Patent US3793486A successfully refreshed from Google Patents.
US3793486A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Data set system employing active filters and multivibrator timing
Assignee: Individual
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Filing: 1971-01-22
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Granted: 1974-02-19
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Expires: 1991-01-22
Abstract
Abstract A data set capable of converting binary encoded data signals into shift keying modulated signals for transmission over telephone lines. The timing element of the data set is a voltage controlled oscillator which is responsive to the binary encoded input information. The oscillator is adapted to operate at one frequency for the mark or binary one level of the input information and to operate at either one of two higher frequencies for the space or binary zero level of input information. An oscillator control means is responsive to the desired bandwidth and is operable to supply either one of two control voltages to the oscillator to generate either of said space frequencies. Operational amplifiers allow elimination of the conventional inductive components in both high and low pass filters thereby making each section an active filter section instead of being a passive filter. Each active filter section provides gain control which is not available in passive sections.
Inventors
- 👤 L Koziol
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 12:04
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/10
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
281 words
A full duplex data set comprising: transmission means for converting binary encoded direct current level data signals into frequency modulated signals for transmission over a telephone network; receiver means for converting the frequency modulated signals received from the telephone network into direct current level data signals according to the frequency of said received signals; transformer means operatively included in the circuit of said transmission means and separate transformer means operatively included in the circuit of said receiver means and each being operable to connect the circuit with which it is associated to a telephone network for respectively transmitting and receiving frequency modulated signals, bandwidth control means operatively connected to said transmission means and to said receiver means for selecting the frequency range of the signals on the telephone network within the predetermined transmission capabilities of the data set and the telephone network, said bandwidth control means including switch means for providing a plurality of selectable voltage levels for differentiating between mark and space signals according to the selected frequency range, filter means operatively connected to the transformer means included in said transmission means and separate filter means operatively connected to the transformer means included in said receiver means, each said filter means being an inductorless multiple feedback active RC filter having an operational amplifier as the active element therein, and the circuit of said receiver means having a further filter means including a pair of series connected inductorless multiple feedback low pass active RC filters each having an operational amplifier as the active element therein and a frequency rejection filter electrically connected in series with said pair of RC filters for rejecting the second harmonic frequency component of the mark frequency.
Claim 2
Dependent Claim
281 words
A full duplex data set comprising: transmission means for converting binary encoded direct current level data signals into frequency modulated signals for transmission over a telephone network; receiver means for converting the frequency modulated signals received from the telephone network into direct current level data signals according to the frequency of said received signals; transformer means operatively included in the circuit of said transmission means and separate transformer means operatively included in the circuit of said receiver means and each being operable to connect the circuit with which it is associated to a telephone network for respectively transmitting and receiving frequency modulated signals, bandwidth control means operatively connected to said transmission means and to said receiver means for selecting the frequency range of the signals on the telephone network within the predetermined transmission capabilities of the data set and the telephone network, said bandwidth control means including switch means for providing a plurality of selectable voltage levels for differentiating between mark and space signals according to the selected frequency range, filter means operatively connected to the transformer means included in said transmission means and separate filter means operatively connected to the transformer means included in said receiver means, each said filter means being an inductorless multiple feedback active RC filter having an operational amplifier as the active element therein, and the circuit of said receiver means having a further filter means including a pair of series connected inductorless multiple feedback low pass active RC filters each having an operational amplifier as the active element therein and a frequency rejection filter electrically connected in series with said pair of RC filters for rejecting the second harmonic frequency component of the mark frequency.
Claim 3
Dependent Claim
115 words
In a duplex data set according to claim 1 wherein said transmission means comprises: an oscillator operable to generate dual frequency, frequency modulated signals wherein a first frequency is representative of the binary one value of the data signals and a second frequency is representative of the binary zero value of the data signals; oscillator control means adapted to receive binary encoded direct current level data signals and operable to control the frequency of said oscillator according to said signals; means for dividing the frequency of the oscillator output by an integer greater than one; and means for cutting off the operation of the oscillator on a predetermined phase level of the signals generated thereby.
Claim 4
Dependent Claim
42 words
In a data set according to claim 2 wherein said frequency dividing means is a flip flop, and said oscillator cut-off means includes gating means responsive to the concurrent receipt of a disabling signal and a signal at said predetermined phase level.
Claim 5
Dependent Claim
226 words
A data set including, in combination: receiver means for converting the frequency modulated signals received from a telephone network into direct current level data signals according to the frequency of said received signals; transformer means operatively included in the circuit of said receiver means and being operable to connect the same to a telephone network for receiving frequency modulated signals; bandwidth control means operatively connected to said receiver means for selecting the frequency range of the signals on the telephone network within the predetermined transmission capabilities of the data set and the telephone netwoRk, said bandwidth control means including switch means for providing a plurality of selectable voltage levels for differentiating between mark and space signals according to the selected frequency range; filter means included in the circuit of said receiver means and operatively connected to the transformer means, said filter means being an inductorless multiple feedback active RC filter having an operational amplifier as the active element therein; and said receiver means having additional filter means in the circuit thereof including a pair of series connected inductorless multiple feedback low pass active RC filters each having an operational amplifier as the active element therein and further having a frequency rejection filter electrically connected in series with said pair of RC filters and cooperating therewith for rejecting the second harmonic frequency component of the mark frequency.
