Noise Reduction Or Compensation Patents (Class 329/353)
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Patent number: 11181409Abstract: A monitoring and control system for a flow duct and a method for determining a component status of an operational component disposed within a flow passage of the flow duct utilizing the system are provided. In one exemplary aspect, the system includes at least two sensors that are disposed within the flow passage and configured to sense a characteristic of a fluid flowing therethrough. The sensors may be averaging sensors. Each sensor extends circumferentially about an axial centerline defined by the flow duct. The sensors are arranged in an overlapped arrangement. Particularly, the sensors extend circumferentially about the axial centerline such that the sensors physically overlap one another circumferentially. Additionally, the sensors may be disposed within the same or substantially the same plane axially. Signals generated by the sensors may be utilized to monitor and control the fluid and various operational components disposed within the flow passage.Type: GrantFiled: August 9, 2018Date of Patent: November 23, 2021Assignee: General Electric CompanyInventors: James Ryan Reepmeyer, Gagan Adibhatla
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Patent number: 10222779Abstract: A semiconductor wafer position display system, a semiconductor wafer position display method, and a semiconductor wafer position display program with which a deviation from an appropriate placement position of a semiconductor wafer mounted in a wafer mounting part can be displayed to a user in an easily understood manner are provided.Type: GrantFiled: March 12, 2015Date of Patent: March 5, 2019Assignee: Epicrew CorporationInventors: Akira Okabe, Masanori Tanoguchi
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Patent number: 9363119Abstract: A method of FSK decoding includes generating a pulse waveform (R'Edge) from a received FSK encoded signal (FSK signal) and a system clock (Sys_clk). From R'Edge and Sys_clk clocks are generated including a first clock and second clock framing a logic ‘0’ level of the FSK signal, and a third clock and fourth clock framing a logic ‘1’ level of the FSK signal. At least four frequency envelopes are generated from the clocks including a logic ‘0’ envelope, a logic ‘1’ envelope, a lower frequency envelope below the logic ‘0’ envelope, and an upper frequency envelope above the logic ‘1’ envelope. R'Edge is compared to the four envelopes, and a decoded output is produced, logic ‘0’ if the R'Edge overlaps the logic ‘0’ envelope, logic ‘1’ if R'Edge overlaps the logic ‘1’ envelope, and a previous output state if R'Edge does not overlap the logic ‘0’ or logic ‘1’ envelope.Type: GrantFiled: July 29, 2015Date of Patent: June 7, 2016Assignee: Honeywell International Inc.Inventors: Balakrishna G. Gudi, Dinesh Kumar Kn, Aravind Sathyanarayana, Sandeep Pai
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Patent number: 9042501Abstract: A receiving circuit, use, and method for receiving an encoded and modulated radio signal is provided. The circuit comprise a demodulator and a digital filter connected downstream of the demodulator for moving averaging. The filter has at least two FIFO registers and subtractors. Whereby for subtracting an output value of the FIFO register from an input value of the FIFO register a subtractor is connected to each FIFO register. Wherein the filter has a weighting unit, which is connected downstream of each FIFO register, and wherein the filter has an integrator, which is connected downstream of the subtractors for integration.Type: GrantFiled: November 14, 2013Date of Patent: May 26, 2015Assignee: Atmel CorporationInventor: Ulrich Grosskinsky
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Patent number: 9036742Abstract: A demapping scheme, having a low computational cost, suitable for any transmission in which only exhaustive demapping can guarantee good performance. The scheme, proposed in this document, can be used in any transmission based on no differential modulation. For example the proposed scheme can be directly applied to a transmission on flat fading AWGN channels or to a transmission on frequency selective channels after equalization or on each sub-carrier of an OFDM System. The proposed solution can be applied for the demapping of any communication system. The proposed scheme can be used for rotated and un-rotated constellation.Type: GrantFiled: March 15, 2012Date of Patent: May 19, 2015Assignee: ALi Europe SarlInventors: Matteo Butussi, Stefano Tomasin
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Patent number: 8884691Abstract: Disclosed herein is a demodulator, including: a splitting/matching section for carrying out a matching process of making the amplitude and phase of a first modulated signal match respectively the amplitude and phase of a second modulated signal; and a demodulation section for generating a demodulated signal on the basis of the first modulated signal and the second modulated signal, which have been subjected to the matching process carried out by the splitting/matching section, wherein the splitting/matching section has a splitting section, a first matching section, and a second matching section, the first circuit-element constants determining the first input impedance of the first matching section and the second circuit-element constants determining the second input impedance of the second matching section are set at values determined in advance in order to make the first input impedance equal to the second input impedance.Type: GrantFiled: January 23, 2012Date of Patent: November 11, 2014Assignee: Sony CorporationInventor: Katsuhisa Ito
