Pulse or digital communications – Systems using alternating or pulsating current – Antinoise or distortion
Patent
1997-08-02
2000-02-15
Bocure, Tesfaldet
Pulse or digital communications
Systems using alternating or pulsating current
Antinoise or distortion
375296, 375346, H04B 1500, H04L 2549, H03D 104
Patent
active
060261234
ABSTRACT:
A digital transmission system that provides high immunity to rapidly changing multipath distortion by sending a normal data block followed by a reciprocal data block with the same random data in an inverted form. The second block of data is comprised of frequency components whose coefficients are the reciprocal of the frequency coefficients found in the equivalent terms in the first block. At the receive site, both blocks are received and transformed into the frequency domain The frequency coefficients of the second block are divided by the corresponding frequency coefficient in the first block using complex arithmetic. The square root is taken on the product, yielding a de-ghosted normal block. If any of the frequency coefficients of the first block of data are zero, creating the reciprocal will involve division by zero. This problem Is remedied by using a modulation system such as orthogonal frequency division multiplexing (OFDM) that can maintain control over coefficient values at all frequencies. A guard interval may be used with the data blocks. Forward error correction may be applied to the data to improve bit error rate performance with large echoes.
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Bocure Tesfaldet
Lacasse Randy W.
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