US3814868A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Telephone line characteristic measuring instrument
Assignee: Individual
•
Filing: 1972-07-12
•
Granted: 1974-06-04
•
Expires: 1992-07-12
Abstract
Abstract There is disclosed an instrument for measuring the characteristics of telephone lines to facilitate the identification of sources of data transmission errors. An automatic gain control circuit is used to normalize a received test tone signal so that the test tone component of the signal is made equal to the reference level of a local oscillator. The difference between the amplified test signal and the local oscillator output is then derived, leaving only the test signal disturbances. In addition to conventional-type test readings which may then be taken, a special measurement of interest is made which represents the relative influences of uncorrelated noise and true phase jitter on a phase jitter measurement so that the major source of measured phase jitter may be identified.
Inventors
- 👤 F Bradley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 01:33
CPC Classifications
H; H04; H04B; H04B3/00; H04B3/02; H04B3/46
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
110 words
A telephone line characteristic measuring instrument comprising oscillator means for generating a tone, means for amplifying a received signal having test tone and disturbance components therein, first means for controlling the frequency and phase of said generated tone to be equal to the frequency and phase of the test tone component in the received amplified signal, second controlling means for adjusting the gain of said amplifying means so that the amplitude of the test tone component in said received amplified signal remains equal to the amplitude of said generated tone, and means for deriving a signal which is the instantaneous difference between the received amplified signal and said generated tone.
Claim 2
Dependent Claim
110 words
A telephone line characteristic measuring instrument comprising oscillator means for generating a tone, means for amplifying a received signal having test tone and disturbance components therein, first means for controlling the frequency and phase of said generated tone to be equal to the frequency and phase of the test tone component in the received amplified signal, second controlling means for adjusting the gain of said amplifying means so that the amplitude of the test tone component in said received amplified signal remains equal to the amplitude of said generated tone, and means for deriving a signal which is the instantaneous difference between the received amplified signal and said generated tone.
Claim 3
Dependent Claim
65 words
A telephone line characteristic measuring instrument in accordance with claim 1 wherein said first controlling means includes means for comparing the test tone component in said received amplified signal with said generated tone and for developing a signal indicative of frequency and phase differences therebetween, said oscillator means including means responsive to said developed signal for changing the frequency and phase of said generated tone.
Claim 4
Dependent Claim
58 words
A telephone line characteristic measuring instrument in accordance with claim 1 wherein said second controlling means includes means for multiplying said difference signal and said generated tone to derive a product signal, means for averaging said product signal, and means for adjusting the gain of said amplifying means in accordance with the magnitude of the averaged product signal.
Claim 5
Dependent Claim
51 words
A telephone line characteristic measuring instrument in accordance with claim 3 wherein said averaging means has an averaging effect on components in said product signal whose frequencies are below 20 Hz and has a negligible response to components in said product signal whose frequencies are between 20 Hz and 300 Hz.
Claim 6
Dependent Claim
40 words
A telephone line characteristic measuring instrument in accordance with claim 4 wherein the gain of said amplifying means varies logarithmically with the averaged product signal so that the averaged product signal is a logarithmic representation of the received signal level.
Claim 7
Dependent Claim
51 words
A telephone line characteristic measuring instrument in accordance with claim 3 wherein said oscillator means further produces a tone which is in quadrature with and has the same amplitude as said generated tone, and further including means for multiplying said quadrature tone and said difference signal to derive a multiplicative signal.
Claim 8
Dependent Claim
30 words
A telephone line characteristic measuring instrument in accordance with claim 6 further including means for measuring the magnitude of signal components in a 20-300 Hz band in said multiplicative signal.
Claim 9
Dependent Claim
47 words
A telephone line characteristic measuring instrument in accordance with claim 7 further including means for measuring the magnitude of signal components in a 20-300 Hz band in said product signal, and means for deriving a signal which is proportional to the difference between the two magnitude measurements.
Claim 10
Dependent Claim
38 words
A telephone line characteristic measuring instrument in accordance with claim 3 further including a C-message weight filter for filtering said difference signal, and means for measuring the magnitude of the difference signal extended through said C-message weight filter.
Claim 11
Dependent Claim
49 words
A telephone line characteristic measuring instrument in accordance with claim 1 wherein said second controlling means includes a feedback path having means therein for averaging components whose frequencies are below 20 Hz and which has a negligible response to components whose frequencies are between 20 Hz and 300 Hz.
Claim 12
Dependent Claim
44 words
A telephone line characteristic measuring instrument in accordance with claim 10 wherein the gain of said amplifying means varies logaRithmically with the signal at the output of said feedback path so that said output signal is a logarithmic representation of the received signal level.
Claim 13
Dependent Claim
28 words
A telephone line characteristic measuring instrument in accordance with claim 1 further including means for multiplying said difference signal and said generated tone to derive a product signal.
Claim 14
Dependent Claim
30 words
A telephone line characteristic measuring instrument in accordance with claim 12 further including means for measuring the magnitude of signal components in a 20-300 Hz band in said product signal.
Claim 15
Dependent Claim
38 words
A telephone line characteristic measuring instrument in accordance with claim 1 further including a C-message weight filter for filtering said difference signal, and means for measuring the magnitude of the difference signal extended through said C-message weight filter.
Claim 16
Dependent Claim
53 words
A telephone line characteristic measuring instrument in accordance with claim 1 wherein said automatic gain controlling means includes means for multiplying said difference signal by said generated tone to derive a product signal, and means for adjusting the gain of said amplifying means in accordance with the magnitude of the averaged product signal.
Claim 17
Dependent Claim
49 words
A telephone line characteristic measuring instrument in accordance with claim 1 wherein said second controlling means includes a feedback path having means therein for averaging components whose frequencies are below 20 Hz and which has a negligible response to components whose frequencies are between 20 Hz and 300 Hz.
Claim 18
Dependent Claim
53 words
A telephone line characteristic measuring instrument in accordance with claim 16 wherein the gain of said amplifying means varies logarithmically with the signal at the output of said feedback path so that said output signal is a logarithmic representation of the loss of the telephone line over which the received signal was transmitted.
Claim 19
Dependent Claim
51 words
A telephone line characteristic measuring instrument in accordance with claim 1 wherein said oscillator means further produces a tone which is in quadrature with and has the same amplitude as said generated tone, and further including means for multiplying said quadrature tone and said difference signal to derive a multiplicative signal.
Claim 20
Dependent Claim
28 words
A telephone line characteristic measuring instrument in accordance with claim 18 further including means for multiplying said difference signal and said generated tone to derive a product signal.
Claim 21
Dependent Claim
30 words
A telephone line characteristic measuring instrument in accordance with claim 19 further including means for measuring the magnitude of signal components in a 20-300 Hz band in said multiplicative signal.
Claim 22
Dependent Claim
47 words
A telephone line characteristic measuring instrument in accordance with claim 20 further including means for measuring the magnitude of signal components in a 20-300 Hz band in said product signal, and means for deriving a signal which is proportional to the difference between the two magnitude measurements.
Claim 23
Dependent Claim
34 words
A telephone line characteristic measuring instrument in accordance with claim 1 further including a filter for filtering said difference signal, and means for measuring the magnitude of the difference signal extended through said filter.
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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) | 1977-06-03 | 1977-12-03 | 1978-06-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-03 | 1981-12-03 | 1982-06-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-03 | 1985-12-03 | 1986-06-04 | $7700.00 | Window Closed / Lapsed |