With Control (e.g., Automatic Gain Control, Automatic Frequency Control, Etc.) Patents (Class 455/136)
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Publication number: 20020111148Abstract: Angle-modulated signals are transmitted in a communications system, in which coding information has been inserted into the transmitted data at regular intervals. The coding information is phase-modulated together with the transmitted data. This coding is used for pulse shaping, so that the receiver can recover the digital transmitted data with less implementation complexity and without carrier phase control by using appropriate signal processing.Type: ApplicationFiled: March 8, 2002Publication date: August 15, 2002Inventor: Andre Neubauer
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Publication number: 20020098814Abstract: An apparatus for providing automatic gain control for use in a satellite terminal of a satellite communication system capable of transmitting a plurality of different modes of data. The apparatus includes a demodulator circuit having an analog to digital converter; a first variable attenuator having an attenuation value set on the basis of a measured power level of a predetermined data signal; and a second variable attenuator having an attenuation value set on the basis of the mode of data being received by the satellite terminal, where each of the data modes have a corresponding predetermined attenuation value associated therewith which is utilized as the attenuation value of the second variable attenuator when the satellite terminal receives the data mode.Type: ApplicationFiled: January 10, 2002Publication date: July 25, 2002Applicant: HUGHES ELECTRONICSInventors: J. Mark Steber, Richard Clewer, Kumud Patel, Bala Subramaniam
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Patent number: 6408195Abstract: An IC for communication includes a single oscillating circuit, which is capable of flexibly dealing with the change of data rate or data processing load, and is produced at a low cost and consumes low electric power. In the IC for communication, a frequency multiplying circuit(61) is inserted between the output of an oscillating circuit(1) and a micro-controller circuit(69), or a frequency dividing circuit(2) is inserted between the oscillating circuit(1) and a data receiving circuit(3). A receiving address is stored in a dual port RAM(16). Further, by controlling a receiving frequency of synchronous codes, battery saving efficiency is increased.Type: GrantFiled: February 14, 2000Date of Patent: June 18, 2002Assignee: Seiko Instruments Inc.Inventors: Yuji Hishiki, Isamu Fujii, Shinichi Idomukai
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Patent number: 6389040Abstract: A frequency offset estimation is generated without explicitly generating a channel estimation for a frequency selective fading communication channel. This is realized by recognizing that, in the absence of additive noise, the channel output at a time n depends only on the last previous predetermined number, L, of data symbols, and that a “state” is a sequence of the last L symbols. Specifically, in a receiver, a received signal is mixed with a locally generated frequency corresponding to a frequency offset to generate a mixed signal. A calculation is made on the mixed signal in which channel outputs of the same state are combined and accumulated. Then, a summation is made over all possible states of the combined and accumulated channel outputs to yield a so-called metric calculation value for that mixed signal. The metric calculation is then repeated for a plurality of different locally generated frequencies corresponding on a one-to-one basis with a plurality of frequency offsets.Type: GrantFiled: September 11, 1998Date of Patent: May 14, 2002Assignee: Lucent Technologies Inc.Inventor: Harish Viswanathan
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Patent number: 6389085Abstract: Apparatus for and method of processing received signals for use with multiple antenna spatial diversity receivers used in a digital communications system. The receiver has received signal phase modulator apparatus for each diversity received signal. The phase modulator provides a two state phase perturbation of zero or pi radians, based on the carrier frequency, which is switched to modulate the phase of the received signal for a fifty percent duty cycle over a symbol period.Type: GrantFiled: January 14, 1998Date of Patent: May 14, 2002Assignee: Wavecom Electronics Inc.Inventor: J. Eric Salt
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Patent number: 6363343Abstract: A gain control circuit for a telephone, the circuit comprising a signal strength calculator for calculating the strength of a signal; a gain controller adapted to modify the strength of the signal in accordance with a predetermined criterion based on the strength of the signal calculated by the signal strength calculator.Type: GrantFiled: November 2, 1998Date of Patent: March 26, 2002Assignee: Nokia Mobile Phones LimitedInventor: Jacek Andrzej Horos
