| 序号 | 专利名 | 申请号 | 申请日 | 公开（公告）号 | 公开（公告）日 | 发明人 |
|---|---|---|---|---|---|---|
| 141 | Composite direct digital synthesizer | US211652 | 1994-04-11 | US5878335A | 1999-03-02 | Lawrence J. Kushner |
| A low-power digital frequency synthesizer combining direct digital frequency synthesis techniques with serrodyne frequency translation principles to produce a wideband frequency response with high spectral purity. A conventional direct digital synthesizer is used to generate a high-resolution analog carrier signal from a low-speed digital clock signal. The carrier signal is phase modulated by a low-resolution signal generated from a high-speed digital clock signal. The modulation signal is a higher frequency signal than the carrier signal. The phase modulation is accomplished by exact decoded gain elements. The spectral purity of the resulting high-resolution output signal is unobtainable by conventional direct digital synthesizers, while providing significant power savings. | ||||||
| 142 | Biphase modulator and method without matching elements | US297081 | 1994-08-29 | US5428320A | 1995-06-27 | Craig E. Lindberg; Michael Dydyk |
| A biphase modulator without matching elements includes a Lange coupler (5) including first, second, third, and fourth ports (1,2, 3, 4), where the first port (1) receives a RF input signal. FETs (6, 7) each have a source, gate, and drain (19, 17, 18 and 22, 20, 21). The drain (18) of the first FET (6) is coupled to the second port (2), the source (19) of the first FET (6) and the second FET (7) are coupled to electrical ground, and the drain (21) of the second FET (7) is coupled to the fourth port (4). The FETs, are switched at the desired modulation frequency by a control input (16) to the gates (17, 20), alternately providing a zero volt signal and a pinch-off voltage signal which produces a biphase modulated RF input signal at the third port (3) of the Lange coupler (5). | ||||||
| 143 | Composite direct digital synthesizer | US851481 | 1992-03-13 | US5303412A | 1994-04-12 | Lawrence J. Kushner |
| A low-power digital frequency synthesizer combining direct digital frequency synthesis techniques with serrodyne frequency translation principles to produce a wideband frequency response with high spectral purity. A conventional direct digital synthesizer is used to generate a high-resolution analog carrier signal from a low-speed digital clock signal. The carrier signal is phase modulated by a low-resolution signal generated from a high-speed digital clock signal. The modularity signal is a higher frequency signal than the carrier signal. The phase modulation is accomplished by exact decoded attenuators. The spectral purity of the resulting high-resolution output signal is unobtainable by conventional direct digital synthesizers, while providing significant power savings. | ||||||
| 144 | Transmission system with suppressed carrier signal amplitude modulation preserving the polarity of the transmitted signal, and corresponding transmitter and receiver | US624411 | 1990-12-07 | US5077542A | 1991-12-31 | Marc Lanoiselee |
| A system of transmission with amplitude modulation for the transmission of signals of all types, analog and/or digital, requiring high performance characteristics with respect to the noise induced by the transmission channel, comprising, at transmission, means for the suppressed carrier amplitude modulation of a useful signal and means for the amplitude modulation, in phase quadrature with said modulated useful signal, of a service signal, making it possible, at reception, to remove the ambiguity on the polarity of the demodulated useful signal. Thus it enables the transmission of signals in suppressed carrier modulation mode, hence with a good signal-to-noise ratio, without losing the polarity of the signal. The transmitters and receivers according to the invention also enable the transmission and reception of the signals modulated in SCAM, VSBAM or VSBSCAM modes. | ||||||
| 145 | Single sideband signal generator | US17125 | 1987-02-20 | US4835791A | 1989-05-30 | Edward D. Daoud |
| The method and apparatus disclosed for more efficient use of the bandwidth of a communication channel includes steps of generating a single sideband signal, including inputting a digital signal into an N-tap Hilbert transform filter, modulating the output of the ((N-1)/2)th tap of the filter onto a first carrier signal, and modulating the output of the Nth tap of the filter onto a second carrier signal. The second carrier signal has the same frequency as, and is separated by 90 degrees in phase from, the first carrier signal. The modulated first and second carrier signals are combined to produce a single sideband signal. A second signal is similarly processed to produce a second single sideband signal. The two single sideband signals may be combined on a single output line. Each single sideband modulation process may be preceded by the steps of receiving an analog signal, sampling the signal to produce a digital signal, and compressing in time the digital signal to produce a compressed signal, wherein each compressed signal is input to the corresponding single sideband signal generator. | ||||||
