Camera LinkTM Introduction

REFERENCE A

Camera Link is a Protocol that is Implemented in Channel Link Hardware

Camera Link is a communication interface for machine vision. The interface extends the underlying technology of Channel Link to provide a specification more useful in this application.

For years, the scientific and industrial digital video market has lacked a standard method of communication. Both frame grabbers and camera manufacturers developed products with different connectors, making cable production difficult for manufacturers and very confusing for consumers. A connectivity standard between digital cameras and frame grabbers has been long overdue and will become even more necessary as data rates continue to increase.

Increasingly, diverse cameras and advanced signal and data transmissions have made a connectivity standard like Camera Link a necessity. The Camera Link interface will reduce support time, as well as the cost of that support. The standard cable will be able to handle the increased signal speeds, and the cable assembly will allow customers to reduce their costs through volume pricing.

Channel Link is a Widely-Used Signaling Method

National Semiconductor initially developed the Channel Link technology for flat-panel displays, and based it on the LVDS physical layer. This technology was then extended for general-purpose data transmission. Channel Link is built up of sets of driver and receiver pairs. Each driver set accepts 28 single-ended data signals and an accompanying single-ended clock. This data is serialized 7:1, and the resulting four data streams and clock signal are driven over five LVDS pairs. The receiver accepts these five signals and drives the full 28 bits and clock signal to its output pins as shown in Figure A.1.

Channel Link's transmission method requires fewer conductors to transfer data and allow for a smaller connector, which is important for compact cameras such as the CAM/CMOS – 2K.LS

The Channel Link chipset provides data transmission rates up to 2.38 Gbit/sec.

Channel Link uses LVDS, a Low-Voltage Differential Signaling Standard

Low Voltage Differential Signaling (LVDS) is a high-speed, low-power general purpose interface standard. The standard, known as ANSI/TIA/EIA-644, was approved in March 1996. LVDS uses differential signaling, with a nominal signal swing of 350mV differential. The low signal swing decreases rise and fall times to achieve a theoretical maximum transmission rate of 1.923 Gbps into a lossless medium. The low signal swing also means that the standard is not dependent on a particular supply voltage. LVDS uses current-mode drivers, which limit power consumption. The differential signals are immune to up to ±1 V common volt noise.

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