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Publication number: 20020032013Abstract: The invention relates to a method of automatic gain control (AGC) in a base station of a cellular radio network and to a network part in a cellular radio network. The method comprises receiving at least one random access burst transmitted by a subscriber terminal of the cellular radio network on a random access channel. Then the received power of the random access burst is measured, followed by generating subscriber terminal-specific AGC data on the basis of the received power of at least one random access burst. Then, subscriber terminal-specific AGC data is stored. Next, a normal burst transmitted by the subscriber terminal on a stand-alone dedicated control channel is received, and the gain of the normal burst received is controlled by the subscriber terminal-specific AGC data. Finally, the controlled normal burst is subjected to analog-to-digital conversion.Type: ApplicationFiled: August 16, 2001Publication date: March 14, 2002Inventors: Timo Pinola, Kari Haataja
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Patent number: 6356604Abstract: The invention relates to a receiving method and a receive for a radio system. The receiver filters a received signal group propagated on several channels using channel filters (31) to generate separate channel specific signals. These channel specific signals are searched in device (35) for one or more signals (50) stronger than the others. Feed back is performed on these strongest signals (50) and they are subtracted from the received signal group in connector (21) in order to equalize the power levels of the signal group.Type: GrantFiled: July 13, 1998Date of Patent: March 12, 2002Assignee: Nokia Telecommunications OyInventor: Matti Kiiski
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Publication number: 20010046844Abstract: An array antenna transceiver includes an antenna section, N transceiver blocks, a common reference signal generating section and a transceiver control section. The antenna section has antenna elements. The N transceiver blocks are connected to the antenna elements. Each of the N transceiver blocks generates an individual reference signal. The transceiver block carries out transmission of a transmission signal and reception of a reception signal based on an common reference signal using a corresponding antenna element as a part of an array antenna in an array mode and based on said individual reference signal using the corresponding antenna element as an individual antenna element in an individual mode. The common reference signal generating section supplies the common reference signal to the N transceiver blocks. The transceiver control section sets said array mode when said common reference signal is used, and said individual mode when said individual reference signal is used.Type: ApplicationFiled: May 16, 2001Publication date: November 29, 2001Applicant: NEC CORPORATIONInventor: Satoshi Oura
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Publication number: 20010008835Abstract: A multiple data stream processing arrangement includes a receiver/signal processor (14) and a plurality of signal input paths (11, 12) which meet at a junction (36). A junction output from the junction (36) provides a single input to the receiver/signal processor (14). A switching arrangement (16) is associated with the plurality of signal input paths (11, 12). The switching arrangement (16) includes a switch (31, 32) connected in each signal input path (11, 12). Each switch (31, 32) responds to an enable signal to allow a data stream applied to the respective input path (11, 12) to pass on to the junction (36) and to the receiver/signal processor (14). Only one signal input path (11, 12) and respective switch (31, 32) is enabled at any given time.Type: ApplicationFiled: March 6, 2001Publication date: July 19, 2001Inventors: Carmen Tawil, Saleem Tawil
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Patent number: 6229991Abstract: By employing AFC range extension, a high frequency communication device (100) can use a low cost, low accuracy crystal (119) in its reference oscillator (118). AFC range extension involves varying receive bandwidth of the communication device (100) to facilitate AFC or automatic frequency control. In particular, the receive bandwidth is set to a first, wide setting for AFC acquisition purposes (208). Frequency error associated with a received AFC signal is determined (212) and receive reception is adjusted (218) to reduce frequency error in the communication device (100). Once the frequency error is below a predetermined threshold (214), the receive bandwidth is set to a second setting different from the first setting for normal reception (220).Type: GrantFiled: October 13, 1998Date of Patent: May 8, 2001Assignee: Motorola, Inc.Inventors: Alexander W. Hietala, Arvind S. Arora
