Input Signal Applied Directly To Local Oscillator Patents (Class 329/359)
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Patent number: 8077818Abstract: A radio receiver including a reception processing system that uses discrete-time frequency conversion to acquire a signal having a sampling rate corresponding to a local frequency, wherein the reception characteristic is improved when the reception processing system is applied to a system having a wide reception channel band. The radio receiver comprises an A/D converting part that quantizes a discrete-time analog signal to a digital value to output a received digital signal; a channel selection filtering part that uses a tap coefficient value to perform a digital filtering process of the received digital signal; and a frequency response characteristic correcting part that generates the tap coefficient in accordance with the sampling rate.Type: GrantFiled: November 21, 2006Date of Patent: December 13, 2011Assignee: Panasonic CorporationInventors: Katsuaki Abe, Akihiko Matsuoka, Kentaro Miyano
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Patent number: 7639821Abstract: A software defined radio detects an amplitude modulated (AM) signal contained within a received signal. This detection involves first receiving a radio frequency (RF) signal that contains the AM signal modulated about a carrier frequency (fc). The RF signal is downconverted using a first local oscillator having a frequency flo. An in-phase (I) channel signal and a quadrature (Q) channel signal are produced. From the I-channel signal, a relationship between the carrier frequency and the frequency of the local oscillator is determined with a frequency detector. The downconverted carrier signal of the I-channel signal is used to create a second set of signals with proper phases and frequencies that can be used to rotate the I-channel and Q-channel signals to account for differences between the downconverted fc and DC.Type: GrantFiled: January 6, 2005Date of Patent: December 29, 2009Assignee: Lockheed Martin CorporationInventor: Richard L. Zinser
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Patent number: 7567641Abstract: Because of the natural ability to reject clock jitter, the SRC circuits include an internal oscillator to provide an operating clock signal. The internal oscillator can be operated independently of any external frequency control signal, including input and output frame clocks. The internal oscillator can be implemented as a relatively low-cost fixed frequency oscillator. The use of a relatively low precision, inexpensive internal oscillator in an SRC circuit reduces the overall cost of SRC circuits while providing acceptable performance. Accordingly, reducing costs of SRC circuits also has a positive cost/benefit affect on the digital signal processing systems that use SRC circuits.Type: GrantFiled: June 16, 2004Date of Patent: July 28, 2009Assignee: Cirrus Logic, Inc.Inventor: Gautham D. Kamath
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Patent number: 7535976Abstract: A receiver to process a RF input signal having a plurality of channels includes a direct down conversion circuit, a demodulation circuit, and a local oscillator circuit. The direct down conversion circuit provides a downconverted signal based on the RF input signal and a local oscillator signal. The demodulation circuit receives the downconverted signal and provides a demodulated signal. The local oscillator circuit sets a frequency of the local oscillator signal based on a selected channel of the plurality of channels.Type: GrantFiled: July 30, 2004Date of Patent: May 19, 2009Assignee: Broadcom CorporationInventors: Steven Jaffee, Donald McMullin, Ramon Gomez
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Patent number: 7480348Abstract: In an I/Q demodulation circuit, an offset amount determined in an offset detection mode is previously stored so that, in a normal reception mode, an offset is corrected for based on the data thus stored. With this configuration, a DC offset and a phase offset can be corrected for without a delay in an I/Q demodulation operation.Type: GrantFiled: August 17, 2004Date of Patent: January 20, 2009Assignee: Sharp Kabushiki KaishaInventor: Yoshiaki Nakano
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Patent number: 7394874Abstract: A multi-channel RF receiver uses an image rejection mixer (e.g. double quadrature mixer) in the IF down conversion stage for image side band rejection (whereby use of an IF narrow band filter for image rejection may be omitted if desired) and comprises a simplified frequency synthesizer which generates both a “wandering” IF oscillator frequency and an RF oscillator frequency for the up/down conversion stages (being, for down conversion, from RF to IF and from IF to base band. The IF used for a particular RF carrier (channel) is selected so as to be both an integer (N) sub-harmonic of that RF carrier and within the operating frequency band of the image rejection mixer. Advantageously, the synthesizer comprises only one loop and one VCO, wherein the IF oscillator signal is produced from the RF oscillator signal by means of a frequency divider.Type: GrantFiled: February 20, 2007Date of Patent: July 1, 2008Assignee: Zarbana Digital Fund LLCInventors: Alexander Neil Birkett, James Stuart Wight
