子分类：
| 序号 | 专利名 | 申请号 | 申请日 | 公开（公告）号 | 公开（公告）日 | 发明人 |
|---|---|---|---|---|---|---|
| 101 | Signal transmission system and a transmitter and a receiver for use in the system | US880399 | 1986-06-30 | US4768187A | 1988-08-30 | Christopher B. Marshall |
| A signal channel system which is particularly suitable for the employment of direct conversion receivers has a block of adjacent transmission frequency bands allocated to it. Each signal channel is split into two sub-channels or parts occupying mutually different frequency bands for transmission and the bands occupied by the sub-channels of the various channels are interleaved. In the receiver the local oscillator is tuned midway between the bands corresponding to the sub-channels of the wanted channel and the corresponding signals are recovered by bandpass filtering, phase-shifting, summing and differencing, demodulating and combining the frequency down-converted outputs of quadrature related mixers to which the received and the local oscillator signals are applied. Although d.c. block capacitors are used in the outputs of the mixers, these can have a low value because the notch formed in the transmission frequency characteristic does not affect the reception of the required signals, so that the receiver can settle rapidly at switch-on. | ||||||
| 102 | Method of and circuit for digitally demodulating an amplitude-modulated signal produced by suppressed-carrier amplitude modulation of two carriers of the same frequencies in a phase-quadrature relationship | US649872 | 1984-09-12 | US4638349A | 1987-01-20 | Gerard Le Floch |
| The invention relates to a method of and a circuit for digitally demodulating a suppressed-carrier amplitude-modulated signal, of two carriers having the same frequencies Fs in a phase-quadrature relationship, and having a sinusoidal reference signal which is in synchronism with said modulated signal. The method consists in determining the initial angular phase shift .alpha..sub.r, between the reference signal and the sampling signal of the frequency Fe by determining the peak amplitude, as well as the sign of the reference signal and the sign of its derivative for a given sampling instant t.sub.n+m. The successive values .alpha..sub.r +k.phi. of the angular phase shifts relative to said modulated signal are thereafter determined by successively adding the phase shift ##EQU1## The amplitudes of the modulated signal of the two quadrature sub-carriers are determined with the aid of tables containing the values of cos (.alpha..sub.r +k.phi.) and sin (.alpha..sub.r +k.phi.). | ||||||
| 103 | US7720179 | 1979-09-20 | US4268915B1 | 1985-12-17 | ||
| 104 | Recursive detector-oscillator circuit | US574028 | 1975-05-02 | US3971998A | 1976-07-27 | Bhaskarpillai Gopinath; Robert Paul Kurshan |
| Disclosed is a recursive circuit capable of serving as a signal detector or as a signal generator. The circuit comprises a shift register capable of storing multilevel signals, and a feedback network responsive to an input signal and to the output signals of selected stages of the shift register. In the feedback network, the output signals of the selected stages are each multiplied by prechosen integers, and then added with the input signal to form a sum signal which is applied to the first stage of the shift register. The sum signal is developed by nonmodulo addition, and the multiplying integers are prechosen to cause the characteristic function of the circuit to be a cyclotomic polynomial. Detection of the presence in the input signal of a signal having a chosen frequency is accomplished by the sum signal excluding a predetermined threshold level. Signal generation is accomplished by presetting the register to a nonzero state and allowing the output signal to develop in accordance with the characteristic function of the circuit. | ||||||
| 105 | Apparatus for accelerating D.C. transient decay by independent keying of a balanced demodulator | US42851473 | 1973-12-26 | US3898478A | 1975-08-05 | RUDOLPH JOHN D; SOLOMON JOSEPH A |
| For use with analog a.c.-to-analog d.c. conversion systems or the like employing balanced demodulators for reducing settling time i.e., the interval between application of a.c. superimposed on d.c. and the provision of a d.c. analog of the superimposed a.c., means for introducing an independent keying signal to force demodulation during part of the settling time.
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| 106 | Search-lock system | US3758866D | 1972-04-03 | US3758866A | 1973-09-11 | HANSEN N; ORENSTEIN N |
| A received RF signal is mixed with the output of a voltagecontrolled local oscillator to provide an IF signal which is simultaneously passed to a frequency discriminator and a circulating memory. Control voltage for the oscillator is provided by an AFC unit which comprises an integrator receiving selected contant voltage inputs. During the search mode a search ramp is generated by the integrator. A flyback circuit causes the search voltage to repeat its traverse over a prescribed range. Bipolar video discriminator outputs above a predetermined threshold place the system in the lock mode and selectively gate two settable, constant voltage inputs to furnish a triangle wave integrator output centered on a voltage corresponding to the desired local oscillator frequency. The oscillator output is mixed with the stored IF to produce a replica of the input signal.