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Patent number: 6195400Abstract: A two-mode demodulating apparatus for use in a radio terminal in a mobile communication system has a linear reception demodulating circuit and a non-linear reception demodulating circuit which can be selectively operated by selecting a mode. The non-linear reception demodulating circuit has a second frequency converting unit for frequency-converting a received signal into a low-frequency signal, a variable-band filtering unit for allowing a signal in a desired band contained in an output of the second frequency converting unit to pass therethrough, and a non-linear reception demodulating process unit for performing a non-linear reception demodulating process on an output from the filtering unit, thereby receiving and demodulating a linear modulated wave and a non-linear modulated wave while suppressing increases of the circuit scale and the power consumption, and generalizing a hardware structure for an applied non-linear modulating system.Type: GrantFiled: March 26, 1998Date of Patent: February 27, 2001Assignee: Fujitsu LimitedInventor: Mitsunori Maeda
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Patent number: 6181923Abstract: The present invention relates to the automatic frequency control circuit and the method of automatic frequency control. The automatic frequency control circuit for processing frequency control of a received signal frequency based on an incoming received signal comprises a first control circuit for processing frequency control based on a precision counter by using the incoming received signal and a second control circuit for processing frequency control based on a coarse counter by using the incoming received signal, wherein the first control circuit and the second control circuit are configured to be used interchangeably in response to the incoming received signal. By employing the circuit which directly counts the received signal and the circuit which counts the regenerative carrier signal in combination, the follow up range of the automatic frequency control circuit is thus expanded.Type: GrantFiled: March 27, 1998Date of Patent: January 30, 2001Assignee: Fujitsu LimitedInventors: Osamu Kawano, Fujio Inagami
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Patent number: 6125109Abstract: Signal delay and combining techniques are used with multipath signals to provide signal diversity gain within CDMA over-the-air repeater and low noise amplifier systems. An incoming signal from a remote user is typically processed through two processing paths, wherein one path adds a delay to the processed signal. The two signal paths are then combined and filtered through a sharp band pass filter, preferably a SAW filter. In an over the air repeater, the filtered signal is retransmitted towards a CDMA rake receiver at a base station, which can process the multipath signal to produce a clean signal representation. In a low noise amplifier, the filtered signal is transferred directly into a base station or repeater. The use of SAW filters protect the latter stages of the low noise amplifier, and also protect the base station from out-of-band signal interference.Type: GrantFiled: February 24, 1998Date of Patent: September 26, 2000Assignee: Repeater TechnologiesInventor: Matthew P. Fuerter
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Patent number: 6108387Abstract: In a frequency scanning receiver having an AFC function, when a desired signal is caught by frequency scanning due to VCO, to which a scanning voltage from a scanning signal oscillator is applied, the scanning is stopped. At this time, an operating circuit calculates to form a setting voltage of the VCO at the convergence of the AFC, based on two voltages, which are the control voltage (scanning voltage) applied to the VCO and an output voltage of a frequency error detector, and the AFC circuit is made function after having applied this setting voltage to the VCO.In this way, it is possible to shorten a header of a packet signal and to improve through-put of data, which can be transmitted, by removing a remaining frequency error in a short period of time, when the frequency scanning is stopped, by the fact that an object signal is caught by the frequency scanning.Type: GrantFiled: December 10, 1997Date of Patent: August 22, 2000Assignee: General Research of Electronics, Inc.Inventor: Kazuo Kawai
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Patent number: 6097972Abstract: The transmitted power of a mobile telephone is established by power control bits that are transmitted in a traffic channel from a base station and that are demodulated by a rake receiver in the telephone. The rake receiver includes a plurality of demodulators that demodulate respective fingers of the traffic channel which may be caused by multipath conditions, with the power control bits from each demodulator being combined with the power control bits of the other demodulators in the rake receiver regardless of whether the demodulators are in lock with their respective fingers. The combined power control signal from a rake receiver associated with a first base station is then tested against a threshold. If the combined power is at least equal to the threshold, the combined power control signal is sent to a logic combiner. If other base stations are communicating with the mobile telephone, the combined power control signal from each of these other base stations is also sent to the logic combiner.Type: GrantFiled: August 29, 1997Date of Patent: August 1, 2000Assignee: QUALCOMM IncorporatedInventors: Keith W. Saints, Edward G. Tiedemann, Jr.
