US3797038A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Data or audio recording and playback apparatus
Assignee: BETTRONE ELCTRONICS CORP
•
Filing: 1971-04-29
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Granted: 1974-03-12
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Expires: 1991-04-29
Abstract
Abstract Apparatus for recording and playing back either data or audio signals by use of modified pulse width modulation techniques. Triangular-shaped signals produced by a carrier generator are combined with data signals in a modulator to produce width modulated pulses containing data information that are recorded by a record head. Pulses containing audio information are also produced in the foregoing manner. However, the pulses are modified by use of a waveform modifying device that causes the peak value of the current conducted through the record head to vary in proportion to the width of the pulses produced by modulation. Recorded audio signals are picked up by a playback head and passed through an integrating amplifier and a shaper circuit which correct the frequency response characteristic of the record-playback process and reproduce the original audio signals. Recorded pulses containing data information are also played back through the playback head, integrating amplifier and shaper circuit to partially reconstruct the width modulated pulses originally produced for recording purposes. A restoring circuit that reduces the transition time of the partially reconstructed pulses is also employed. The pulses produced by the restoring circuit are filtered by a low pass filter to reproduce the original data signals.
Inventors
- 👤 R Brander
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 01:08
CPC Classifications
H; H03; H03K; H03K7/00; H03K7/08; G; G11; G11B; G11B20/00; G11B20/02; G11B20/08; H03F; H03F3/00; H03F3/45; H03F3/45071
Claims Analysis
Total Claims: 35
Claim 1
Independent Claim
410 words
In a recorder, improved apparatus for accurately recording on a recording medium data information occurring over a predetermined bandwidth extending to zero fre-quency in the form of modulated pulses, said apparatus comprising in combination: input means for receiving data signals containing the data information; generator means for producing a carrier signal at a carrier frequency; modulator means comprising a first switch device having a first input terminal, a second input terminal and a first output terminal and comprising a second switch device having a third input terminal, a fourth input terminal and a second output terminal, said first and second switch devices being arranged as a difference amplifier in which the second and fourth input terminals are biased by a common constant current source, the first input terminal is connected to the generator means and the third input terminal is connected to the input means so that the first switch device is switched to a conductive state and the second switch device is switched to a non-conductive state as the magnitude of the data signal exceeds the magnitude of the carrier signal and so that the first switch device is switched to a non-conductive state and the second switch device is switched to a conductive state as the magnitude of the carrier signal exceeds the magnitude of the data signal; A record head having a first terminal and a second terminal, said record head being adapted to record signals on the recording medium; and driver means connected between said modulator means and said record head, said driver means comprising a first current path extending from a source of voltage to said first terminal, a second current path extending from said source of voltage to said second terminal, a third switch device operatively connected between said first current path and a voltage sink and having an input terminal connected to the first output terminal of the first switch device and a fourth switch device operatively connected between said second current path and a voltage sink and having an input terminal connected to the second output terminal of the second switch device, whereby said modulator means drives said third and fourth switch devices in phase opposition so that current is conducted through the third switch device and through the record head in one direction during a first time period and current is conducted through the fourth switch device and through the record head in the opposite direction during a second time period.
Claim 2
Dependent Claim
410 words
In a recorder, improved apparatus for accurately recording on a recording medium data information occurring over a predetermined bandwidth extending to zero fre-quency in the form of modulated pulses, said apparatus comprising in combination: input means for receiving data signals containing the data information; generator means for producing a carrier signal at a carrier frequency; modulator means comprising a first switch device having a first input terminal, a second input terminal and a first output terminal and comprising a second switch device having a third input terminal, a fourth input terminal and a second output terminal, said first and second switch devices being arranged as a difference amplifier in which the second and fourth input terminals are biased by a common constant current source, the first input terminal is connected to the generator means and the third input terminal is connected to the input means so that the first switch device is switched to a conductive state and the second switch device is switched to a non-conductive state as the magnitude of the data signal exceeds the magnitude of the carrier signal and so that the first switch device is switched to a non-conductive state and the second switch device is switched to a conductive state as the magnitude of the carrier signal exceeds the magnitude of the data signal; A record head having a first terminal and a second terminal, said record head being adapted to record signals on the recording medium; and driver means connected between said modulator means and said record head, said driver means comprising a first current path extending from a source of voltage to said first terminal, a second current path extending from said source of voltage to said second terminal, a third switch device operatively connected between said first current path and a voltage sink and having an input terminal connected to the first output terminal of the first switch device and a fourth switch device operatively connected between said second current path and a voltage sink and having an input terminal connected to the second output terminal of the second switch device, whereby said modulator means drives said third and fourth switch devices in phase opposition so that current is conducted through the third switch device and through the record head in one direction during a first time period and current is conducted through the fourth switch device and through the record head in the opposite direction during a second time period.
