Abstract: A proximal cable-less communication system employs the physical placement of the units to each other to achieve information transfer. Local oscillators of each of the receivers are modulated and this modulated signal containing intelligence is received by other receivers due to the leakage radiation from the local oscillators.

Abstract: A system and method for detecting the level of random noise contained in a band-limited amplitude-modulated signal. A sychronizing signal is produced which is .pi./2 out of phase with respect to the carrier of the amplitude-modulated signal. The amplitude-modulated signal and the synchronizing signal are multiplied together. Only a low frequency component is extracted from the multiplication output, and the low frequency component is taken as an indication of the level of the random noise contained in the amplitude-modulated signal.

Abstract: A tuning device of a liquid crystal television at first tunes by a PLL synthesizer system, and then maintains an obtained tuning voltage by an AFT signal for deciding an intermediate frequency after the PLL tuning. The device interrupts the power to at least the prescaler of the PLL loop when in the AFT mode, to reduce overall power consumption.

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. Initially, 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 frequency modulated for tone coded squelch, with the modulating source being located in the return end of the phase lock loop filter. A unique filter is provided to insure acquisition of the pilot tone.

Abstract: An automatic frequency control circuit having the ability to resolve the frequency of an incoming signal to an extreme level of accuracy and to tolerate amplitude and pulse modulation on the incoming signal is disclosed. Two negative feedback loops are utilized. A coarse adjustment feedback loop resolves the frequency of the incoming signal to within the authority of a fine adjustment feedback loop. A computer is a common element of both loops and makes decisions regarding whether to resolve incoming a signal frequency using the coarse or the fine adjustment loops. Phase differences between a signal derived from the incoming signal and a reference signal are sampled at controllable time intervals apart to determine frequency adjustments within the fine adjustment loop.

Abstract: A method and apparatus are described for phase and frequency locking a reference oscillator to an incoming modulated signal. The method and apparatus enable the carrier recovery of the incoming modulated signal. Phase and frequency locking devices are connected in feedback loops with a coherent detector that determine the amount of phase and frequency error between the reference oscillator of the coherent detector and the incoming modulated signal. The feedback loops correct such frequency and phase error so as to enable the reference oscillator to be in phase and frequency step with the modulated signal.

Abstract: An A.F.C. control system for reception of wide-band F.M. transmission such as satellite transmissions, in which a center frequency of an F.M. I.F. signal is repetitively and alternately compared with an upper and a lower frequency limit value so long as the center frequency lies between these values, with the results of the comparisons being respectively stored in two latch memories, whose contents thereby indicate any error of the center frequency relative to the frequency limits. Any departure of the center frequency from between the limits is corrected by successive frequency shifts of the local oscillator frequency, with the results of correction being indicated by the latch memory contents and with the number of frequency shifts being determined accordingly.

Abstract: A circuit for processing an intermediate frequency signal comprises a limiter connected to receive the intermediate frequency signal to generate a carrier component of the intermediate frequency signal as an output, a phase locked loop circuit connected to receive one of the intermediate frequency signal and the carrier component from the limiter to generate an output signal which is phase-locked onto the carrier component of the intermediate frequency signal, a synchronous detector for synchronously detecting the intermediate frequency signal depended on the output signal from the phase locked loop circuit, and an automatic frequency circuit connected to receive the carrier component from the limiter and the output signal from the phase locked loop circuit to generate an output signal, as an automatic frequency tuning signal, in response to a frequency difference therebetween.

Abstract: A frequency converting circuit converts an input frequency into a desired frequency. To obtain the desired frequency, a first frequency converter converts the input frequency, by using an output frequency of a first local oscillator, into an intermediate frequency. The first local oscillator is a voltage controlled oscillator as a part of a phase locked loop circuit. A second frequency converter converts the intermediate frequency into the desired frequency by using an output frequency of a second local oscillator. A phase comparing circuit compares the phase of the output signal of the second frequency converter with that of the output signal of the first local oscillator. The phase comparing circuit is contained in the phase locked loop circuit. The result of the comparison is used for controlling the oscillating frequency of the first local oscillator.