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Patent number: 6081564Abstract: An apparatus and methods for tracking a power level of a signal received at a base station of a code division multiple access (CDMA) digital cellular communication system. The apparatus comprises a storage unit for storing a first table comprising automatic gain control voltages corresponding to a series of received signal levels and a second table comprising variable attenuation control voltages corresponding to the automatic gain control voltages.Type: GrantFiled: December 30, 1997Date of Patent: June 27, 2000Assignee: Samsung Electronics Co., Ltd.Inventor: Deog-Su Han
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Patent number: 6067449Abstract: Antenna selection control apparatus for a diversity antenna system including at least two antennas. The received power strength is measured from a selected antenna and compared with a reference power level. The reference power level is adjusted depending upon the signal to noise ratio of received signals, and if the selected antenna falls below the adjusted threshold another antenna is selected.Type: GrantFiled: December 10, 1996Date of Patent: May 23, 2000Assignee: Nokia Mobile Phones LimitedInventor: Michael David Jager
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Patent number: 6038435Abstract: An AGC method and apparatus is provided for a receiver to control the signal power of a received RF signal over a wide dynamic range and significantly reduce the ADC clipping time to a level appropriate for cellular communications. The AGC apparatus comprises an ADC (analog-to-digital converter) for generating digital samples of a received signal, a controller for providing a receiver gain setting based on the digital samples generated and an actuator for applying the receiver gain setting. The controller compares digital samples generated by the ADC to a first predetermined reference level, accumulates an error signal, calculates an attenuation adjustment based on the accumulated error signal and sums the attenuation adjustment with a previously calculated receiver gain setting for providing the actuator with an updated receiver gain setting which is applied therein.Type: GrantFiled: December 24, 1997Date of Patent: March 14, 2000Assignee: Nortel Networks CorporationInventor: Jin-Yun Zhang
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Patent number: 5913155Abstract: A broadcasting signal receiving apparatus includes a first signal receiving portion for receiving selectively frequency-modulated broadcasting signals to obtain a frequency-modulated intermediate frequency signal, a first band pass filter through which the frequency-modulated intermediate frequency signal passes, a first demodulator for frequency-demodulating the frequency-modulated intermediate frequency signal to obtain a first demodulation output signal, a second signal receiving portion for receiving selectively amplitude-modulated broadcasting signals to obtain an amplitude-modulated intermediate frequency signal, a second band pass filter through which the amplitude-modulated intermediate frequency signal passes, a second demodulator for amplitude-demodulating the amplitude-modulated intermediate frequency signal to obtain a second demodulation output signal, an output portion for obtaining a reproduced information output based on one of the first and second demodulation output signals, a signal supplyiType: GrantFiled: January 29, 1997Date of Patent: June 15, 1999Assignee: Sony CorportaionInventor: Hitoshi Tomiyama
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Patent number: 5859875Abstract: Transmission mode selection is enabled, so communication reliability, transmission speed, and equipment utilization efficiency are all high. A first transmission system whereby spectrum spreading is accomplished with a spread code 1 and data is transmitted, and a second transmission system whereby data is transmitted with a spread code 2, are provided. In high-reliability transmission mode, identical data from a data buffer is transmitted through both the first and second transmission systems to achieve space diversity. In high-speed mode, data divided by a data division circuit is transmitted simultaneously through the first and second transmission systems, making possible efficient data transfer. Control information insertion circuits append transmission mode data to the transmitted data.Type: GrantFiled: January 28, 1997Date of Patent: January 12, 1999Assignee: Uniden CorporationInventors: Hideki Kato, Shinichi Yamazaki, Hideaki Ugawa, Kazuhiko Seki
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Patent number: 5809406Abstract: Herein disclosed are a radio receiving apparatus and a receiving system switching control method used in the radio receiving apparatus. The radio receiving apparatus has an active receiving system and a standby receiving system including respective equalizers, and a changeover switch for performing a switching between the active receiving system and the standby receiving system. The radio receiving apparatus further includes an alarm predicting information predicting means for detecting alarm predicting information in each of the equalizers and a switching control means for controlling a switching condition of the changeover switch on the basis of the alarm predicting information detected by the alarm predicting information detecting means, where the alarm predicting information as internal information of the equalizers is monitored to predict a malfunction of a receiving circuit to switch the circuit before the circuit is hit. It is therefore possible to reduce a hit rate of the circuit.Type: GrantFiled: August 31, 1995Date of Patent: September 15, 1998Assignee: Fujitsu LimitedInventors: Yoshihiko Taki, Kenichi Oide