Claim 3
Dependent Claim
223 words
In a playback unit, improved apparatus for reproducing over a predetermined bandwidth extending to zero frequency data information signals recorded on a recording medium in the form of width modulated pulses, said apparatus comprising in combination: a playback head for receiving recorded pulses from the recording medium; an amplifier connected to said playback head, said amplifier having a frequency response characteristic which compensates for the frequency response characteristic of the playback head; shaper means connected to said amplifier for subtracting from the amplified pulses a signal corresponding to the second derivative of said amplified pulses to compensate for frequency dependent losses in the record-playback process and thereby to produce shaped pulses more nearly corresponding to the originally recorded pulses; restoring means connected to said shaper means comprising clamping means for determining the mid-point voltage midway between the maximum and minimum voltages exhibited by each of said shaped pulses and further comprising trigger means for producing one output state when the pulse voltage is greater than the mid-point voltage and for producing a second output state when the pulse voltage is less than the mid-point voltage; a low pass filter connected to said restoring means for producing a signal corresponding to the original data signal from said restored pulses; and output means connected to said low pass filter for delivering said reproduced data signals.
Claim 4
Dependent Claim
223 words
In a playback unit, improved apparatus for reproducing over a predetermined bandwidth extending to zero frequency data information signals recorded on a recording medium in the form of width modulated pulses, said apparatus comprising in combination: a playback head for receiving recorded pulses from the recording medium; an amplifier connected to said playback head, said amplifier having a frequency response characteristic which compensates for the frequency response characteristic of the playback head; shaper means connected to said amplifier for subtracting from the amplified pulses a signal corresponding to the second derivative of said amplified pulses to compensate for frequency dependent losses in the record-playback process and thereby to produce shaped pulses more nearly corresponding to the originally recorded pulses; restoring means connected to said shaper means comprising clamping means for determining the mid-point voltage midway between the maximum and minimum voltages exhibited by each of said shaped pulses and further comprising trigger means for producing one output state when the pulse voltage is greater than the mid-point voltage and for producing a second output state when the pulse voltage is less than the mid-point voltage; a low pass filter connected to said restoring means for producing a signal corresponding to the original data signal from said restored pulses; and output means connected to said low pass filter for delivering said reproduced data signals.
Claim 5
Dependent Claim
95 words
Apparatus, as claimed in claim 2, wherein the clamping means comprises: a first clamping circuit wherein the positive peaks of the shaped pulses are clamped to a first predetermined DC voltage; a second clamping circuit wherein the negative peaks of the shaped pulses are clamped to a second predetermined DC voltage; and summing means for producing an output signal proportional to the sum of the signals produced by the first and second clamping circuits such that the output signal exhibits equal positive and negative excursions about a fixed reference level corresponding to the mid-point voltage.
Claim 6
Dependent Claim
26 words
Apparatus, as claimed in claim 2, wherein the trigger means is a zero hysteresis bistable trigger network designed to become astable when no signal is present.
Claim 7
Dependent Claim
50 words
Apparatus, as claimed in claim 2, wherein said shaper means comprises: an input terminal and an output terminal; an inductor connected between the input and output terminals; an inverting amplifier connected to the input terminal; and a capacitor connected between the output of the inverting amplifier and the output terminal.
Claim 8
Dependent Claim
29 words
Apparatus, as claimed in claim 5, wherein shaper means further comprises: means for damping out resonances and for reducing the gain of the inverting amplifier above a predetermined frequency.
Claim 9
Dependent Claim
134 words
In a playback unit, improved apparatus for reproducing over a predetermined bandwidth extending to zero frequency data information signals recorded on a recording medium in the form of modulated pulses, said apparatus comprising in combination: a playback head for receiving recorded pulses from the recording medium; an amplifier connected to said playback head, said amplifier having a frequency response characteristic which compensates for the frequency response characteristic of the playback head; shaper means connected to said amplifier for subtracting from the amplified pulses a signal corresponding to the second derivative of the amplified pulses to produce shaped pulses more nearly corresponding to the originally-recorded pulses; restoring means for converting said shaped pulses into reproduced signals corresponding to the original data signals; and output means connected to said restoring means for deliverIng said reproduced signals.