Abstract: A PSK and phase modulation transmission system has a modulator and a demodulator. The modulator has a carrier frequency generator (21) coupled to a voltage controlled phase shifter (22). The modulation of the signal in the shifter (22) is controlled by modulation voltage generator (23). A transmitter (24) receives the output from the shifter (22) and transmits the modulated signal. The demodulator (30) includes a receiver section (31) for receiving the signal transmitted by the transmitter (24). The receiver (31) is coupled to a modified phase locked loop comprising a phase detector (32), a low pass filter (33), a sample and a hold circuit (34) and a voltage controlled oscillator (35). A lock control circuit (36) receives either the output from the receiver (31) or the output from the filter (33) to produce a lock in pulse from changes in the received signal or changes in the demodulated signal at the filter (33) for controlling the sample and hold circuit (34).

Abstract: A signal acquisition circuit for a synchronous receiver that requires frequency sweep to acquire a digitally modulated signal but tends to false lock onto data sidebands or for a receiver that cannot use a frequency discriminator because of wideband noise. The receiver must provide a phase error output signal and also a signal-acquired indication that does not assert during false locks. The circuit comprises an integrator selectively coupled either to the phase error signal or to a square wave sweep waveform used for signal acquisition. The integrator is controlled by a detector output analysis circuit that compares the envelope of the signal received during frequency sweeps with the peak of the envelope determined from successive sweeps by a peak detector with a long time constant. The circuit avoids false locks and continues to sweep through successive false locks until the signal-acquired indication asserts to indicate true lock.

Abstract: There is disclosed a clock circuit for a PBX system that uses phase locked loop technology to perform synchronization between two input signals. The system can switch between different reference sources without introducing error and without requiring the entire circuit to become realigned with the phase of the newly selected reference signal. This is accomplished with a phase build-out circuit that uses a phase locked loop divider to change the phase of the internal control signal to match the phase of the newly selected reference thereby eliminating timing changes on the system clock bus. The system can also be used to change between redundant clock circuits.

Abstract: A radio pager for receiving FSK signals has optimally narrow gaussian bandpass filters (F1, F2) and a phase lock loop (11, 12, 13, 14) for preventing local oscillator drift controlled in dependence of the derivation frequency (.+-.4.5 KHz) which is accurately controlled at the transmitter and which is derived from the decoder logic circuit (20).A significant increase in sensitivity is achieved over existing pagers.

Abstract: In a receiver for satellite broadcasting service, a selected audio subcarrier is converted into an IF signal demodulated into a demodulated signal which is applied to a feedback voltage generating means which converts the applied signal into a feedback voltage at a voltage ratio corresponding to the maximum frequency deviation of the selected audio subcarrier. The feedback voltage is applied by an operational amplifier to a varactor diode in a voltage-controlled oscillator. The oscillation frequency of the voltage-controlled oscillator is therefore varied dependent on the frequency deviation of the selected audio subcarrier to cause the maximum frequency deviation of the IF signal from a frequency mixer to match the bandwidth of a bandpass filter.

Abstract: Apparatus for acquiring and demodulating a communication signal employing a feedforward approach to minimize acquisition time. The apparatus includes a phase detection circuit for generating a phase difference signal indicative of the phase difference between an incoming signal and a local reference oscillator, and a phase rotation circuit for adjusting the phase of the local reference by the amount of the phase difference signal, so that the rotated local reference matches the phase of the incoming signal. Basically the same approach is used for carrier acquisition and for data clock acquisition or bit synchronization. A data resolution circuit removes the phase-angle effect of data modulation from the phase error signal, so that an accurate carrier phase error signal is obtained even when the carrier is modulated by data. A special embodiment of the data resolution circuit is provided for the case of non-random data signals.

Abstract: A dual conversion variable bandwidth telemetry receiver employs a phase locked loop which controls the second local oscillator to maintain lock on the carrier frequency; the phase locked loop employing a loop filter with a variable time constant integrator, the time constant of which can be varied as a function of receiver bandwidth and the integrator with its associated capacitor and resistor banks being employed in a sweep, i.e. search, oscillator circuit enabled when the carrier signal is lost. A coherent double-balanced mixer is employed to detect carrier lock and if lock is lost but the carrier is still detected, a rapid response anti-sideband circuit in the phase detector of the phase locked loop is employed to suppress the sidebands and greatly increase the probability of relocking on the carrier. A synchronous AM detector employs quadrature IF and reference signals at the same frequency to produce a dc signal when phase lock occurs; the signal falling rapidly upon loss of lock.

Abstract: A receiver for receiving a signal modulated on an RF-carrier, includes amplitude and phase control for reducing, to a very low value, deviations in the amplitude and phase correspondence of the signals in two signal paths therein in order to avoid an image interference signal due to incomplete mutual cancellation or image frequency rejection of unwanted modulation signals.