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Patent number: 5732336Abstract: A reception clock signal used for a data sampling unit to sample received data is generated by a reception clock generator based on a reference clock signal, which is generated by a reference clock generator based on a reference bit rate frequency. The reference bit rate frequency is produced by a reference oscillator which is controlled by a control voltage. The control voltage is generated by a phase difference-to-voltage converter depending on the phase difference, detected by the reception clock generator, between the timing of a change in the received data and the reference clock signal. If good reception sensitivity is not available due to a phase difference, then the phase difference-to-voltage converter generates a control voltage in a manner to eliminate the phase difference, and applies the generated control voltage to a variable capacitor connected to the reference oscillator for automatically adjusting the reference bit rate frequency.Type: GrantFiled: July 18, 1996Date of Patent: March 24, 1998Assignee: Kokusai Electric Co., Ltd.Inventor: Shunji Tochihara
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Patent number: 5678169Abstract: An improved navigation satellite receiver with a super heterodyne receiver channel configured to provide a first local oscillator frequency between L1 and L2 such that the down converted intermediate frequencies of L1 and L2 can be processed by the same intermediate frequency stages and a second mixer stage. A radio frequency (RF) selector switch is provided to select between inputting L1 and L2 to the first mixer. The RF switch is controlled by a digital signal processor (DSP) that also provides automatic gain control (AGC) to an intermediate frequency amplifier. Histories and expected levels of AGC for each of L1 and L2 are maintained by the DSP. The RF switch is briefly toggled over to select one of L1 or L2, while tracking a satellite on the other carrier frequency, just long enough to sample the AGC level needed. If the level is too high, given the histories and expectations for such levels, the sampled carrier frequency is assumed to be jammed, and a high risk for switching over.Type: GrantFiled: June 30, 1995Date of Patent: October 14, 1997Assignee: Trimble Navigation LimitedInventor: Paul F. Turney
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Patent number: 5640431Abstract: A method and apparatus for improved offset frequency estimation includes in a first embodiment a receiver (100) for coherent reception of a signal having known reference information, the receiver including an extractor (106) for extracting the reference information (107) from the signal, and an offset frequency estimator (110). The offset frequency estimator (110) includes a filter (121) for filtering the reference information and outputting a filtered reference sequence; a correlator (122, 124) for correlating the filtered reference sequence against a predetermined reference signal to form correlation values; and a peak detector (126) for determining an offset frequency estimate (131) from the correlation values. Other embodiments are also shown.Type: GrantFiled: March 10, 1995Date of Patent: June 17, 1997Assignee: Motorola, Inc.Inventors: Eugene J. Bruckert, Fuyun Ling, Thomas A. Sexton
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Patent number: 5594757Abstract: A method and apparatus for digital automatic frequency control includes circuitry for frequency controlling a first information portion of a digital input signal, correlating the output with a known characteristic of the first information portion, and outputting a timing signal and channel estimation signal. The digital input signal is also decimated using the timing signal and frequency controlled into a frequency controlled output signal. This signal is used, along with a signal quality estimate derived from the channel estimation signal and first information portion, to determine an estimated frequency correction signal. The estimated frequency correction signal is used to control the frequency correction steps.Type: GrantFiled: July 28, 1994Date of Patent: January 14, 1997Assignee: Motorola, Inc.Inventor: Kamyar Rohani
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Patent number: 5548594Abstract: In an automatic gain control circuit which has a variable gain amplifier 30 for amplifying an input TDM reception signal 160 in accordance with a controllable gain, an analog-to-digital converter 40 for converting an amplified TDM reception signal 170 into a digital signal 180, and control section 50 for determining an optimized value of the controllable gain in response to the digital signal 180 so as to supply the variable gain amplifier 30 with the optimized value of the controllable gain, the optimized value of the controllable gain is determined by the use of a signal of the time slot S(-1) immediately before the predetermined time slot S(0) when receiving the input TDM reception signal 160.Type: GrantFiled: December 27, 1994Date of Patent: August 20, 1996Assignee: NEC CorporationInventor: Naoyuki Nakamura
