US4577328A
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Method and circuit for detecting a training signal
Assignee: NEC Corp
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Filing: 1983-10-31
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Granted: 1986-03-18
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Expires: 2003-10-31
Abstract
Abstract Receipt of a training signal by a circuit wherein a demodulated data sequence is compared with a corresponding pre-recorded sequence and an impulse produced upon coincidence therebetween, is acknowledged by two consecutive signals occuring at a time interval corresponding to the period of the data sequence.
Inventors
- 👤 Keiichi Senoo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 13:36
CPC Classifications
H; H04; H04L; H04L25/00; H04L25/02; H04L25/03; H04L25/03006; H04L25/03012; H04L25/03114; F; F02; F02B; F02B75/00; F02B75/02; F02B2075/022; F02B2075/025
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
242 words
A method of detecting a training signal for use in initial adjustment of an automatic equalizer with respect to channel characteristics, comprising the steps of: (a) receiving and shifting a demodulated training signal in synchronism with data modulating rate, said training signal comprising at least two periodic data sequences each having a period L and the autocorrelation function of said periodic data sequence assumes an impulse; (b) calculating the correlation between said demodulated training signal and a first periodic data sequence with the period L, and obtaining a first square value indicative of said correlation; (c) calculating the correlation between said demodulated training signal and a second periodic data sequence and obtaining a second square value indicative of said correlation, wherein said second periodic data sequence is circulated in synchronism with the data modulating rate and has the same sequence as said first data sequence; (d) dividing said first square value by said second square value; (e) comparing the quotient obtained in the step (d) with a first and second threshold values; (f) setting the order of said second periodic data sequence to the order of said first periodic data sequence shifted by one, if said quotient exceeds the second threshold value; (g) producing a signal if said quotient exceeds the first threshold value; and (h) detecting the presence of said training signal by detecting said at least two periodic data sequences occuring at a time interval equal to said period L.
Claim 2
Independent Claim
242 words
A method of detecting a training signal for use in initial adjustment of an automatic equalizer with respect to channel characteristics, comprising the steps of: (a) receiving and shifting a demodulated training signal in synchronism with data modulating rate, said training signal comprising at least two periodic data sequences each having a period L and the autocorrelation function of said periodic data sequence assumes an impulse; (b) calculating the correlation between said demodulated training signal and a first periodic data sequence with the period L, and obtaining a first square value indicative of said correlation; (c) calculating the correlation between said demodulated training signal and a second periodic data sequence and obtaining a second square value indicative of said correlation, wherein said second periodic data sequence is circulated in synchronism with the data modulating rate and has the same sequence as said first data sequence; (d) dividing said first square value by said second square value; (e) comparing the quotient obtained in the step (d) with a first and second threshold values; (f) setting the order of said second periodic data sequence to the order of said first periodic data sequence shifted by one, if said quotient exceeds the second threshold value; (g) producing a signal if said quotient exceeds the first threshold value; and (h) detecting the presence of said training signal by detecting said at least two periodic data sequences occuring at a time interval equal to said period L.
Claim 3
Dependent Claim
274 words
A circuit for detecting a training sigal for use in initial adjustment of an automatic equalizer with respect to channel characteristics, comprising: a first means for receiving and shifting a demodulated training signal in synchronism with the data modulating rate, said training signal comprising at least two periodic data sequences each having a period L and the autocorrelation function of said periodic data sequence assumes an impulse; a second means for calculating the correlation between said demodulated training signal and a first periodic data sequence with the period L, and obtaining a first square value indicative of said correlation; a third means for calculating the correlation between said demodulated training signal and a second periodic data sequence and obtaining a second square value indicative of said correlation, wherein said second periodic data sequence is circulated in synchronism with the data modulating rate and has the same sequence as said first data sequence; a fourth means for dividing said first square value by said second square value; a fifth means for comparing the quotient produced by said fourth means with a first and second threshold values; a sixth means for setting the sequence order of said second periodic data sequence to the sequence order of said first periodic data sequence shifted by one, if said quotient exceeds the second threshold value; a seventh means for producing a signal if said quotient exceeds the first threshold value; and an eighth means responsive to the output of said seventh means for detecting the presence of said training signal by detecting said at least two periodic data sequences occuring at a time interval equal to said period L.
Claim 4
Dependent Claim
274 words
A circuit for detecting a training sigal for use in initial adjustment of an automatic equalizer with respect to channel characteristics, comprising: a first means for receiving and shifting a demodulated training signal in synchronism with the data modulating rate, said training signal comprising at least two periodic data sequences each having a period L and the autocorrelation function of said periodic data sequence assumes an impulse; a second means for calculating the correlation between said demodulated training signal and a first periodic data sequence with the period L, and obtaining a first square value indicative of said correlation; a third means for calculating the correlation between said demodulated training signal and a second periodic data sequence and obtaining a second square value indicative of said correlation, wherein said second periodic data sequence is circulated in synchronism with the data modulating rate and has the same sequence as said first data sequence; a fourth means for dividing said first square value by said second square value; a fifth means for comparing the quotient produced by said fourth means with a first and second threshold values; a sixth means for setting the sequence order of said second periodic data sequence to the sequence order of said first periodic data sequence shifted by one, if said quotient exceeds the second threshold value; a seventh means for producing a signal if said quotient exceeds the first threshold value; and an eighth means responsive to the output of said seventh means for detecting the presence of said training signal by detecting said at least two periodic data sequences occuring at a time interval equal to said period L.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-03-17 | 1989-09-16 | 1990-03-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-03-17 | 1993-09-16 | 1994-03-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-03-17 | 1997-09-16 | 1998-03-18 | $7700.00 | Window Closed / Lapsed |