Patent US3210041A successfully refreshed from Google Patents.
US3737584A
Expired / Lapsed
US
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Malfunction monitoring equipment for a time division multiplexed transmission system
Assignee: NEC Corp
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Filing: 1970-12-09
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Granted: 1973-06-05
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Expires: 1990-12-09
Abstract
Abstract A malfunction monitoring system for the analog circuit of a time division multiplexed pulse code modulation system uses a noise signal as the pilot signal.
Inventors
- 👤 H Kaneko
- 👤 K Yano
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 20:36
CPC Classifications
H; H04; H04J; H04J3/00; H04J3/02; H04J3/14
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
137 words
A malfunction monitoring system for a time division multiplexed pulse code modulation communication system including a transmitting terminal and a receiving terminal; said malfunction monitoring system comprising means in the transmitting terminal for modulating and time-division multiplexing a plurality of information signals, a noise signal source, means for inserting said noise signal as the pilot signal into an idle selected channel of said time-division multiplexed modulated signals, the frequency spectrum distribution of said noise signal being substantially continuous with a portion of the bandwidth corresponding to said idle selected channel, and means for coding and transmitting said multiplexed information and noise signals; said receiving terminal including means for decoding said signals, and a pilot signal channel having means for demodulating said decoded noise pilot signal, and means for monitoring the demodulated output of said pilot signal channel.
Claim 2
Dependent Claim
137 words
A malfunction monitoring system for a time division multiplexed pulse code modulation communication system including a transmitting terminal and a receiving terminal; said malfunction monitoring system comprising means in the transmitting terminal for modulating and time-division multiplexing a plurality of information signals, a noise signal source, means for inserting said noise signal as the pilot signal into an idle selected channel of said time-division multiplexed modulated signals, the frequency spectrum distribution of said noise signal being substantially continuous with a portion of the bandwidth corresponding to said idle selected channel, and means for coding and transmitting said multiplexed information and noise signals; said receiving terminal including means for decoding said signals, and a pilot signal channel having means for demodulating said decoded noise pilot signal, and means for monitoring the demodulated output of said pilot signal channel.
Claim 3
Dependent Claim
76 words
The malfunction monitoring system claimed in claim 1, further comprising means in said transmitting terminal for limiting the bandwidth of said noise signal; and means in the receiving terminal for separating the demodulated pilot signal channel output into a first power spectrum falling within said bandwidth and a second power spectrum falling outside of said bandwidth, said monitoring means including means for sensing the amplitude of at least one of said first and second power spectrums.
Claim 4
Dependent Claim
55 words
The malfunction monitoring equipment of claim 2, in which said separating means comprising a high-pass filter and a low-pass filter coupled to said pilot signal demodulating means, and said monitoring means comprises comparing means coupled to the outputs of said low-pass and high-pass filters for comparing the relative levels of the outputs of said filters.
Claim 5
Dependent Claim
31 words
The malfunction monitoring system of claim 2, further comprising means coupled to said bandwidth limiting means for maintaining the output power of said bandwidth limiting means at a substantially constant level.
Claim 6
Dependent Claim
36 words
The malfunction monitoring system of claim 4, in which said bandwidth limiting means comprises a band-pass filter, and further comprising at said receiver terminal a low-pass filter coupled between said separating means and said monitoring means.
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) | 1976-06-04 | 1976-12-04 | 1977-06-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-04 | 1980-12-04 | 1981-06-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-04 | 1984-12-04 | 1985-06-05 | $7700.00 | Window Closed / Lapsed |