HD-CVI offers an HD-Over-Coax Solution with Long-Distance Transmission
The industry is quickly moving from standard definition video to high definition. Customers have many choices when looking for a HD surveillance video and HD-CVI is one of the latest choices to hit the market. HD-CVI which stands for High Definition Composite Video Interface offers customers the ability to use existing coax wiring to upgrade their standard analog systems to HD video resolution.
Why the New Technology?
There is approximately 400 million analog camera systems deployed worldwide. These coaxial cabling based systems continue to dominate today’s video surveillance market. Customers looking to upgrade to High Definition Surveillance Video would typically need to change their existing cabling in order to install a higher resolution system.
HDCVI is a simple solution for upgrading existing analog systems from standard definition to high definition, while offering longer transmission via coax cable at a lower total cost.
What is HDCVI?
HDCVI is basically a surveillance solution for megapixel HD
applications, offering no latency, long-distance transmission at a very
low cost. The name derives from its base-band and quadrature amplitude
modulation technology, that is able to avoid any CVBS cross talk,
completely separate hue signal and brightness, and enhances video
HDCVI surveillance products incorporate both cameras and security DVRs. The CVI system is star topology structured and the DVR serves as a node for an over coax Point-to-Point (P2P) transmission to the camera. Currently the technology comes in 3 resolution sizes: : 1080p (1920×1080), 960P (1280×960) and 720p (1280×720). HD-CVI also offers the Auto Signal Compensation (ASC) patent which allows extremely low signal distortion as well as long-distance transmissions.
CVI technology allows for transmitting data over 500m over coaxial cable. It is recommended to use 75-3 cable or 75-5 cable for transmissions within 500m, cable 75-5 and above for any distance over 500m. Connectors, splices and can affect the transmission distance.
1 Coaxial Cable – 3 Signals
HDCVI allows for the transmission of video, audio, and control signals (RS485) over one coaxial cable, simplifying installation.
To allow multiple-signal transmission over one cable, both the audio and dual-way data communication signals are embedded in a whats called a blanking zone. This allows for enhancing synchronization with the video signal and supports a max sampling rate of 44.1kHz thanks to ASC.
The bidirectional data channels are composited in the frame blanking zone, brining a two-way, end-to-end transmission that supports control commands such as PTZ control, camera focus, real-time alarm, etc.
Forward output data supports high transmission baud rates. The electrical signal baud rate and sending time are predictable, and the receiving end is of high ASC performance.
On the flip side, the reverse output data supports a lower baud rate due to its low signal frequency and limited data, which is affected by channel transmission uncertainty and impedance matching. Since HD-CVI adopts ASC, the reverse channel can restore some degree of the electrical signal during those long-distance transmissions.
HD-CVI chipsets are comprised of a receiving chip (RX) and transmitting chip (TX), which are specifically designed for front-end HDCVI security cameras and DVRs, respectively. These chips may also be applied to distributors, fiber optics transceivers, and matrixes as well.
TX chip interfaces are a I2S audio interface, BT1120/BT656 digital video interface, and I2C configuration interface, which are all of industrial standard design. This allows the TX chip to be used in any standard interface for ISPs and audio chips on the market.
The TX chips also allow for analog output, in addition to the HDCVI format, the TX chip is compatible with CVBS as well. The TX chip supports 720p@25fps/30fps/50fps/60fps and 1080p@25fps/30fps.
Figure 1: TX Flow Chart
The figure above shows the simplicity of the HDCVI solution with the adopted TX chip. The tiny size of the chip also makes it suitable for application in all kinds of camera sizes.
The RX chip supports HDCVI HD inputs and digital video outputs — I2S audio output, multiple-chip audio cascade output, as well as I2C configuration interface. It also supports flexible mapping of HDCVI video input channel and digital output channel. Each of these channels has its own format and built-in equalizer that support setup for video parameters such as brightness, contrast, hue, saturation, and dual-way control signal transmission.
Figure 2: RX Flow Chart
As seen in Figure 2, the RX chip has the same interface as the AD chip in a conventional analog DVR, which is to say, that it provides seamless integration with conventional DVRs. The built in equalizer allows HDCVI DVRs to receive HD video signals from up to 500m. The TX chip supports 1080p@25fps/30fps/50fps/60fps
HDCVI offers Long-Distance HD transmission
Besides rendering a smooth HD transmission during long-distance wire runs HDCVI also allows for you to minimize the IP hassles typically involved with IP cameras and allows for simple installation; it also features a no-latency for a real-time performance. Since there is no need for video compression processing to maintain its original video quality HD-CVI is able to provide high quality vivid images. When comparing CVI to traditional analog systems, HDCVI has the advantage on the transmission distance front, as it can transmit 500m by simply using 75-3 cable for general transmission while offering a low signal distortion rate.
SO to wrap things up, HDCVI not only gives you a good solution that offers HD megapixel image quality over long-distance transmission, but it also allows for easy installation at a very low cost.