Controlling packet transmission timing with delays
Document number: AW000649
The document deals with camera settings for efficient use of the available bandwidth of Gigabit Ethernet (GigE) connections. Single-camera and simultaneous multiple camera operation are considered.
- The structures of data packets, used for data transmission via the GigE connection, are described. The parameters determining transmission efficiency of data packets relate to packet length (“packet size”) and time intervals (“interpacket delays”) between consecutive packets. Sensor readout time is mentioned to define the shortest possible interpacket delay (the “native delay”).
- An example for one packet and its payload data is given: The example illustrates how to calculate the time needed for sensor readout of the payload data, for packet assembly and for packet transmission.
- Efficient use of several simultaneously operating cameras is possible when avoiding that the cameras “clog” the GigE connection by simultaneously tying to transmit packets to the PC. This can be achieved by starting packet transmission for each camera at a different time (employing the frame start delay) and by setting the interpacket delay such that only one packet is transmitted at a time.