Abstract: A radio frequency transmission system contains at least one coherently modulated information signal, for example, a T.V. signal. At a transmission, the information signal is combined with two pilot tones, F1 and F2, related by the equation F1=N/M F2, where N and M are integers. The combined signal is suppressed-carrier modulated at microwave frequencies and transmitted to a receiver. At the receiver, the signals are demodulated by a local oscillator. The two pilot tones are then separated from the information signal and are compared to each other. The local oscillator frequency is controlled in response to this comparison such that the pilot tones at the receiver bear the same relationship to each other that they had at the transmitter. When this is achieved, the local oscillator frequency is the same as the suppressed-carrier frequency and co-channel interference is prevented.

Abstract: Non-inverting amplifier, with bandpass filter in regenerative feedback path, forms color reference oscillator in a color TV receiver. Phase shift circuit, responsive to an oscillator output, supplies signals to a first phase shifted signal amplifier, which shares a load with the non-inverting amplifier, and is subject to control by complementary outputs of a phase comparator functioning to compare the phase of an oscillator output with the phase of incoming color synchronizing bursts. A voltage comparator, responsive to the respective phase comparator outputs, is periodically enabled by field rate keying pulses. The voltage comparator output controls the charging or discharging of a capacitor during the keying intervals.

Abstract: An FM receiver for demodulating an RF carrier signal containing a pilot frequency signal is provided. The receiver includes first and second frequency control loops. The first frequency control loop selects the local oscillator signal frequency. The reference signal oscillator in the first frequency control loop forms a part of a second frequency control loop. The second frequency control loop locks the phase of the reference signal oscillator with a detected pilot signal. In this way, the tuning signal of the local oscillator is kept phase locked to the detected pilot signal. Additional provisions are provided for changing the divisor of the second phase lock loop such that the time for establishing phase lock is reduced.

Abstract: Disclosed, herein, is an Automatic Gain Control (AGC) signal processor and a method for generating an AGC signal in a phase-locked receiver. An incoming signal, exhibiting both coherent and incoherent characteristics, is filtered to obtain the desired bandwidth. The filtered signals are amplified to maintain an amplitude relationship between the coherent and incoherent signals. The incoherent signals are conditioned in the same circuit, but in a different manner, than coherent signals are conditioned. The conditioned signals are utilized to generate an AGC signal such that an AGC signal is generated in a single circuit for both coherent and incoherent signals, although by differing circuit responses, depending upon the conditioning of the incoming signal.The preferred embodiment of the novel AGC processing contemplates a full wave rectifier as its signal conditioner. Another embodiment contemplates negative peak detection as its conditioner.

Abstract: In automatic fine tuning (AFT) apparatus in a superheterodyne receiver, the IF carrier is selectively filtered and is applied to a signal multiplier arrangement. An auxiliary heterodyning signal is also applied to the multiplier arrangement, so as to produce an offset signal having a frequency proportional to the frequency difference between the IF carrier and the heterodyning signal. The offset signal is applied to a microprocessor programmed to produce a control signal for controlling the local oscillator to reduce frequency deviation between the IF signal and a nominal IF frequency.

Abstract: An automatic frequency control circuit for a single side band receiver employing a split-loop phase locked loop system is disclosed. Initially, both a first and second voltage controlled oscillator lock to a received pilot taken after the IF strip of the SSB receiver. Once lock is achieved, a sample is taken of the control line voltage of the first VCO whereafter the first VCO control line is held at the sampled voltage and will no longer track the received pilot until such time as the second VCO deviates from a predetermined range. Simultaneous to switching the first VCO, the loop filter of the second VCO is adapted to maintain identical loop dynamics both before and after switching control of the first VCO.

Abstract: A PSK demodulator has two phase detectors for detecting the phase of a PSK signal and a carrier generator for supplying carriers of different phases to the two phase detectors, respectively. The PSK demodulator also includes squaring means for squaring output signals from the two phase detectors, difference computing means for computing the difference between output signals from the squaring means, product computing means for computing the product of the output signals from the two phase detectors, and product detecting means for detecting the product of an output signal from the product computing means and an output signal from the difference computing means, the arrangement being such that the frequencies and phases of the carriers generated by the carrier generator are controlled by an output signal from the product detecting means.

