Timing recovery for variable bit-rate video on asynchronous transfer mode (ATM) networks

Apparatus for use in an asynchronous transfer mode (ATM) transmission network for recovering timing in a receiver comprising:

• means for receiving an asynchronous digital signal including system clock reference values and transmission rate values;
• means for extracting said system clock reference values and said transmission rate values from the received asynchronous digital signal;
• means supplied with said extracted system clock reference values and extracted transmission rate values for generating estimated clock reference values between the times indicated by said extracted system clock reference values, said means for generating including means for adjusting the values of the extracted system clock reference values and the generated estimated clock reference values to be a value representative of the time that a corresponding cell was supplied as an output from a remote encoder and means for generating an estimated clock reference value for each received cell in the asynchronous digital signal between the times indicated by said extracted system clock reference values;
• means for utilizing said extracted system clock reference values and estimated clock reference values for generating a system time clock at the receiver, said means for utilizing including means responsive to said system time clock, said extracted system clock reference values and said estimated clock reference values for generating an error signal representative of the difference between said system time clock and said estimated clock reference values;
• and
• means for determining when said extracted system clock reference values and extracted transmission rate values occur in the same received cell, said means for utilizing further including means for inhibiting generation of said error signal when said extracted system clock reference values and said extracted transmission rate values are not in the same cell.