Synchronous method for the clock recovery for CBR services over the ATM network
AssigneeTelefonaktiebolaget LM Ericsson (publ)
InventorSilvia Restivo
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Abstract
A synchronous method for clock recovery for use with constant bit rate (CBR) services over an ATM network is disclosed. A square wave related to the source frequency is compared to a square wave related to the network frequency using an exclusive OR to obtain a duty cycle transported to the receiver. The duty cycle includes information which is sufficient to recover the source clock when the network frequency duty cycle is known.
Claims14
A synchronous method of clock recovery in the transport, from a transmitter to a receiver, of constant bit rate (CBR) services over an ATM network, comprising:
- comparing the square wave related to the source frequency to the square wave related to the network frequency using an exclusive OR in order to get a signal from which a duty cycle is obtained, and
- transporting information to the receiver by the duty cycle, which information is necessary and sufficient to recover the source clock, when the network clock is known once having produced a similar duty cycle at the receiver and having compared the values of the above-mentioned duty cycle signals in subsequent timing instants.
A transmitter for synchronous clock recovery related to constant bit rate (CBR) service over an asynchronous transfer mode (ATM) network, comprising:
- a comparator for comparing a time-varying source signal related to the source frequency to a time-varying network signal related to an ATM network frequency using and exclusive-OR operation;
- a duty cycle generator for generating a duty cycle signal from an output of the comparator;
- and
- a transmitter for transmitting the duty signal to the receiver as part of the CBR service over the ATM network,
- wherein the duty cycle signal and the periodic network signal are used by the receiver to recover the source frequency.
A receiver for synchronous clock recovery related to a constant bit rate (CBR) service over an asynchronous transfer mode (ATM) network, comprising:
- receiving circuitry for receiving a duty cycle signal transmitted from a transmitter as part of the CBR service over the ATM network, the duty cycle signal being produced by the transmitter comparing a time-varying source signal related to the source frequency and a time-varying network signal related to an ATM network frequency;
- a comparator for comparing the time-varying source signal to the time-varying network signal using a exclusive-OR operation;
- and
- a duty cycle generator for generating a duty cycle signal from an output from the comparator,
- wherein the receiving circuitry is configured to use the duty cycle signal and the time-varying network signal to recover the source frequency.
Dependencies are inferred from the claim text.