Abstract: A device for aligning the phase and amplitude of a quadrature-detected coent two-channel receiver utilizing a mixer in each channel comprising a circuit for providing a sweep frequency signal to each receiver channel; a circuit for detecting the envelopes of the receiver channels at the outputs of the mixers and determining the voltage difference between the envelopes; and a circuit for controlling the amplitude level in one of the receiver channels in accordance with this voltage difference. Simultaneously, the output signals from the two mixers are added with the resulting sum signal being envelope-detected, and also subtracted from each other with the resulting difference signal being envelope-detected. The sum envelope and the difference envelope are subtracted from each other to generate a control signal for controlling the phase of one of the mixer local oscillator signals to ensure that the mixer local oscillator signals are in phase quadrature.

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. Initially, 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 clock-frequency recovery device applicable to digital transmission systems for radiocommunications by tropospheric or ionospheric propagation as well as from moving vehicles includes a rectification circuit, a filter circuit, a switching circuit and an output circuit comprising a delay line controlled by a phase-locked oscillator. The input of the output circuit is connected to the output of the filter circuit when the noise level of the transmission is below a predetermined threshold value. The input of the output circuit is connected to its own output when the noise level of the transmission is higher than said threshold value.

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 modulated signal level detecting circuit comprising a synchronized detector 1 of the modulated input signal, a phase-locked loop 5, 14, 16 connected to the input signal for providing a reproduced carrier wave of the input signal, a switch 21 included in the phase-locked loop, and a signal level detecting circuit 22, 23 for detecting the level of the unmodulated signal and opening the switch and thereby breaking the loop when this level exceeds a fixed limit.

Abstract: Radio-receiver having a frequency-locked loop which comprises, arranged one after the other, a tunable voltage-controlled oscillator, a mixer stage, a filtering element, as well as a frequency-voltage converter which is connected to the tunable voltage-controlled oscillator, several stable tunings being possible for each transmitter. An unambiguous selection is made from these stable tunings of a tuning to a desired station by muting the radio receiver in the other stable tuning frequency ranges. To this end the radio receiver according to the invention comprises a muting circuit as well as a control circuit for the muting circuit in which use is made of a further frequency voltage converter comprising an all-pass frequency-dependent 180.degree. phase shifting network, a phase detector and a limiter.

Abstract: First and second rectangular signals which are 90.degree. out of phase with each other are derived by comparators and an RS flip-flop from a symmetrical triangular wave signal. The first rectangular signal is halved in frequency by a frequency divider, the output of which is supplied to an adder. The second rectangular wave signal is also delivered to the adder. An output from the adder is converted by a bandpass filter into a sine-wave subcarrier signal in synchronism with a stereo pilot signal in an FM stereo tuner. The first and second rectangular signals may be derived by a pair of D-type flip-flops from a pulse signal.

Abstract: A genlock circuit has a reference signal that is frequency divided to provide an internal vertical sync signal. When an external sync signal is present, the division ratio is temporarily changed to provide a slow locking of the internal sync signal to the external sync signal. This avoids picture disturbances. The circuit can be used in a camera control unit and camera heads.

Abstract: In order to reduce signal loss particularly when transmitting data in a quasi-synchronous area coverage scheme utilizing sideband diversity, it is necessary to effect coherent demodulation by locking the local oscillator signal to the received carrier signal, even when the carrier has been completely suppressed. The demodulator includes first and second mixers (48, 50) having first inputs to which a frequency converted input signal having sideband diversity is applied. Second inputs of the first and second mixers (48, 50) receive a local oscillator signal. Phase shifting is applied to the input or local oscillator signal so that the outputs of the first and second mixers have a relative phase difference of 90.degree.. The outputs of the first and second mixers are applied to respective audio bandpass filters (56, 58) the outputs of which are mixed in a further mixer (60) to provide a sideband error signal (E.sub.s) which is low-pass filtered in a filter (62). A carrier error signal (E.sub.

Abstract: Apparatus for synchronizing the frequency of locally generated pilot signals with those of remotely generated pilot signals where frequency errors are introduced during transmission. A pair of demodulated pilot signals F1' and F2' are filtered and mixed to derive a third signal having a frequency equal to F2'-F1'. The difference frequency has no frequency error component so the third signal is used in a phase locked loop to regenerate a reference frequency (fr) signal.Two methods are disclosed to extract a control signal which is proportional to the error frequency. In one embodiment one of the received pilots (F1') is divided in frequency by 1/k1 and then subtracted from fr to yield 1/k1 times the error frequency df. By integrating this signal it becomes usable as an AFC signal to control a local oscillator.

