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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
161	Method and apparatus for routing a digitized RF signal to a plurality of paths	US619229	1996-03-21	US5754597A	1998-05-19	Daniel M. Lurey; Yuda Y. Luz; Sheila M. Rader; Alan P. Rottinghaus
Generally stated, an apparatus and method for routing a digitized radio frequency (RF) signal 140-143 to a plurality of paths is described herein. In accordance with a first preferred embodiment, the apparatus comprises a digital upconverter/modulator (DUC) 125, 129 coupled to a scaling and switching network 100N which is comprised of, at minimum, a first, second, third and fourth digital switch, and a first, second and third adder. Within the scaling and switching network 100N, the first digital switch is responsive to the DUC 125,129. The first adder is responsive to the first and second digital switches, while the second adder is responsive to the third and fourth digital switches. Finally, the third adder is responsive to the first and second adders.
162	Method and apparatus for reducing quantization noise	US389474	1995-02-14	US5602874A	1997-02-11	Yuda Y. Luz; James F. Long
In a quantization noise reduction circuit (200), a feedback signal (W)is added to an input signal (X) to the quantization circuit to reduce quantization noise. The feedback signal is generated as a filtered difference between a sample of a N bit signal (X') and a time coincident sample of a M bit quantized signal, where M<N. The feedback signal is subtracted from the input signal (X) prior to quantization thereby introducing out of band noise into the input signal for reducing in band noise in the quantized signal (Y).
163	Amplification apparatus and method including modulator component	US255722	1994-06-07	US5469127A	1995-11-21	Timothy P. Hulick; Julian L. Brookes
The present invention provides a system and method in which an arbitrary information-modulated signal is efficiently amplified to high power levels. The arbitrary information-modulated signal is received at a low power level and is separated into elemental signals. In a preferred embodiment, a frequency/phase information signal and an amplitude information signal are the elemental signals which collectively represent the essential information in the original information-modulated signal. The circuit uses the elemental signals to provide an amplified replica of the original information-modulated signal. The amplification preferably, though not necessarily, involves using the digital amplitude modulators disclosed in U.S. Pat. No. 4,804,931, U.S. Pat. No. 5,260,674, or U.S. Pat. No. 5,367,272. Accordingly, the strategic use of specially-arranged non-linear amplifiers collectively forming an amplitude modulator operating as a linear amplifier, allows generation of a high power level signal which accurately replicates the amplitude, frequency and phase information of the original signal. In this manner, the present invention exploits the advantages of modulators operating on the principles of U.S. Pat. No. 4,804,931, while performing a function traditionally performed by linear amplifiers.
164	Power amplifier having nested amplitude modulation controller and phase modulation controller	US201284	1994-02-23	US5430416A	1995-07-04	Gregory R. Black; Alexander W. Hietala
Transmitting signals containing amplitude modulated (AM) and phase modulation (PM) components requires a transmitter having AM and PM control loops. The PM control loop provides phase modulation, frequency translation and phase predistortion for the transmitter. The phase predistortion/correction is accomplished by using an oscillator, thus, the amount of PA phase correction is essentially unlimited. Additionally, the PM control loop is nested about a power amplifier (PA), allowing the PM control loop to correct for any distortion introduced by the PA.
165	Digital signal processor exciter	US950241	1992-09-22	US5418818A	1995-05-23	Robert F. Marchetto; Todd A. Stewart; Paul A. Goud; David W. Kroeger; Charles B. Cox; Timothy J. Linderer; Richard J. Hinkle; Robert J. Shade
A digital exciter (30) for selectively modulating digital or analog input data. The digital exciter includes a digital signal modulator (32) and a digital quadrature modulator (DQM)(36) comprising two digital signal processors (DSPs). The signal modulator is controlled by a control (40). An operator can selectively determine whether the digital exciter is used for modulating either two level or four level NRZ digital data and whether the device is to provide linear modulation or frequency modulation (FM) of the input signal. An interpolator (38) interpolates a 662/3 kHz timer interrupt rate used in the signal modulator to a 400 kHz rate, thereby reducing the processing load on the DSP comprising the DQM by simplifying the sine and cosine values used in the quadrature modulation. An operator can select from among a plurality of operating parameters on a menu for controlling the signal modulator, either from a local or a remote video display terminal (VDT).
