converts an error signal from the phase comparator into a unipolar pulsating voltage which, upon integration, yields a control voltage adjusting the phase shifter to correct any relative phase displacement.

Abstract: The local signal generation arrangement employed in a radio communication system for transmitting and/or receiving an upper sideband (USB) and a lower sideband (LSB) signal, but not simultaneously, employs a method in which the generation and/or detection of both USB and LSB signals is accomplished by utilizing only one bandpass filter, a so-called single sideband (SSB) filter, together with a balanced modulator arranged to receive a carrier signal produced from an oscillator whose frequency is accordance with the characteristic frequency of either of a pair of crystal resonators, which correspond to the upper cut-off and the lower cut-off frequencies of the SSB bandpass filter, respectively. The output signal from the said SSB filter is referred to herein as the intermediate frequency (IF) signal.The local signal generation arrangement includes a phase-locked loop (PLL) including at least a phase comparator, a low pass filter, and a voltage-controlled oscillator (VCO).

Abstract: The inventor discloses an ultra narrow band relatively ultra stable radio apparatus for communicting paging or control signals from a central transmitter to a multiplicity of remotely located receivers, which receivers may be carried on the person of individuals or may be fixed to other devices which they control, such as city traffic control lights, programmable signs, machines, or the like, wherein the central transmitting device and the remote receiving device are both phase locked to a local broadcast station RF carrier so as to provide a means to precisely synchronize the transmitting device with the receiving device and thereby achieve very high signal-to-noise ratio transmissions. The apparatus is capable of transmitting a digital identification code or a digital message and the receiving devices may output a simple on-off signal indicating the presence of a call, or digital message may be output to control an apparatus attached to said receiver.

Abstract: A common indicator unit for a radio receiver and transceiver includes a segment type indicator consisting of a plurality of digits. An indication output corresponding to the receiving frequency of the radio receiver and an indication output corresponding to the channel of the transceiver are applied to the input terminal of the indicator after selection by switching.

Abstract: A frequency modulated radio frequency broadcast network in which re-transmitting stations employ a synchronous frequency modulated booster system. Included in the frequency modulated booster system is a synchronous frequency .[.modualted.]. .Iadd.modulated .Iaddend.exciter for converting a frequency modulated intermediate frequency into a frequency modulated broadcast signal. The synchronous frequency modulated .[.exicter.]. .Iadd.exciter .Iaddend.includes phase locked loop circuits for synchronizing the re-transmitted frequency modulated broadcast signal with the frequency modulated intermediate frequency signal by detecting reference signals in the composite baseband of the intermediate frequency signal and in the composite signal frequency modulated broadcast signal.

Abstract: A frequency modulated ratio frequency broadcast network in which re-transmitting stations employ a synchronous frequency modulated booster system. Included in the frequency modulated booster system is a synchronous frequency modulated exciter for converting a frequency modulated intermediate frequency into a frequency modulated broadcast signal. The synchronous frequency modulated exciter includes phase locked loop circuits for synchronizing the re-transmitted frequency modulated broadcast signal with the frequency modulated intermediate frequency signal by detecting reference signals in the composite baseband of the intermediate frequency signal and in the composite signal frequency modulated broadcast signal.