Method and circuit for generating an auxiliary symbol for adjusting a QAM demodulator
October 8, 2023. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesConverting and decoding receiver for digital data recorded in analog form on magnetic tape Method of obtaining a phase difference signal Circuit for recovering the carrier in digital transmission systems Carrier recovery system using acquisition and tracking modes and automatic carrier-to-noise estimation Methods and apparatuses for fast decision directed carrier recovery with wide locking range QAM detector which compensates for received symbol distortion induced by a cellular base station Decision-feedback equalizer for digital communication system Phase error detector for a quadrature amplitude modulated (QAM) receiver Patent #: 7283599 InventorsAssigneeApplicationNo. 10532554 filed on 10/08/2003US Classes:375/322Angle modulationExaminersPrimary: Payne, David CAssistant: Flores, Leon Attorney, Agent or FirmForeign Patent References
International ClassH03D 3/00AbstractIn a quadrature amplitude (QAM) demodulator, an auxiliary symbol may be utilized in place of the decision symbol to adjust the decision-feedback loops within the demodulator. For the formation and definition of the auxiliary symbol, the radius and angle information of the received signal or of the preliminary symbol may be used. Through use of the auxiliary symbol instead of the decision symbol, any error in the angle information due to the unknown frequency and phase deviation of the local oscillator may be ignored. An auxiliary symbol generator may be provided which, instead of assigning to the received signal an element from the predetermined symbol alphabet, generates an auxiliary symbol that lies on the most probable one of the nominal radii. Nominal radii may mean those radii on which in QAM the predetermined symbols of the alphabet lie in the plane determined by the quadrature signal pair. For the angle component of the auxiliary symbol, the angle information of the sampled digital signal may be used. In polar coordinates, the auxiliary symbol may thus correspond to the vector intersection point of the sampled digital signal with the most probable nominal radius.Other References
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