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Patent number: 5390342Abstract: A receiver has a plurality of receiving systems connected to a plurality of antennas, respectively, and a selective switching circuit for carrying out selective switching between output signals from the plurality of receiving systems to output an output signal from a receiving system in the most satisfactory receiving state, wherein the selective switching circuit has a fuzzy inference operation unit for discriminating receiving states of respective receiving states by a fuzzy inference. Accordingly, it is possible to synthetically judge the receiving state of the receiver to easily and stably select the optimum receiving system in the receiver.Type: GrantFiled: March 12, 1991Date of Patent: February 14, 1995Assignee: Pioneer Electronic CorporationInventors: Masami Takayama, Toshihito Ichikawa
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Patent number: 5361404Abstract: Two or more signal paths are provided for receiving a radio frequency signal. One or more signal paths include conventional bandpass filters for eliminating interference and noise signals. One or more remaining signal paths include reduced filtering devices for increasing the sensitivity of a radio frequency receiver to the desired signal. Each of the receiving paths is coupled to a respective radio frequency amplifier. Provided that each radio frequency amplifier has equivalent current-source output impedances, the output signals from each amplifier are added constructively if they are in-phase. If the output signals are out-of-phase, a phase inverter inverts the phase of one signal so that the signals may be added constructively. The combined signals of the two or more radio frequency amplifiers pass through various signal processing components associated with conventional superheterodyne receivers. A control unit produces gain variation signals for controlling the gain of each radio frequency amplifier.Type: GrantFiled: May 14, 1993Date of Patent: November 1, 1994Assignee: Ericsson-GE Mobile Communications Inc.Inventor: Paul W. Dent
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Patent number: 5355141Abstract: A channelised bearing processor comprises a channelised receiver consisting of a plurality of i.f. receivers (34 to 42) covering contiguous parts of a predetermined frequency range. Each of the receivers (34 to 42) is connected to a respective, continuously energised local oscillator (35 to 43). A plurality of direction finding antennas (10 to 15) are coupled to respective receiving channels for producing an amplitude signal. Each receiving channel includes a tunable i.f. receiver (24A to 24F) having an input (26A to 26F) for a local oscillator signal. A local oscillator selector (50) is responsive to an output from one of the channelised receivers (34 to 42) to connect the local oscillator (35 to 43) connected to that one of the channelised receivers (34 to 42) to the local oscillator signal inputs (26A to 26F) of the tunable i.f. receivers (24A to 24F) in the receiving channels.Type: GrantFiled: December 18, 1992Date of Patent: October 11, 1994Assignee: Thorn EMI Electronics LimitedInventors: Stephen P. Graham, Michael W. Keeping
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Patent number: 5335359Abstract: In a digital radio communications system, a transmit signal is delayed and sent on a first diversity channel and a nondelayed version of the signal sent on a second diversity channel. At the receiving site, first and second diversity channel signals are recovered and normalized into first and second constant-amplitude signals. Predominant components of the constant-amplitude signals are phase-and-amplitude aligned with each other by feedback loops including phase-and-amplitude alignment circuits, an adder and an AGC amplifier. The output of the AGC amplifier or the output of the subtracter is selected and applied to a matched filter to which a decision feedback equalizer is coupled.Type: GrantFiled: May 30, 1991Date of Patent: August 2, 1994Assignee: NEC CorporationInventors: Ichiro Tsujimoto, Yoshiyuki Fujimoto
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Patent number: 5303396Abstract: A diversity reception apparatus which has a plurality of antennas and in which one of the antennas having the best receiving condition is automatically selected and connected to a broadcasting signal receiver. The diversity reception apparatus has a feature in that after demodulated signals, obtained by the receiver respectively corresponding to the plurality of antennas, are converted into digital signals by an A/D converter, the best demodulated signal and the antenna corresponding thereto are selected by comparing the digital signals with each other, and that the width of a switch driving pulse from a switch driving pulse generator is made not more than 3 .mu.s.Type: GrantFiled: June 5, 1991Date of Patent: April 12, 1994Assignees: Hitachi, Ltd., Hitachi Video & Information Systems, Inc., Hitachi Automotive Engineering Co., Ltd.Inventors: Kazuhiro Ooyagi, Nobutaka Hotta, Keiro Shinkawa
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Patent number: 5239698Abstract: A method and device are set forth for providing improved diversity reception to a receiver system in a communication system, the receiver system having at least one receiver on each of at least a first and a second receiver branch. The method and device provide, upon receipt of signals on the receiver branches, for utilizing received signal strength voltages to determine control voltage values, utilizing the control voltage values to amplify the designated signal (the designated signal being, for example, a signal having a received signal strength (RSSI) greater than a predetermined threshold) to obtain an amplified designated signal, and generating a resultant signal in view of the at least first amplified designated signal. The control voltage values are utilized to obtain at least one weighted difference. The at least one weighted difference is utilized to obtain an adjusted amplification of the at least one designated signal in accordance with a linear approximation.Type: GrantFiled: September 28, 1990Date of Patent: August 24, 1993Assignee: Motorola, Inc.Inventors: James Dejmek, Michael K. Alwine
