US3743786A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Signal level supervising system for a pulse code modulation communicating system
Assignee: NEC Corp
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Filing: 1971-10-13
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Granted: 1973-07-03
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Expires: 1991-10-13
Abstract
Abstract A signal level supervising system for a pulse code modulation communication system transmitting pulse code modulation signals representing frequency division multiplex signals containing a pilot signal, the pilot signal being used for signal level supervision purposes. Pilot signal recovery is provided by modulating the decoded frequency division multiplex signal with a carrier, derived from a pulse source used in the control of the pulse code modulation system, to frequency shift the decoded frequency division multiplex signal in a direction to increase the signal bandwidth ratio. The pilot signal is extracted from this frequency shifted signal.
Inventors
- 👤 Ichi Hiratsuka Ken
- 👤 D Kawakami
- 👤 H Kaneko
- 👤 T Takahashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 16:22
CPC Classifications
H; H04; H04J; H04J1/00; H04J1/02; H04J1/16; H04J3/00; H04J3/02; H04J3/14
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
90 words
A level supervising system for a pulse code modulation communication system transmitting a frequency division multiplex signal containing a pilot signal, comprising, at the receiving end of said pulse code modulation communication system, means for frequency-shifting the recovered frequency division multiplexed signal in the direction of extending band width ratio for the extraction of said pilot signal using a carrier wave, means for deriving said carrier wave from a pulse source controlling the pulse code modulation system and means for extracting said pilot from the frequency-shifted frequency division multiplex signal.
Claim 2
Dependent Claim
90 words
A level supervising system for a pulse code modulation communication system transmitting a frequency division multiplex signal containing a pilot signal, comprising, at the receiving end of said pulse code modulation communication system, means for frequency-shifting the recovered frequency division multiplexed signal in the direction of extending band width ratio for the extraction of said pilot signal using a carrier wave, means for deriving said carrier wave from a pulse source controlling the pulse code modulation system and means for extracting said pilot from the frequency-shifted frequency division multiplex signal.
Claim 3
Dependent Claim
39 words
The level supervising system as claimed in claim 1, wherein said means for deriving said carrier wave includes means for producing a carrier wave of a frequency equal to one-half the sampling frequency of said pulse code modulation system.
Claim 4
Dependent Claim
88 words
In a pulse code modulation receiver for demodulating a pulse code modulated analog signal including a fixed frequency and level pilot signal for use in a signal level supervising system, a pilot signal recovery system comprising; means for frequency shifting the demodulated analog signal in a direction to cause an increase in the signal bandwidth ratio, said means including means for deriving a carrier signal from a pulse source controlling the pulse code modulation receiver, and means for extracting said pilot signal from said frequency shifted analog signal.
Claim 5
Dependent Claim
88 words
In a pulse code modulation receiver for demodulating a pulse code modulated analog signal including a fixed frequency and level pilot signal for use in a signal level supervising system, a pilot signal recovery system comprising; means for frequency shifting the demodulated analog signal in a direction to cause an increase in the signal bandwidth ratio, said means including means for deriving a carrier signal from a pulse source controlling the pulse code modulation receiver, and means for extracting said pilot signal from said frequency shifted analog signal.
Claim 6
Dependent Claim
74 words
The pilot signal recovery system of claim 3 wherein said means for frequency shifting includes modulator means for modulating said demodulated analog signal with said derived carrier, said means for deriving a carrier signal including divider means, responsive to the clock signal of said pulse code modulated signal, for frequency dividing said clock signal and buffer amplifier means responsive to said reduced frequency clock signal for supplying said carrier signal to said modulator means.
Claim 7
Dependent Claim
31 words
The pilot signal recovery system of claim 4 wherein said divider means includes means for reducing the clock signal frequency to one-half of the sampling frequency of said pulse modulation receiver.
Claim 8
Dependent Claim
40 words
The pilot signal recovery system of claim 5 wherein said analog signal is a frequency division multiplex signal containing said pilot signal, said modulator means comprising means for modulating the recovered frequency division multiplex signal with said derived carrier signal.
Claim 9
Dependent Claim
122 words
In a pulse code modulation system, a pulse code modulation receiver for decoding a received pulse code modulation signal representing a frequency division multiplex signal including a pilot signal for signal level supervision, said receiver including a pilot signal recovery system comprising; a. means for recovering the pulse code modulation clock signal, b. means for reducing the frequency of said recovered clock signal, c. means for deriving a carrier signal from said reduced frequency clock signal, d. means for modulating the decoded frequency division multiplex signal with said derived carrier to frequency shift the frequency division multiplex signal in a direction to increase the bandwidth ratio, and e. means for extracting the pilot signal from said frequency shifted frequency division multiplex signal.
Claim 10
Dependent Claim
122 words
In a pulse code modulation system, a pulse code modulation receiver for decoding a received pulse code modulation signal representing a frequency division multiplex signal including a pilot signal for signal level supervision, said receiver including a pilot signal recovery system comprising; a. means for recovering the pulse code modulation clock signal, b. means for reducing the frequency of said recovered clock signal, c. means for deriving a carrier signal from said reduced frequency clock signal, d. means for modulating the decoded frequency division multiplex signal with said derived carrier to frequency shift the frequency division multiplex signal in a direction to increase the bandwidth ratio, and e. means for extracting the pilot signal from said frequency shifted frequency division multiplex signal.
Claim 11
Dependent Claim
92 words
In a pulse code modulation system, a method for recovering a signal level supervising pilot signal from a pulse code modulated analog signal including a pilot signal comprising the steps of; a. demodulating said pulse code modulated signal to recover said analog signal, b. modulating said analog signal with a carrier derived from a pulse source used in the control of the pulse code modulation system to frequency shift the analog signal in a direction to increase the signal bandwidth ratio, and c. extracting said pilot signal from said frequency shifted signal.
Claim 12
Dependent Claim
92 words
In a pulse code modulation system, a method for recovering a signal level supervising pilot signal from a pulse code modulated analog signal including a pilot signal comprising the steps of; a. demodulating said pulse code modulated signal to recover said analog signal, b. modulating said analog signal with a carrier derived from a pulse source used in the control of the pulse code modulation system to frequency shift the analog signal in a direction to increase the signal bandwidth ratio, and c. extracting said pilot signal from said frequency shifted signal.
Claim 13
Dependent Claim
22 words
The method of claim 8 wherein said carrier is derived by frequency dividing the clock signal of said pulse code modulated signal.
Claim 14
Dependent Claim
26 words
The method of claim 9 wherein the frequency of said carrier is made to correspond to one-half the sampling frequency of the pulse code modulation system.
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) | 1976-07-02 | 1977-01-01 | 1977-07-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-02 | 1981-01-01 | 1981-07-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-02 | 1985-01-01 | 1985-07-03 | $7700.00 | Window Closed / Lapsed |