EP0876017A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Digital clock recovery
Assignee: LSI Corp
•
Filing: 1997-05-02
•
Granted: —
•
Expires: 2017-05-02
Abstract
Abstract A clock recovery mechanism for an ATM receiver recovers a service (source) clock transmitted over an ATM network. The mechanism includes an input for receiving an SRTS from the ATM network, a local SRTS generator for locally generating an SRTS, a comparator for comparing a received SRTS and a locally generated SRTS and a recovered service clock generator responsive to an output of the comparator for generating the recovered service clock and for controlling the local SRTS generator. The locally generated SRTS is compared directly with the received SRTS. The local SRTS is generated using the same method as used to generate the transmitted SRTS, that is using the network clock fnx and a locally generated clock, at frequency fs. The difference between the locally generated SRTS and the received SRTS can be expressed directly in a number of fnx pulse clocks to be added or removed to the generated fs clock. Thus a service clock can be recovered at a receiver location using SRTSs by means of a digital technique.
Inventors
- 👤 Régis Lauret
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 21:12
CPC Classifications
H; H04; H04J; H04J3/00; H04J3/02; H04J3/06; H04J3/062; H04J3/0632; H04Q; H04Q11/00; H04Q11/04; H04Q11/0428; H04Q11/0478; H04L; H04L12/00; H04L12/54; H04L12/56; H04L12/5601; H04L2012/5638; H04L2012/5646; H04L2012/5649; H04L2012/5672; H04L2012/5674
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
78 words
A clock recovery mechanism for an ATM receiver for recovering a service
clock transmitted over an ATM network, said mechanism comprising: an input for receiving an SRTS from said ATM network; a local SRTS generator for locally generating an SRTS; a comparator for comparing a received SRTS and a locally generated SRTS; and a recovered service clock generator responsive to an output of said comparator
for generating said recovered service clock and for controlling said local SRTS
generator.
Claim 2
Dependent Claim
20 words
A mechanism according to Claim 1, wherein said local SRTS generator is
controllable in response to said recovered service clock.
Claim 3
Dependent Claim
22 words
A mechanism according to Claim 2, wherein said local SRTS generator
comprises a divider for dividing said recovered service clock by N.
Claim 4
Dependent Claim
25 words
A mechanism according to Claim 3, wherein said local SRTS generator has
the structure which mirrors that of an SRTS generator at an ATM transmitter.
Claim 5
Dependent Claim
90 words
A mechanism according to any preceding Claim, wherein said local SRTS
generator comprises: a latch, an output of which provides said locally generated SRTS; a p-bit free running counter, driven by a submultiple of an ATM network
clock, said latch being connected to receive an output from said counter; and a divider having an output connected to a latch input of said latch for latching
said output from said counter and an input connected to receive said recovered service
clock, said divider outputting said recovered service clock divided by N.
Claim 6
Dependent Claim
15 words
A mechanism according to any one of Claims 4 to 6, wherein N is 3008.
Claim 7
Dependent Claim
87 words
A mechanism according to any preceding Claim, wherein: said recovered service clock generator comprises a controller and a digitally
controlled oscillator; said controller comprises an input connected to said comparator, and an output
connected to a control input of said digitally controlled oscillator, said controller
outputting control signals for controlling said digitally controlled oscillator; and said digitally controlled oscillator has an output for said recovered service
clock, said digitally controlled oscillator outputting said recovered service clock under
the control of said control signals at said control input.
Claim 8
Dependent Claim
36 words
A mechanism according to Claim 7, wherein said controller comprises a look-up
table, said controller being responsive to said comparator outputs for accessing
control signals from said look-up table for output to said digitally controlled
oscillator.
Claim 9
Dependent Claim
26 words
A mechanism according to any preceding Claim, wherein said input for
receiving an SRTS from said ATM network comprises an SRTS buffer for buffering
received STRSs.
Claim 10
Dependent Claim
12 words
An ATM receiver circuit comprising a mechanism according to any preceding
Claim.
Claim 11
Dependent Claim
17 words
An integrated ATM receiver circuit comprising a mechanism according to any
one of Claims 1 to 9.
Claim 12
Dependent Claim
15 words
An ATM receiver comprising a mechanism according to any one of Claims
1 to 9.
Claim 13
Dependent Claim
67 words
A clock recovery method at an ATM receiver for recovering a service clock
transmitted over an ATM network, said method comprising: receiving an SRTS from said ATM network; generating locally an SRTS; comparing a received SRTS and a locally generated SRTS; and generating a recovered service clock in response to an output of said
comparator and using said recovered service clock to control said local SRTS
generation.
Claim 14
Dependent Claim
20 words
A method according to Claim 13, comprising dividing said recovered service
clock by N for controlling said local SRTS generation.
Claim 15
Dependent Claim
24 words
A method according to Claim 14, comprising generating said local SRTS in
the same manner the generation of an SRTS at an ATM transmitter.
Claim 16
Dependent Claim
47 words
A method according to Claim 13, wherein said local SRTS generation
comprises: latching an output of a p-bit free running counter, driven by a submultiple of
an ATM network clock, at timings determined by the output of a divide-by-N divider
connected to receive said recovered service clock.
Claim 17
Independent Claim
15 words
A method according to any one of Claims 14 to 16, wherein N is 3008.
Claim 18
Independent Claim
38 words
A method according to any one of Claims 14 to 17, wherein said recovered
service clock generation comprises: generating control signals in response to said comparison for controlling a
digitally controlled oscillator to output said recovered service clock.
Claim 19
Dependent Claim
22 words
A method according to Claim 18, wherein said control signals are generated
from a look-up table in response to said comparison outputs.
Claim 20
Independent Claim
93 words
A method of circuit emulation over an ATM network comprising, at an ATM
transmitter, using a first SRTS generator for generating SRTSs for transmission in
response to a CBR service clock and, at an ATM receiver: receiving SRTSs from said ATM network; generating locally SRTSs using a second SRTS generator equivalent to said
first SRTS generator; comparing said received SRTSs and said locally generated SRTSs; and generating a recovered CBR service clock in response to an output of said
comparator and using said recovered CBR service clock to control said local SRTS
generation.
References Cited (Backward Citations)
US5260978A
Cited
JPH0746230A
Cited
WO1995006358A1
Cited
EP0671828A1
Cited
EP0705000A2
Cited
EP0720319A2
Cited
US5608731A
Cited
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.