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Patent number: 5184349Abstract: A receiver module 140 controls the amplitude of a random burst signal 200 in a TDMA system. A random burst signal 200 presence detector 330 detects when the random burst signal 200 has arrived during a timeslot reserved for the random access burst 200. After detection, a control processor monitors the signal strength or amplitude of the random access burst 200 for a predetermined time period, determines the amount of AGC attenuation required, and inserts the required AGC attenuation to control the amplitude of the random access burst 200 for the duration of the timeslot.Type: GrantFiled: August 21, 1992Date of Patent: February 2, 1993Assignee: Motorola, Inc.Inventor: Kenneth B. Riordan
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Patent number: 5152010Abstract: A radio receiver having a narrow effective beamwidth includes a receiver antenna, a receiver and a receiver transmission line interconnecting the two, and an interference cancellation system having an auxiliary antenna, a first directional coupler connected to the auxiliary antenna, a second directional coupler connected to the receiver transmission line, a synchronous detector connected to the first and second directional couplers, a signal controller and a subtractor connected to the signal controller and to the receiver transmission line. The receiver antenna is selected to exhibit an omni-directional antenna pattern, while the auxiliary antenna is selected to exhibit a null in its antenna pattern.Type: GrantFiled: December 29, 1989Date of Patent: September 29, 1992Assignee: American Nucleonics CorporationInventor: Ashok K. Talwar
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Patent number: 5136645Abstract: A phase locked loop utilizing digital techniques to control the closed loop bandwidth of the RF carrier phase locked loop in a receiver provides high sensitivity and a wide dynamic range for signal reception. After analog to digital conversion, a digital phase locked loop bandwidth controller provides phase error detection with automatic RF carrier closed loop tracking bandwidth control to accommodate several modes of transmission.Type: GrantFiled: July 9, 1990Date of Patent: August 4, 1992Inventor: Milton H. Brockman
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Patent number: 5134631Abstract: A novel programmable digital gain controller is provided for the automatic gain control loop of a communications receiver. The digital gain controller comprises a pair of digital detectors coupled to the real and imaginary components of a data stream for providing digital data magnitude output signals which are coupled to an adder whose output is coupled to a first input of a comparator having a second input coupled to a predetermined reference level command. The output of the comparator generates a digital error signal which is coupled to the input of a programmable gain accumulator having a second input proportional gain command so as to provide at the output of the programmable gain accumulator a digital gain command which may be coupled to a variable gain controlled amplifier which is connected in the input data stream of the channel of a communications receiver to provide a predetermine amplifier output level.Type: GrantFiled: July 26, 1990Date of Patent: July 28, 1992Assignee: Unisys Corp.Inventors: Samuel C. Kingston, Steven T. Barham, Harold L. Simonsen
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Patent number: 4956864Abstract: A receiver utilizing a plurality of small paraboloid antennas in lieu of a single large antenna of equal area, each antenna connected to a separate phase coherent heterodyne receiver channel includes a main channel and branch channels, the channels being summed to provide a carrier phase locked loop local oscillator signal that is distributed to all channels producing phase coherent IF signals in all the channels. These are summed to enhance the carrier margin or dB from the sensitivity threshold, of the system combining the receiver channels, to a level greater than that of the single antenna of equivalent area with its single receiver. The tendency toward cycle slipping near threshold is further reduced by providing summed additional amplified uncorrelated predetection receiver noise in the IFs of the branch receiver coupled to the main receiver.Type: GrantFiled: July 17, 1987Date of Patent: September 11, 1990Inventor: Milton H. Brockman
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Patent number: 4756023Abstract: A diversity reception radio receiver has a two-receiver system incorporating first and second receivers. A wave envelope detector is provided for each receiver to generate an output voltage corresponding to the strength of the electromagnetic signal wave which is picked up by the receiver. A hysteresis comparator compares the outputs of the two wave envelope detectors and generates a switching control signal. A switching device responds to the switching control signal by selecting between the signals which are repoduced by the first and second receivers. Because the amount of hysteresis in the comparator is automatically adjusted in accord with the strength of the signal wave, there is a minimum of hunting between the outputs of the two receivers.Type: GrantFiled: July 16, 1986Date of Patent: July 5, 1988Assignee: NEC CorporationInventor: Tatsuru Kojima