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Patent number: 8831147Abstract: A desired signal and interfering signal are transmitted in the same timeslot and on the same frequency using an Adaptive Quadrature Phase Shift Keying (AQPSK) modulated carrier. When the Sub-Channel Power Imbalance Ratio (SCPIR) for the AQPSK modulated carrier is large and favors the interfering signal, the interfering signal is demodulated first to obtain demodulated soft bits. The demodulated soft bits corresponding to the interfering signal are then used to estimate receiver control parameters, such as Doppler shift, frequency offset, timing error, gain, etc. Using the demodulated soft bits corresponding to the interfering signal improves the accuracy of the receiver control parameters when the SCPIR is large, and results in better overall performance of the receiver.Type: GrantFiled: March 11, 2013Date of Patent: September 9, 2014Assignee: Telefonaktiebolaget L M Ericsson (Publ)Inventors: Naveen Jacob, Amit Singhal
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Patent number: 8804791Abstract: A communication device according to an embodiment of the present invention includes a communication antenna that receives a transmission signal where a spectrum spread signal subjected to a spectrum spread is modulated; an intermediate frequency converting unit that converts the transmission signal received by the communication antenna into an intermediate frequency signal having a predetermined frequency; an analog to digital converting unit that discretizes the intermediate frequency signal and outputs a discretization signal; a noise removing unit that detects a noise other than a normal thermal noise included in the discretization signal and removes the detected noise from the discretization signal; and a demodulating unit that demodulates the spectrum spread signal, based on the discretization signal that is output from the noise removing unit.Type: GrantFiled: July 15, 2013Date of Patent: August 12, 2014Assignee: Sony CorporationInventors: Katsuyuki Tanaka, Hideki Takahashi
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Patent number: 8625723Abstract: A method and apparatus for performing demapping in a wireless communication system utilizing a modulo operation are disclosed. The demapping method of a receiver in a wireless communication system includes receiving an input signal and first information indicating whether a first modulo operation is performed on the input signal from a transmitter; if the first information indicates execution of the first modulo operation, performing a second modulo operation of the input signal, and acquiring a reception signal; generating a maximum function value having a highest probability that the reception signal corresponds to a candidate constellation point of an extended constellation; and generating a log-likelihood ratio (LLR) using the generated maximum function value.Type: GrantFiled: March 2, 2012Date of Patent: January 7, 2014Assignee: LG Electronics Inc.Inventors: Wookbong Lee, Inuk Jung, Jinsam Kwak, Kiseon Ryu
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Patent number: 8594259Abstract: A receiving circuit, use, and method for receiving an encoded and modulated radio signal is provided. The circuit comprise a demodulator and a digital filter connected downstream of the demodulator for moving averaging. The filter has at least two FIFO registers and subtractors. Whereby for subtracting an output value of the FIFO register from an input value of the FIFO register a subtractor is connected to each FIFO register. Wherein the filter has a weighting unit, which is connected downstream of each FIFO register, and wherein the filter has an integrator, which is connected downstream of the subtractors for integration.Type: GrantFiled: February 19, 2010Date of Patent: November 26, 2013Assignee: Atmel CorporationInventor: Ulrich Grosskinsky
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Patent number: 8542777Abstract: An amplitude modulation (AM) demodulating circuit applied to a radio frequency identification (RFID) system attenuates carrier signals by a notch filter to increase a signal-to-carrier ratio and to reduce complexity and cost of circuit design. The AM demodulating circuit includes an envelope detector, a notch filter, a low-pass filter, and a comparing circuit. The envelope detector performs envelope detection on an AM signal modulated by a carrier frequency to generate an envelope signal. The notch filter filters the envelope signal to generate a first filtered signal, and a zero point of the notch filter corresponds to the carrier frequency of the AM signal. The low-pass filter filters the first filtered signal to generate a second filtered signal, and the carrier frequency of the AM signal corresponds to a stop band of the low-pass filter. The comparing circuit converts the second filtered signal to a digital signal according to a level value.Type: GrantFiled: January 6, 2011Date of Patent: September 24, 2013Assignee: MStar Semiconductor, Inc.Inventor: Chien-Shan Chiang
