US3668570A
Expired / Lapsed
US
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Adaptive switched filter arrangement for use in rapid frequency tracking
Assignee: International Business Machines Corp
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Filing: 1970-12-04
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Granted: 1972-06-06
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Expires: 1990-12-04
Abstract
Abstract An adaptive switched filter arrangement formed from two switched filters to each of which is applied the same input signal. The first switched filter is switched at an independent predetermined frequency. The second switched filter, however, is tuned by the output frequency extracted by the first filter. This minimizes phase tracking time and cancels systematic phase error.
Inventors
- 👤 Alex Honore Lautier
- 👤 Jean Louis Monrolin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 22:26
CPC Classifications
H; H03; H03H; H03H19/00; H03H19/002
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
77 words
A filter arrangement for recovering the repetition frequency omega of a communication signal comprising: a phase locked oscillator of frequency omega o responsive to the communication signal for producing a signal of frequency omega 1 when omega is within the oscillator frequency passband; and a switchable filter also responsive to the communications signal and being switched at the omega 1 rate by the oscillator output for producing an output when omega lies within the filter frequency passband.
Claim 2
Dependent Claim
77 words
A filter arrangement for recovering the repetition frequency omega of a communication signal comprising: a phase locked oscillator of frequency omega o responsive to the communication signal for producing a signal of frequency omega 1 when omega is within the oscillator frequency passband; and a switchable filter also responsive to the communications signal and being switched at the omega 1 rate by the oscillator output for producing an output when omega lies within the filter frequency passband.
Claim 3
Dependent Claim
48 words
A filter arrangement according to claim 1, wherein: a switchable filter defines a frequency band-pass characteristic where omega 1 is the center frequency, omega 1 + 1/ Tau is the upper limit, omega 1 - 1/ Tau is the lower limit, and Tau is the filter time constant.
Claim 4
Dependent Claim
21 words
A filter arrangement according to claim 1 wherein: the bandwidth of the switchable filter is less than the phase locked oscillator.
Claim 5
Dependent Claim
182 words
A filter arrangement for recovering the repetition frequency omega of a communications signal comprising: a source of clock signals of frequency omega o; a first switchable filter responsive to the communications signal, said filter being switched by the clock source at the omega o rate and defining a frequency band-pass characteristic where omega o is the center frequency, omega o + 1/ Tau 1 is the upper limit, omega o - 1/ Tau 1 is the lower limit, and Tau 1 is the filter time constant, said filter further producing a signal frequency omega 1 when omega lies within the first filter frequency passband; and a second switchable filter responsive to the communications signal, said filter being switched by the first filter output at the omega 1 rate and defining a frequency band-pass characteristic where omega 1 is the center frequency, omega 1 + 1/ Tau 2 is the upper limit, omega 1 - 1/ Tau 2 is the lower limit; and Tau 2 is the filter time constant, for producing an output when omega lies within the second filter frequency passband.
Claim 6
Dependent Claim
182 words
A filter arrangement for recovering the repetition frequency omega of a communications signal comprising: a source of clock signals of frequency omega o; a first switchable filter responsive to the communications signal, said filter being switched by the clock source at the omega o rate and defining a frequency band-pass characteristic where omega o is the center frequency, omega o + 1/ Tau 1 is the upper limit, omega o - 1/ Tau 1 is the lower limit, and Tau 1 is the filter time constant, said filter further producing a signal frequency omega 1 when omega lies within the first filter frequency passband; and a second switchable filter responsive to the communications signal, said filter being switched by the first filter output at the omega 1 rate and defining a frequency band-pass characteristic where omega 1 is the center frequency, omega 1 + 1/ Tau 2 is the upper limit, omega 1 - 1/ Tau 2 is the lower limit; and Tau 2 is the filter time constant, for producing an output when omega lies within the second filter frequency passband.
Claim 7
Dependent Claim
13 words
A filter arrangement according to claim 4 wherein: Tau 1 < Tau 2.
Claim 8
Dependent Claim
113 words
A filter arrangement for recovering sinusoidal carrier signal of frequency omega o as shifted by frequency of epsilon , comprising: a source of clock signals of frequency omega o; a first switchable filter responsive to the shifted sinusoidal carrier signal of frequency omega o + epsilon and switchable by the clock signal source at the omega o rate for producing a sinusoidal signal output of omega o + epsilon + phi , phi being the first filter phase shift; and a second switchable filter responsive to the shifted carrier signal switchable at the omega o + epsilon + phi rate by the first fiLter output for passing the omega o + epsilon signal.
Claim 9
Dependent Claim
113 words
A filter arrangement for recovering sinusoidal carrier signal of frequency omega o as shifted by frequency of epsilon , comprising: a source of clock signals of frequency omega o; a first switchable filter responsive to the shifted sinusoidal carrier signal of frequency omega o + epsilon and switchable by the clock signal source at the omega o rate for producing a sinusoidal signal output of omega o + epsilon + phi , phi being the first filter phase shift; and a second switchable filter responsive to the shifted carrier signal switchable at the omega o + epsilon + phi rate by the first fiLter output for passing the omega o + epsilon signal.
References Cited (Backward Citations)
US3403345A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-06-06 | 1975-12-06 | 1976-06-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-06 | 1979-12-06 | 1980-06-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-06 | 1983-12-06 | 1984-06-06 | $7700.00 | Window Closed / Lapsed |