Patents by Inventor Chow Loong Cheah
Chow Loong Cheah 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: 11711102Abstract: A very low intermediate frequency receiver and methods for controlling the same. One method includes providing, using a local oscillator, a first intermediate frequency, detecting, using an interferer detector, an adjacent or alternate channel interference signal and an image of the adjacent or adjacent channel interference signal causing interference with a desired signal, and determining, using an electronic processor, whether the desired signal is an analog signal. In response to determining that the desired signal is an analog signal, the method includes controlling, using the electronic processor, the local oscillator to provide a second intermediate frequency.Type: GrantFiled: November 1, 2021Date of Patent: July 25, 2023Assignee: MOTOROLA SOLUTIONS, INC.Inventors: Moh Lim Sim, Chow Loong Cheah, Jesus F. Corretjer, Kevin Doberstein, Boon Heng Fong, Ariel L. Galan
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Publication number: 20230140647Abstract: A very low intermediate frequency receiver and methods for controlling the same. One method includes providing, using a local oscillator, a first intermediate frequency, detecting, using an interferer detector, an adjacent or alternate channel interference signal and an image of the adjacent or adjacent channel interference signal causing interference with a desired signal, and determining, using an electronic processor, whether the desired signal is an analog signal. In response to determining that the desired signal is an analog signal, the method includes controlling, using the electronic processor, the local oscillator to provide a second intermediate frequency.Type: ApplicationFiled: November 1, 2021Publication date: May 4, 2023Inventors: Moh Lim Sim, Chow Loong Cheah, Jesus F. Corretjer, Kevin Doberstein, Boon Heng Fong, Ariel L. Galan
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Patent number: 9800277Abstract: A radio frequency (RF) receiver and method of controlling an RF receiver are provided. The method includes receiving an RF signal and down-converting the RF signal to a substantially baseband signal. A direct current (DC) transition is detected in a portion of the substantially baseband signal. The substantially baseband signal is then filtered using a first filter configuration at the portion of the substantially baseband signal including the DC transition and a second filter configuration at a portion of the substantially baseband signal not including the DC transition.Type: GrantFiled: October 11, 2013Date of Patent: October 24, 2017Assignee: MOTOROLA SOLUTIONS, INC.Inventors: Moh Lim Sim, Chow Loong Cheah, Shu Chen, Raviteja Chinta, Yadunandana N Rao, V. C. Prakash V K Chacko
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Patent number: 9608679Abstract: A very low intermediate frequency (VLIF) receiver and a method of controlling a VLIF receiver. The method comprises estimating energy levels in first and second signals and detecting interference from a first adjacent channel interferer based upon a difference in energy in the first and second signals. The first signal comprising a first on-channel portion and an adjacent channel portion and the second signal comprises an intermediate frequency translation of the first on-channel portion. The energy levels are estimated for corresponding time instances and the adjacent channel interferer is of the adjacent channel portion. The VLIF receiver is then controlled based upon the detected interference.Type: GrantFiled: November 7, 2012Date of Patent: March 28, 2017Assignee: MOTOROLA SOLUTIONS, INC.Inventors: Chow Loong Cheah, Kim Loy Lai, Kar Boon Oung, Moh Lim Sim, V. C. Prakash V K Chacko
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Publication number: 20160211872Abstract: A radio frequency (RF) receiver and method of controlling an RF receiver are provided. The method includes receiving an RF signal and down-converting the RF signal to a substantially baseband signal. A direct current (DC) transition is detected in a portion of the substantially baseband signal. The substantially baseband signal is then filtered using a first filter configuration at the portion of the substantially baseband signal including the DC transition and a second filter configuration at a portion of the substantially baseband signal not including the DC transition.Type: ApplicationFiled: October 11, 2013Publication date: July 21, 2016Inventors: Moh Lim SIM, Chow Loong CHEAH, Shu CHEN, RaviTeja CHINTA, Yadunandana N RAO, V. C. Prakash V K CHACKO
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Publication number: 20150295604Abstract: A very low intermediate frequency (VLIF) receiver and a method of controlling a VLIF receiver. The method comprises estimating energy levels in first and second signals and detecting interference from a first adjacent channel interferer based upon a difference in energy in the first and second signals. The first signal comprising a first on-channel portion and an adjacent channel portion and the second signal comprises an intermediate frequency translation of the first on-channel portion. The energy levels are estimated for corresponding time instances and the adjacent channel interferer is of the adjacent channel portion. The VLIF receiver is then controlled based upon the detected interference.Type: ApplicationFiled: November 7, 2012Publication date: October 15, 2015Inventors: Chow Loong Cheah, Kim Loy Lai, Kar Boon Oung, Moh Lim Sim, V. C. Prakash V K Chacko