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Patent number: 8503510Abstract: A communication device according to an embodiment of the present invention includes a communication antenna that receives a transmission signal where a spectrum spread signal subjected to a spectrum spread is modulated; an intermediate frequency converting unit that converts the transmission signal received by the communication antenna into an intermediate frequency signal having a predetermined frequency; an analog to digital converting unit that discretizes the intermediate frequency signal and outputs a discretization signal; a noise removing unit that detects a noise other than a normal thermal noise included in the discretization signal and removes the detected noise from the discretization signal; and a demodulating unit that demodulates the spectrum spread signal, based on the discretization signal that is output from the noise removing unit.Type: GrantFiled: July 18, 2012Date of Patent: August 6, 2013Assignee: Sony CorporationInventors: Katsuyuki Tanaka, Hideki Takahashi
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Patent number: 8472571Abstract: Direct detection of wireless interferers in a communication device for multiple modulation types. One or more radios implemented within a communication device is/are operative to receive and process wireless communications. A wireless communication signal is processed to extract symbols there from. Various symbols groups are processed in accordance with correlation processing to identify potential interferers (e.g., other communication devices using common portions of frequency spectra). Alternatively, matched filter processing (e.g., using a Barker matched filter in some embodiments) operates on the various symbol groups to identify some potential interferers. Various combinations of correlation processing and matched filter processing may be employed in other instances (e.g., using any of a desired means of comparison, combining, etc.) in considering interferers identified in accordance with each of these two means.Type: GrantFiled: July 23, 2012Date of Patent: June 25, 2013Assignee: Broadcom CorporationInventor: Prasanna Desai
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Patent number: 8462894Abstract: In a receiver circuit, an analog signal processor frequency-converts an input high frequency signal into a baseband signal, and performs low pass filtering at a cutoff frequency below a desired-wave band. An ADC converts an output of the analog signal processor into a digital signal. A digital signal processor compensates an output of the ADC for a signal component in the desired-wave band which has been attenuated by the filtering operation of the analog signal processor.Type: GrantFiled: October 14, 2011Date of Patent: June 11, 2013Assignee: Panasonic CorporationInventors: Yoshifumi Hosokawa, George Hayashi, Ippei Kanno
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Patent number: 8284869Abstract: A method of demodulating a signal on which is modulated, using a quadrature amplitude modulation scheme, a plurality of information symbols, the method including: determining at least one QAM detection threshold corresponding to one or more of said information symbols; and demodulating each information symbol on the basis of at least one respective QAM detection threshold.Type: GrantFiled: December 12, 2007Date of Patent: October 9, 2012Assignee: NEC CorporationInventors: Xinhua Wang, Nikolay Vaptzarov, Shikand Satheesh
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Patent number: 8270546Abstract: In a transmission diversity control method in which a request to start or stop transmission diversity is issued by a reception station to a transmission station having a transmission diversity function, the reception station is provided with an equalizer to reduce multipath interference on the basis of a signal correlation, a transmission diversity start request is issued from the reception station to the transmission station when an effect generated by the equalizer is small, and a transmission diversity stop request is issued from the reception station to the transmission station when the effect generated by the equalizer is large.Type: GrantFiled: February 18, 2010Date of Patent: September 18, 2012Assignee: Fujitsu LimitedInventors: Yasumitsu Ban, Akira Ito
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Patent number: 8254484Abstract: A method of Dirty Paper Coding DPC using nested lattices is disclosed. The complexity of DPC can be reduced by scaling nested lattices and mapping interference to a lattice point of the scaled lattice.Type: GrantFiled: January 13, 2010Date of Patent: August 28, 2012Assignees: Samsung Electronics Co., Ltd., The Board of Regents of the University of Texas SystemInventors: Sung Hwan Kim, Song Soo Hwang, Sang Boh Yun, Sang Hyun Lee, Sung Yoon Jung, Sriram Viswanath
