eNEWSLETTER SIGNUP

Q+A CENTER

Cameras with Gigabit Ethernet (GigE) interfaces are cropping up in imaging applications everywhere, and there is good reason for that. GigE delivers full-duplex connectivity at one gigabit per second (Gb/s) over standard, low-cost infrastructure. It has long-distance reach, supports almost any network configuration that can be envisioned, and allows heavy-duty processing tasks to be handled by scaleable stacks of economical PCs.

All GigE cameras look about the same from the back, with a RJ-45 LAN plug. But when it comes to performance, the interface electronics inside can make a world of difference.

GigE camera interfaces must perform, at minimum, six functions:

• acquire imaging data from the camera head;
• convert the data to IP packets;
• queue the IP data for GigE transfer;
• transfer the data to the IP link;
• deliver control signals from the GigE link to the camera head; and
• handle network functions such as boot-up and packet resend.

Basically, two design approaches can be taken to meet these requirements: build purpose-built hardware from the ground up, or write a software application for an embedded processor. Deciding which approach to take can be tricky and, in the end, usually reflects a combination of application needs and business priorities.

Hardware = Low Power, High Performance

In general, purpose-built hardware yields a high-performance, reliable GigE interface that can accommodate just about any camera sensor, including those with high resolutions and fast frame rates. Hardware interfaces operate with clock-cycle accuracy, and so perform processing tasks quickly, efficiently, and deterministically. They fit into compact footprints, important for small-body cameras.

Hardware interfaces also draw a small amount of power — as low as 2.0 watts (W) — and this level varies only slightly with different sensors. This is a key point, and one that gives hardware interfaces a clear advantage over software solutions, because it means camera manufacturers can use one interface to GigE-enable a wide range of cameras in their portfolios.