Television – Image signal processing circuitry specific to television – Noise or undesired signal reduction
Patent
1997-01-28
1999-03-23
Hsia, Sherrie
Television
Image signal processing circuitry specific to television
Noise or undesired signal reduction
348611, 348914, H04N 5213
Patent
active
058867490
ABSTRACT:
A system and method for demodulation of an RF signal on a transmission channel is provided. The RF signal is demodulated to baseband as an in-phase (I) data signal and a quadrature (Q) data signal. A first block of I data is captured and a first block of Q data is captured. A time domain guard interval is provided in the captured first blocks of I and Q data. A complex discrete Fourier transform is performed on the captured first I and Q data blocks. An inverse frequency response for the transmission channel is determined. The inverse frequency response is multiplied by the complex discrete Fourier transform of the guard-interval protected first I and Q data blocks to generate a frequency domain product signal. An inverse Fourier transform on the product of the multiplying step is performed to generate a first equalized time domain signal. In a preferred embodiment, the method also includes using an overlapped Fourier transform and discarding a first portion of each equalized time domain signal.
REFERENCES:
patent: 5371548 (1994-12-01), Williams
patent: 5568202 (1996-10-01), Koo
T. Williams &M. Chelehmal, "Using Orthogonal Frequency Division Multiplexing in the Vertical Interval of an NTSC TV Transmission", National Association of Broadcasters Proceeding, 1995.
H. Sari, G. Karam, and I. Jeanclaude, "Transmission Techniques for Digital Terrestrial TV Broadcasting", IEEE Communications Magazine vol. 33, No. 2., Feb. 1995.
Chelehmal Majid
Ito Yasuhiro
Williams Thomas H.
Cable Television Laboratories, Inc.
Hsia Sherrie
Langley Stuart T.
Nippon Hoso Kyokai
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