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Patent number: 8254502Abstract: The present patent application discloses a method and apparatus for decoding, comprising decoding signals iteratively, mutually exchanging extrinsic information, calculating APP LLRs for both systematic and parity bits and making a hard decision after a plurality of iterations is completed based on accumulated soft information. The present patent application also discloses a method and apparatus for post decoding soft interference canceling, comprising generating updated a posteriori probabilities for systematic and parity bits from a turbo decoder, mapping the posteriori probabilities to soft symbols, quantizing the soft symbols, re-encoding a data packet, filtering a chip sequence, reconstructing an interference waveform, and scaling reconstruction filter coefficients using the symbols.Type: GrantFiled: June 18, 2009Date of Patent: August 28, 2012Assignee: QUALCOMM IncorporatedInventors: Sharad D. Sambhwani, Wei Zeng, Wei Zhang, Jan K Wegrzyn, Mehraban Iraninejad
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Patent number: 8249203Abstract: Methods and systems are described for processing a signal in wireless communications. The signal may have synchronization information. A method of processing a signal having synchronization information may include receiving the signal, and determining a truncation region of the time domain estimated channel, the estimated channel having taps. The method further includes processing the channel taps within the truncation region.Type: GrantFiled: September 22, 2008Date of Patent: August 21, 2012Assignee: QUALCOMM IncorporatedInventors: Thomas Sun, Raghuraman Krishnamoorthi, Fuyun Ling, Krishna Kiran Mukkavilli, Tao Tian, Bojan Vrcelj
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Patent number: 8243776Abstract: A communication device according to an embodiment of the present invention includes a communication antenna that receives a transmission signal where a spectrum spread signal subjected to a spectrum spread is modulated; an intermediate frequency converting unit that converts the transmission signal received by the communication antenna into an intermediate frequency signal having a predetermined frequency; an analog to digital converting unit that discretizes the intermediate frequency signal and outputs a discretization signal; a noise removing unit that detects a noise other than a normal thermal noise included in the discretization signal and removes the detected noise from the discretization signal; and a demodulating unit that demodulates the spectrum spread signal, based on the discretization signal that is output from the noise removing unit.Type: GrantFiled: February 25, 2009Date of Patent: August 14, 2012Assignee: Sony CorporationInventors: Katsuyuki Tanaka, Hideki Takahashi
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Patent number: 8229041Abstract: Direct detection of wireless interferers in a communication device for multiple modulation types. One or more radios implemented within a communication device is/are operative to receive and process wireless communications. A wireless communication signal is processed to extract symbols there from. Various symbols groups are processed in accordance with correlation processing to identify potential interferers (e.g., other communication devices using common portions of frequency spectra). Alternatively, matched filter processing (e.g., using a Barker matched filter in some embodiments) operates on the various symbol groups to identify some potential interferers. Various combinations of correlation processing and matched filter processing may be employed in other instances (e.g., using any of a desired means of comparison, combining, etc.) in considering interferers identified in accordance with each of these two means.Type: GrantFiled: January 8, 2010Date of Patent: July 24, 2012Assignee: Broadcom CorporationInventor: Prasanna Desai
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Patent number: 8223907Abstract: A method for deriving interference signals from modulated, digital signals is provided. The receiver end reconstructs the modulated digital signals sent by a transmitter. These reconstructed modulated digital signals are then subtracted from the received modulated digital signals, and the result of the subtraction is used to estimate the interference signals without influence by prior filtering at the receiver end. By way of example, it is possible to demodulate the interference signals estimated at the receiver end in order to ascertain possible unauthorized carrier frequencies which disturb the regular carrier frequencies, even if the interference signals are not completely in the bandwidth of the regular carrier frequency or carrier frequencies.Type: GrantFiled: September 28, 2006Date of Patent: July 17, 2012Assignee: Siemens AG ÖsterreichInventor: Lukas Pauk
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Patent number: 8218687Abstract: A receiver estimates I/Q imbalance in I and Q input signals using circuitry to separate different frequency components of the I and Q input signals, and estimation circuitry arranged to estimate I/Q imbalance at the different frequency bands. The separating of the bands may be carried out in the frequency domain, and may involve combining corresponding values representing corresponding negative and positive frequency bands, and converting the separated frequency domain representations to a time domain representation before the estimation. The estimated imbalance may be used to correct the I and Q signals at the different frequency bands.Type: GrantFiled: February 27, 2009Date of Patent: July 10, 2012Assignee: ST-Ericsson SAInventor: Anthony D. Sayers
