CDCTI Compatible Duty Cycle Timing Information

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CDCTICompatible Duty Cycle Timing Information

• A receiver function for the clock recovery of CBR
  services over ATM compatible with the existing
  SRTS and DCTI methods

2
CDCTI the idea

• Instead of using the standard SRTS receiver an
  new receiver can be taken into account using the
  concepts already used in our previous patents
  (DCTI).

3
CDCTI the idea

• The DCTI uses only 3 bits among the 4 reserved
  for synchronization porpose with in the CSI
  structure of 8 consecutive ATM cells, while the
  SRTS uses the whole set of 4 bits
• In the DCTI method the most significant bit is
  always zero and this info can be used in order to
  distinguish the 2 methods

DCTI Generator
SRTS Generator
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DCTI Generator and Oscillator System

• These two blocks are exactly the same respect the
  ones used in DCTI methods

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The Method Recognizer
This block implements the following algorithm.
The simulations showed max 30 is a the optimum
choise.
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DCTI Control Parameter Generator

• This block included the DCTI Control Parameter
  Generator and a simple circuit called Input
  Selection performing the following operation
• INi Zi selZi where Zi is a DCTI or SRTS
  sample depending on the sel signal

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The Results
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Advantages

• Compatibility with DCTI and SRTS methods
• Long term oscillations very low with respect to
  the SRTS ones and similar to the DCTI ones
• Locking time shorter than the SRTS one
• Quick response to rapid change in the source
  clock frequency
• Almost uneffected by any cell loss