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Publication number: 20150171906Abstract: A very-low intermediate frequency (VLIF) receiver and a method of controlling a VLIF receiver. The method comprises receiving a first signal, the first signal including one or both of an on-channel signal portion and an adjacent channel interferer (ACI) portion; determining that the first signal includes a portion having a strength that is above a threshold; in response to determining that the first signal includes a portion having a strength that is above the threshold, estimating one or more IQ imbalance parameters for at least a portion of the first signal; and compensating for an IQ imbalance in at least the portion of the first signal using the one or more IQ imbalance parameters.Type: ApplicationFiled: December 17, 2013Publication date: June 18, 2015Applicant: MOTOROLA SOLUTIONS, INCInventors: YEW LEONG WONG, CHOW LOONG CHEAH, LI CHOO CHEN, YADUNANDANA N. RAO, MOH LIM SIM, ONDY DHARMA INDRA SUKMA
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Patent number: 9048920Abstract: An apparatus and method for reducing FM audio artifacts in a receiver are provided. A direct conversion radio frequency (RF) receiver converts an analog FM signal into a phase shifted digital low IF signal. A digital controller coupled to the analog FM receiver provides adaptive frequency translation for different channel spacing and provides adaptive low IF configuration through the different channel spacing, thereby suppressing audio artifacts.Type: GrantFiled: March 30, 2012Date of Patent: June 2, 2015Assignee: Motorola Solutions, Inc.Inventors: Chow Loong Cheah, Kar Boon Oung, V. C. Prakash V K Chacko
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Patent number: 9042500Abstract: A very-low intermediate frequency (VLIF) receiver and a method of controlling a VLIF receiver. The method comprises receiving a first signal, the first signal including one or both of an on-channel signal portion and an adjacent channel interferer (ACI) portion; determining that the first signal includes a portion having a strength that is above a threshold; in response to determining that the first signal includes a portion having a strength that is above the threshold, estimating one or more IQ imbalance parameters for at least a portion of the first signal; and compensating for an IQ imbalance in at least the portion of the first signal using the one or more IQ imbalance parameters.Type: GrantFiled: December 17, 2013Date of Patent: May 26, 2015Assignee: Motorola Solutions, Inc.Inventors: Yew Leong Wong, Chow Loong Cheah, Li Choo Chen, Yadunandana N Rao, Moh Lim Sim, Ondy Dharma Indra Sukma
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Publication number: 20150071392Abstract: An apparatus and method for reducing FM audio artifacts in a receiver are provided. A direct conversion radio frequency (RF) receiver converts an analog FM signal into a phase shifted digital low IF signal. A digital controller coupled to the analog FM receiver provides adaptive frequency translation for different channel spacing and provides adaptive low IF configuration through the different channel spacing, thereby suppressing audio artifacts.Type: ApplicationFiled: March 30, 2012Publication date: March 12, 2015Inventors: Chow Loong Cheah, Kar boon Oung, V. C. Prakash V K Chacko
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Patent number: 7860196Abstract: A method and circuit are described for estimating I and Q amplitude imbalance occurring in a signal received by a direct conversion receiver (DCR). The DCR generates a mixing signal having a frequency substantially the same as the carrier signal of the signal received by an antenna. A mixing module mixes the mixing signal at different phases with the received signal to generate I and Q baseband signals. A frequency offset circuit generates an offset signal having a frequency offset from the carrier signal frequency. A coupling circuit selectively decouples the antenna from the DCR and couples the offset signal to the mixing module to generate a baseband test signal in the I and Q signal paths for determining an imbalance in the amplitudes of the baseband test signals between the I and Q signal paths.Type: GrantFiled: January 10, 2007Date of Patent: December 28, 2010Assignee: Motorola, Inc.Inventors: Chow Loong Cheah, Siew Yin Lee, Vc Prakash Vk Chacko
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Publication number: 20080166978Abstract: A circuit (100) comprising an antenna (105) for receiving a carrier signal modulated by a data signal, a direct conversion receiver (180) for receiving the modulated carrier signal, a signal generator circuit (140, 145, 150) arranged to generate a mixing signal having a frequency substantially the same as the carrier signal, a mixing module (125i, 125q) having an in-phase and a quadrature phase signal path (120i, 120q) arranged to mix the mixing signal at different phases with the received modulated carrier signal in order to generate an in-phase and a quadrature baseband signal, a frequency offset circuit (155, 200) arranged to generate an offset signal having a frequency offset from the frequency of the carrier signal, a coupling circuit (170a, 170b, 170c) arranged to selectively decouple the antenna from the direct conversion receiver and to couple the offset signal to the mixing module in order to generate a baseband test signal in the in-phase and quadrature signal paths for determining an imbalance in tType: ApplicationFiled: January 10, 2007Publication date: July 10, 2008Applicant: MOTOROLA, INC.Inventors: CHOW LOONG CHEAH, SIEW YIN LEE, VC PRAKASH VK CHACKO
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Patent number: 6397049Abstract: A two-way radio (1) that has a radio frequency receiver (2) having a modulated radio frequency signal output and a variable bandwidth filter (3) with an input coupled to the modulated radio frequency signal output. The radio (1) also has demodulator circuitry (4), a speaker (6) and processing circuitry (5). In use when the radio (1) is operating in squelch mode, the processing circuitry (5) controls the variable bandwidth filter (3) to have a first bandwidth and when in unsquelch mode the processing circuitry (5) controls the variable bandwidth filter (3) to have a second bandwidth which has a smaller frequency range and the first bandwidth.Type: GrantFiled: November 1, 1999Date of Patent: May 28, 2002Assignee: Motorola, Inc.Inventors: Siew Yin Lee, Chow Loong Cheah