Claim 10
Dependent Claim
134 words
In a playback unit, improved apparatus for reproducing over a predetermined bandwidth extending to zero frequency data information signals recorded on a recording medium in the form of modulated pulses, said apparatus comprising in combination: a playback head for receiving recorded pulses from the recording medium; an amplifier connected to said playback head, said amplifier having a frequency response characteristic which compensates for the frequency response characteristic of the playback head; shaper means connected to said amplifier for subtracting from the amplified pulses a signal corresponding to the second derivative of the amplified pulses to produce shaped pulses more nearly corresponding to the originally-recorded pulses; restoring means for converting said shaped pulses into reproduced signals corresponding to the original data signals; and output means connected to said restoring means for deliverIng said reproduced signals.
Claim 11
Dependent Claim
50 words
Apparatus, as claimed in claim 7, wherein the shaper means comprises: an input terminal and an output terminal; an inductor connected between the input and output terminals; an inverting amplifier connected to the input terminal; and a capacitor connected between the output of the inverting amplifier and the output terminal.
Claim 12
Dependent Claim
30 words
Apparatus, as claimed in claim 8, wherein the shaper means further comprises: means for damping out resonances and for reducing the gain of the inverting amplifier above a predetermined frequency.
Claim 13
Dependent Claim
201 words
In a playback unit, improved apparatus for reproducing over a predetermined bandwidth extending to zero frequency data information recorded on a recording medium in the form of modulated pulses, said apparatus comprising in combination: a playback head for receiving recorded pulses from the recording medium; first means connected to said playback head for altering the waveform of the playback signals produced by the playback head by compensating for the frequency response characteristic of the playback head and by subtracting from said playback signals a signal corresponding to the second derivative of said playback signals to produce shaped pulses more nearly corresponding to the originally recorded pulses; restoring means connected to said first means comprising clamping means for determining the mid-point voltage midway between the maximum and minimum voltages exhibited by each of said shaped pulses and further comprising trigger means for producing one output state when the pulse voltage is greater than the mid-point voltage and for producing a second output state when the pulse voltage is less than the mid-point voltage; second means for converting the restored pulses into reproduced signals corresponding to the original data information; and output means connected to said second means for delivering said reproduced signals.
Claim 14
Dependent Claim
201 words
In a playback unit, improved apparatus for reproducing over a predetermined bandwidth extending to zero frequency data information recorded on a recording medium in the form of modulated pulses, said apparatus comprising in combination: a playback head for receiving recorded pulses from the recording medium; first means connected to said playback head for altering the waveform of the playback signals produced by the playback head by compensating for the frequency response characteristic of the playback head and by subtracting from said playback signals a signal corresponding to the second derivative of said playback signals to produce shaped pulses more nearly corresponding to the originally recorded pulses; restoring means connected to said first means comprising clamping means for determining the mid-point voltage midway between the maximum and minimum voltages exhibited by each of said shaped pulses and further comprising trigger means for producing one output state when the pulse voltage is greater than the mid-point voltage and for producing a second output state when the pulse voltage is less than the mid-point voltage; second means for converting the restored pulses into reproduced signals corresponding to the original data information; and output means connected to said second means for delivering said reproduced signals.
Claim 15
Dependent Claim
95 words
Apparatus, as claimed in claim 10, wherein the clamping means comprises: a first clamping circuit wherein the positive peaks of the shaped pulses are clamped to a first predetermined DC voltage; a second clamping circuit wherein the negative peaks of the shaped pulses are clamped to a second predetermined DC voltage; and summing means for producing an output signal proportional to the sum of the signals produced by the first and second clamping circuits such that the output signal exhibits equal positive and negative excursions about a fixed reference level corresponding to the midpoint voltage.
Claim 16
Dependent Claim
26 words
Apparatus, as claimed in claim 10, wherein the trigger means is a zero hysteresis bistable trigger network designed to become astable when no signal is present.
