US4130806A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Filter and demodulation arrangement
Assignee: US Philips Corp
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Filing: 1977-05-23
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Granted: 1978-12-19
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Expires: 1997-05-23
Abstract
Abstract A digital filter and demodulation arrangement for passband signals, whose corresponding baseband signal has a bandwidth limited to a given maximum frequency. The passband signals are filtered according to two bandpass characteristics which, apart from their asymmetrical distortion relative to their central frequency, are versions from one another shifted 90° in phase. The filtered passband signals are demodulated with an in-phase carrier and a quadrature carrier and the demodulated signals are combined to a baseband signal. In the digital filtering process the sampling frequency is reduced from a value higher than twice the highest frequency in the passband signals to a value which is not higher than twice said maximum frequency in the baseband signal and in the digital demodulation and combination processes the reduced sampling frequency is also used so that a considerable reduction in the internal processing speed is obtained.
Inventors
- 👤 Petrus J. VAN Gerwen
- 👤 Rudolf A. Van Doorn
- 👤 Wilfred A. M. Snijders
- 👤 Hendrik A. VAN Essen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 13:50
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/02; H04L27/06; H03; H03D; H03D3/00; H03D3/007; H03D5/00; H03D2200/00; H03D2200/0041; H03D2200/0047; H03D2200/0054; H03D2200/0056; H03D2200/006; H03D2200/0082; H03D7/00; H03D7/16; H03D7/165
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
212 words
An arrangement for filtering and demodulating passband signals which are obtained by modulating a carrier in accordance with a baseband signal whose bandwidth is limited to a given maximum frequency, said arrangement comprising means for filtering the passband signals according to a first and a second bandpass characteristic for generating first and second filtered passband signals, which bandpass characteristics apart from the asymmetrical distortion relative to their central frequency are versions of one another shifted 90° in phase, means for demodulating the first and second filtered passband signals with an inphase carrier and a quadrature carrier respectively for generating first and second demodulated signals, means for combining the first and second demodulated signals, all said means for filtering, demodulating and combining being digital means, the digital filter means including means for sampling frequency reduction for converting signal samples of the passband signals occurring with a first sampling frequency which is higher than twice the highest frequency in the passband signals into signal samples of the first and second filtered passband signals occurring with a second sampling frequency which is not higher than twice said maximum frequency of the baseband signal, and the digital means for demodulating and combining each include means for processing signal samples occurring with the same second sampling frequency.
Claim 2
Dependent Claim
212 words
An arrangement for filtering and demodulating passband signals which are obtained by modulating a carrier in accordance with a baseband signal whose bandwidth is limited to a given maximum frequency, said arrangement comprising means for filtering the passband signals according to a first and a second bandpass characteristic for generating first and second filtered passband signals, which bandpass characteristics apart from the asymmetrical distortion relative to their central frequency are versions of one another shifted 90° in phase, means for demodulating the first and second filtered passband signals with an inphase carrier and a quadrature carrier respectively for generating first and second demodulated signals, means for combining the first and second demodulated signals, all said means for filtering, demodulating and combining being digital means, the digital filter means including means for sampling frequency reduction for converting signal samples of the passband signals occurring with a first sampling frequency which is higher than twice the highest frequency in the passband signals into signal samples of the first and second filtered passband signals occurring with a second sampling frequency which is not higher than twice said maximum frequency of the baseband signal, and the digital means for demodulating and combining each include means for processing signal samples occurring with the same second sampling frequency.
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) | 1981-12-18 | 1982-06-19 | 1982-12-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-12-18 | 1986-06-19 | 1986-12-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-12-18 | 1990-06-19 | 1990-12-19 | $7700.00 | Window Closed / Lapsed |