CDCTI Compatible Duty Cycle Timing Information

1. 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. Receiver fs’ fs Control Variable Generator Oscillator System DCTI Generator ATM Network DCTI Generator SRTS Generator fn SRTS Generator 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. Control Parameter Generator fs’ Oscillator System ATM Network DCTI Generator M U X SRTS Generator fn Method Recognizer CDCTI Receiver 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

4. DCTI Generator Oscillator System DCTI Generator and Oscillator System These two blocks are exactly the same respect the ones used in DCTI methods

5. The Method Recognizer This block implements the following algorithm. The simulations showed max = 30 is a the optimum choise.

6. 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 + sel*Zi where Zi is a DCTI or SRTS sample depending on the sel signal

7. The Results

8. 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