Coaxial cables were in common use during the initial years of imaging for analogue cameras, providing a cost-efficient and robust solution with marginal signal loss over long cable lengths. In the course of the digital (r)evolution, these traditional cables are now also making inroads in both, CoaXPress digital transmission standard and also the HD-SDI broadcast standard. For this, a parallel digital signal which is generated by the camera is serialised and then send to the frame grabber through a single 75 ohm coaxial line in data packages at a correspondingly higher frequency and with electronic conditioning. Due to the fact that CoaXPress, unlike IEEE 1394 or Gigabit Ethernet, is not using standard mass market technologies, the CoaXPress specification comprises the electrical specification of the signals on the cable, in addition to the protocol definition. CoaXPress establishes a point-to-point link between the camera and the frame grabber, so that the complete bandwidth is always available to the image data of the camera.
As described, in the simplest case, CoaXPress uses a single coaxial line for forward and return channels, so that it is fairly easy to route the connection of the camera through a slip ring to provide a movable camera installation with little effort. Unlike in the case of GigE Vision or IEEE 1394, a frame grabber is needed which receives the data in the PC and sends control data to the camera. The drawback of the frame grabber is that an additional card must be installed in the PC; its advantage is that extra preprocessing can be integrated on it and higher bandwidth which was the original intention of CXP.