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Publication number: 20120119827Abstract: Disclosed herein is a demodulator, including: a splitting/matching section for carrying out a matching process of making the amplitude and phase of a first modulated signal match respectively the amplitude and phase of a second modulated signal; and a demodulation section for generating a demodulated signal on the basis of the first modulated signal and the second modulated signal, which have been subjected to the matching process carried out by the splitting/matching section, wherein the splitting/matching section has a splitting section, a first matching section, and a second matching section, the first circuit-element constants determining the first input impedance of the first matching section and the second circuit-element constants determining the second input impedance of the second matching section are set at values determined in advance in order to make the first input impedance equal to the second input impedance.Type: ApplicationFiled: January 23, 2012Publication date: May 17, 2012Applicant: Sony CorporationInventor: Katsuhisa Ito
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Patent number: 8120420Abstract: Disclosed herein is a demodulator, including: a splitting/matching section for carrying out a matching process of making the amplitude and phase of a first modulated signal match respectively the amplitude and phase of a second modulated signal; and a demodulation section for generating a demodulated signal on the basis of the first modulated signal and the second modulated signal, which have been subjected to the matching process carried out by the splitting/matching section, wherein the splitting/matching section has a splitting section, a first matching section, and a second matching section, the first circuit-element constants determining the first input impedance of the first matching section and the second circuit-element constants determining the second input impedance of the second matching section are set at values determined in advance in order to make the first input impedance equal to the second input impedance.Type: GrantFiled: July 27, 2010Date of Patent: February 21, 2012Assignee: Sony CorporationInventor: Katsuhisa Ito
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Patent number: 7994852Abstract: An electronic circuit includes: a circuit generating first and second balanced differential input signals; a first envelope detection circuit including a first output terminal and first and second input terminals receiving the first and second input signals, respectively, via first and second impedance elements, respectively, and outputs from the first output terminal a first output signal that is the sum of the squares of the first and second input signals; a second envelope detection circuit including a second output terminal and third and fourth input terminals receiving the first and second input signals, respectively, via third and fourth impedance elements, respectively, and outputs from the second output terminal a second output signal that is twice the value obtained by squaring the average of the first and second input signals; and a differential circuit generating a differential signal from the first and second output signals.Type: GrantFiled: November 17, 2009Date of Patent: August 9, 2011Assignee: Seiko Epson CorporationInventor: Masayuki Ikeda
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Patent number: 7932775Abstract: A digital demodulation device for demodulating an amplitude modulation (AM) signal whose carrier has a first frequency includes: a processing circuit for performing first path digital processing and second path digital processing according to a second frequency and digital values of the AM signal, where the first path digital processing represents performing down conversion by mixing the AM signal with a first sinusoidal signal whose frequency is equal to the second frequency, the second path digital processing represents performing down conversion by mixing the AM signal with a second sinusoidal signal whose frequency is equal to the second frequency, the second frequency is equal to the first frequency plus a predetermined frequency shift, and the second sinusoidal signal is orthogonal to the first sinusoidal signal; and an output stage for outputting an output signal according to processing results of the first path digital processing and the second path digital processing.Type: GrantFiled: February 5, 2009Date of Patent: April 26, 2011Assignee: Mediatek Inc.Inventor: Yu-Chi Chang
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Patent number: 7907006Abstract: According to one embodiment, a threshold adjusting apparatus for a clocked comparator, the clocked comparator comparing an input signal with a threshold in accordance with a clock, the threshold adjusting apparatus comprises an output detection module configured to detect an output from the clocked comparator with the threshold while changing the threshold and a setting module configured to set the threshold when the output detection module detects a change in the output from the clocked comparator as an adjusted threshold.Type: GrantFiled: March 6, 2009Date of Patent: March 15, 2011Assignee: Kabushiki Kaisha ToshibaInventors: Shigeyasu Iwata, Toshifumi Yamamoto, Takashi Minemura, Toshiyuki Umeda
