Method and circuit for insertion of time stamp into real time data
View Patent ↗A system for adding a time stamp to transmission traffic on a network comprises a front end processor that receives a packet from the network and generates a Start Of Frame pulse and a LENGTH field corresponding to a length of the packet. A time stamp generator generates a time stamp by sampling the system master time counter. A synchronizer receives the SOF pulse and the LENGTH field from the front end processor, and generates a control signal. A multiplexer inputs the packet from the front end processor, the control signal and the time stamp, and outputs a modified packet with a field in the packet replaced by the time stamp.
1. A system for adding a time stamp to transmission traffic comprising:
a front end processor that receives a packet and generates a start of frame (SOF) pulse and a LENGTH field that corresponds to a length of the packet;
a time stamp generator that generates a time stamp;
a synchronizer that receives the LENGTH field and the SOF pulse from the front end processor and generates a control signal; and
a multiplexer that inputs the packet from the front end processor, the control signal and the time stamp, and outputs a modified packet with a field in the packet replaced by the time stamp.
2. The system of claim 1 , wherein a length of the modified packet is the same as the length of the packet.
3. The system of claim 1 , wherein the field in the packet is a cyclic redundancy check field.
4. The system of claim 1 , wherein the field in the packet is a checksum field.
5. The system of claim 1 , wherein the field in the packet is a reserved DOCSIS field.
6. The system of claim 1 , wherein the field in the packet is a destination address field.
7. The system of claim 1 , wherein the field in the packet is a source address field.
8. The system of claim 1 , wherein the field in the packet is four bytes long.
9. The system of claim 1 , wherein the field in the packet is two bytes long.
10. The system of claim 1 , wherein the timestamp is four bytes long.
11. The system of claim 1 , further including a memory for storing the modified packet.
12. The system of claim 11 , wherein the memory is a local memory.
13. The system of claim 1 , wherein the packet is a MAC (Media Access Controller) frame.
14. The system of claim 1 , wherein the packet is a data packet.
15. A method of time stamping transmission traffic comprising the steps of:
receiving a packet from a network;
generating a real-time timestamp;
generating a Start Of Frame signal and a control signal; and
outputting a modified packet with a field in the packet replaced by the real-time timestamp in response to the control signal and the Start Of Frame signal.
16. The method of claim 15 , further including the step of storing the modified packet locally.
17. The method of claim 15 , wherein a length of the modified packet is the same as a length of the packet.
18. The method of claim 15 , wherein the field in the packet is a cyclic redundancy check field.
19. The method of claim 15 , wherein the field in the packet is a checksum field.
20. The method of claim 15 , wherein the field in the packet is a reserved DOCSIS field.
21. The system of claim 16 , wherein the field in the packet is a destination address field.
22. The system of claim 16 , wherein the field in the packet is a source address field.
23. The method of claim 15 , wherein the field in the packet is four bytes long.
24. The method of claim 15 , wherein the field in the packet is two bytes long.
25. The method of claim 15 , wherein the real-time timestamp is four bytes long.
26. The method of claim 15 , further including the step of outputting a LENGTH signal corresponding to a length of the packet to a synchronizer.
27. The method of claim 26 , further including the step of determining a position of the field based on the LENGTH signal.
28. The method of claim 15 , further including the step of storing the modified packet in a memory.
29. The method of claim 15 , wherein the packet is a MAC frame packet.
30. The method of claim 15 , wherein the packet is a data packet.