166	Modulator having improved encoding	US226565	1994-04-12	US5392007A	1995-02-21	David W. Cripe
A pulse step modulator includes a plurality of N series connected unit step modules each including a DC voltage source having a value V. A plurality of M series connected binary step modules are connected together in series with the series connected unit step modules with each binary step module including a DC voltage source having a value which is a fraction of V. Each module has an associated actuatable switch means for, when actuated, turning on the associated module to provide a step voltage. An output circuit connected to the series connected modules for providing an output voltage to a load wherein the magnitude of the output voltage is equal to the sum of all of the voltage sources of the modules that are turned on. An analog input signal is converted into digital words, each word including first and second multi-bit digital portions. The first portion is converted into N unit step control signals for controlling actuation of the N unit step modules so that the number of the unit step modules that are turned on is dependent upon the magnitude of the analog input signal. The second multi-bit digital portion includes an M bit binary pattern that varies with increasing and decreasing values of the input analog signal. An encoder responds to the binary bit pattern reaching a preselected binary bit pattern and changes the value thereof by a given amount.
167	Digital amplitude modulators involving (1) modification of amplitude during synchronization pulse, (2) automatic gain control of signal components, and/or (3) analog representation of less significant signal components	US84026	1993-06-30	US5367272A	1994-11-22	Timothy P. Hulick
A first aspect of the present modulator provides for a reduction in an otherwise maximum level of an analog input signal during a particular time period (for example, the period of the synchronization pulse in an analog television format). When the normally predictable high-amplitude portion is reduced in amplitude, combiner power efficiency is increased. To regain the full amplitude, the gain of the amplifier corresponding to the most significant bit of the digitized signal being modulated, is increased. A second aspect of the present modulator provides an automatic gain control AGC arrangement especially suitable for the modulator of U.S. Pat. No. 4,804,931. The AGC arrangement is based on a circuit that is governed by the output of a respective amplifier as well as by the binary value of the respective bit corresponding to the significance of the amplifier and a reference value related to the bit's significance. Finally, a third aspect of the modulator minimizes component count by providing a hybrid modulator-transmitter. Lower-order bits of a signal to be modulated contribute to the modulated waveform via an analog-processed portion which does not closely follow the teachings of the '931 patent, providing an optimum balance between power savings and component cost and complexity.
168	Synchronous single cycle sample and control amplitude modulator	US927206	1992-08-07	US5291154A	1994-03-01	Freddie O. Sconce
Disclosed herein is a synchronous single cycle sample and control amplitude modulator for use with any carrier frequency. The modulator includes both a data input and a sine wave generator coupled with a sample and hold device. The sample and hold device synchronizes the data and the sine wave signal and then transmits the synchronized signal to a modulator. The modulator modulates the synchronized data and the sine wave signal such that a sampled and controlled, synchronous single cycle amplitude modulated signal is produced.
169	Linear transmitter	US651375	1991-04-19	US5251330A	1993-10-05	Kouji Chiba; Toshio Nojima; Yasushi Yamao; Shigeru Tomisato; Tadao Takami
This invention relates to a linear transmitter which controls the bias voltage of either the drain electrode or collector electrode of an amplifier for radio frequency based on the envelope of the modulated signal, and is characterized in that it controls the bias voltage of the radio frequency amplifier in digital arithmetic processing by generating the envelope using in-phase envelope component and quadrature envelope component obtained from the base band signals.
170	Single side band harmonic frequency converter, in particular for high-frequency receiving and transmitting systems	US927486	1986-11-06	US4817201A	1989-03-28	Paolo Bonato
Two harmonic mixers arranged in parallel are connected to a first signal frequency gate and to a second local frequency gate by means of a single radiofrequency hybrid circuit in quadrature or by means of respective hybrid circuits of which one in quadrature and centered on the signal frequency and the other in phase, quadrature or opposition of phase and centered on the local frequency. Another intermediate frequency hybrid circuit in quadrature connects the two mixers to a third intermediate frequency gate and to a fourth gate closable on a termination. In this manner there is obtained a harmonic frequency conversion with image suppression.
