Patent US5693021A successfully refreshed from Google Patents.
US3825892A
Expired / Lapsed
US
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Error detector for low disparity code signals
Assignee: International Standard Electric Corp
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Filing: 1973-05-11
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Granted: 1974-07-23
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Expires: 1993-05-11
Abstract
Abstract This relates to error detection in a PCM system employing a low disparity code. A low disparity code is that type of code that over a long period of time the average number of MARKS and SPACES are approximately equal. When such a code is error free no direct current component is produced, but when an error occurs a low frequency component is introduced into the average signal value. According to the present invention errors in a low disparity code signal are detected by employing a low pass filter that will respond to the low frequency component of the average signal value.
Inventors
- 👤 R Catchpole
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 21:09
CPC Classifications
H; H04; H04L; H04L1/00; H04L1/24; H04L1/245; H04L1/247
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
120 words
An error detector in a digital transmission system employing a low disparity code comprising: a transmission arrangement for said low disparity code; low pass filter coupled to said transmission system, said low pass filter having characteristics such that for error free transmission no significant output signal is provided by said low pass filter but when transmission with error occurs a significant output signal is provided by said low pass filter; an inverter means coupled to the output of said low pass filter; and a circuit arrangement coupled to the output of said low pass filter and the output of said inverter means to provide an OR function of both the true and inverted output signals of said low pass filter.
Claim 2
Dependent Claim
120 words
An error detector in a digital transmission system employing a low disparity code comprising: a transmission arrangement for said low disparity code; low pass filter coupled to said transmission system, said low pass filter having characteristics such that for error free transmission no significant output signal is provided by said low pass filter but when transmission with error occurs a significant output signal is provided by said low pass filter; an inverter means coupled to the output of said low pass filter; and a circuit arrangement coupled to the output of said low pass filter and the output of said inverter means to provide an OR function of both the true and inverted output signals of said low pass filter.
Claim 3
Dependent Claim
90 words
An error detector according to claim 1, wherein said transmission arrangement provides pulses of opposite polarity, said opposite polarity pulses being representative of digital signals of different significances; and further including a difference amplifier having two inputs and an output, one of said two inputs being coupled to said transmission arrangement responsive to one of said opposite polarity signals, the other of said two inputs being coupled to said transmission arrangement responsive to the other of said opposite polarity signals and said output being coupled to said low pass filter.
Claim 4
Dependent Claim
20 words
An error detector according to claim 2, wherein said difference amplifier has a reduced gain at a predetermined low frequency.
Claim 5
Dependent Claim
27 words
An error detector according to claim 3, further including a capacitor and inductor network to couple said two inputs of said difference amplifier to said transmission arrangement.
Claim 6
Dependent Claim
27 words
An error detector according to claim 2, further including a capacitor and inductor network to couple said two inputs of said difference amplifier to said transmission arrangement.
Claim 7
Dependent Claim
113 words
An error detector in a digital transmission system employing a low disparity code comprising: a transmission arrangement for said low disparity code; filter means coupled to said transmission system, said filter means having characteristics such that for error free transmission no significant output signal is provided by said filter means but when transmission with error occurs a significant output signal is provided by said filter means; an inverter means coupled to the output of said filter means; and a circuit arrangement coupled to the output of said filter means and the output of said inverter means to provide an OR function of both the true and inverted output signals of said filter means.
Claim 8
Dependent Claim
113 words
An error detector in a digital transmission system employing a low disparity code comprising: a transmission arrangement for said low disparity code; filter means coupled to said transmission system, said filter means having characteristics such that for error free transmission no significant output signal is provided by said filter means but when transmission with error occurs a significant output signal is provided by said filter means; an inverter means coupled to the output of said filter means; and a circuit arrangement coupled to the output of said filter means and the output of said inverter means to provide an OR function of both the true and inverted output signals of said filter means.
Claim 9
Dependent Claim
145 words
An error detector in a digital transmission system employing a low disparity code comprising: a transmission arrangement for said low disparity code; filter means coupled to said transmission system, said filter means having characteristics such that for error free transmission no significant output signal is provided by said filter means but when transmission with error occurs a significant output signal is provided by said filter means; said transmission arrangement providing pulses of opposite polarity, said opposite polarity pulses being representative of digital signals of different significances; and a difference amplifier having two inputs and an output, one of said two inputs being coupled to said transmission arrangement responsive to one of said opposite polarity signals, the other of said two inputs being coupled to said transmission arrangement responsive to the other of said opposite polarity signals and said output being coupled to said filter means.
Claim 10
Dependent Claim
145 words
An error detector in a digital transmission system employing a low disparity code comprising: a transmission arrangement for said low disparity code; filter means coupled to said transmission system, said filter means having characteristics such that for error free transmission no significant output signal is provided by said filter means but when transmission with error occurs a significant output signal is provided by said filter means; said transmission arrangement providing pulses of opposite polarity, said opposite polarity pulses being representative of digital signals of different significances; and a difference amplifier having two inputs and an output, one of said two inputs being coupled to said transmission arrangement responsive to one of said opposite polarity signals, the other of said two inputs being coupled to said transmission arrangement responsive to the other of said opposite polarity signals and said output being coupled to said filter means.
Claim 11
Dependent Claim
27 words
An error detector according to claim 7, further including a capacitor and inductor neTwork to couple said two inputs of said difference amplifier to said transmission arrangement.
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) | 1977-07-22 | 1978-01-21 | 1978-07-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-07-22 | 1982-01-21 | 1982-07-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-07-22 | 1986-01-21 | 1986-07-23 | $7700.00 | Window Closed / Lapsed |