What Is AHD?

AHD, short for Analog High Definition, is a video transmission format for CCTV cameras. Developed by the Korean chip maker Nextchip and launched around 2014, it sends HD video from a camera to a recorder as an analogue signal over coaxial cable, the same cable used by older standard-definition CCTV.

Inside an AHD camera, the image sensor’s digital output is converted to a high-bandwidth analogue signal and sent down the coax. At the other end, a recorder or capture card samples that signal and turns it back into digital frames. Because the picture is never compressed or packetised on the way, it arrives with very little delay, and the cable can usually run much further than an Ethernet link. Many AHD systems also send camera control, such as on-screen menu commands, over the same coax.

AHD gave older analogue CCTV systems a cheap path to HD: swap the cameras and recorder, keep the cable. It is still common on vehicles and in retrofits.

The format has gone through several versions. AHD 1.0 introduced 720p HD over coax. AHD 2.0 raised it to 1080p, which is now the most common resolution for AHD cameras. Later versions added higher resolutions of around 4 to 8 megapixels on some cameras, although support for these varies between recorders. Most AHD equipment also falls back to standard-definition CVBS (composite) for compatibility with older recorders and monitors.

When mixing equipment, check that the recorder or capture card supports the exact AHD resolution and frame rate of each camera, not just the AHD name.

Three analogue HD formats compete for the same job, and two digital standards cover the rest.

AHD, HD-TVI and HD-CVI look alike on the cable but are not compatible with each other, so a recorder or capture card must support the camera’s format. Many recent recorders and capture devices accept all three, and many cameras can be switched between them.

AHD runs over standard 75 ohm coaxial cable, usually RG-59 or the thicker RG-6, terminated with a BNC connector at each end. Analogue HD typically reaches several hundred metres on good-quality coax, far beyond the 100 m limit of a copper Ethernet link, although the exact distance depends on resolution, cable grade and the receiver. Cameras are usually powered separately, often through a combined video and power cable, and some systems send power over the coax itself.

Old cable can still cause trouble. Copper-clad steel cores, water ingress and worn connectors all show up as noise or colour faults at HD resolutions that went unnoticed in standard definition, so test existing runs before reusing them.

AHD is common in retrofits, where a building already has coax back to a control room, and on vehicles, where buses, trucks, trains and plant use rugged AHD cameras for reversing, blind spots and passenger monitoring. Low latency matters there: a driver reversing needs to see what is behind the vehicle now, not half a second ago.

AHD cameras are normally recorded on a DVR or a hybrid XVR, which accepts AHD, HD-TVI, HD-CVI and IP cameras together. For fleets that want analytics as well as recording, the recorder can be replaced by an edge AI computer with analogue inputs: our range includes a fanless NVIDIA Jetson Orin Nano computer that takes three AHD, TVI or CVI cameras directly, so detection runs on the vehicle without a separate DVR.

To analyse those feeds with AI, a capture card brings AHD into an edge computer. Our object tracking case study takes AHD and SDI cameras into a rugged Jetson computer through Yuan capture cards, and our SDI capture guide explains the digital side. For HD-TVI feeds, our analogue TVI capture cards do the same job in PCIe, M.2, Mini PCIe and USB formats.

We fit analogue and SDI capture cards in rugged edge AI computers as standard, install the drivers and test each camera input before the system ships.