US3829670A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Digital filter to realize efficiently the filtering required when multiplying or dividing the sampling rate of a digital signal by a composite integer
Assignee: Massachusetts Institute of Technology
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Filing: 1972-04-10
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Granted: 1974-08-13
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Expires: 1992-04-10
Abstract
Abstract A digital filter employing a plurality of unit cells connected in cascade. Each unit cell includes a duplicating filter (typically a plurality of boxcar integrators connected in cascade). A switch is connected between the output of each duplicating filter and the output of the unit cell of which it is a part. The switch is operable to reduce the data rate to a submultiple of the input data rate to the associated duplicating filter, the sub-multiple being equal to the parameter R of the duplicating filter, where R is the number of points in the boxcar integrator impulse response when the duplicating filter is composed of boxcar integrators. In another form the switch is placed between the input to the unit cell and the input to the duplicating filter to increase the data rate and R in this latter situation is the multiple by which the data rate is increased. Two or more digital filters wherein the rate is reduced may be combined to form a band-pass filter or a bank of band-pass filters.
Inventors
- 👤 P Kebabian
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 21:04
CPC Classifications
H; H03; H03H; H03H17/00; H03H17/02; H03H17/0248; H03H17/0264; H03H17/0266; H03H17/04; H03H17/0416; H03H17/0427; H03H17/0438; H03H17/0444; H03H17/045; H03H17/06; H03H17/0621; H03H17/0635; H03H17/065; H03H17/0657; H03H17/0664
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
144 words
A digital filter having, in combination, a plurality of unit cells connected in cascade, each unit cell comprising a plurality of digital boxcar integrators connected in cascade and switch means serially connected between the output of the last boxcar integrator of the cascade in a unit cell and the output of that cell, each unit cell of the filter having the same number of boxcar integrators and each boxcar integrator within a particular cell having the same length, the switch means acting to reduce the data rate to a sub-multiple of the input data rate to the unit cell of which it is a part, data being transmitted from the output of said switch means at said sub-multiple rate, the submultiple being equal to the number of points in the boxcar integrator impulse response of the unit cell of which it is a part.
Claim 2
Dependent Claim
144 words
A digital filter having, in combination, a plurality of unit cells connected in cascade, each unit cell comprising a plurality of digital boxcar integrators connected in cascade and switch means serially connected between the output of the last boxcar integrator of the cascade in a unit cell and the output of that cell, each unit cell of the filter having the same number of boxcar integrators and each boxcar integrator within a particular cell having the same length, the switch means acting to reduce the data rate to a sub-multiple of the input data rate to the unit cell of which it is a part, data being transmitted from the output of said switch means at said sub-multiple rate, the submultiple being equal to the number of points in the boxcar integrator impulse response of the unit cell of which it is a part.
Claim 3
Dependent Claim
23 words
A digital filter as claimed in claim 1 in which the boxcar integrators each comprise at least one shift register and one adder.
Claim 4
Dependent Claim
155 words
A digital filter having, in combination, a plurality of unit cells connected in cascade, each unit cell comprising a long shift register, a short shift register, an adder, first switch means, and further switch means, said further switch means having two inputs and one output connected to permit an input number to enter the adder and the long shift register, the adder having one of its inputs connected to the input to the long shift register, the other input to the adder being connected to receive the output of the long shift register, the output of the adder being connected as the input to the short shift register and the output of the short shift register being connected to one input of the further switch means and also through the first switch means to the output of the unit cell, the unit cell input being connected to the other input of the further switch means.
Claim 5
Dependent Claim
155 words
A digital filter having, in combination, a plurality of unit cells connected in cascade, each unit cell comprising a long shift register, a short shift register, an adder, first switch means, and further switch means, said further switch means having two inputs and one output connected to permit an input number to enter the adder and the long shift register, the adder having one of its inputs connected to the input to the long shift register, the other input to the adder being connected to receive the output of the long shift register, the output of the adder being connected as the input to the short shift register and the output of the short shift register being connected to one input of the further switch means and also through the first switch means to the output of the unit cell, the unit cell input being connected to the other input of the further switch means.
Claim 6
Dependent Claim
146 words
A digital filter having, in combination, a plurality of unit cells connected in cascade, each unit cell comprising a plurality of digital boxcar integrators connected in cascade and switch means serially connected between the input to the unit cell and the input to the first boxcar integrator of the cascade in a unit cell, each unit cell of the filter having the same number of boxcar integrators and each boxcar integrator within a particular cell having the same length, the switch means acting to increase the data rate to a multiple of the input data rate to the unit cell of which it is a part, data being transmitted from the output of said switch means at said multiple data rate, the multiple being equal to the number of points in the boxcar integrator inpulse response of the unit cell of which it is a part.
Claim 7
Dependent Claim
146 words
A digital filter having, in combination, a plurality of unit cells connected in cascade, each unit cell comprising a plurality of digital boxcar integrators connected in cascade and switch means serially connected between the input to the unit cell and the input to the first boxcar integrator of the cascade in a unit cell, each unit cell of the filter having the same number of boxcar integrators and each boxcar integrator within a particular cell having the same length, the switch means acting to increase the data rate to a multiple of the input data rate to the unit cell of which it is a part, data being transmitted from the output of said switch means at said multiple data rate, the multiple being equal to the number of points in the boxcar integrator inpulse response of the unit cell of which it is a part.
Claim 8
Dependent Claim
143 words
A digital filter adapted to act upon a time series of numbers to effect a total change in the data rate of the numbers as a plurality of smaller changes and having, in combination, a plurality of unit cells connected in cascade, each unit cell comprising a plurality of digital boxcar integrators connected in cascade, each unit cell having the same number of digital boxcar integrators in cascade and each digital boxcar integrator within a unit cell having the same number of points in its impulse response, and switch means, the switch means being connected in series with the cascade of boxcar integrators to provide an output data rate from each unit cell that differs from the input data ratE to that particular cell, the combined changes in data rate of the cascade of unit cells being said total change in data rate.
Claim 9
Dependent Claim
143 words
A digital filter adapted to act upon a time series of numbers to effect a total change in the data rate of the numbers as a plurality of smaller changes and having, in combination, a plurality of unit cells connected in cascade, each unit cell comprising a plurality of digital boxcar integrators connected in cascade, each unit cell having the same number of digital boxcar integrators in cascade and each digital boxcar integrator within a unit cell having the same number of points in its impulse response, and switch means, the switch means being connected in series with the cascade of boxcar integrators to provide an output data rate from each unit cell that differs from the input data ratE to that particular cell, the combined changes in data rate of the cascade of unit cells being said total change in data rate.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-08-12 | 1978-02-11 | 1978-08-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-08-12 | 1982-02-11 | 1982-08-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-08-12 | 1986-02-11 | 1986-08-13 | $7700.00 | Window Closed / Lapsed |