US5115468A
Expired / Lapsed
US
⏱️ 0.0 years remaining
SSB digital modulator
Assignee: Kenwood KK
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Filing: 1990-05-09
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Granted: 1992-05-19
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Expires: 2010-05-09
Abstract
Abstract A digital SSB modulator in which an analog signal such as a vocal signal is temporarily converted to a digital signal, which is then subjected to SSB modulation using digital phase shifters and digital orthogonal amplitude modulators, and the resulting signal is converted back to an analog modulated signal. A digital filter may be provided after each digital phase shifter for eliminating direct-current signal components. Another digital filter may be provided after each digital orthogonal amplitude modulator for eliminating carrier signal components.
Inventors
- 👤 Nobumitsu Asahi
- 👤 Seiji Kawase
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 13:56
CPC Classifications
H; H03; H03C; H03C1/00; H03C1/52; H03C1/60
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
182 words
A digital single sideband modulator for producing a carrier suppressed single sideband signal of a signal bandwidth ΔF and carrier frequency fc, the modulator comprising: an analog to digital converter for converting an analog baseband signal into a digital baseband signal; modulation means for taking a multiplication of the digital baseband signal with two orthogonal carriers to produce a digital signal sideband signal; and a digital to analog converter for converting the digital single sideband signal produced by said modulation means into an analog single sideband signal; wherein said modulation means includes a digital sawtooth filter provided with an n stage delay element and feedback loop, n being an integer equal to or larger than 2 and the frequency response of the filter having dips at a plurality of equally spaced frequencies for suppressing a residual carrier signal component in the digital single sideband signal prior to the conversion by said digital to analog converter and said digital to analog converter converts the digital single sideband signal from which the residual carrier signal component has been suppressed by said digital sawtooth filter.
Claim 2
Dependent Claim
182 words
A digital single sideband modulator for producing a carrier suppressed single sideband signal of a signal bandwidth ΔF and carrier frequency fc, the modulator comprising: an analog to digital converter for converting an analog baseband signal into a digital baseband signal; modulation means for taking a multiplication of the digital baseband signal with two orthogonal carriers to produce a digital signal sideband signal; and a digital to analog converter for converting the digital single sideband signal produced by said modulation means into an analog single sideband signal; wherein said modulation means includes a digital sawtooth filter provided with an n stage delay element and feedback loop, n being an integer equal to or larger than 2 and the frequency response of the filter having dips at a plurality of equally spaced frequencies for suppressing a residual carrier signal component in the digital single sideband signal prior to the conversion by said digital to analog converter and said digital to analog converter converts the digital single sideband signal from which the residual carrier signal component has been suppressed by said digital sawtooth filter.
Claim 3
Dependent Claim
39 words
A digital single sideband modulator according to claim 1, wherein said dips are positioned at frequencies of 0, fs/n, 2fs/n . . . mfs/n, where fs is a sampling frequency, and m is a positive integer less than n/2.
Claim 4
Dependent Claim
66 words
A digital single sideband modulator according to claim 1, wherein said modulation means includes a 90° phase shift means and an orthogonal amplitude multiplier means in a series and said digital sawtooth filter is inserted between the shift means and multiplier means to reduce a DC signal component in the phase shifted digital baseband signal due to an offset error in said analog to digital converter.
Claim 5
Dependent Claim
46 words
A digital single sideband modulator according to claim 1, wherein said digital sawtooth filter is inserted between said modulation means and digital to analog converter to reduce the carrier signal component in the modulated digital signal due to an arithmetic operation error in the modulating means.
Claim 6
Dependent Claim
28 words
A digital single sideband modulator according to claim 1, wherein said n is selected so as to satisfy an inequality of fs/n>ΔF where fs is a sampling frequency.
Claim 7
Dependent Claim
23 words
A digital signal sideband modulator according to claim 5, wherein n is the maximum one among integers which satisfy the inequality of fs/n>ΔF.
Claim 8
Dependent Claim
37 words
A digital single sideband modulator according to claim 1, wherein said carrier frequency fc is either one among frequencies of fs/n, 2fs/n -mfs/n, where m is the maximum positive integer less than n/2 for a preselected n.
Claim 9
Dependent Claim
120 words
A digital single sideband modulator for producing a carrier suppressed single sideband signal of a signal bandwidth ΔF and carrier frequency fc, the modulator comprising: input means for inputting a digital baseband signal; digital sawtooth filter means provided with an n stage delay element and feedback loop, n being an integer equal to or larger than 2 and the frequency response of the filter having dips at a plurality of equally spaced frequencies for eliminating DC components in the input digital baseband signal; and modulation means for taking a multiplication of the digital baseband signal from which the DC components have been eliminated by said digital sawtooth filter means, with two orthogonal carriers to produce a digital single sideband signal.
Claim 10
Dependent Claim
120 words
A digital single sideband modulator for producing a carrier suppressed single sideband signal of a signal bandwidth ΔF and carrier frequency fc, the modulator comprising: input means for inputting a digital baseband signal; digital sawtooth filter means provided with an n stage delay element and feedback loop, n being an integer equal to or larger than 2 and the frequency response of the filter having dips at a plurality of equally spaced frequencies for eliminating DC components in the input digital baseband signal; and modulation means for taking a multiplication of the digital baseband signal from which the DC components have been eliminated by said digital sawtooth filter means, with two orthogonal carriers to produce a digital single sideband signal.
Claim 11
Dependent Claim
126 words
A digital single sideband modulator for producing a carrier suppressed single sideband signal of a signal bandwidth ΔF and carrier frequency fc, the modulator comprising: input means for inputting a digital baseband signal; modulation means for digitally taking a multiplication of the input digital baseband signal with two orthogonal carriers to produce a digital single sideband signal; and a digital sawtooth filter provided with an n stage delay element and feed back loop, n being an integer equal to or larger than 2 and the frequency response of the filter having dips at a plurality of equally spaced frequencies, and in response to the digital single sideband signal produced by said modulation means for eliminating a residual carrier frequency component in the digital single sideband signal.
Claim 12
Dependent Claim
126 words
A digital single sideband modulator for producing a carrier suppressed single sideband signal of a signal bandwidth ΔF and carrier frequency fc, the modulator comprising: input means for inputting a digital baseband signal; modulation means for digitally taking a multiplication of the input digital baseband signal with two orthogonal carriers to produce a digital single sideband signal; and a digital sawtooth filter provided with an n stage delay element and feed back loop, n being an integer equal to or larger than 2 and the frequency response of the filter having dips at a plurality of equally spaced frequencies, and in response to the digital single sideband signal produced by said modulation means for eliminating a residual carrier frequency component in the digital single sideband signal.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-05-19 | 1995-11-18 | 1996-05-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-05-19 | 1999-11-18 | 2000-05-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-05-19 | 2003-11-18 | 2004-05-19 | $7700.00 | Window Closed / Lapsed |