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Patent number: 7864879Abstract: A system having a signal processor for detection of a signal type of a signal is disclosed. One embodiment includes a processor designed to determine a first variable which is characteristic of a first spectrum element of the signal spectrum, and to determine a second variable which is characteristic of a second spectrum element of the signal spectrum. A system is provided for determination of a ratio between the first variable and the second variable, and a detector which is designed to detect the signal type on the basis of the ratio.Type: GrantFiled: February 15, 2007Date of Patent: January 4, 2011Assignee: Infineon Technologies AGInventors: Xiaofeng Wu, Martin Krueger
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Patent number: 7724836Abstract: In order to compensate for a frequency offset or a change in the phase of the transmission channel over time during mobile radio transmission of data symbols, the data symbols are transmitted by way of carrier-frequency, modulated data bursts. Sample values of the received signal, which are known in advance and correspond to first and second symbols, are evaluated in order to estimate the frequency offset or the change in the phase of the transmission channel over time. These first and second symbols are transmitted with a defined phase angle by way of the data burst, and are arranged separated from one another in the data burst. Edge symbols in a data burst are advantageously used as first and second symbols, or as a symbol pair, for estimation.Type: GrantFiled: September 7, 2004Date of Patent: May 25, 2010Assignee: Infineon Technologies AGInventors: Ralf Hartmann, Martin Krüger, Hartmut Wilhelm
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Patent number: 7623990Abstract: A system for reducing signal interference in modulated signal communication includes a measurement processor. The measurement processor measures amplitudes of noise components of a received amplitude modulated signal prior to demodulation. The measurement processor also identifies a frequency of a noise component having an amplitude larger than the amplitude of another noise component. A carrier frequency generator generates a carrier frequency substantially at a harmonic of the identified noise component. The carrier frequency is used to generate and demodulate the amplitude modulated signal.Type: GrantFiled: November 3, 2005Date of Patent: November 24, 2009Assignee: Draeger Medical Systems, Inc.Inventors: Ralph Anderson, Michael Bernstein
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Patent number: 7184487Abstract: A receiver (202) has a down-conversion receiver (304) for transforming a signal (201) from a first operating frequency to a second operating frequency that is lower than the first operating frequency, and a receiver filter (308) with chopper stabilization for filtering unwanted portions of the signal (306) at the second operating frequency and for generating a final filtered signal (203) at the second operating frequency.Type: GrantFiled: December 21, 2004Date of Patent: February 27, 2007Assignee: Motorola, Inc.Inventors: Jerry T. Bolton, Jr., Joseph P. Heck
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Patent number: 6861901Abstract: A voltage follower comprising a first field-effect transistor (MN1) whose gate forms the input of the voltage follower. Further provided is a second field-effect transistor (MN2) whose drain connected to the gate forms the output of the voltage follower. The sources of the two field-effect transistors (MN1, MN2) are connected to each other and to the drain of a third field-effect transistor (MN3) serving as current source and to the gate of which a predefined bias voltage is applied. The invention employs in addition a fourth field-effect transistor (MN4) whose source-drain path is circuited between the output of the voltage follower and the drain of the third field-effect transistor (MN3) and whose gate is connected to the gate of the third field-effect transistor (MN3). As compared to prior art voltage followers the voltage follower in accordance with the invention comprises a wider voltage range in which it can be put to use. This can be made use of e.g.Type: GrantFiled: June 12, 2003Date of Patent: March 1, 2005Assignee: Texas Instruments Deutschland, GmbHInventors: Franz Prexl, Wolfgang Steinhagen, Ralph Oberhuber
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Patent number: 6751264Abstract: Embodiments of the present invention relate generally to receivers. One embodiment relates to a digital FM receiver having multiple sensors (e.g. antennas). In one embodiment, the digital receiver includes a baseband unit having a channel processing unit. In one embodiment, the channel processing unit is capable of calculating or estimating a phase difference between the incoming signals prior to combining them. One embodiment uses phase estimation method for diversity combining the signals while another embodiment utlizes a hybrid phase lock loop method. Also, some embodiments of the present invention provide for echo-cancelling after diversity combining. An alternate embodiment of the channel processing unit utilizes a space-time unit to diversity combine and provide echo cancelling for the incoming signals.Type: GrantFiled: July 27, 2001Date of Patent: June 15, 2004Assignee: Motorola, Inc.Inventors: Yui-Luen Ho, Junsong Li, Azfar Inayatullah
