Delivery delay compensation on synchronised communication devices in a packet switching network

1. A reference station configured to deliver packets in a packet switching network having a non-constant transmission time to communication devices connected to the network, said reference station comprising:

means for retrieving image ticks from a sync signal received by said reference station;

means for initializing an image counter from said image ticks;

means for initializing a counter at each m th reset of the image counter, the counter being cadenced by a clock produced by the image counter, m being a positive, non-zero integer;

means for sampling the counter at each T ech period, T ech being issued by a time base synchronized on all stations of the network,

means for delivering packets comprising samples of the counter; and,

means for inserting at least a temporal offset in said packets, wherein said temporal offset describes a data delivery duration on a pre-determined path of said network in order to address the non-constant transmission time of said packets.

2. Reference station according to claim 1 , wherein every delivered packet contain temporal offset.

3. A receiving communication device connected over a packet switching network having a non-constant transmission time, said receiving communication device being able to receive packets from a reference station connected to the network, said receiving communication device being able to receive data stream from Content Delivery device being connected to the network, said receiving communication device comprising: means for receiving packets comprising samples, said samples resulting from a sampling operation realized at a Tech period ° Tech being issued by a time base synchronized on all stations of the network; means for generating a counter ramp with a Phase Locked Loop receiving the samples and delivering a synthesized clock and local samples at each Tech period; means for initializing an image counter cadenced by the synthesized clock each time the counter ramp is equal to zero; means for generating image ticks each time the image counter is equal to zero; means for generating a sync signal from the said image ticks; means for receiving at least a temporal offset value inserted in said packets in order to address the non-constant transmission time of said packets; means for receiving data stream from sending communication device; means for determining from received data stream which temporal offset it has to consider among received temporal offsets; and means for shifting temporally the received data stream with considered temporal offset.

4. Receiving communication device according to claim 3 , further comprising means for shifting temporally the generated sync signal with considered temporal offset.

5. A sending communication device connected over a packet switching network having a non-constant transmission time, said sending communication device being able to receive packets from a reference station connected to the network, said sending communication device being able to send data stream over the network, said sending device comprising: means for receiving packets comprising samples, said samples resulting from a sampling operation realized at a Tech period, Tech being issued by a time base synchronized on all stations of the network; means for generating a counter ramp with a Phase Locked Loop receiving the sample and delivering a synthesized clock and local samples at each Tech period; means for initializing an image counter cadenced by the synthesized clock each time the counter ramp is equal to zero; means for generating image ticks each time the image counter is equal to zero; means for generating a sync signal from said image ticks; means for sending data stream over the network synchronously to the sync signal; and means for inserting an identification of said sending communication device in said data stream in order to address the non-constant transmission time of said data stream.

6. The reference station according to claim 1 , wherein the sync signal comprises a Genlock signal.

7. The reference station according to claim 1 , wherein the non-constant transmission time comprises jitter introduced by transportation over the network.

8. The reference station according to claim 7 , wherein the network comprises an IP network.

9. A method of delivering packets in a packet switching network having a non-constant transmission time to communication devices connected to the network, said reference station comprising:

retrieving image ticks from a sync signal received by said reference station;

initializing an image counter from said image ticks;

initializing a counter at each m th reset of the image counter, the counter being cadenced by a clock produced by the image counter, m being a positive, non-zero integer;

sampling the counter at each T ech period, T ech being issued by a time base synchronized on all stations of the network,

delivering packets comprising samples of the counter; and

inserting at least a temporal offset in said packets, wherein said temporal offset describes a data delivery duration on a pre-determined path of said network in order to address the non-constant transmission time of said packets.

10. The method according to claim 9 , wherein every delivered packet contains temporal offset.

11. The reference station according to claim 9 , wherein the sync signal comprises a Genlock signal.

12. The reference station according to claim 9 , wherein the non-constant transmission time comprises jitter introduced by transportation over the network, and wherein the network comprises an IP network.

13. A method of receiving communication over a packet switching network having a non-constant transmission time, said method comprising:

receiving packets comprising samples, said samples resulting from a sampling operation realized at a T ech period ·T ech being issued by a time base synchronized on all stations of the network;

generating a counter ramp with a Phase Locked Loop receiving the samples and delivering a synthesized clock and local samples at each T ech period;

initializing an image counter cadenced by the synthesized clock each time the counter ramp is equal to zero;

generating image ticks each time the image counter is equal to zero;

generating a sync signal from the said image ticks;

receiving at least a temporal offset value inserted in said packets in order to address the non-constant transmission time of said packets;

receiving data stream from sending communication device connected to the network;

determining from received data stream which temporal offset it has to consider among received temporal offsets; and

shifting temporally the received data stream with considered temporal offset.

14. The method according to claim 12 , further comprising:

shifting temporally the generated sync signal with considered temporal offset.

15. The method according to claim 12 , wherein the sync signal comprises a Genlock signal.

16. The method according to claim 12 , wherein the non-constant transmission time comprises jitter introduced by transportation over the network, and wherein the network comprises an IP network.

17. The method according to claim 12 , further comprising:

receiving regularly a plurality of temporal offset values each being associated with a Genlock plane; and

receiving an identification of the Genlock plane from which the data is sent in parallel with the data stream; and

determining a temporal offset to consider among the plurality of temporal offset values received based on the identification of the Genlock plane.

18. A method of sending communication over a packet switching network having a non-constant transmission time, after receiving packets from a reference station connected to the network, said method comprising:

receiving packets comprising samples, said samples resulting from a sampling operation realized at a T ech period, T ech being issued by a time base synchronized on all stations of the network;

generating a counter ramp with a Phase Locked Loop receiving the samples and delivering a synthesized clock and local samples at each T ech period;

initializing an image counter cadenced by the synthesized clock each time the counter ramp is equal to zero;

generating image ticks each time the image counter is equal to zero;

generating a sync signal from said image ticks;

sending data stream over the network synchronously to the sync signal; and

inserting an identification of said sending communication device in said data stream in order to address the non-constant transmission time of said packets.

19. The method according to claim 17 , wherein the sync signal comprises a Genlock signal.

20. The method according to claim 17 , wherein the non-constant transmission time comprises jitter introduced by transportation over the network, and wherein the network comprises an IP network.

21. The method according to claim 17 , wherein the identification of the sending communication device enables a receiving device to select a temporal offset among a plurality of received temporal offset values.