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| 107 | Amplitude modulation detector for radio receivers | US3716793D | 1971-12-07 | US3716793A | 1973-02-13 | PARKER L |
| THE IF CARRIER IN A RADIO RECEIVER IS USED TO CONTROL THE DEFLECTION CIRCUITS OF A CATHODE RAY TUBE TO CAUSE A CIRCULAR SWEEP OF THE TUBE BEAM. LIGHT FROM THE RESULTANT CIRCULAR OSCILLOGRAM IS PROJECTED ONTO TWO RING-SHAPED CONCENTRIC PHOTOCELLS IN SUCH FASHION THAT THE LIGHT FALLS PARTIALLY BETWEEN AND PARTIALLY ON SAID PHOTOCELLS WITH EACH PHOTOCELL RECEIVING ONE POLARITY OF THE AF WAVE. THE SIZES OF THE PHOTOCELL SURFACES ARE SELECTED SO AS TO EXTEND ONLY TO THE PEAK AMPLITUDE OF MODULATION ON BOTH THE POSITIVE AND NEGATIVE HALVES OF THE AF CYCLE, TO EFFECT CLIPPING OF ANY NOISE RIDING ON THE OSCILLOGRAM. THE COMBINED OUTPUTS OF THE PHOTOCELLS PROVIDE THE DESIRED DEMODULATED AF SIGNAL. THE BRILLIANCE OF THE OSCILLOGRAM IS MAINTAINED BY A SEPARATE PHOTOCELL CONTROLLED CIRCUIT. VARIATIONS IN THE BASIC CIRCUIT INCLUDE THE USE OF RING-SHAPED SECONDARY EMISSION PLATES WITHIN THE CATHODE RAY TUBE, INSTEAD OF RING-SHAPED PHOTOCELLS.
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| 108 | Search-lock system | US3675132D | 1970-08-31 | US3675132A | 1972-07-04 | HANSEN NEIL W; ORENSTEIN NATHAN |
| A received RF signal is mixed with the output of a voltagecontrolled local oscillator to provide an IF signal which is simultaneously passed to a frequency discriminator and a circulating memory. Control voltage for the oscillator is provided by an AFC unit which comprises an integrator receiving selected constant voltage inputs. During the search mode a search ramp is generated by the integrator. A flyback circuit causes the search voltage to repeat its traverse over a prescribed range. Bipolar video discriminator outputs above a predetermined threshold place the system in the lock mode and selectively gate two settable, constant voltage inputs to furnish a triangle wave integrator output centered on a voltage corresponding to the desired local oscillator frequency. The oscillator output is mixed with the stored IF to produce a replica of the input signal.
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| 109 | Continuous wave presence detection circuit | US3613010D | 1970-01-21 | US3613010A | 1971-10-12 | PODOLSKI GERALD A; BALSHEM HAROLD; VICTOR STANLEY |
| A continuous wave detection system having a crystal detector DC coupled to a threshold circuit. The output of the threshold circuit is fed directly to a coincidence circuit and also via a delay of one frequency period. The driven gated output from the coincidence circuit representing the continuous wave signal can be selected for chopping.
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| 110 | Amplifier-detector having wide dynamic range | US3435353D | 1966-02-04 | US3435353A | 1969-03-25 | SAUBER JAMES W |
| 111 | Digital differentiator for amplitude modulated carrier | US24145062 | 1962-11-30 | US3274503A | 1966-09-20 | PETERSON HERBERT L; FINNEY WILLIAM J |
| 112 | Apparatus for recognizing waveforms of variable time duration representing waveforms on a logarithmic time scale | US30221463 | 1963-08-14 | US3237112A | 1966-02-22 | COATES JR CLARENCE L; LEWIS II PHILIP M |
| 113 | Apparatus for recognizing waveforms of variable time duration representing the spectrum of waveforms on a logarithmic scale | US30221263 | 1963-08-14 | US3237111A | 1966-02-22 | COATES JR CLARENCE L; LEWIS II PHILIP M |
| 114 | Adaptive system | US727560 | 1960-02-08 | US3235844A | 1966-02-15 | WHITE GERALD M |
| 115 | Signal amplitude discriminator | US22237262 | 1962-09-10 | US3192481A | 1965-06-29 | PINCUS RALPH M |
| 116 | Electromagnetic energy detector | US10076561 | 1961-04-04 | US3160814A | 1964-12-08 | HERSKOVITZ SHCLDON B |
| 117 | Modulator envelope detector | US18569862 | 1962-04-06 | US3154749A | 1964-10-27 | PERKINS DONALD W |
| 118 | Automatic signal detector | US7057560 | 1960-11-21 | US3136952A | 1964-06-09 | HAMBY JEFFERSON O; SVENSSON EMIL L |
| 119 | Adaptive filter | US727660 | 1960-02-08 | US3114884A | 1963-12-17 | JAKOWATZ CHARLES V |
| 120 | Combination generator and detector for a wave of predetermined shape | US83053559 | 1959-07-30 | US3082377A | 1963-03-19 | FILIPOWSKY RICHARD F J |
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