US3860871A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Phase control system for demodulation carrier in carrier band multilevel signal transmission
Assignee: Fujitsu Ltd
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Filing: 1973-06-05
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Granted: 1975-01-14
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Expires: 1993-06-05
Abstract
Abstract In narrow band transmission by BSB and VSB modulation, phase distortion due to the transmission line occurs in the carrier signal, followed by a phase shift from accurate pulse response of the multilevel signal demodulated by the carrier signal subjected to the line phase distortion. A reference level signal having a predetermined level lower than the multilevel signal is inserted at a specified interval into the multilevel signal train to be transmitted. The intersymbol interference of the reference level signal is detected at the receiver, so that the phase shift from the accurate response of the multilevel signal is compensated by controlling the phase of the demodulation carrier signal to be supplied to the demodulator.
Inventors
- 👤 Shigehiko Hinoshita
- 👤 Shoji Hagiwara
- 👤 Naohide Sata
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 12:40
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/02; H04L27/06; H04L27/066
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
185 words
A multilevel signal transmission system for transmitting a signal via a transmission line, said transmission system comprising transmitting means connected to one end of the transmission line, said transmitting means including means for inserting a reference level signal into a multilevel signal at predetermined intervals, the reference level signal having a lower level than the multilevel signal, and means for transmitting the multilevel signals and the reference level signals to the transmission line by carrier band; and receiving means connected to the other end of the transmission line for receiving transmitted signals, said receiving means included demodulating means for demodulating the received transmitted signals and deriving a demodulation carrier therefrom, said demodulating means including a demodulator producing a demodulated signal, means for detecting intersymbol interference which is used as a control signal between the reference level signal and adjacent multilevel signals from the demodulated signal of the demodulator, and means coupled between the detecting means and the demodulating means for controlling the phase of the demodulation carrier derived from the received signal by the demodulating means at the demodulator in accordance with the intersymbol interference.
Claim 2
Dependent Claim
185 words
A multilevel signal transmission system for transmitting a signal via a transmission line, said transmission system comprising transmitting means connected to one end of the transmission line, said transmitting means including means for inserting a reference level signal into a multilevel signal at predetermined intervals, the reference level signal having a lower level than the multilevel signal, and means for transmitting the multilevel signals and the reference level signals to the transmission line by carrier band; and receiving means connected to the other end of the transmission line for receiving transmitted signals, said receiving means included demodulating means for demodulating the received transmitted signals and deriving a demodulation carrier therefrom, said demodulating means including a demodulator producing a demodulated signal, means for detecting intersymbol interference which is used as a control signal between the reference level signal and adjacent multilevel signals from the demodulated signal of the demodulator, and means coupled between the detecting means and the demodulating means for controlling the phase of the demodulation carrier derived from the received signal by the demodulating means at the demodulator in accordance with the intersymbol interference.
Claim 3
Dependent Claim
32 words
A multilevel signal transmission system as claimed in claim 1, wherein the detecting means of the receiving means detects intersymbol interference between the reference level signal and preceding and succeeding multilevel signals.
Claim 4
Dependent Claim
170 words
A multilevel signal transmission system as claimed in claim 1, wherein the receiving means comprises carrier regenerating means for regenerating a demodulation carrier from the received transmitted signals, said regenerating means having an output, shifting means connected to the output of the regenerating means for shifting the phase of the carrier provided by the regenerating means, said shifting means having inputs and an output, demodulating means connected to the output of the shifting means for demodulating the received transmitted signals in accordance with the carrier output of the shifting means, said demodulating means having an output, converting means connected to the output of the demodulating means for converting demodulated signals produced by the demodulating means to digital signals, said converting means providing polarity bits and having an output, and control means connected between the output of the converting means and an input of the shifting means for providing a control signal for controlling the shifting operation of the shifting means in accordance with polarity bits provided by the converting means.
Claim 5
Dependent Claim
92 words
A multilevel signal transmission system as claimed in claim 3, wherein the control means comprises delay means having an input connected to the output of the converting means and an output for delaying the polarity bits provided by the converting means, exclusive OR means connected between the input and the output of the delay means for providing exclusive OR gating of the input and output of the delay means, said OR means having outputs, and coupling means coupling the outputs of the exclusive OR means to said input of the shifting means.
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) | 1978-01-13 | 1978-07-15 | 1979-01-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-01-13 | 1982-07-15 | 1983-01-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-01-13 | 1986-07-15 | 1987-01-14 | $7700.00 | Window Closed / Lapsed |