Method and Devices for Packet Selection

1. A method of selecting packets transmitted from a first device to a second device over a packet network, the method including the steps of: sending, from the first device to the second device, packets; recording the time of receipt of said packets according to a clock in the second device; repeatedly, for each of a plurality of groups of said packets: determining an optimal inter-arrival time between successive packets at the second device; calculating, for each packet in said group, the inter-arrival time between the packet and the preceding packet; selecting the packet in said group which has an inter-arrival time which is the closest to the optimal inter-arrival time; sending, from the first device to the second device, timestamps which are the time of sending said packets from the first device according to a clock in the first device; determining, for each packet in said group, the inter-departure time between the packet and the preceding packet from the first device, wherein an optimal inter-arrival time is determined for each packet as the inter-departure time between said packet and the preceding packet; and using the selected packets in the synchronization of the clock in the second device to the clock in the first device.

2. A method according to claim 1 wherein the groups of packets are all the packets arriving within a selected time window prior to the current time.

3. A method according to claim 1 wherein the second device is a master device and the first device is a slave device and the packets are timing messages sent from the master device to the slave device over the packet network.

4. A first networked device connected to a second networked device over a packet network, wherein the first networked device has a clock, a memory, and a processor coupled to the memory, the processor configured to: receive packets from the second device; record the time of receipt of said packets according to said clock; repeatedly, for each of a plurality of groups of said packets: determine an optimal inter-arrival time between successive packets at the first device; calculate, for each packet in said group, the inter-arrival time between the packet and the preceding packet; select the packet in said group which has an inter-arrival time which is the closest to the optimal inter-arrival time; receive, from the second networked device, timestamps which are the time of sending said packets from the second device according to a clock in the second device; and determine, for each packet in said group, the inter-departure time between the packet and the preceding packet from the second device, wherein an optimal inter-arrival time is determined for each packet as the inter-departure time between said packet and the preceding packet; and synchronize the clock in the first networked device to the clock in the second networked device using the selected timing messages.

5. A networked device according to claim 4 wherein the groups of packets are all the packets arriving within a selected time window prior to the current time.

6. A networked device according to claim 4 wherein the second networked device is a master device and the first networked device is a slave device and the packets are timing messages sent from the master device to the slave device over the packet network.

7. A networked system, the system including: a first networked device; a second networked device having a clock, a memory, and a processor coupled to the memory; and a packet network connecting the first and second devices, wherein the processor of the second networked device is configured to: receive packets from the first device; record the time of receipt of said packets according to said clock; repeatedly, for each of a plurality of groups of said packets: determine an optimal inter-arrival time between successive packets at the second device; calculate, for each packet in said group, the inter-arrival time between the packet and the preceding packet; select the packet in said group which has an inter-arrival time which is the closest to the optimal inter-arrival time; receive, from the first device, timestamps which are the time of sending said packets from the first device according to a clock in the first device; and determine, for each packet in said group, the inter-departure time between the packet and the preceding packet from the first device, wherein an optimal inter-arrival time is determined for each packet as the inter-departure time between said packet and the preceding packet; and synchronize the clock in the second device to the clock in the first device using the selected timing messages.

8. A networked system according to claim 7 wherein the groups of packets are all the packets arriving within a selected time window prior to the current time.

9. A networked system according to claim 7 wherein the first networked device is a master device and the second networked device is a slave device and the packets are timing messages sent from the master device to the slave device over the packet network.