Claim 17
Dependent Claim
220 words
In a playback unit, improved apparatus for reproducing over a predetermined bandwidth extending to zero frequency data information signals recorded on a recording medium in the form of modulated pulses, said apparatus comprising in combination: a playback head for receiving recorded pulses from the recording medium; an amplifier connected to said playback head for producing amplified pulses, said amplifier having a frequency response characteristic which compensates for the frequency response characteristic of the playback head; shaper means connected to said amplifier for subtracting from the amplified pulses a signal corresponding to the second derivative of said amplified pulses to compensate for frequency dependent loses in the record-playback process and thereby to produce shaped pulses more nearly corresponding to the originally recorded pulses; restoring means connected to said shaper means comprising clamping means for determining the mid-point voltage between the maximum and minimum voltages exhibited by each of said shaped pulses and further comprising trigger means for producing one output state when the pulse voltage is greater than the mid-point voltage and for producing a second output state when the pulse voltage is Less than the mid-point voltage; means for converting the restored pulses into reproduced data signals corresponding to the original data signals; and output means connected to said means for converting in order to transmit the reproduced data signals.
Claim 18
Dependent Claim
220 words
In a playback unit, improved apparatus for reproducing over a predetermined bandwidth extending to zero frequency data information signals recorded on a recording medium in the form of modulated pulses, said apparatus comprising in combination: a playback head for receiving recorded pulses from the recording medium; an amplifier connected to said playback head for producing amplified pulses, said amplifier having a frequency response characteristic which compensates for the frequency response characteristic of the playback head; shaper means connected to said amplifier for subtracting from the amplified pulses a signal corresponding to the second derivative of said amplified pulses to compensate for frequency dependent loses in the record-playback process and thereby to produce shaped pulses more nearly corresponding to the originally recorded pulses; restoring means connected to said shaper means comprising clamping means for determining the mid-point voltage between the maximum and minimum voltages exhibited by each of said shaped pulses and further comprising trigger means for producing one output state when the pulse voltage is greater than the mid-point voltage and for producing a second output state when the pulse voltage is Less than the mid-point voltage; means for converting the restored pulses into reproduced data signals corresponding to the original data signals; and output means connected to said means for converting in order to transmit the reproduced data signals.
Claim 19
Dependent Claim
173 words
In a recorder, improved apparatus for recording audio signals on a recording medium in analog form, comprising in combination: input means for receiving said audio signals; generator means for producing a triangle carrier wave at a carrier frequency; modulator means connected to said generator means and to said input means for producing at an output conductor width modulated rectangular pulses at the carrier frequency; a record head having a first terminal and a second terminal, said record head being adapted to record signals on a recording medium; driver means having an input conductor operatively connected to the output conductor of the modulator means, said driver means also having output conductors connected to the first and second terminals of the record head for conducting current through said record head in response to said rectangular pulses; and waveform modifying means connected across the first and second terminals of said record head for causing the peak value of the current conducted through said record head to vary in proportion to the width of said rectangular pulses.
Claim 20
Dependent Claim
173 words
In a recorder, improved apparatus for recording audio signals on a recording medium in analog form, comprising in combination: input means for receiving said audio signals; generator means for producing a triangle carrier wave at a carrier frequency; modulator means connected to said generator means and to said input means for producing at an output conductor width modulated rectangular pulses at the carrier frequency; a record head having a first terminal and a second terminal, said record head being adapted to record signals on a recording medium; driver means having an input conductor operatively connected to the output conductor of the modulator means, said driver means also having output conductors connected to the first and second terminals of the record head for conducting current through said record head in response to said rectangular pulses; and waveform modifying means connected across the first and second terminals of said record head for causing the peak value of the current conducted through said record head to vary in proportion to the width of said rectangular pulses.
Claim 21
Dependent Claim
45 words
Apparatus, as claimed in claim 14, wherein the modulator means comprises a comparator for producing a first output state when the audio signal is greater than the triangle wave and producing a second output state when the audio signal is less than the triangle wave.
Claim 22
Dependent Claim
101 words
Apparatus, as claimed in claim 14, wherein the driver means comprises a first switch device operatively connected to the first terminal of the record head and a second switch device operatively connected to the second terminal of the record head, and wherein said modulator means drives said first and second switch devices in phase opposition so that current is conducted through the first switch device and through the record head in one direction during a first time period and current is conducted through the second switch device and through the record head in the opposite direction during a second time period.
Claim 23
Dependent Claim
21 words
Apparatus, as claimed in claim 14, wherein the waveform modifying means comprises a capacitor connected in parallel with the record head.
