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| Number | Title | Issue Date |
| 4361894 | Band-pass filter circuit A band-pass filter circuit comprising a band-pass filter for removing noise modulation components from an input signal comprising a carrier sine wave, a phase detector for detecting a phase difference between input and output signals of the band-pass filt... | 11/30/1982 |
| 4344178 | Costas loop QPSK demodulator A decision-directed Costas loop demodulator, rather than employing decision circuits, i.e. sample and hold circuits, in the path of each of the I and Q channels, contains a single sample and hold circuit at the output of the crosstalk measurement subtract... | 08/10/1982 |
| 4334312 | Phase synchronizing circuit for use in multi-level, multi-phase, superposition-modulated signal transmission system A multi-level, multi-phase, superposition-modulated signal is phase detected in a four-phase phase detector with the output from a voltage controlled oscillator (VC0). The P and Q outputs from the phase detector are supplied to a plurality of phase shifte... | 06/08/1982 |
| 4330863 | Demodulator arrangement A demodulator arrangement having a demodulator and a digital phase locked loop responsive to input diphase digitally modulated signals to produce output signals which are applied to the demodulator for effecting the demodulation of the input signals. The ... | 05/18/1982 |
| 4322850 | Sampling system for decoding biphase-coded data messages A receiving station of a data-transmission system decodes an incoming pulse train in the shape of a differentially biphase-coded carrier wave whose cycles represent rspective message bits; the wave undergoes a phase reversal at the beginning of every cycl... | 03/30/1982 |
| 4320345 | Adaptive differential PSK demodulator An adaptive differential phase shift keyed (PSK) signal demodulator which optimally tracks changes in the symbol rate of the signal. An input signal is delayed by one symbol period by passing the signal through a charge coupled device (CCD) clocked by pul... | 03/16/1982 |
| 4308503 | Phase shift keyed demodulator using recovered carrier with controlled phase offset This invention relates to an adaptive demodulator for use in a phase shift keyed microwave communication system. The adaptive demodulator improves the system error rate at a particular carrier to noise ratio by monitoring the output of the demodulator and... | 12/29/1981 |
| 4305151 | Digital discriminator for determining frequency error of an oscillator An adjustable alternating signal having a desired period, P, is applied to a cycle counter arranged to count n cycles and applied to a timer arranged to time out n.multidot.P after a first cycle is applied to the counter and timer. A comparator is coupled... | 12/08/1981 |
| 4292800 | Textile machine data link apparatus An improvement in a data link, such as is used for continuously transferring data concerning operations of textile yarn forming machines such as ring spinning frames, wherein a transmitter and receiver each use particular combinations of oscillators and p... | 10/06/1981 |
| 4283682 | Erasure zone decision feedback phase lock loop for carrier recovery in data modems An improved decision feedback phase lock loop having an erasure zone detector and a feedback loop interrupting switch responsive to the output of the erasure zone detector which cooperate to eliminate from the feedback loop those error signals correspondi... | 08/11/1981 |
| 4270221 | Phaselocked receiver with orderwire channel 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 audi... | 05/26/1981 |
| 4255713 | Carrier regeneration circuit for polyphase modulation system An n (=8, 9)-valued polyphase modulation system having circuit construction for carrier regeneration in which not only correct phase demodulation is effected but also any AM components of the regenerated carrier wave are effectively compensated for and in... | 03/10/1981 |
| 4254503 | Radio receiver for tone modulated signals A radio receiver for frequency modulated (FM) tones. Received signals are split and one split portion of the signal is phase shifted relative to the other and mixed with a local oscillator. The signal as received clocks a flip-flop. The phase shifted sign... | 03/03/1981 |
| 4243941 | Digital signal receiver having a dual bandwidth tracking loop A DPSK digital signal receiver is disclosed that has a dual bandwidth offset Costas loop that is switchable from an acquire bandwidth to a narrower tracking bandwidth in response to detection of a start code preceding a message signal included in the digi... | 01/06/1981 |
| 4238783 | Telemetry system for transmitting analog data over a telephone line An FSK receiver for a single channel analog telemetry system comprises an FSK demodulator, a frequency multiplier, and a frequency-to-voltage converter. An FSK transmitter comprises a voltage-to-frequency converter, a frequency divider, and an FSK tone ge... | 12/09/1980 |
| 4229822 | Data detector for a data communication system A data communication system for use in the control and monitoring of mobile stations, for example, in a bus monitoring system, from a central station over a communication channel carrying both data and voice information. Information is encoded into digita... | 10/21/1980 |
| 4217551 | Phase modulated data transmission system A data transmission system, particularly useful for transmission of computer data by radio frequency cables, makes use of a phase demodulator which eliminates the usual requirement for a coherent local oscillator for use in the demodulation process. The d... | 08/12/1980 |
| 4143322 | Carrier wave recovery system apparatus using synchronous detection A carrier wave recovery apparatus of the decision feedback type having analog multipliers of lower dynamic range. The modulated signal is phase detected by comparison with a VCO signal. The analog multipliers receive a signal derived by subtraction of the... | 03/06/1979 |
| 4142241 | Harmonic insensitive phase sensitive demodulator A harmonic insensitive phase sensitive demodulator which converts complex AC waveforms to a DC voltage proportional to the fundamental component at an arbitrary phase with respect to a reference voltage and eliminates, to any desired degree, the effects o... | 02/27/1979 |
| 4105975 | Offset correction circuit for phase detectors An offset error correction circuit for improved reception of signals by compensating for any offset error voltage produced by a phase detector in the absence of an input signal to the detector. The error correction circuit translates the offset error volt... | 08/08/1978 |