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Patent number: 6590932Abstract: Methods, systems and receiver devices are provided which may reduce the average power of a signal disturbance by whitening the signal disturbance. In one aspect, a finite impulse response filter (FIR) is provided which whitens the signal disturbance by filtering a downsampled received signal using filter coefficients adaptively established using known signal information in each signal burst of the received signal. Alternatively, a noise-whitening equalizer is utilized having a modified metric that whitens the signal disturbance again using coefficients adaptively established using known signal information in each signal burst of the received signal. The noise-whitening equalizer approach further allows the noise-whitening coefficients to be updated by treating symbol estimates from the equalizer as known signal information to generate updated noise-whitening coefficients. A novel receiver containing a modified Euclidean metric equalizer to provide noise-whitening is also provided.Type: GrantFiled: November 24, 1999Date of Patent: July 8, 2003Assignee: Ericsson Inc.Inventors: Dennis Hui, Kambiz C. Zangi, Rajaram Ramesh
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Patent number: 6577182Abstract: A device for demodulating a modulated signal resulting from an amplitude modulation of a sinusoidal signal of frequency fo by a signal of frequency fm according to an unknown modulation rate, comprising a transistor (10) where the gate is connected to the modulated signal (Et) so as to obtain in the transistor (10) output a derived signal (St) equal to a power N of the modulated signal, N being an integer greater than 1, and a filter for selecting the frequency component fm in the transistor output signal. The device can be used to demodulate an amplitude-modulated signal received by a scanner of a system identifying contactless portable objects.Type: GrantFiled: August 27, 2001Date of Patent: June 10, 2003Assignee: Ask S.A.Inventor: Sébastien Morand
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Patent number: 6442218Abstract: The present invention relates to a demodulator which receives a signal transmitted via phase modulation or multivalue QAM modulation, and decides transmitted data based on the received signal. The present invention enhances a transmission-line estimate by using tentatively decided data symbols as pilot symbols and in estimating a transmission line without a decrease in accuracy of transmission-line estimate even when an error rate of the tentatively decided data symbols is increased. The demodulator includes a pilot-based transmission-line estimation unit for estimating transmission-line characteristics by using pilot symbols. A tentative-data-decision unit for tentatively deciding data symbols based on the pilot-based transmission-line estimate. A data-based transmission-line estimation unit for estimating the transmission-line characteristics by using the tentatively decided data.Type: GrantFiled: August 19, 1999Date of Patent: August 27, 2002Assignee: Fujitsu LimitedInventors: Michiharu Nakamura, Yasuyuki Oishi, Kazuo Nagatani, Hajime Hamada, Yoshihiko Asano, Hiroyuki Seki, Yoshinori Tanaka
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Patent number: 6400778Abstract: A DC-offset canceller in a receiver of a communication system using a burst signal including a training sequence with a predetermined periodicity at the head thereof is disclosed. In the canceller, a quadrature demodulator 112 converts the received burst signal to a base band signal. An AD converter 113 converts an output signal of the quadrature demodulator to a digital signal. A one-cycle delay element 114 makes a delay of an output signal of the AD converter 113 corresponding to one-cycle of the training sequence. A DC-offset detector 115 detects a DC-offset component in the converted signal by the AD converter 113 on the basis of an output signal of the AD converter 113 and an output signal of the one-cycle delay element 114. A subtractor 116 removes the DC-offset component detected by the DC-offset detector 115 from the output signal of the AD converter 113.Type: GrantFiled: December 4, 1998Date of Patent: June 4, 2002Assignee: NEC CorporationInventor: Hitosi Matui
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Patent number: 6075409Abstract: A method for demodulating a radio frequency signal having a frequency, by oscillating a demodulator at a frequency different from the signal frequency, and measuring a DC offset value at this different frequency, the DC offset value being associated with interference. Then the demodulator is oscillated at the signal, thereby providing a demodulated signal. The DC offset value is subtracted from the demodulated signal in order to provide a demodulated signal with a substantially reduced DC component. The demodulated signal is then monitored for further DC offset components, and these further DC offset components are subtracted from the demodulated signal.Type: GrantFiled: April 1, 1999Date of Patent: June 13, 2000Assignee: Motorola, Inc.Inventor: Nadim Khlat
