US3921073A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Arrangement for carrier recovery in carrier frequency video and data transmission systems
Assignee: Siemens AG
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Filing: 1973-04-23
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Granted: 1975-11-18
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Expires: 1993-04-23
Abstract
Abstract An arrangement for carrier recovery in carrier frequency video and data transmission systems comprising transmitting and receiving converters which operate with over modulation has a suppressed carrier modulator in the transmitting converter with a Nyquist filter connected to its output for creating a vestigial side band and a pre-emphasis circuit connected at the input for strongly damping low frequency signals so that a degree of modulation of less than 100% results in carrier frequency signals. The receiving converter includes a carrier recovery device having a band pass filter followed by a limiter. The limiter is connected to a demodulator and a de-emphasis circuit is connected to the output of the demodulator.
Inventors
- 👤 Guenther Pexa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 08:21
CPC Classifications
H; H03; H03D; H03D1/00; H04; H04B; H04B1/00; H04B1/06; H04B1/16; H04B1/30; H04B1/302; H04B1/68; H04J; H04J1/00; H04J1/02; H04J1/06; H04J1/065
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
224 words
An arrangement for carrier recovery in carrier frequency video and data vestigal side band transmission systems in which over modulation may occur at the transmitting end, comprising: transmitting and receiving converters, said transmitting converter including a source of carrier, a modulator connected to said source, a hybrid connected to said source and to the output of said modulator for providing a carrier and a modulated carrier, a Nyquist filter connected to said hybrid to provide a vestigal side band with a carrier for transmission, and a preemphasis circuit having an information signal input, said preemphasis circuit connected to the input of said modulator for attenuating low frequency signals to provide a level of modulation of less than 100% for frequencies in a frequency region in the vicinity of the carrier, said receiving converter including a demodulator having an input for receiving transmitted signals from said transmitting converter, a device having an input connected to the input of said demodulator for receiving signals transmitted from said transmitting converter to recover the carrier and an output connected to said demodulator to feed the recovered carrier thereto, said device including a bandpass filter connected to the input of said demodulator and a limiter connected to said bandpass filter and having an output connected to said demodulator, and a de-emphasis circuit connected to the output of said demodulator.
Claim 2
Dependent Claim
224 words
An arrangement for carrier recovery in carrier frequency video and data vestigal side band transmission systems in which over modulation may occur at the transmitting end, comprising: transmitting and receiving converters, said transmitting converter including a source of carrier, a modulator connected to said source, a hybrid connected to said source and to the output of said modulator for providing a carrier and a modulated carrier, a Nyquist filter connected to said hybrid to provide a vestigal side band with a carrier for transmission, and a preemphasis circuit having an information signal input, said preemphasis circuit connected to the input of said modulator for attenuating low frequency signals to provide a level of modulation of less than 100% for frequencies in a frequency region in the vicinity of the carrier, said receiving converter including a demodulator having an input for receiving transmitted signals from said transmitting converter, a device having an input connected to the input of said demodulator for receiving signals transmitted from said transmitting converter to recover the carrier and an output connected to said demodulator to feed the recovered carrier thereto, said device including a bandpass filter connected to the input of said demodulator and a limiter connected to said bandpass filter and having an output connected to said demodulator, and a de-emphasis circuit connected to the output of said demodulator.
Claim 3
Dependent Claim
33 words
An arrangement according to claim 1 comprising a clamping circuit in said receiving converter coupled to the output of said de-emphasis circuit for improving the signal to noise ratio by attenuating interference signals.
Claim 4
Dependent Claim
30 words
An arrangement according to claim 2 wherein said pre-emphasis circuit includes means for causing a less attenuation of low frequency signals than the interference signal attenuation of said clamping circuit.
Claim 5
Dependent Claim
41 words
An arrangement according to claim 1, wherein said bandpass filter is an n-path filter and comprising a phase shift circuit in said carrier recovery device having an input for receiving a scanning frequency and an output connected to said n-path filter.
Claim 6
Dependent Claim
15 words
An arrangement according to claim 1, wherein said band pass filter is an n-path filter.
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) | 1978-11-17 | 1979-05-19 | 1979-11-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-17 | 1983-05-19 | 1983-11-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-17 | 1987-05-19 | 1987-11-18 | $7700.00 | Window Closed / Lapsed |