Abstract: In a communications receiver where the AGC signal derived from a phaselock detector is used to measure input signal strength, and that measurement is subject to error as a result of the nonlinear devices used in the carrier demodulation, a signal having inversely corresponding error characteristics is summed to the phaselock detector AGC signal to produce an improved AGC signal which is substantially linearly related to the input signal. That signal, having the inversely corresponding error characteristics, has been found to be the signal representation of the envelope of either the positive or negative cycles of the input signal.

Abstract: Two pilot signals, derived so that there is a predetermined ratio between the frequency difference of the tones and the absolute frequency of either of the pilot signals, are transmitted from a reference station to each of a number of remote stations. At each receiving station, the frequency error is derived from the frequency difference of the two pilot signals, and this frequency error is used to adjust the frequency of the local oscillator.

Abstract: A synchronous receiver comprising a high frequency section realized by analog components, including an input preamplifier followed by two quadrature operated mixers with associated .pi./2 phase shifter and a voltage controlled oscillator wherein the high frequency signal is converted by multiplication by means of a phase locked loop directly into the base band and lowpass filters following the mixers for select out interfering mixed products, and a low frequency section following the high frequency section. The receiver is used as a radio or television receiver and the low frequency section is realized by digital components.

Abstract: A receiver for tracking and demodulating several types of phase modulated communications, either analog or digital data, for either residual carrier or suppressed carrier signal and for phase modulation or keying of two, four or higher phase angles, from 0.degree. through 360.degree.. A carrier component signal and a converted series sideband component signal are obtained from the incoming signal and summed to produce a carrier tracking signal, permitting more accurate tracking of the above types of phase modulated data.

Abstract: In a broadcast signal receiving system, which includes a phase control loop composed of a first mixer having two inputs and an output and arranged to provide at its output a signal proportional to the product of the signals applied to its two inputs, one output being supplied with the received high frequency signal, a voltage controlled oscillator connected for supplying to the other input of the first mixer an alternating voltage of substantially constant amplitude, a first lowpass filter connected to the output of the first mixer for providing a filtered output signal representative of the first mixer output signal with the sum frequency component of that signal suppressed, and means for delivering the output signal of the first low-pass filter to the control input of the oscillator, the received high frequency signal is directly demodulated by multiplication with a local oscillator signal synchronized to a substantially fixed difference to the phase or the carrier phase of the received high frequency signa

Abstract: The double phase lock loop arrangement of the invention comprises a first feedback loop including a first voltage controlled oscillator (16), a second feedback loop including a second voltage controlled oscillator (20) and first (PSD1), second (PSD2) and third (PSD3) phase sensitive detectors. Each of the detectors have first and second inputs and an output, each first input being coupled to receive a signal which is derived from the first voltage controlled oscillator (16). The second voltage controlled oscillator (20) is connected to the second inputs of the first and second phase sensitive detectors (PSD1, PSD2) and via a phase shifter (21) to the second input of the third phase sensitive detector (PSD3) on whose output a lock signal is produced in response to the signals on its first and second inputs being in a desired phase relationship. The output of the second phase sensitive detector (PSD2) is an A.C.

Abstract: In a satellite which asynchronously receives radio frequency signals from a lurality of beacons scattered at the surface of the earth, each signal received has a pure carrier wave portion followed by a phase modulated message carrying portion. The frequencies of the signals are not known within a predetermined frequency band. The satellite has a plurality of essentially identical processing units which each receive on their input all the signals present at any given instant in the input frequency band. Each processing unit has a phase locked loop which may be progressively tuned to the frequency of one of these input signals in response to a frequency estimate of this signal to which the operating frequency of the phase locked loop is preset. This frequency estimate is updated until the phase lock occurs on this input signal, ready for demodulation of the message part to begin. The estimate frequencies are derived from an input band frequency spectrum analyzer.