| 146 | Single sideband modulation | US838542 | 1977-10-03 | US4300237A | 1981-11-10 | Harvey L. Morgan |
| A system for single sideband modulation, and a method implemented by the system. The system includes a double sideband, suppressed carrier modulator and a phase locked loop circuit receiving the output of the modulator and tuned to lock to one of the sidebands of the modulator output. The phase locked loop circuit produces an output having a constant amplitude, but otherwise tracking the signal contained in the one sideband. The output of the phase locked loop is processed by an amplifier having a controllable gain. Open and closed loop circuits are provided for deriving the amplitude of the signal contained in the one sideband. The latter amplitude is imparted to the output of the phase locked loop by using the signal amplitude to control the gain of the amplifier. | ||||||
| 147 | Quantized modulation systems | US20175 | 1979-03-13 | US4205241A | 1980-05-27 | Charles B. Fisher; Sidney T. Fisher |
| A system for modulation of the amplitude of a d-c voltage, the amplitude of an a-c carrier, or the frequency of an a-c carrier by signal, in which the signal amplitude is continuously compared against a predetermined series of equally-spaced d-c voltages, and coincidence-sensing and switching means associated with each d-c voltage connects a corresponding d-c voltage to the output circuit in the case of an instantaneous compressor, an instantaneous expandor or a signal amplifier, connects a carrier of corresponding amplitude to the output circuit in the case of an amplitude modulator, and connects a carrier of corresponding frequency to the output circuit in the case of an angle modulator. | ||||||
| 148 | Double sideband transmission system | US637660 | 1975-12-04 | US4176319A | 1979-11-27 | Leonard R. Kahn |
| An improved system and method for processing and amplifying double-sideband suppressed or reduced carrier waves using high efficiency amplifiers and not requiring frequency dividers. Typical practice of the invention involves generating a double-sideband suppressed carrier wave in a balanced modulator; for example, at a sub-harmonic carrier frequency and multiplying the frequency of the output of the balanced modulator by an odd multiplication factor greater than one in the modulated amplifier.The required envelope modulation (amplitude modulation) component is derived from the original balanced modulator output by use of an envelope demodulator and the component is used to modulate the modulated stage so as to reproduce the double-sideband suppressed carrier wave at a high power level.This invention may also be used in reduced carrier double-sideband transmitters; i.e., where the carrier is not fully suppressed but where the carrier is smaller in amplitude than the peak amplitude of the combined upper and lower sideband waves. | ||||||
| 149 | Side band generator | US3555458D | 1967-11-13 | US3555458A | 1971-01-12 | FOMBONNE PAUL |
| A SIDE BAND GENERATOR PROVIDING TWO PAIRS OF SIDE BANDS IN QUADRATURE AND COMPRISING TWO PHASE SHIFTERS WHICH ARE VARIABLE AND CONTROLLED IN A DIGITAL MANNER, AND WHICH PHASE SHIFT, SIMULTANEOUSLY AND IN OPPOSITE DIRECTIONS, EACH HALF OF THE ENERGY OF THE HIGH FREQUENCY WAVE CARRIER, THE PHASE SHIFT REACHING 2$ AT THE END OF A PERIOD OF THE LOW FREQUENCY MODULATING WAVE.
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| 150 | Amplitude modulation to single or double sideband suppressed carrier converter | US27134163 | 1963-04-08 | US3284711A | 1966-11-08 | MESSENGER CHARLES A; MARYGOLD ALFRED E |
| 151 | Variable power level frequency modulation transmitter | US28298263 | 1963-05-24 | US3262056A | 1966-07-19 | JOHNSON WAYNE R; BRANCO FLAVIO S C |
| 152 | Suppressed carrier transmitter | US8028561 | 1961-01-03 | US3066259A | 1962-11-27 | LENNON III GEORGE V |
| 153 | Electronic computer | US73931958 | 1958-06-02 | US3057555A | 1962-10-09 | CASE JR ROBERT O |
| 154 | Interrogator-responder signalling system | US855760 | 1960-02-15 | US3022492A | 1962-02-20 | KLEIST ROBERT A; JONES CLARENCE S |
| 155 | Signal-translating apparatus | US58760056 | 1956-05-28 | US3011026A | 1961-11-28 | DRUZ WALTER S |
| 156 | Emergency vehicle alarm device | US67730957 | 1957-08-09 | US2994765A | 1961-08-01 | ADAM EUGENE C |
| 157 | Modulator and modulation system | US58886156 | 1956-06-01 | US2940056A | 1960-06-07 | NORGAARD DONALD E |
| 158 | Electron beam tubes and circuits therefor | US36785053 | 1953-07-14 | US2912613A | 1959-11-10 | DONAL JR JOHN S; LOUIS CUCCIA CARMEN |
| 159 | Suppressed carrier modulator | US62084956 | 1956-11-07 | US2870414A | 1959-01-20 | ISLEY JR CARY T |
| 160 | Carrier frequency rejection amplifiers or the like | US45786754 | 1954-09-23 | US2796471A | 1957-06-18 | JACOBSEN LANCE R |
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