for cooperating with the retrieval unit 14 as will be made clear hereafter a terminal c of the switch s is coupled to an input of a counter 20 a 42 bit wide output 21 of the counter 20 is coupled to a first input of a comparator 16 the b terminal of the switch s is coupled to a second input of the comparator 16 an output of the comparator 16 is coupled to a control input of a controllable oscillator 22 which preferably runs at a 27 mhz frequency on the average the output of the oscillator 22 is coupled to clock inputs of the counters 20 and 24 the counter 24 has a 22 bit wide output which is coupled to a second input of the signal combination unit 12 an output of the signal combination unit 12 is coupled to an input of a write unit 18 the write unit 18 is well known in the art and needs no further explanation the counter generates the time stamps for the packets these time stamps being combined with their corresponding packets in the signal combination unit 12 further a central processing unit 84 is present for controlling among others the position of the switch s a further description of the retrieval of the pcr signals in the retrieval unit 14 will now be given the retrieval.