| 4100499 | Carrier synchronization system for coherent phase demodulators This invention concerns a carrier synchronization system for a four-phase coherent PSK demodulator. The four-phase PSK signal is demodulated by an in-phase reference carrier and a quadrature reference carrier both of which are locally generated by a refer... | 07/11/1978 |
| 4087628 | Carrier lock detector Apparatus for indicating a phase lock condition between an incoming multiphase carrier signal and a local oscillator in a phase-locked loop demodulator. A phase error signal is generated by phase comparing the carrier signal and the local oscillator signa... | 05/02/1978 |
| 4086539 | First-order phase-lock loop A first order phase-lock loop that provides lower phase-error variance than classical systems at all frequencies when operated above threshold. The linear, minimum-variance filter described, in preferred form, employs three summers, two integrators, four ... | 04/25/1978 |
| 4085378 | QPSK demodulator An improved quadraphase shift keyed (QPSK) adaptive demodulator includes a Costas loop modified to independently cross couple the inphase (I) and quadraphase ($c;) channels so that minimum cross talk takes place between the I and Q channels. Advantageo... | 04/18/1978 |
| 4079329 | Signal demodulator including data normalization A digital demodulator for recovering a baseband signal from a selectable bit rate PSK modulated signal. Carrier recovery and bit timing recovery are accomplished by using the digital equivalent of an analog in phase-quadrature (I/Q) phase locked loop. The... | 03/14/1978 |
| 4072905 | Wide acquisition range MSK demodulator input circuit An input circuit for a wide acquisition range minimum shift keying demodulator includes a pair of phase-locked loops (PLL). Each PLL is designed to receive from a frequency doubler a respective one of two discrete spectral lines in the frequency spectrum ... | 02/07/1978 |
| 4066978 | Digital phase-locked loop filter A phase processing system which includes at least one digital phase-locked loop wherein the phase of the input signal to the loop is compared with the phase of the loop output signal to produce a pulse-width modulated phase error signal. The error signal ... | 01/03/1978 |
| 4057762 | Device for phase synchronizing a reproduced reference carrier signal with windows specified for preselected ones of amplitude and phase modulated signal points A phase synchronizer for a reference carrier signal reproduced in a receiver for a combined amplitude and phase modulated signal comprises a window specifier for specifying windows for preselected ones of true signal points of which the demodulated signal... | 11/08/1977 |
| 4054838 | QAM phase jitter and frequency offset correction system A system is provided for correcting phase jitter and frequency offsets in QAM modems. The system comprises (i) a narrow bandwidth, decision directed, phase-locked loop for tracking the average phase and frequency offsets followed by (ii) a phase jitter co... | 10/18/1977 |
| 4053836 | Device for transmission of information by pulse code frequency shift modulation A device for transmission of information by pulse code frequency shift modulation. The device incorporates a phase-locked superheterodyne receiver including a single voltage controlled oscillator, and a demodulator including a phase comparator and a phase... | 10/11/1977 |
| 4042884 | Phase demodulator with offset frequency reference oscillator A phase-locked demodulator for demodulating a phase-difference modulated carrier having a repeated phase offset increment introduced therein. The demodulator includes, in common with conventional phase locked demodulators, a mixer having a first input con... | 08/16/1977 |
| 4037171 | High speed tone decoder utilizing a phase-locked loop A narrow-band tone decoder has a controllable oscillator, connected in a fast-capture phase-locked loop, for generating a signal having a frequency determined by a control signal produced within the loop. A synchronous detector, which responds to an input... | 07/19/1977 |
| 4027265 | Unbalanced quadriphase demodulator A new and improved apparatus and method for demodulation of quaternary phase shift keyed (QPSK) data, particularly unbalanced QPSK, with phase adjustment of the output of a phase-locked loop local oscillator to reduce sensitivity to amplitude variations i... | 05/31/1977 |
| 4021743 | Phase logic demodulator A demodulator for a biphase or quadriphase shift-keying system. The demodulator includes two AND gates for biphase demodulation. The AND gate is one which will provide an output signal if and only if the two input signals are in phase. Each of the AND gat... | 05/03/1977 |
| 4017803 | Data recovery system resistant to frequency deviations The data stream input to the recovery logic is taken from a point at which its transitions are timecoincident with those of the data stream input to the phase comparator of the phase locked oscillator loop used to control the generation of the recovery wi... | 04/12/1977 |
| 3984778 | Carrier recovery scheme for a SSB-SC signal A system is provided for extracting the proper carrier phase from a single sideband suppressed carrier signal. A received signal is equalized and then product demodulated by estimated in-phase and quadrature carriers produced by a voltage controlled oscil... | 10/05/1976 |
| 3983501 | Hybrid tracking loop for detecting phase shift keyed signals A hybrid tracking loop detector system that accurately demodulates phase ft keyed acoustic telemetry signals. The system internally determines the received carrier frequency and detects phase shifts that denote the digital format depicted by the phase sh... | 09/28/1976 |
| 3944940 | Versatile phase-locked loop for read data recovery A clock pulse generating system is disclosed for recovery of read data from magnetic record media comprised of a phase-locked loop for tracking data pulses. The loop employs simple digital logic gates for phase error detection, third-order filtering for t... | 03/16/1976 |
| 3934205 | Frequency lock loop employing a gated frequency difference detector having positive, zero and negative threshold detectors This invention relates to a gated frequency difference detector for use in a frequency lock loop. The gated frequency difference detector consists of a dual output hybrid quadrature mixer, two parallel video signal processing channels, a digital phase/fre... | 01/20/1976 |