Claim 24
Dependent Claim
110 words
In a recorder, improved apparatus for recording audio signals on a recording medium in analog form, comprising in combination: input means for receiving said audio signals; modulator means connected to said input means for producing modulated rectangular pulses at a carrier frequency, said carrier frequency being higher than the range of frequencies effectively recorded on the recording medium; a record head adapted to record signals on the recording medium; and waveform modifying means connected between said modulator means and said record head for attenuating frequencies above the carrier frequency, whereby the envelope of the current conducted through said record head varies in proportion to the width of said rectangular pulses.
Claim 25
Dependent Claim
110 words
In a recorder, improved apparatus for recording audio signals on a recording medium in analog form, comprising in combination: input means for receiving said audio signals; modulator means connected to said input means for producing modulated rectangular pulses at a carrier frequency, said carrier frequency being higher than the range of frequencies effectively recorded on the recording medium; a record head adapted to record signals on the recording medium; and waveform modifying means connected between said modulator means and said record head for attenuating frequencies above the carrier frequency, whereby the envelope of the current conducted through said record head varies in proportion to the width of said rectangular pulses.
Claim 26
Dependent Claim
21 words
Apparatus, as claimed in claim 18, wherein the waveform modifying means comprises a capacitor connected in parallel with the record head.
Claim 27
Dependent Claim
123 words
In a playback unit, improved apparatus for reproducing audio signals recorded on a recording medium in analog form, said apparatus comprising in combination: a playback head for receiving recorded signals from the recording medium; amplifier means connected to said playback head, said amplifier means having a frequency response characteristic with compensates for the frequency dependence of the basic transducer ratio of the playback head; shaper means connected to said amplifier means for subtracting from the amplified signals another signal corresponding to the second derivative of said amplified signals to compensate for the frequency dependent losses in the record-playback process, thereby producing a more accurate reproduction of said audio signals; and output means connected to said shaper means for delivering said reproduced audio signals.
Claim 28
Dependent Claim
123 words
In a playback unit, improved apparatus for reproducing audio signals recorded on a recording medium in analog form, said apparatus comprising in combination: a playback head for receiving recorded signals from the recording medium; amplifier means connected to said playback head, said amplifier means having a frequency response characteristic with compensates for the frequency dependence of the basic transducer ratio of the playback head; shaper means connected to said amplifier means for subtracting from the amplified signals another signal corresponding to the second derivative of said amplified signals to compensate for the frequency dependent losses in the record-playback process, thereby producing a more accurate reproduction of said audio signals; and output means connected to said shaper means for delivering said reproduced audio signals.
Claim 29
Dependent Claim
50 words
Apparatus, as claimed in claim 20, wherein the shaper means comprises: an input terminal and an output terminal; an inductor connected between the input and output terminals; an inverting amplifier connected to the input terminal; and a capacitor connected between the output of the inverting amplifier and the output terminal.
Claim 30
Dependent Claim
30 words
Apparatus, as claimed in claim 21, wherein the shaper means further comprises: means for damping out resonances and for reducing the gain of the inverting amplifier above a predetermined frequency.
Claim 31
Dependent Claim
317 words
In a recorder, improved apparatus for accurately recording on a recording medium data signals occurring over a predetermined bandwidth extending to zero frequency in the form of width modulated pulses and for recording audio signals on a recording medium in analog form, said apparatus comprising in combination: second input means for receiving the audio signals; first generator means for producing a first triangle wave carrier signal at a first predetermined carrier frequency; second generator means for producing a second triangle wave carrier signal at a second predetermined carrier frequency that is higher than the first predetermined carrier frequency; modulator means connected to said input means; first switch means for conducting the first triangle wave carrier signal to the modulator means during the recording of data signals in order to produce a first set of width modulated rectangular pulses at the first predetermined carrier frequency; second switch means for conducting the second triangle wave carrier signal to the modulator means during the recording of audio signals in order to produce a second set of width modulated rectangular pulses at the second predetermined carrier frequency; a record head having a first terminal and a second terminal, said record head being adapted to record signals on the recording medium; driver means connected between said modulator means and said record head for conducting current through said record head in response to said width modulated rectangular pulses; and waveform modifying means coupled to said record head for causing the peak value of the current pulses conducted through said record head during recording of audio signals to vary in proportion to the width of each pulse in the second set of width modulated rectangular pulses and for causing the width of the current pulses conducted through said record head during recording of data signals to vary in proportion to the width of each pulse in the first set of width modulated rectangular pulses.
