US4125866A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Non-recursive discrete filter
Assignee: US Philips Corp
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Filing: 1977-06-16
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Granted: 1978-11-14
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Expires: 1997-06-16
Abstract
Abstract A non-recursive discrete filter for simultaneously realizing for example two band-pass filter characteristics starting from a given lowpass transfer characteristic, wherein one bandpass filter has an in-phase transfer characteristic and the other filter the quadrature transfer characteristic of this in-phase filter. The central frequency of these filters is fo and the output sampling frequency is fs = 8fo. This discrete filter comprises multiplying means in which input signal samples x(n) are modified by an associated filter coefficient a(i) for generating modified input signal samples z(n,i) = a(i)x(n-i). The coefficients a(i) are the same for both transfer characteristics and are given by: a(i) = h1(i) ¦ cos ( pi i/4) ¦ for cos( pi i/4) NOTEQUAL 0 a(i) = h 1(i) ¦ sin ( pi i/4) ¦ for cos( pi i/4) = 0 WHEREIN H1(I) REPRESENTS THE DISCRETE IMPULSE RESPONSE OF THE LOWPASS FILTER.
Inventors
- 👤 Hendrik A. VAN Essen
- 👤 Petrus J. VAN Gerwen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 04:35
CPC Classifications
H; H03; H03H; H03H17/00; H03H17/02; H03H17/06
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
245 words
A non-recursive discrete filter for processing input signal samples x(m) to generate output signal samples y(n) occurring at a predetermined output sampling frequency f s , said discrete filter having a transfer characteristic with a center frequency f o , where f s = 8f o , said transfer characteristic being related to the transfer characteristic of a predetermined lowpass filter with an impulse response h 1 (i), said discrete filter comprising input means for receiving said input signal samples x(m); first storage means for storing and supplying a given number of input signal samples x(m); second storage means for storing and supplying filter coefficients a(i), where: ##EQU12## first multiplying means for modifying each input signal sample from said first storage means by a corresponding filter coefficient from said second storage means to generate modified input signal samples z(n,i) = a(i)x(n- i); second multiplying means for modifying the modified signal samples z(n,i) from said first multiplying means by a coefficient sgn{cos(π i/4)} to generate signal samples of the form z(n,i) sgn{cos(π i/4)}; third multiplying means for modifying the modified signal sampls z(n,i) from said first multiplying means by a coefficient sgn{sin(π i/4)} to generate signal samples of the form z(n,i) sgn{sin(π i/4); first summing means connected to the output of said second multiplying means for generating output signal samples of the form ##EQU13## and second summing means connected to the output of said third multiplying means for generating output signal samples of the form ##EQU14##
Claim 2
Dependent Claim
245 words
A non-recursive discrete filter for processing input signal samples x(m) to generate output signal samples y(n) occurring at a predetermined output sampling frequency f s , said discrete filter having a transfer characteristic with a center frequency f o , where f s = 8f o , said transfer characteristic being related to the transfer characteristic of a predetermined lowpass filter with an impulse response h 1 (i), said discrete filter comprising input means for receiving said input signal samples x(m); first storage means for storing and supplying a given number of input signal samples x(m); second storage means for storing and supplying filter coefficients a(i), where: ##EQU12## first multiplying means for modifying each input signal sample from said first storage means by a corresponding filter coefficient from said second storage means to generate modified input signal samples z(n,i) = a(i)x(n- i); second multiplying means for modifying the modified signal samples z(n,i) from said first multiplying means by a coefficient sgn{cos(π i/4)} to generate signal samples of the form z(n,i) sgn{cos(π i/4)}; third multiplying means for modifying the modified signal sampls z(n,i) from said first multiplying means by a coefficient sgn{sin(π i/4)} to generate signal samples of the form z(n,i) sgn{sin(π i/4); first summing means connected to the output of said second multiplying means for generating output signal samples of the form ##EQU13## and second summing means connected to the output of said third multiplying means for generating output signal samples of the form ##EQU14##
References Cited (Backward Citations)
US3639848A
Cited
US3906347A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-11-13 | 1982-05-15 | 1982-11-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-11-13 | 1986-05-15 | 1986-11-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-11-13 | 1990-05-15 | 1990-11-14 | $7700.00 | Window Closed / Lapsed |