Claim 6
Dependent Claim
226 words
A data set including, in combination: receiver means for converting the frequency modulated signals received from a telephone network into direct current level data signals according to the frequency of said received signals; transformer means operatively included in the circuit of said receiver means and being operable to connect the same to a telephone network for receiving frequency modulated signals; bandwidth control means operatively connected to said receiver means for selecting the frequency range of the signals on the telephone network within the predetermined transmission capabilities of the data set and the telephone netwoRk, said bandwidth control means including switch means for providing a plurality of selectable voltage levels for differentiating between mark and space signals according to the selected frequency range; filter means included in the circuit of said receiver means and operatively connected to the transformer means, said filter means being an inductorless multiple feedback active RC filter having an operational amplifier as the active element therein; and said receiver means having additional filter means in the circuit thereof including a pair of series connected inductorless multiple feedback low pass active RC filters each having an operational amplifier as the active element therein and further having a frequency rejection filter electrically connected in series with said pair of RC filters and cooperating therewith for rejecting the second harmonic frequency component of the mark frequency.
Claim 7
Dependent Claim
187 words
A data set including, in combination: receiver means for converting the frequency modulated signals received from a telephone network into direct current level data signals according to the frequency of said received signals; transformer means operatively included in the circuit of said receiver means and being operable to connect the same to a telephone network for receiving frequency modulated signals; bandwidth control means operatively connected to said receiver means for selecting the frequency range of the signals on the telephone network within the predetermined capabilities of the data set and the telephone network, said bandwidth control means including switch means for providing a plurality of selectable voltage levels for differentiating between mark and space signals according to the selected frequency range; and filter means operatively included in the circuit of said receiver means, said filter means including a pair of series connected inductorless multiple feedback low pass active RC filters each having an operational amplifier as the active element therein and a frequency rejection filter electrically connected in series with said pair of active RC filters for rejecting the second harmonic frequency component of the mark frequency.
Claim 8
Dependent Claim
187 words
A data set including, in combination: receiver means for converting the frequency modulated signals received from a telephone network into direct current level data signals according to the frequency of said received signals; transformer means operatively included in the circuit of said receiver means and being operable to connect the same to a telephone network for receiving frequency modulated signals; bandwidth control means operatively connected to said receiver means for selecting the frequency range of the signals on the telephone network within the predetermined capabilities of the data set and the telephone network, said bandwidth control means including switch means for providing a plurality of selectable voltage levels for differentiating between mark and space signals according to the selected frequency range; and filter means operatively included in the circuit of said receiver means, said filter means including a pair of series connected inductorless multiple feedback low pass active RC filters each having an operational amplifier as the active element therein and a frequency rejection filter electrically connected in series with said pair of active RC filters for rejecting the second harmonic frequency component of the mark frequency.
Claim 9
Dependent Claim
160 words
A data set including, in combination: receiver means for converting the frequency modulated signals received from a telephone network into direct current level data signals according to the frequency of said received signals; transformer means forming part of the input of said receiver means and being operable to connect the same to the telephone network for receiving frequency modulated signals; first filter means operatively connected to said transformer means, said first filter means including at least one inductorless multiple feedback active RC filter having an operational amplifier as the active element therein; and second filter means forming part of the output of said receiver means and including a pair of series connected inductorless multiple feedback low pass active RC filters each having an operational amplifier as the active element therein and a frequency rejection filter electrically connected in series with said pair of active RC filters and cooperating therewith for rejecting the second harmonic frequency component of the mark frequency.
Claim 10
Dependent Claim
160 words
A data set including, in combination: receiver means for converting the frequency modulated signals received from a telephone network into direct current level data signals according to the frequency of said received signals; transformer means forming part of the input of said receiver means and being operable to connect the same to the telephone network for receiving frequency modulated signals; first filter means operatively connected to said transformer means, said first filter means including at least one inductorless multiple feedback active RC filter having an operational amplifier as the active element therein; and second filter means forming part of the output of said receiver means and including a pair of series connected inductorless multiple feedback low pass active RC filters each having an operational amplifier as the active element therein and a frequency rejection filter electrically connected in series with said pair of active RC filters and cooperating therewith for rejecting the second harmonic frequency component of the mark frequency.
Claim 11
Dependent Claim
51 words
The data set as defined in claim 6 wherein said first filter means comprises a pair of series connected inductorless multiple feedback active RC filters each having an operational amplifier as the active element therein and of which one is a high pass filter and the other a low pass 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) | 1977-02-18 | 1977-08-20 | 1978-02-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-18 | 1981-08-20 | 1982-02-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-18 | 1985-08-20 | 1986-02-19 | $7700.00 | Window Closed / Lapsed |