Claim 32
Dependent Claim
317 words
In a recorder, improved apparatus for accurately recording on a recording medium data signals occurring over a predetermined bandwidth extending to zero frequency in the form of width modulated pulses and for recording audio signals on a recording medium in analog form, said apparatus comprising in combination: second input means for receiving the audio signals; first generator means for producing a first triangle wave carrier signal at a first predetermined carrier frequency; second generator means for producing a second triangle wave carrier signal at a second predetermined carrier frequency that is higher than the first predetermined carrier frequency; modulator means connected to said input means; first switch means for conducting the first triangle wave carrier signal to the modulator means during the recording of data signals in order to produce a first set of width modulated rectangular pulses at the first predetermined carrier frequency; second switch means for conducting the second triangle wave carrier signal to the modulator means during the recording of audio signals in order to produce a second set of width modulated rectangular pulses at the second predetermined carrier frequency; a record head having a first terminal and a second terminal, said record head being adapted to record signals on the recording medium; driver means connected between said modulator means and said record head for conducting current through said record head in response to said width modulated rectangular pulses; and waveform modifying means coupled to said record head for causing the peak value of the current pulses conducted through said record head during recording of audio signals to vary in proportion to the width of each pulse in the second set of width modulated rectangular pulses and for causing the width of the current pulses conducted through said record head during recording of data signals to vary in proportion to the width of each pulse in the first set of width modulated rectangular pulses.
Claim 33
Dependent Claim
21 words
Apparatus, as claimed in claim 23, wherein the waveform modifying means comprises a capacitor connected in parallel with the record head.
Claim 34
Dependent Claim
255 words
In a playback unit, improved apparatus for accurately reproducing data signals recorded on a recording medium in the form of width modulated pulses and for reproducing audio signals recorded on a recording medium in direct form, said apparatus comprising in combination: a playback head for receiving recorded signals from the recording medium; an amplifier connected to said playback head, said amplifier having a frequency response characteristic which compensates for the frequency dependence of the basic transducer ratio of the playback head; shaper means connected to said amplifier for subtracting from the amplified signal another signal corresponding to the second derivative of said amplified signal to compensate for the frequency dependent losses in the record-playback process, thereby producing a more accurate reproduction of the originally recorded data and audio signals; audio signal output means connected to said shaper means for delivering reproduced audio signals; restoring means connected to said shapeR means comprising clamping means for determining the mid-point voltage midway between the maximum and minimum voltages exhibited by each of the shaped pulses and further comprising trigger means for producing a first predetermined voltage when the voltage of the shaped pulses is greater than the midpoint voltage and for producing a second predetermined voltage when the voltage of the shaped pulses is less than the midpoint voltage; a low pass filter connected to said restoring means for producing a signal corresponding to the original data signal from the restored pulses; and data signal output means connected to the low pass filter for delivering reproduced data signals.
Claim 35
Dependent Claim
255 words
In a playback unit, improved apparatus for accurately reproducing data signals recorded on a recording medium in the form of width modulated pulses and for reproducing audio signals recorded on a recording medium in direct form, said apparatus comprising in combination: a playback head for receiving recorded signals from the recording medium; an amplifier connected to said playback head, said amplifier having a frequency response characteristic which compensates for the frequency dependence of the basic transducer ratio of the playback head; shaper means connected to said amplifier for subtracting from the amplified signal another signal corresponding to the second derivative of said amplified signal to compensate for the frequency dependent losses in the record-playback process, thereby producing a more accurate reproduction of the originally recorded data and audio signals; audio signal output means connected to said shaper means for delivering reproduced audio signals; restoring means connected to said shapeR means comprising clamping means for determining the mid-point voltage midway between the maximum and minimum voltages exhibited by each of the shaped pulses and further comprising trigger means for producing a first predetermined voltage when the voltage of the shaped pulses is greater than the midpoint voltage and for producing a second predetermined voltage when the voltage of the shaped pulses is less than the midpoint voltage; a low pass filter connected to said restoring means for producing a signal corresponding to the original data signal from the restored pulses; and data signal output means connected to the low pass filter for delivering reproduced data signals.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-03-11 | 1977-09-10 | 1978-03-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-11 | 1981-09-10 | 1982-03-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-11 | 1985-09-10 | 1986-03-12 | $7700.00 | Window Closed / Lapsed |