171	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.
172	Baseband phase modulator apparatus employing digital techniques	US33144	1987-04-02	US4761798A	1988-08-02	Stanley R. Griswold, Jr.; Bryan G. Mussatti
There is disclosed a Zero IF modulator apparatus for modulating carrier signals with baseband signals, the modulator includes digital logic circuitry including a sine/cosine amplitude converter which is responsive to the baseband signals for providing first and second digital quadrature baseband signals. These digital quadrature baseband signals are then employed by coupling the same to digital-to-analog converters where the outputs of each converter is indicative of a first and second quadrature signal. These signals can then be translated to a given carrier signal for transmission over a desired communication channel.
173	Angle modulated waveform synthesizer	US709154	1985-03-07	US4745566A	1988-05-17	John J. Ciardi
An angle modulated periodic waveform is synthesized by generating three digital number sequences. In a first number sequence, one number thereof is generated on each occurrence of a periodic clock signal and has a magnitude which is a selected first periodic function of the number of prior occurring clock signals. In a second number sequence, one number thereof is generated on each occurrence of the clock signal and has a magnitude which is a selected second function of prior occurring numbers of the first number sequence and an applied constant carrier waveform frequency parameter. Each number of the second number sequence is added as it is generated to a stored second address number. In the third number sequence, one number thereof is generated on each occurrence of the clock signal and has a magnitude which is a selected third periodic function of the stored second address number. Each number of the third number sequence is converted to a voltage of proportional magnitude by a digital-to-analog converter, the output of which includes the synthesized angle modulated waveform. The second function may be selectively adjusted by application of an external control signal such that the output waveform may exhibit either frequency or phase modulation.
174	Function generator	US662320	1984-10-18	US4680726A	1987-07-14	Jacob H. Malka; Marc Osetec
A function generator having the capability of providing a repetitive output signal with a high degree of versatility in waveform, frequency and amplitude, and with a high degree of resolution. Low frequency (76) and high frequency (86) signal are provided separately, or are combined (108) to provide an amplitude modulated output signal in either a full or suppressed carrier mode (110). Low frequency waveforms are stored (20) and high frequency and user defined waveforms are downloaded from a central processing unit (2). An output attenuator (72, 78, 82, 88) controls the output signal amplitude with a high degree of resolution. An output selective built-in test capability (116) is provided.
175	Apparatus for the gated modulation of a radio-frequency carrier signal	US714406	1985-03-21	US4602226A	1986-07-22	Dimitrios Vatis
Apparatus for the gated modulation of an RF carrier signal uses a balanced circuit for amplitude-modulating the carrier signal, and a circuit having a predetermined minimum on-off amplitude-ratio for providing respective very high attenuation and very low attenuation to the modulated carrier signal responsive to respective off and on levels of a binary logic gate signal. Each of the RF carrier, modulation and gate signals may be individually buffered and/or amplified prior to use of that signal in one of the modulation or gate processes. The modulated RF carrier signal and/or the gated RF signal may also be buffered and/or amplified prior to being respectively gated in, or output from, the apparatus. Each of the buffer-amplifiers, except the gate signal buffer-amplifier, may itself be gated responsive to the gate signal, to provide a desired degree of apparatus output signal on-off ratio.
176	Switched capacitor AM modulator/demodulator	US392972	1982-06-28	US4507625A	1985-03-26	Man S. Lee; Chieh Chang
A first embodiment of an integrable switched capacitor modulator comprises a differential input operational amplifier A1 having a virtual ground potential impressed on its inverting input terminal; capacitors C1, C2 and C3; and switch means operative for alternately (1) charging C1 with an input voltage while connecting C2 and C3 in series with A1 and across it, respectively, for causing it to produce an inverted version of the input voltage, and (2) discharging C2 and C3 while connecting the sample of the input voltage on C1 across A1 for causing it to output a non-inverted sample of the input voltage. The modulated output signal from A1 is preferably bandpass filtered to eliminate baseband spectral components fed through A1 when C2 is connected in series with the input terminal thereof. In a second embodiment which is insensitive to feedthrough and which requires only two capacitors C1 and C4, the switch means alternately (1) charges C1 with the input voltage while connecting a prior sample of the input voltage on C4 across A1 for causing it to output an inverted sample of the input voltage, and (2) charges C4 with the input signal while connecting the sample of the input voltage on C1across A1 in the opposite polarity for causing it to output a non-inverted sample of the input voltage. This embodiment has particular advantage as a demodulator since the built-in sample-and-hold function provides low pass filtering of the output signal of A1.