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Patent number: 7194044Abstract: A multi-channel RF receiver uses an image rejection mixer (e.g. double quadrature mixer) in the IF down conversion stage for image side band rejection (whereby use of an IF narrow band filter for image rejection may be omitted if desired) and comprises a simplified frequency synthesizer which generates both a “wandering” IF oscillator frequency and an RF oscillator frequency for the up/down conversion stages (being, for down conversion, from RF to IF and from IF to base band. The IF used for a particular RF carrier (channel) is selected so as to be both an integer (N) sub-harmonic of that RF carrier and within the operating frequency band of the image rejection mixer. Advantageously, the synthesizer comprises only one loop and one VCO, wherein the IF oscillator signal is produced from the RF oscillator signal by means of a frequency divider.Type: GrantFiled: May 22, 2002Date of Patent: March 20, 2007Inventors: Alexander Neil Birkett, James Stuart Wight
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Patent number: 6356599Abstract: An AFC (Automatic Frequency Control) device and a method of controlling reception frequency in a dual-mode terminal. When a dual-mode terminal uses one or two AFC devices, the time required for acquiring tracking synchronization in a PLL circuit for a first frequency can be reduced using a test augmentation frequency which is an integer multiple of a tracking synchronization acquiring residual frequency of a PLL circuit for a second frequency to which the first frequency transitions for reliable synchronization acquisition. Errors with respect to an output dynamic range caused by use of two AFCs are reduced and thus the demodulation performance of a receiver is ensured by varying quantization bits of an A/D clock based on the dynamic range of residual errors in a frequency area. The demodulation performance can also be ensured by operating an ACPE circuit for an AFC device having many residual frequency errors.Type: GrantFiled: September 2, 1999Date of Patent: March 12, 2002Assignee: Samsung Electronics Co., Ltd.Inventor: Hyun-Kyu Lee
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Patent number: 5751197Abstract: A low-power, self-quenching superregenerative receiver utilizes a single-port SAW device coupled to an RF oscillator to establish the frequency of oscillation at the output of the RF oscillator. A diode detector is coupled from the oscillator output for detecting a predetermined amplitude of the oscillation output signal. A time-constant circuit is coupled from the signal detector for generating an oscillator quench signal when the oscillator signal is detected and the oscillator quench signal has a predetermined duration set by the time-constant circuit. A feedback circuit couples the oscillator quench signal to the RF oscillator to cause the RF oscillator to switch to a non-oscillating condition only during the predetermined duration of the RF oscillator quench signal. The RF oscillator then switches to the oscillating condition and the system repeats itself.Type: GrantFiled: June 18, 1996Date of Patent: May 12, 1998Assignee: RF Monolithics, Inc.Inventor: Harry O. Boling, III
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Patent number: 5603111Abstract: An improved synchronous tracking AM receiver having low power requirements and a small size. The synchronous tracking AM receiver provides signal tracking capability and sensitivity approaching a conventional superhetrodyne receiver. The synchronous tracking AM receiver includes an RF amplifier synchronous input section which couples input signals to a synchronization filter circuit, including a modified Colpitts oscillator. The Colpitts oscillator recycles the signal to generate a high Q output signal. The output signal of the synchronization circuit is coupled to a low pass filter, then amplified by a low frequency amplifier and triggered to produce a digital output signal.Type: GrantFiled: June 29, 1995Date of Patent: February 11, 1997Assignee: Honeywell Inc.Inventor: Michael A. Wyatt
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Patent number: 5241687Abstract: Apparatus for demodulating information signals frequency-modulated on an RF carrier signal carrying spectral components within the audio frequency range, a pilot carrier signal having an imparted phase shift from the phase of the transmitted pilot carrier signal, and amplitude-modulated spectral components having another imparted phase shift in a subcarrier channel frequency range above the audio frequency range. The apparatus includes a demodulator for demodulating the frequency-modulated information signals to provide a detected composite signal which includes a detected pilot carrier characterized by an imparted phase shift due to the effects of multipath reception, and detected amplitude modulated spectral components exhibiting another multipath induced phase shift.Type: GrantFiled: February 14, 1991Date of Patent: August 31, 1993Assignee: Bose CorporationInventor: William R. Short
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Patent number: 5105162Abstract: An electrically tuned super-regenerative receiver (10) comprises a feedback type oscillator having a signal output and a signal input, phase shift components (30) connected in a feedback loop for coupling the signal output to the signal input to cause oscillations, and a quench oscillator (35) coupled to the signal input for switching the oscillator between an oscillating and a non-oscillating condition. A variable capacitance device (40), such as a varactor diode, is connected between the signal output and a reference potential (21), and a microprocessor (105) provides a tuning voltage (42) which is applied at the signal output for varying the current in the varactor diode, thereby varying the oscillator center operating frequency. The oscillator center operating frequency is detected by a spectrum analyzer (112) and compared to a desired center operating frequency by a controller (118).Type: GrantFiled: June 20, 1991Date of Patent: April 14, 1992Assignee: United Technologies AutomotiveInventors: Thomas Fleissner, Gerald M. Brehmer