Abstract: A receiver for demodulating a single sideband signal which is subject to rapid phase jitter employs a Hilbert splitter for obtaining the Hilbert transform of the single sideband signal, and a local oscillator for signal demodulation. A post-oscillator feedback loop instantaneously derives the amount of phase jitter in the single sideband signal, and employs the derived phase jitter to adjust the phase of the local oscillator so that the local oscillator tracks the single sideband signal.Instantaneous derivation of the phase jitter is obtained because all post-oscillator signal manipulations are algebraic; post-oscillator Hilbert transform generation is not required. A first embodiment derives the exact amount of phase jitter. A second embodiment, more simple than the first, derives the approximate amount of phase jitter.

Abstract: A synchronous detector suitable for use in a color television receiver detects both a video signal and an audio IF signal, but in a fashion in which these two signals do not interfere with one another. In the detector, a tuner provides an IF signal in which the video signal and audio or sound IF signals are modulated on a carrier; a signal generator, such as a phase-locked loop, provides both a detecting signal synchronized with the carrier of the IF signal, and a comparing signal having the same frequency as the carrier of the IF signal but phase-shifted .pi./2 therefrom; a synchronous detecting circuit for synchronously detecting the IF signal by the detecting signal to produce the video signal; and a phase comparator for phase comparing the IF signal with the comparing signal to provide the sound IF signal. In one arrangement, the phase comparator provides a filtered version of the sound IF signal as an AFT control signal to control the fine tuning of the tuner.

Abstract: A receiver for a facsimile system in which a local carrier is either derived from a modulated signal or is generated when the carrier component of that signal is not detectable which employs a first variable frequency oscillator and a second variable frequency oscillator responsive to the first variable frequency oscillator for reducing the frequency variation of the local carrier in response to the first variable frequency oscillator. In the preferred embodiment, the second variable frequency oscillator which is frequency controlled while the first variable frequency oscillator is voltage controlled. The frequency controlled variable frequency oscillator preferably includes a stable clock driving one counter and a second counter being driven by the output frequency of the first oscillator.

Abstract: A radio receiver includes a phaselocked loop including a main phase detector which accomplishes both carrier extraction and demodulation of an FM orderwire signal. The loop bandwidth characteristic is made suitable for de-emphasis of the FM orderwire audio signal, and the output of a quadrature phase detector is applied as a divisor to an analog divider in the phaselocked loop to cause the bandwidth of the phaselocked loop to remain substantially constant despite changes in input signal level.

Abstract: A system is described for synchronously detecting a video signal along a selectable detection axis. The system includes a limiter receiving an input video signal and a phase-locked loop for developing an oscillator signal whose frequency is locked to the frequency of the video signal. A phase-adjustment network recieves the oscillator signal from the phase-locked loop for adjusting the phase of the oscillator signal such that it corresponds to the desired axis of detection. A synchronous detector receives the input video signal and the phase-adjusted oscillator signal for detecting the video signal along the selected detection axis.

Abstract: Radio receiver systems for recovering stereo program signals from a composite stereo signal which has been modulated with either quandrature modulation or modified quadrature modulation techniques. In one embodiment, a receiver is provided which directly recovers the program signals from the composite signal by means of product detectors, without first converting the composite signal into an IF signal. In another embodiment an IF stage is provided, but is designed to have broad bandpass characteristics. This embodiment additionally includes a phase locked loop for forcing the IF frequency into the center of the IF passband. In either case, the stereo demodulation is accomplished by product detectors which multiply the composite signal by phase reference signals. Several methods of synthesizing stable phase reference signals are shown.

Abstract: A phaselock loop in a phaselock receiver includes a voltage-controlled oscillator, and a main phase detector receptive to an output of the oscillator and a received signal. Means to detect when the oscillator is phase locked with the received signal includes a quadrature phase detector receptive to a quadrature-phase-shifted oscillation from the oscillator and the received signal. Means are provided to subtract the direct-current component of the output of the main phase detector from the direct-current component of the output of the quadrature phase detector to provide a phaselock-indicating signal which is substantially zero when the oscillator is out-of-lock with the received signal, and which is high when the oscillator is in-lock with the received signal.

Abstract: A data transmission system comprising a transmitter producing a high-frequency carrier modulated with data and swept in a repetitive time pattern over a wide frequency range. The modulation of the carrier is so controlled that a characteristic of the data signal modulation has a predetermined relationship with respect to the repetitive sweep time pattern. The system receiver comprises a narrow-band IF channel coupled to the output of a mixer arranged to receive the incoming swept-carrier signal and a correspondingly-swept local oscillator signal. The sweep control signal for the local oscillator is developed by a circuit coupled to the mixer output and responsive to the data modulation on the IF signal.