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序号	专利名	申请号	申请日	公开（公告）号	公开（公告）日	发明人
61	Arrangement for compensating errors in a quadrature modulator	US270259	1988-11-14	US4890301A	1989-12-26	Bo G. Hedberg
An arrangement for compensating errors occurent in a quadrature modulator. Two quadrature signals (cos a(t), sin a(t)) in the baseband are generated, each of which signals is delivered to a respective branch in the modulator two high frequency signals (cos wt, sin wt) with a mutual phase difference of 90 degrees are generated and mixed with the quadrature signals (cos a(t), sin a(t)) and an adder (5) produces the sum of the output signals of the mixers (3, 4). Amplitude errors and phase errors are compensated with the aid of a separate compensating network (11, 12, 14, 16, 17, 19, 21) which is incorporated in the low frequency part of the modulator and which includes adjustable signal generator (14, 16). Local oscillator leakage is compensated with the aid of a second compensating network (13, 15, 18, 20) which is also incorporated in the low frequency part of the modulator and which also includes an adjustable signal generator (15, 18). The signals (k4, k5) from the latter generator (15, 18) are subtracted from the signals occuring in the two branches of the modulator.
62	Digital signal synthesis using low frequency sampling clock	US103997	1987-10-02	US4823090A	1989-04-18	Mike R. Coleman; John J. Ciardi
A digital signal synthesizer stores a representation of a desired analog signal in the form of digital samples. The digital samples are converted to an analog signal by a sample clock having a frequency greater than or equal to twice the bandwidth of the desired analog signal. The analog signal is band pass filtered to recover the desired analog signal.
63	Modulation signal generator and apparatus using such generator	US27718772	1972-08-02	US3794995A	1974-02-26	THOMPSON B
Improved apparatus for generating a time-varying analog signal, as for example, a chirp modulation signal for a pulse compression radar, is shown. The disclosed apparatus incorporates: a memory for storing a set of digital words representative of samples of the time-varying analog signal; at least two digital-to-analog converters having their outputs connected to a common bus; and means for distributing, at a predetermined rate, successively read digital words from the memory to the digital-to-analog converters. Each one of the latter elements is actuated also by a time-varying weighting signal so the frequency spectrum of the desired time-varying analog signal is within predetermined limits.
64	Digital signal generator synthesizer	US3654450D	1970-04-03	US3654450A	1972-04-04	WEBB JOSEPH A
Illustrative embodiments of the present invention shown and described include digital logic systems for generating signal waveforms of desired types. A relatively few digital logic modules are connected to generate a variety of desired waveshapes in a linear manner. Apparatus for generating rectangular waves, saw-tooth waves, sine waves, and sine waves having amplitude, pulse, frequency and phase modulation applied to them are disclosed.
65	Electronic circuit for converting dc to ac analogue signals	US3622800D	1970-10-01	US3622800A	1971-11-23	ABELA SHIBLY JOSEPH
The disclosure teaches a completely electronic circuit for converting a DC analogue signal to a corresponding AC analogue signal. An AC reference signal is fed to the noninverting input terminal of a high gain differential amplifier whose output position modulates a pulse oscillator. The output of the oscillator is fed to a first low pass filter, which has a cutoff frequency slightly higher than the frequency of the AC reference. The output of the first filter is fed to the inverting terminal of the amplifier so that, when the gain of the amplifier is great enough, the output of the filter is substantially identical to the AC reference signal. The output of the oscillator is fed to the control terminal of a gate whose signal input is fed with the DC analogue signal so that the output of the gate is the pulse train of the oscillator multiplied by the DC analogue level. The gated output is fed to a second filter, which is substantially identical to the first filter, and whose output constitutes the AC analogue signal.
66	Quantum wave current control in super-conductors	US3533018D	1965-02-16	US3533018A	1970-10-06	JAKLEVIC ROBERT C; LAMBE JOHN J; MERCEREAU JAMES E; SILVER ARNOLD H

67	Gated operational amplifier	US3497830D	1968-03-20	US3497830A	1970-02-24	COLTON JOHN R; SHEEHAN JOHN R; VACHON PATRICK A

68	Art of modulating an electronic circuit	US75453547	1947-06-13	US2503352A	1950-04-11	PETERS ABNER G

69	Radio transmission and testing system utilizing pulse type generators	US50834043	1943-10-30	US2394933A	1946-02-12	MUELLER WILLIAM P; BURROUGHS FRANKLIN L

70	Piezoelectric resonator circuit	US33596340	1940-05-18	US2274486A	1942-02-24	KOCH WINFIELD R

71	Communication system using modulated waves	US22092838	1938-07-23	US2252062A	1941-08-12	HENRI CHIREIX

72	Modulation system	US65460533	1933-02-01	US2136479A	1938-11-15	BERTRAM TREVOR

73	Control circuits for space discharge devices	US44369630	1930-04-12	US1893031A	1933-01-03	LLEWELLYN FREDERICK B

74	Absorption control modulating system	US13650226	1926-09-20	US1795714A	1931-03-10	DELORAINE EDMOND M

75	Arrangement for wireless telegraphy and telephony	US67905323	1923-12-07	US1734772A	1929-11-05	WILHELM MOSER

76	Signaling system	US11477716	1916-08-14	US1712993A	1929-05-14	HEISING RAYMOND A

77	Wireless telephone system	US48146121	1921-06-30	US1595794A	1926-08-10	LITTLE DONALD G

78	Constant frequency system	US13953316	1916-12-29	US1586524A	1926-06-01	HEISING RAYMOND A

79	Modulation of electrical waves	US32054619	1919-08-29	US1507913A	1924-09-09	FITCH ALBERT L

80	Wireless signaling system	US1914835433	1914-04-30	US1501830A	1924-07-15	ALEXANDERSON ERNST F W

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