Patents by Inventor Larry E. Nielsen
Larry E. Nielsen has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 6647074Abstract: Circuits for removing clock related artifacts in an offset QAM generated VSB signal includes a transmitter arrangement and a receiver arrangement. In the transmitter, a detector detects the artifacts and a correlator determines whether the artifacts repeat over two symbols or over four symbols. A signal indicative of the artifacts is used to control processing circuits for adjusting the ratios and levels of the I and Q signal components of the QAM signal for substantially eliminating the artifacts. In the receiver, the received VSB signal is divided into four parallel signals. Each parallel signal is processed to develop an average symbol level that is subtracted before the parallel signals are recombined. The four symbol repeat rate artifacts reflect a DC offset of the VSB signal symbols, which are both positive-going and negative-going and which therefore average to zero for random signals. Averaging is done over N symbols where N is a power of 2.Type: GrantFiled: October 18, 2001Date of Patent: November 11, 2003Assignee: Zenith Electronics CorporationInventors: Richard W. Citta, Larry E. Nielsen
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Publication number: 20020034262Abstract: Circuits for removing clock related artifacts in an offset QAM generated VSB signal includes a transmitter arrangement and a receiver arrangement. In the transmitter, a detector detects the artifacts and a correlator determines whether the artifacts repeat over two symbols or over four symbols. A signal indicative of the artifacts is used to control processing circuits for adjusting the ratios and levels of the I and Q signal components of the QAM signal for substantially eliminating the artifacts. In the receiver, the received VSB signal is divided into four parallel signals. Each parallel signal is processed to develop an average symbol level that is subtracted before the parallel signals are recombined. The four symbol repeat rate artifacts reflect a DC offset of the VSB signal symbols, which are both positive-going and negative-going and which therefore average to zero for random signals. Averaging is done over N symbols where N is a power of 2.Type: ApplicationFiled: October 18, 2001Publication date: March 21, 2002Applicant: Zenith Electronics CorporationInventors: Richard W. Citta, Larry E. Nielsen
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Patent number: 6166594Abstract: A reference signal source produces a substantially distortion free reference signal which is supplied to a demodulator that is arranged to demodulate the substantially distortion free reference signal. A calibration filter and an equalizer are included downstream of the demodulator. A controller sets the calibration filter to initially pass the reference signal to the equalizer without substantial change to the reference signal. The controller subsequently calibrates the calibration filter in accordance with the demodulator caused distortion reduced by the equalizer.Type: GrantFiled: September 1, 1999Date of Patent: December 26, 2000Assignee: Zenith Electronics CorporationInventors: Larry E. Nielsen, Gary J. Sgrignoli
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Patent number: 6052158Abstract: A digital television receiver includes a filter for minimizing NTSC interference with a received signal having a constant symbol rate. An equalizer has two one symbol delays for each tap. A filtered and a non-filtered version of the received signal are applied to a multiplexer at the input of the equalizer, which is operated at twice the symbol rate. The outputs of the multipliers in the equalizer are combined and applied to a demultiplexer. The filtered and non-filtered equalized signals are compared and a selection as to which of the filtered or non-filtered received signals is to be processed is made based upon the comparison.Type: GrantFiled: April 24, 1998Date of Patent: April 18, 2000Assignee: Zenith Electronics CorporationInventor: Larry E. Nielsen
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Patent number: 5821988Abstract: A digital television receiver operating in the presence of an NTSC co-channel signal includes an NTSC rejection filter that is selectively inserted in the digital television signal path to minimize interference from the NTSC co-channel signal. The energy around the NTSC picture carrier is sampled. This is compared with sampled white noise energy between the NTSC picture and color carriers, after field combing the digital television signal to eliminate the effects of static signals. The comparison is used to determine whether or not the NTSC rejection filter is inserted in the digital television signal path.Type: GrantFiled: December 19, 1995Date of Patent: October 13, 1998Assignee: Zenith Electronics CorporationInventors: Richard W. Citta, Larry E. Nielsen, Gary J. Sgrignoli
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Patent number: 5692010Abstract: A digital receiver receives a multi level symbol signal that includes a frame sync. An equalizer is supplied with the signal and corrects for errors that are determined to exist therein on the basis of comparing the frame sync with a known value thereof or comparing the average level of the multi level symbols to an estimated (known) value thereof. A threshold circuit is included for rejecting impulse noise in the error signal that exceeds a threshold level that is higher than the maximum symbol level in the symbol.Type: GrantFiled: January 17, 1996Date of Patent: November 25, 1997Assignee: Zenith Electronics CorporationInventor: Larry E. Nielsen
