US4160134A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Digital signal level measurement
Assignee: U S Holding Co Inc
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Filing: 1977-08-25
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Granted: 1979-07-03
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Expires: 1997-08-25
Abstract
Abstract An accurate, low cost and stable digital decibel indicating level meter having a wide amplitude and frequency range in decibels is described having a dynamic range of greater than 80 decibels with high decibel linearity over an extended decibel range. A dual slope integration technique minimizes drift and simplifies calibration, and uses a voltage reference which is compared to an exponentially decaying integration voltage such that when a time duration elapses from the beginning of the discharge to the time when the reference and discharge voltages are equal, the time duration is logarithmically proportional to the voltage being measured. A counter is enabled to provide a digital indication of the signal level measured in decibels, which indication is stored in a latch circuit displayed or coupled out.
Inventors
- 👤 James C. Carroll
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 17:41
CPC Classifications
H; H04; H04B; H04B3/00; H04B3/02; H04B3/46; H04B3/48
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
155 words
An instrument for measuring the level of an input ac electrical signal comprising: rectification means having said ac input signal coupled thereto for deriving a dc voltage having an amplitude which is substantially linearly proportional to the RMS value of said input ac signal; means for providing a reference voltage; integration means having said dc voltage coupled thereto to derive an exponentially decaying integration voltage wherein said integration means comprises a dual slope integrator for generating a ramp voltage having a rate of change of voltage with respect to time which is substantially linearly proportional to the output of said rectification means; means for comparing said reference voltage and said exponentially decaying integration voltage and for generating a comparator output signal when said compared reference voltage and said integration voltage are equal; and logic means for converting said comparator output into a digital indication in decibels of the level of said input ac electrical signal.
Claim 2
Dependent Claim
155 words
An instrument for measuring the level of an input ac electrical signal comprising: rectification means having said ac input signal coupled thereto for deriving a dc voltage having an amplitude which is substantially linearly proportional to the RMS value of said input ac signal; means for providing a reference voltage; integration means having said dc voltage coupled thereto to derive an exponentially decaying integration voltage wherein said integration means comprises a dual slope integrator for generating a ramp voltage having a rate of change of voltage with respect to time which is substantially linearly proportional to the output of said rectification means; means for comparing said reference voltage and said exponentially decaying integration voltage and for generating a comparator output signal when said compared reference voltage and said integration voltage are equal; and logic means for converting said comparator output into a digital indication in decibels of the level of said input ac electrical signal.
Claim 3
Dependent Claim
41 words
An instrument in accordance with claim 1 wherein said integration means includes a integration capacitor through which said ramp voltage is discharged; and means associated with said logic means for generating a control pulse which is determinative of the integration period.
Claim 4
Dependent Claim
47 words
An instrument in accordance with claim 2 wherein the time duration from the initiation of said discharge through said integration capacitor to the time when said discharging voltage is equal to said reference voltage is proportional to the logarithm of the magnitude of said input electrical signal.
Claim 5
Dependent Claim
16 words
An instrument in accordance with claim 3 wherein said input electrical signal is an ac voltage.
Claim 6
Dependent Claim
16 words
An instrument in accordance with claim 4 wherein said ac voltage is a sinusoidal test tone.
Claim 7
Dependent Claim
27 words
An instrument in accordance with claim 4 wherein said dc voltage derived from said rectification means is proportional to the RMS value of said sinusoidal input voltage.
Claim 8
Dependent Claim
27 words
An instrument in accordance with claim 4 further comprising: buffer amplifier means having said input voltage coupled thereto and having an output coupled to said rectification means.
Claim 9
Dependent Claim
34 words
An instrument in accordance with claim 4 further comprising: data latch means having said digital indication in decibels from said logic means coupled thereto and clocked by said count for storing said digital indication.
Claim 10
Dependent Claim
31 words
An instrument in accordance with claim 8 further including: visual display means having said stored data from said data latch means coupled thereto for deriving a visual display of said data.
Claim 11
Dependent Claim
188 words
In a PCM telephone communications system for deriving a plurality of channels of multiplexed PCM data from a plurality of telephone subscriber lines associated with each of said channels coupled thereto for retransmission, a level measurement circuit for measuring the level of an input ac signal comprising: rectification means having said ac input signal coupled thereto for deriving a dc voltage having an amplitude which is linearly proportional to the RMS value of said input ac signal; means for providing a reference voltage; integration means having said dc voltage coupled thereto to derive an exponentially decaying integration voltage, and wherein said integration means comprises: a dual slope integrator for generating a ramp voltage having a rate of change of voltage with respect to time which is substantially linearly proportional to the output of said rectification means; means for comparing said reference voltage and said exponentially decaying integration voltage and for generating a comparator output signal when said compared reference voltage and said integration voltage are equal; and logic means for converting said comparator output into a digital indication in decibels of the level of said input electrical signal.
Claim 12
Dependent Claim
188 words
In a PCM telephone communications system for deriving a plurality of channels of multiplexed PCM data from a plurality of telephone subscriber lines associated with each of said channels coupled thereto for retransmission, a level measurement circuit for measuring the level of an input ac signal comprising: rectification means having said ac input signal coupled thereto for deriving a dc voltage having an amplitude which is linearly proportional to the RMS value of said input ac signal; means for providing a reference voltage; integration means having said dc voltage coupled thereto to derive an exponentially decaying integration voltage, and wherein said integration means comprises: a dual slope integrator for generating a ramp voltage having a rate of change of voltage with respect to time which is substantially linearly proportional to the output of said rectification means; means for comparing said reference voltage and said exponentially decaying integration voltage and for generating a comparator output signal when said compared reference voltage and said integration voltage are equal; and logic means for converting said comparator output into a digital indication in decibels of the level of said input electrical signal.
Claim 13
Dependent Claim
99 words
In a PCM telephone communications system in accordance with claim 10 an input signal level measurement circuit wherein said integration means includes: a dual slope integrator for generating a ramp voltage having a rate of change of voltage with respect to time which is proportional to a time constant circuit and to the output of said rectification means; and wherein the time duration from the initiation of said discharge through said integration capacitor to the time when said discharging voltage is equal to said reference voltage is proportional to the logarithm of the magnitude of said input electrical signal.
Claim 14
Dependent Claim
26 words
In a PCM telephone communications system in accordance with claim 11 an input signal level measurement circuit wherein said input electrical signal is an ac voltage.
Claim 15
Dependent Claim
26 words
In a PCM telephone communications system in accordance with claim 12, an input signal level measurement circuit wherein said ac voltage is a sinusoidal test tone.
Claim 16
Dependent Claim
37 words
In a PCM telephone communications system in accordance with claim 12, an input signal level measurement circuit further comprising: buffer amplifier means having said input voltage coupled thereto and having an output coupled to said rectification means.
Claim 17
Dependent Claim
44 words
In a PCM telephone communications system in accordance with claim 14, an input signal level measurement circuit further comprising: data latch means having said digital indication in decibels from said logic means coupled thereto and clocked by said count for storing said digital indication.
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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) | 1982-07-02 | 1983-01-01 | 1983-07-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-07-02 | 1987-01-01 | 1987-07-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-07-02 | 1991-01-01 | 1991-07-03 | $7700.00 | Window Closed / Lapsed |