Patent US3755736A successfully refreshed from Google Patents.
US3755736A
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Phase tracking system for an automatic equalization
Assignee: NEC Corp
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Filing: 1971-09-01
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Granted: 1973-08-28
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Expires: 1991-09-01
Abstract
Abstract Disclosed herein is a phase tracking system adapted for use with an automatic equalization circuit. This system causes a reference timing pulse, derived from a timing component of a received reference signal, to track the peak of the equalized reference signal, the phase of the extracted timing component randomly varying with respect to the reference signal. Tracking is accomplished by generating a variable level signal and first and second timing pulses occurring respectively, at a selected time before and after the derived reference timing pulse. When the first and second timing pulses are generated, the level of the equalized reference signal is compared with the level of the variable level signal. If the level of the equalized reference signal is greater than that of the variable level signal at one of the comparison times and less than the level of the variable level signal at the other of the comparison times, the phases of the first, second and reference timing pulses are varied in a direction to tend to cause coincidence between the peak of the equalized reference signal and the reference timing pulse. Further, if the equalized reference signal is greater than or less than the level of the variable level signal at both comparison times, the level of the variable level signal at the other comparison time. In this manner, the system causes the reference timing pulse to attempt to align itself with the peak of the equalized reference signal.
Inventors
- 👤 H Kaneko
- 👤 S Shigaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 16:26
CPC Classifications
H; H04; H04B; H04B3/00; H04B3/02; H04B3/04; H04B3/14; H04B3/142
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
484 words
An automatic equalizing system for a long distance transmission channel for an information signal, said information signal having such a large frequency band width that the linear distortion due to the time varying nature of said channel is not negligible at a receiving end of said channel and having a timing burst signal and a reference pulse of a specific wave form inserted at a predetermined time at a transmitting end of said channel, comprising: an equalizer unit for receiving the information signal transmitted via said channel for equalizing the ampliTude and delay responses of said channel; means for extracting a timing signal synchronized with said timing burst signal from the information signal transmitted; means responsive to a delay-increase-instruction signal and a delay-decrease-instruction signal for delaying the extracted timing signal in comparison with said reference pulse in the time domain by a predetermined value at a preset rate; reference timing pulse group generation means for producing from the output of the phase delaying means three reference timing pulses spaced apart by a predetermined interval; a direct current voltage source; means coupled with the voltage source for producing an output amplitude signal controlled in response to an amplitudeincrease-instruction signal and an amplitude-decreaseinstruction signal; timed voltage signal discriminating means responsive to the most and least delayed ones of the three reference timing pulses for level-comparing the output amplitude signal with the output of said equalizer unit at the time points defined by the most and least phase delayed ones of said three reference timing pulses thereby to deliver a pair of binary detection signals each assuming a first value of said binary signal when the level of said reference signal exceeds that of said output amplitude signal and a second value of said binary signal when the level of said output amplitude signal exceeds that of said reference signal; logic means coupled with said timed voltage level discriminating means for producing said delay-decrease-instruction signal when said pair of binary detection signals assume said second value at the least phase-delayed reference timing pulse and said first value at the most phase-delayed reference timing pulse, said delay-increase-instruction signal when said pair of detection signals assume said first value at the least phasedelayed reference timing pulse and said second value at the most phase-delayed reference timing pulse, said amplitudeincrease-instruction signal when said pair of detection signals assumes said first value at both the most and least phasedelayed reference timing pulses and said amplitude-decreaseinstruction signal when said pair of detection signals assume said second value at both the most and least phase-delayed reference timing pulses; and means for supplying the second phase-delayed one of said three reference timing pulses to said equalizing unit as an equalizer-control signal, whereby the peak value of the transmitted reference pulse is always brought into coincidence with a fixed time relationship with said timing signal to achieve a desired equalization operation of said equalizing unit.
Claim 2
Dependent Claim
484 words
An automatic equalizing system for a long distance transmission channel for an information signal, said information signal having such a large frequency band width that the linear distortion due to the time varying nature of said channel is not negligible at a receiving end of said channel and having a timing burst signal and a reference pulse of a specific wave form inserted at a predetermined time at a transmitting end of said channel, comprising: an equalizer unit for receiving the information signal transmitted via said channel for equalizing the ampliTude and delay responses of said channel; means for extracting a timing signal synchronized with said timing burst signal from the information signal transmitted; means responsive to a delay-increase-instruction signal and a delay-decrease-instruction signal for delaying the extracted timing signal in comparison with said reference pulse in the time domain by a predetermined value at a preset rate; reference timing pulse group generation means for producing from the output of the phase delaying means three reference timing pulses spaced apart by a predetermined interval; a direct current voltage source; means coupled with the voltage source for producing an output amplitude signal controlled in response to an amplitudeincrease-instruction signal and an amplitude-decreaseinstruction signal; timed voltage signal discriminating means responsive to the most and least delayed ones of the three reference timing pulses for level-comparing the output amplitude signal with the output of said equalizer unit at the time points defined by the most and least phase delayed ones of said three reference timing pulses thereby to deliver a pair of binary detection signals each assuming a first value of said binary signal when the level of said reference signal exceeds that of said output amplitude signal and a second value of said binary signal when the level of said output amplitude signal exceeds that of said reference signal; logic means coupled with said timed voltage level discriminating means for producing said delay-decrease-instruction signal when said pair of binary detection signals assume said second value at the least phase-delayed reference timing pulse and said first value at the most phase-delayed reference timing pulse, said delay-increase-instruction signal when said pair of detection signals assume said first value at the least phasedelayed reference timing pulse and said second value at the most phase-delayed reference timing pulse, said amplitudeincrease-instruction signal when said pair of detection signals assumes said first value at both the most and least phasedelayed reference timing pulses and said amplitude-decreaseinstruction signal when said pair of detection signals assume said second value at both the most and least phase-delayed reference timing pulses; and means for supplying the second phase-delayed one of said three reference timing pulses to said equalizing unit as an equalizer-control signal, whereby the peak value of the transmitted reference pulse is always brought into coincidence with a fixed time relationship with said timing signal to achieve a desired equalization operation of said equalizing unit.