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Patent number: 5684827Abstract: An adaptive equalizer decision circuit for a digital television signal, including a field synchronizing signal, consisting of multilevel symbols and a DC offset representing a pilot. The variation of the DC level of the received signal during the field sync with respect to a predetermined threshold is derived for placing the equalizer in a training signal or data directed operating mode. Another approach determines the difference between a current value of the field sync and each of a plurality of values of the field sync in previous fields and determining therefrom whether the equalizer should be in its data directed mode of operation or in its training signal mode of operation. A modification consists in controlling the step size of the equalizer based upon either the DC level variation or the field sync differences of the received signal. The modification may be used alone or in combination with the equalizer operating mode control.Type: GrantFiled: October 4, 1995Date of Patent: November 4, 1997Assignee: Zenith Electronics CorporationInventor: Larry E. Nielsen
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Patent number: 5619269Abstract: An ATV signal includes a field sync reference having a relatively long pseudo-random number symbol sequence followed by three relatively short pseudo-random number symbol sequences, with the middle of the three short pseudo-random number symbol sequences having inverted polarity in alternate fields.Type: GrantFiled: June 7, 1995Date of Patent: April 8, 1997Assignee: Zenith Electronics CorporationInventors: Ronald B. Lee, Larry E. Nielsen
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Patent number: 5594496Abstract: A receiver receives an ATV (e.g. HDTV) signal in an area that is subject to NTSC co-channel and other interference. The received signal is precoded at the transmitter for enabling reduction of NTSC co-channel interference in the received signal. The received signal includes field sync signals that are successively field combed to produce a subtraction signal. The subtraction signal is comb filtered to reduce NTSC co-channel interference and applied to a comparator along with the unfiltered subtraction signal. The comparator determines whether the level of NTSC co-channel interference is sufficiently great to subject the received ATV signal to comb filtering for reducing the NTSC co-channel interference.Type: GrantFiled: June 7, 1995Date of Patent: January 14, 1997Assignee: Zenith Electronics CorporationInventors: Larry E. Nielsen, Gary J. Sgrignoli
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Patent number: 5574496Abstract: A technique for enhancing the robustness of an ATV transmission system in the presence of NTSC or ATV co-channel interference comprises positioning the ATV signal relative to the co-channel NTSC/ATV signal to reduce interference into the ATV receiver. In a preferred embodiment, the ATV signal is positioned relative to a co-channel NTSC signal such that the demodulated difference f.sub.v -f.sub.p in the ATV receiver is equal to 70.5 f.sub.seg, where f.sub.v is the NTSC visual carrier frequency, f.sub.p is the ATV pilot carrier frequency and f.sub.seg is the ATV segment repetition rate, and relative to a co-channel ATV signal such that their respective pilot frequencies differ by an amount equal to 1.5 f.sub.seg.Type: GrantFiled: June 7, 1995Date of Patent: November 12, 1996Assignee: Zenith Electronics CorporationInventors: Larry E. Nielsen, David A. Willming
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Patent number: 5572547Abstract: An adaptive equalizer decision circuit for a digital television signal, including a field synchronizing signal, consisting of multilevel symbols and a DC offset representing a pilot. The variation of the DC level of the received signal during the field sync with respect to a predetermined threshold is derived for placing the equalizer in a training signal or data directed operating mode. Another approach determines the difference between a current value of the field sync and each of a plurality of values of the field sync in previous fields and determining therefrom whether the equalizer should be in its data directed mode of operation or in its training signal mode of operation. A modification consists in controlling the step size of the equalizer based upon either the DC level variation or the field sync differences of the received signal. The modification may be used alone or in combination with the equalizer operating mode control.Type: GrantFiled: October 4, 1995Date of Patent: November 5, 1996Assignee: Zenith Electronics CorporationInventors: Richard W. Citta, Larry E. Nielsen
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Patent number: 5060067Abstract: An adaptive filter for equalizing a received information signal is controlled by an error signal generated in response to a reference signal alternately transmitted in inverted and non-inverted form. The received reference signal transmitted in inverted form is reinverted prior to generating the error signal for negating the effects of DC offsets acquired by the reference signal during transmission and reception.Type: GrantFiled: November 26, 1990Date of Patent: October 22, 1991Assignee: Zenith Electronics CorporationInventors: Ronald B. Lee, Larry E. Nielsen