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Patent number: 4742563Abstract: A diversity reception of signals involves first and second mobile receivers which recover first and second baseband signals. The first and second receivers have first and second wave detectors, respectively, for generating output voltages corresponding to the strength of an FM modulated signal. When the difference in output voltages between the first and second detectors exceeds a predetermined value, a comparator gives an output detection signal. An adder circuit combines the first and second recovered baseband signals. First and second switching circuits selectively cut off the lower level one of the first or second recovered signal, which is then being supplied to the adder circuit. A third switching circuit adjusts the gain of the adder circuit. When the comparator does not give an output detection signal, the first and second switching circuits feed both the first and second recovered baseband signals to the adder circuit.Type: GrantFiled: June 3, 1986Date of Patent: May 3, 1988Assignee: NEC CorporationInventor: Yukio Fukumura
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Patent number: 4641141Abstract: Improved gain control in a multiplexed adaptive array processor having main and a reference channel receiver is achieved by means of an AGC circuit controlling the gain of the reference channel receiver over its dynamic range, an AGC circuit slaved to the reference channel receiver AGC circuit controlling the main channel receiver, and a separate AGC circuit controlling the output of the main channel receiver.Type: GrantFiled: May 2, 1984Date of Patent: February 3, 1987Assignee: The United States of America as represented by the Secretary of the Air ForceInventor: Raymond J. Masak
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Patent number: 4591940Abstract: A signal quality monitor, and a protective relay system using the monitor, which utilizes both AC and DC signals from the receiver agc stage to monitor a plurality of different signal parameters. A signal responsive to the noise in the communication channel which transmits at least one of the protective relay signals used in a protective relay comparison function, is also used in the trip circuits of the associated circuit interrupter to continuously adapt or modify the trip level in response to channel noise.Type: GrantFiled: December 17, 1984Date of Patent: May 27, 1986Assignee: Westinghouse Electric Corp.Inventors: Shan C. Sun, James P. McGivern
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Patent number: 4553105Abstract: A multistage amplifier with a low noise figure linearly amplifies an input signal having a level which varies over a wide range. The first stage of the amplifier provides a low noise figure and sufficient power gain to ensure overall low noise performance. An interstage amplifier is protected from saturation by first and second variable attenuators, which are controlled by a level detector. The level detector detects the level of the input or output signal of the interstage amplifier and controls the forward bias current of a diode in each of the variable attenuators. The first variable attenuator functions as a level compressor for signals input to the interstage amplifier having a level higher than a preset level. The second variable attenuator functions as a level expander of the output signal from the interstage amplifier to equalize the signal level compressed by the first variable attenuator.Type: GrantFiled: January 30, 1984Date of Patent: November 12, 1985Assignee: Fujitsu LimitedInventor: Susumu Sasaki
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Patent number: 4349914Abstract: A bit synchronous switching system is disclosed which has applicability in a space diversity system of digital telecommunications. Two versions of a signal waveform are received at two remote locations from the same signal source. The end user is able always to receive the more intelligible signal by means of instantaneous switching logic. An acquisition and tracking circuit, which can include a delay lock loop, keeps the two signal streams synchronized. One data stream is used as a reference and the time delay of the other is varied so that the time differential between the two streams is tracked out. The system features continuous tracking and does not require any frame synchronization to be superimposed on the data stream.Type: GrantFiled: April 1, 1980Date of Patent: September 14, 1982Assignee: Ford Aerospace & Communications Corp.Inventor: Randall G. Evans
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Patent number: 4347627Abstract: A processing circuit (50) in a communication system performs multi-channel adaptive array processing using a summed reference technique. A plurality of adaptive modules (56 and 58) modify the magnitude and phase of antenna element signals from a plurality of antenna elements. The outputs of the adaptive modules are combined by a combiner (60) to produce a summation signal. A modem (64) processes and divides the summation signal into a plurality of reference channel signals on channels 1 through K. A summer (70) adds the reference channel signals together to produce a composite reference signal that is subtracted by a subtractor (74) from the summation signal to produce an error signal. The error signal is applied to the adaptive modules (56 and 58) which respond to nullify interfering and noise signals and to enhance the signal-to-interference ratio for the summation signal.Type: GrantFiled: February 26, 1979Date of Patent: August 31, 1982Assignee: E-Systems, Inc.Inventor: Larry D. Alter