Patent US3928725A successfully refreshed from Google Patents.
US3928725A
Expired / Lapsed
US
⏱️ 0.0 years remaining
PAM/PCM interface network for TDM telecommunication system
Assignee: Italtel SpA
•
Filing: 1974-11-12
•
Granted: 1975-12-23
•
Expires: 1994-11-12
Abstract
Abstract At a central office communicating with a remote exchange via a PCM link carrying recurrent frames of 32 channels each, a coupler comprises 30 parallel circuit branches for exchanging analogvoltage samples between as many local lines and a PCM terminal. Each branch includes a tuned circuit for resonant transfer of voltage samples between a storage capacitor, individual to a local line, and the PCM link which contains an A/D converter or coder in an outgoing path and a D/A converter or decoder in an incoming path. The tuned circuit of each branch comprises two filter sections in cascade, each with a shunt condenser, separated by a normally open circuit breaker which closes once per scanning cycle, i.e. in a time slot (No. 0) immediately preceding a series of 15 time slots in the first half of this 32slot cycle for the first 15 branches and in another time slot (No. 16) immediately preceding another series of 15 time slots in the second half thereof for the second 15 branches. A transmit switch individual to each branch discharges the terminal-side shunt condenser thereof into a common storage capacitor for delivery of its sample to the coder; an associated receive switch closes less than half a cycle thereafter to charge that condenser from the output of the decoder. As the operating frequencies of the groups of transmit and receive switches are not exactly identical, a delay circuit in the incoming path with a delay time of half a cycle is cut either in or out and the closure times of the receive switches are retarded or advanced to the same extent by a monitoring unit whenever the deviation between corresponding switch-closing phases reaches a predetermined limit. Binary supervisory signals, registered in circulating caller and responder memories, are exchanged in the 16th time slot between a processor and the PCM terminal over paths bypassing the coupler.
Inventors
- 👤 Giuseppe Valbonesi
- 👤 Roberto Camiciottoli
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 08:01
CPC Classifications
H; H04; H04J; H04J3/00; H04J3/20; H04Q; H04Q11/00; H04Q11/04
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
387 words
In a telecommunication system, in combination: a central office; a multiplicity of local lines terminating at said central office; sampling means at said central office including a set of individual capacitors respectively connected to said local lines for receiving analog message samples originating at and destined for at least some of said lines during respective time slots of a recurrent scanning cycle; a pulse-code-modulation link with an outgoing path and an incoming path extending from said central office to a remote exchange for carrying messages to and from said local lines in a PCM frame recurring at substantially the same frequency as said scanning cycle, said frame being divided into a number of channels equal to the number of said time slots; a coupler between said sampling means and said link with a plurality of parallel branches each including a pair of cascaded sections for the temporary storage of a message sample, one section of each branch being periodically connectable by said sampling means to the individual capacitor of an assigned local line; a set of circuit breakers normally isolating said one section of each branch from the other section thereof; a set of normally open transmit switches between said other section of each branch and said outgoing path; a set of normally open receive switches between said other section of each branch and said incoming branch; locally controlled first timing means for momentarily closing each of said circuit breakers and each of said transmit switches in staggered relationship once per scanning cycle for transferring departing message samples from said one section of any of said branches via said other section thereof to said outgoing branch; second timing means controlled from said remote exchange via said link for momentarily closing each of said receive switches in staggered relationship once per scanning cycle for transferring arriving message samples from said incoming path to said other section of any of said branches preparatorily to delivery to a local line by way of said one section thereof, said first and second timing means having substantially the same operating frequency; and monitoring means connected to said first and second timing means for relatively phase-shifting same upon deviation of the relative closure times of said transmit and receive switches from a predetermined range, thereby maintaining an invariable closure sequence in each branch.