177	Switched capacitor balanced modulator/demodulator	US393229	1982-06-28	US4504804A	1985-03-12	Chieh Chang; Man S. Lee
An integrated single-sideband modulator comprises six integrated capacitors C1-C6 and first switch means alternately connecting C1 and C2 as feedback capacitors across a differential input operational amplifier A1. The amplifier has a virtual ground potential on its inverting input terminal for causing it to operate as a voltage source and render the circuit relatively insensitive to parasitic capacitance effects associated with capacitor plates. Second switch means cooperates with A1, C1 and C2 and is responsive to 4-phase clock signals for driving input capacitors C3-C6 so as to convert first and second quadrature-phase input signal voltages into first and second electrical charge flow signals on the inverting input terminal that are a function of products of representations of the first and second voltages in switch state time intervals and associated pulse trains which have a 90.degree. phase difference therebetween and a repetitive pattern such as +1, +1, -1, -1, etc. The amplifier and feedback capacitors combine the charge signals for producing a single-sideband signal on A1's output terminal. This circuit is converted to a balanced modulator by omitting C5 and C6. In an alternate embodiment of a single sidebank modulator that requires only a pair of switched capacitors C11 and C12, a 4-phase switch means alternately charges C11 and C12 with associated ones of the quadrature-phase input signal voltages while alternately connecting C12 and C11 as feedback capacitors across A1, the polarity of each capacitor's feedback voltage being reversed each time that capacitor is connected across the amplifier. This circuit is operated as a balanced modulator by omitting one of the capacitors.
178	Cascaded digital broadcast transmitter	US278454	1981-06-29	US4399558A	1983-08-16	Charles F. Smollin
A digital AM broadcast transmitter features a plurality of stages that are controlled by a digital signal representing an audio modulating signal. At least some of the stages are cascade coupled together using transformers. This reduces the need for high turns ratios and allows most or all transformers to be identical.
179	Radio transmitter energy recovery system	US147575	1980-05-08	US4319359A	1982-03-09	Roger E. Wolf
An AM transmitter includes an RF signal generator and a switching-type RF signal amplifier. The RF amplifier output depends upon the energizing voltage applied thereacross, so it acts as a modulator. The energizing voltage is produced by a high-power audio amplifier which includes a pulse-width modulator driving a high-power audio switch. The switch terminals are coupled in series with an audio-frequency filter, energizing terminals of the RF amplifier and a source of direct energizing potential, for varying the voltage across the RF amplifier at an audio rate in response to the duty cycle of the width-modulated pulses for audio modulating the RF carrier. In order to reduce modulation distortion at low duty cycles resulting from the finite turn-on and turn-off time of the audio switch, an offset voltage generator is coupled to the filter by a diode. Energy stored in inductive components of the filter cause a voltage pulse during each turn-off of the audio switch. The voltage pulse is coupled to the offset voltage generator by the diode, and the voltage at the filter is maintained at the offset voltage while current flows in the offset voltage generator and the inductors lose energy. The offset generator includes a capacitor for storing energy resulting from the current flow in the inductor. A DC to AC inverter is coupled to the capacitor and generates alternating voltage. The AC is rectified and a pulsating direct current is coupled to the energizing source for recovering the energy in the inductive pulse.
180	Multiple oscillator modulator circuit	US724441	1976-09-20	US4052682A	1977-10-04	Milton E. Wilcox
A plurality of oscillator-modulator combinations is incorporated into a monolithic integrated circuit. A single pole multiple position switch is used to energize a single oscillator at a time, and a filter having a plurality of inputs and a common output is coupled to the modulator outputs. The modulators each have a common modulation input. Using this combination, a very simple switch can be used to control the modulated signal output at different carrier frequencies.

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