Automatic compensation of a delay of a synchronization signal in a packet switching network

1. A device operative to send packets in a packet communication network comprising at least two stations, said device comprising:

means for extracting image pips on the basis of a synchronization signal;

means for initializing an image counter on the basis of the said image pips;

means for initializing a counter in response to zero-crossings of the image counter, the counter being regulated by a clock produced by the image counter;

means for sampling the counter every period T smp , where T smp emanates from a time base synchronized on all the stations of the network;

means for sending packets containing the samples of the counter in the network;

means for receiving packets containing samples sent by a station of the network as echo samples to the samples of the counter sent by the device in the network;

means for evaluating a duration of propagation of samples over an outward-return trip between said device and said station in response to the echo samples;

means for determining a phase shift value Δφ on the basis of the duration of propagation; and

means for sending the phase shift value Δφ in the network.

2. The device according to claim 1 , wherein the phase shift value Δφ is determined so that the samples of the counter sent by the device in the network are identical to the echo samples.

3. The device according to claim 1 , wherein the phase shift value Δφ to be applied corresponds to an integer number of periods T smp .

4. The device according to claim 1 , wherein the evaluation of the duration of propagation includes a comparison between the echo samples and the samples of the counter.

5. The device according to claim 1 , wherein the synchronization signal is of Genlock type.

6. The device according to claim 1 , wherein the time base synchronized on all the stations of the network is according to the IEC 61588 standard.

7. A device operative to receive packets in a packet communication network comprising at least two stations, said device comprising:

means for receiving packets containing samples of the network, the samples originating from data sampled every period T smp , where T smp emanates from a time base synchronized on all the stations of the network;

means for regenerating a counting ramp via a phase-locked loop receiving the samples and furthermore delivering local samples every period T smp and a reconstituted clock;

means for initializing, at every zero-crossing of the counting ramp, an image counter which is regulated by the reconstituted clock;

means for generating image pips every zero-crossing of the image counter;

means for reconstituting a synchronization signal on the basis of the image pips;

means for receiving packets containing a phase shift value Δφ;

means for sending in the network packets containing the local samples;

means for phase-shifting the samples received by the phase shift value Δφ, to generate phase-shifted samples in response to the phase shift value Δφ; and

means for supplying the phase-locked loop with the phase-shifted samples.

8. The device according to claim 7 , wherein the counting ramp is a program clock reference (PCR) counter.

9. The device according to claim 7 , wherein the time base synchronized on all the stations of the network is according to the IEC 61588 standard.