Claim 2
Dependent Claim
387 words
In a telecommunication system, in combination: a central office; a multiplicity of local lines terminating at said central office; sampling means at said central office including a set of individual capacitors respectively connected to said local lines for receiving analog message samples originating at and destined for at least some of said lines during respective time slots of a recurrent scanning cycle; a pulse-code-modulation link with an outgoing path and an incoming path extending from said central office to a remote exchange for carrying messages to and from said local lines in a PCM frame recurring at substantially the same frequency as said scanning cycle, said frame being divided into a number of channels equal to the number of said time slots; a coupler between said sampling means and said link with a plurality of parallel branches each including a pair of cascaded sections for the temporary storage of a message sample, one section of each branch being periodically connectable by said sampling means to the individual capacitor of an assigned local line; a set of circuit breakers normally isolating said one section of each branch from the other section thereof; a set of normally open transmit switches between said other section of each branch and said outgoing path; a set of normally open receive switches between said other section of each branch and said incoming branch; locally controlled first timing means for momentarily closing each of said circuit breakers and each of said transmit switches in staggered relationship once per scanning cycle for transferring departing message samples from said one section of any of said branches via said other section thereof to said outgoing branch; second timing means controlled from said remote exchange via said link for momentarily closing each of said receive switches in staggered relationship once per scanning cycle for transferring arriving message samples from said incoming path to said other section of any of said branches preparatorily to delivery to a local line by way of said one section thereof, said first and second timing means having substantially the same operating frequency; and monitoring means connected to said first and second timing means for relatively phase-shifting same upon deviation of the relative closure times of said transmit and receive switches from a predetermined range, thereby maintaining an invariable closure sequence in each branch.
Claim 3
Dependent Claim
44 words
The combination defined in claim 1 wherein the number of said time slots exceeds the number of said branches, said first timing means being operative to close said circuit breakers in a time slot other than those during which said transmit switches are closed.
Claim 4
Dependent Claim
93 words
The combination defined in claim 2 wherein said branches are divided into two substantially equal groups, the circuit breakers of one group being closable in a time slot immediately preceding a series of time slots in one-half of a scanning cycle during which the transmit switches of said one group are successively closed, the circuit breakers of the other group being closable in a time slot immediately preceding a series of time slots in the other half of a scanning cycle during which the transmit switches of said other group are successively closed.
Claim 5
Dependent Claim
94 words
The combination defined in claim 3, further comprising pulse-generating means controlled by said first timing means for producing a guard signal lasting for substantially half a scanning cycle, said monitoring means including a coincidence circuit connected to said pulse-generating meaNs and to said second timing means for respectively receiving therefrom said guard signal and a closure pulse for one of said receiver switches, said monitoring means further including phase-shifting means for said second timing means and delay means selectively insertable in said incoming path in response to a phase-shift instruction from said coincidence means.
Claim 6
Dependent Claim
37 words
The combination defined in claim 4 wherein said second timing means comprises a clock-pulse extractor in said incoming path and counting means controlled by said extractor, said phase-shifting means including a stepping circuit for said counting means.
Claim 7
Dependent Claim
30 words
The combination defined in claim 5, further comprising a digital/analog converter in said incoming path downstream of said extractor, said delay means being insertable between said extractor and said converter.
Claim 8
Dependent Claim
77 words
The combination defined in claim 6 wherein the PCM frames carried on said link form a recurrent multiframe sequence, said counting means including a frame counter and a channel counter, said stepping circuit being connected to said channel counter for resetting same by half the number of channels per frame, said stepping circuit being further connected to said frame counter for reducing the count thereof by one upon insertion of said delay means into said incoming path.
Claim 9
Dependent Claim
48 words
The combination defined in claim 7 wherein said counting means has an output generating an execution signal in a predetermined time position of one frame of said multiframe sequence, said coincidence circuit including memory means for ineffectually preserving said phase-shift instruction until the appearance of said execution signal.
Claim 10
Dependent Claim
36 words
The combination defined in claim 1, further comprising processor means for binary supervisory signals relating to the exchange of messages, and circuitry bypassing said coupler for transmitting said supervisory signals between said processor and said link.
Claim 11
Dependent Claim
59 words
The combination defined in claim 1 wherein each of said sections comprises a respective shunt condenser forming part of a tuned circuit for the resonant transfer of charges therebetween, said outgoing path including a common storage capacitor accessible to said branches through said transmit switches, said branches comprising inductances tuning said individual and common capacitors to the resonant-transfer frequency.
References Cited (Backward Citations)
US3761633A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-22 | 1979-06-23 | 1979-12-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-22 | 1983-06-23 | 1983-12-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-22 | 1987-06-23 | 1987-12-23 | $7700.00 | Window Closed / Lapsed |