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Patent number: 5535248Abstract: A digital radio communication system includes a first demodulator, a second demodulator, a non-break switch, and a switching controller. The first demodulator receives a signal from a first antenna and outputs demodulated data and a line quality degradation signal. The second demodulator receives a signal from a second antenna and outputs demodulated data and a line quality degradation signal. The non-break switch receives the demodulated data output from the first and second demodulators and selects and outputs one of the demodulated data. The switching controller receives line quality degradation signals output from the first and second demodulators to output a switching control signal to the non-break switch on the basis of the received line quality degradation signals. The first and second demodulators output the line quality degradation signals before the demodulated data are set in an interrupt state when abrupt frequency selective fading occurs.Type: GrantFiled: December 23, 1994Date of Patent: July 9, 1996Assignee: NEC CorporationInventor: Yuzo Kurokami
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Patent number: 5442655Abstract: In receiving apparatus of a digital communication system, a received signal burst is demodulated to produce inphase (I) and quadrature (Q) baseband signals which are digitized to provide a set of signal-value pairs for the burst. Each pair consists of an I-value and a corresponding Q-value. The modulation is such that the pairs, if plotted on a complex signal space (I-Q) diagram, would lie substantially on a common circle. To cancel DC offsets in the I and Q signal paths, the average I-value and average Q-value over the burst are found and subtracted respectively from the I- and Q-values of each signal-value pair, to shift the circle so the origin of the I-Q diagram lies within the circle. Then, to restore the DC content of the I and Q signals, the distances I.sub.i1, Q.sub.i2, I.sub.i3 and Q.sub.i4 of signal-value pairs from the I- or Q-axis are averaged in four regions of the I-Q diagram.Type: GrantFiled: May 27, 1993Date of Patent: August 15, 1995Assignee: Fujitsu LimitedInventors: Ian J. Dedic, Dominic C. Royce
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Patent number: 5341106Abstract: There is described an electronic circuit which operates an Amplitude Locked Loop. The circuit comprises a voltage controlled amplifier, a modulus detector and an integrator combined in a feedback loop. An FM signal decoder is also described as are a number of applications of Amplitude Locked Loop.Type: GrantFiled: July 22, 1992Date of Patent: August 23, 1994Assignee: The Governors of Paisley College of TechnologyInventor: Archibald M. Pettigrew
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Patent number: 5260974Abstract: An improvement in an apparatus which uses a carrier detection threshold level for detecting a carrier signal modulated with binary data. The threshold level is dynamically changed and generally seeks a level above the background noise. The threshold level is maintained constant when the detected signal exceeds the threshold level. An evaluation circuit is able to examine the detected signal to determine whether it contains data or only noise, and if it contains only noise, a possible trapped condition is avoided by raising the threshold level to a level higher than the background noise.Type: GrantFiled: May 10, 1991Date of Patent: November 9, 1993Assignee: Echelon CorporationInventors: Howard W. Johnson, Chin-Chen Lee, Amy O. Hurlbut
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Patent number: 5157343Abstract: Electronic receive arrangement for receiving a modulated carrier signal, which arrangement comprises a mixer/demodulator driven with the carrier frequency fc, at least one adder included in a closed signal loop, a low-pass filter, and a pulse shaper constituted by a sigma-delta (one-bit) signal converter and driven with the sampling frequency fs and also comprises a digital decimation filter. The signal loop includes the mixer/demodulator so that the modulated carrier signal is applied to the adder and the output signal of the adder is applied to the mixer/demodulator. The signal loop also comprises a second mixer driven with frequency fc, and the frequencies fs and fc present a common multiple.Type: GrantFiled: May 31, 1991Date of Patent: October 20, 1992Assignee: U.S. Philips CorporationInventor: Johannes O. Voorman
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Patent number: 5097222Abstract: There is disclosed a system and method for demodulating an analog signal using digital conversion of the analog signal. In one embodiment the incoming modulated signal is digitally sampled and a calculation is made as to both the short term and long term energy of the digitized version of the analog signal. The deviation between the short and long term energy levels is used to determine the amount of modulation of the incoming analog signal. An analog demodulated signal is then reconstructed from the digitized deviation calculations. In an alternate embodiment, a digital signal processor is used to derive the demodulated signal.Type: GrantFiled: July 18, 1991Date of Patent: March 17, 1992Assignee: Texas Instruments IncorporatedInventor: Peter R. Dent