Patent US3670255A successfully refreshed from Google Patents.
US3670255A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Phase-lock-stabilized system for generating carrier frequencies usable in multiplex communication
Assignee: Italtel SpA
•
Filing: 1970-11-12
•
Granted: 1972-06-13
•
Expires: 1990-11-12
Abstract
Abstract A voltage-responsive carrier-frequency oscillator, with a limited range of adjustability designed to compensate for frequency drifts, works through a frequency divider into a phase comparator also receiving a relatively low base frequency harmonically related to the desired carrier frequency. The output of the phase comparator is fed back to the oscillator to maintain a predetermined phase relationship between the two low frequencies. The phase comparator includes a pair of differentiation circuits, deriving respective pulse trains from these low frequencies, and a flip-flop alternately set and reset by interleaved pulses from the two trains; the integrated output wave of the flip-flop constitutes the feedback voltage controlling the output frequency of the oscillator.
Inventors
- 👤 Giuliano De Nicolay
- 👤 Piero Venturini
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 23:50
CPC Classifications
H; H03; H03L; H03L7/00; H03L7/06; H03L7/16; H03L7/18; H03L7/181
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
227 words
A system for generating a plurality of stabilized carrier frequencies usable in multiplex communication, comprising: an adjustable generator for producing a limitedly variable operating frequency equaling a multiple of several carrier frequencies to be generated; a plurality of frequency dividers connected to the output of said adjustable generator for stepping down said operating frequency to said several carrier frequencies; a reference generator for producing a relatively low base frequency harmonically related to said operating frequency; frequency-dividing means in the output of said adjustable generator for deriving from said operating frequency a steppeddown frequency on the order of magnitude of said base frequency; first and second differentiation means respectively connected to said reference generator and to said frequency-dividing means for converting said base frequency and said stepped-down frequency into first and second pulse trains, respectively; a bistable element connected to said first and second differentiation means for setting and resetting by pulses from said first and second pulse trains, respectively; integrating means in the output of said bistable element for generating a control voltage varying with the relative phasing of the pulses of said first and second pulse trains; and feedback means connected between said integrating means and said adjustable generator for varying said operating frequency in response to said control voltage to maintain a predetermined phase relationship between the pulses of said first and second pulse trains.
Claim 2
Independent Claim
227 words
A system for generating a plurality of stabilized carrier frequencies usable in multiplex communication, comprising: an adjustable generator for producing a limitedly variable operating frequency equaling a multiple of several carrier frequencies to be generated; a plurality of frequency dividers connected to the output of said adjustable generator for stepping down said operating frequency to said several carrier frequencies; a reference generator for producing a relatively low base frequency harmonically related to said operating frequency; frequency-dividing means in the output of said adjustable generator for deriving from said operating frequency a steppeddown frequency on the order of magnitude of said base frequency; first and second differentiation means respectively connected to said reference generator and to said frequency-dividing means for converting said base frequency and said stepped-down frequency into first and second pulse trains, respectively; a bistable element connected to said first and second differentiation means for setting and resetting by pulses from said first and second pulse trains, respectively; integrating means in the output of said bistable element for generating a control voltage varying with the relative phasing of the pulses of said first and second pulse trains; and feedback means connected between said integrating means and said adjustable generator for varying said operating frequency in response to said control voltage to maintain a predetermined phase relationship between the pulses of said first and second pulse trains.
Claim 3
Dependent Claim
22 words
A system as defined in claim 1 wherein at least one of said generators comprises a sine-wave oscillator followed by a squarer.
Claim 4
Dependent Claim
31 words
A system as defined in claim 1, further comprising threshold means controlled by said voltage for blocking the output of said adjustable generator upon said voltage falling outside a predetermined range.
Claim 5
Dependent Claim
29 words
A system as defined in claim 1 wherein said adjustable generator comprises a crystal-controlled oscillator with a range of adjustability slightly exceeding the drift range of said operating frequency.
Claim 6
Dependent Claim
17 words
A system as defined in claim 1 wherein said frequency-dividing means comprises a multistage binary frequency divider.
Claim 7
Dependent Claim
22 words
A system as defined in claim 1 wherein said frequency-dividing means includes one of said frequency dividers as a first stage thereof.
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) | 1975-06-13 | 1975-12-13 | 1976-06-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-13 | 1979-12-13 | 1980-06-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-13 | 1983-12-13 | 1984-06-13 | $7700.00 | Window Closed / Lapsed |