Claim 3
Dependent Claim
116 words
The system of claim 1 wherein said reference signal is an equalized reference signal obtained from an equalizer unit inserted in a transmission channel carrying an information signal, which includes a timing burst signal and a reference signal of a waveform satisfying the function (sin theta / theta ), said means for generating first and second timing pulses including means for extracting said first timing pulse from said reference signal carried by said transmission channel, said extracted pulse being synchronized with said timing burst signal. first delay means for delaying said first timing pulse to produce said reference timing pulse and second delay means for delaying said reference timing pulse to produce said second timing pulse.
Claim 4
Dependent Claim
426 words
In an automatic equalizing system for a long distance transmission channel for an information signal, said information signal having such a large frequency band width that the linear distortion due to the time varying nature of said channel is not negligible at a receiving end of said channel and having a timing burst signal and a reference signal of a specific wave form inserted at a predetermined time at a transmitting end of said channel comprising: means, responsive to said information signal for extracting a timing signal synchronized with said timing bUrst signal; means responsive to a delay-increase-instruction signal and a delay-decrease-instruction signal for selectively delaying the extracted timing signal; reference timing pulse group generating means for producing from the output of the phase-delaying means three reference timing pulses spaced apart by a predetermined interval, the center one of said timing pulses to have a predetermined phase relative to the phase of said reference signal; means for generating a variable level signal; means for comparing the level of said reference signal with the level of said variable level signal at the times of occurrence of the two timing pulses phase-advanced and phase-delayed respectively from said center timing pulse; means, responsive to said comparing means, for applying a delay-decrease-instruction signal to said phase-delaying means when the level of said reference signal is greater than the level of said variable level signal at the time of occurrence of said phase-advanced one of said timing pulses and less than the level of said variable level signal at the time of occurrence of the phase-delayed one of said timing pulses and for applying a delay-increase-instruction to said phase-delaying means when the level of said reference signal is less than the level of said variable level signal at the time of occurrence of said phase-advanced timing pulse and greater than that of the variable level signal at the time of occurrence of said phase-delayed timing pulse; and means responsive to said comparing means for increasing the level of said variable level signal when the level of said reference signal is greater than that of the variable level signal at the times of occurrence of both the phase-advanced timing pulse and phase-delayed timing pulse and for decreasing the level of said variable level signal when the level of said reference signal is less than that of the variable level signal at the times of occurrence of said phase-advanced timing pulse and phase-delayed timing pulse; whereby the center one of said timing pulses is caused to track the peak of said reference signal.
Claim 5
Dependent Claim
426 words
In an automatic equalizing system for a long distance transmission channel for an information signal, said information signal having such a large frequency band width that the linear distortion due to the time varying nature of said channel is not negligible at a receiving end of said channel and having a timing burst signal and a reference signal of a specific wave form inserted at a predetermined time at a transmitting end of said channel comprising: means, responsive to said information signal for extracting a timing signal synchronized with said timing bUrst signal; means responsive to a delay-increase-instruction signal and a delay-decrease-instruction signal for selectively delaying the extracted timing signal; reference timing pulse group generating means for producing from the output of the phase-delaying means three reference timing pulses spaced apart by a predetermined interval, the center one of said timing pulses to have a predetermined phase relative to the phase of said reference signal; means for generating a variable level signal; means for comparing the level of said reference signal with the level of said variable level signal at the times of occurrence of the two timing pulses phase-advanced and phase-delayed respectively from said center timing pulse; means, responsive to said comparing means, for applying a delay-decrease-instruction signal to said phase-delaying means when the level of said reference signal is greater than the level of said variable level signal at the time of occurrence of said phase-advanced one of said timing pulses and less than the level of said variable level signal at the time of occurrence of the phase-delayed one of said timing pulses and for applying a delay-increase-instruction to said phase-delaying means when the level of said reference signal is less than the level of said variable level signal at the time of occurrence of said phase-advanced timing pulse and greater than that of the variable level signal at the time of occurrence of said phase-delayed timing pulse; and means responsive to said comparing means for increasing the level of said variable level signal when the level of said reference signal is greater than that of the variable level signal at the times of occurrence of both the phase-advanced timing pulse and phase-delayed timing pulse and for decreasing the level of said variable level signal when the level of said reference signal is less than that of the variable level signal at the times of occurrence of said phase-advanced timing pulse and phase-delayed timing pulse; whereby the center one of said timing pulses is caused to track the peak of said reference signal.
References Cited (Backward Citations)
US3509279A
Cited
US3633108A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-08-27 | 1977-02-26 | 1977-08-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-27 | 1981-02-26 | 1981-08-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-27 | 1985-02-26 | 1985-08-28 | $7700.00 | Window Closed / Lapsed |