Published on 14 December, 2012
|HDCVI has an advantage in installation and costs
The video surveillance segment has enjoyed great progress over the past few years and there is no denying that HD is currently very popular and the industry is becoming more active, with companies trying hard to lead in this trend. The three main HD solutions, namely, IP HD, HD-SDI HD and analogue HD have been intensively discussed on their limitations and restrictions, to decipher which one will be the optimal solution in the long-run.
Although surveillance technology and its market are undergoing a profound change, the IP solution is popular due to its qualities such as high image quality, easy cabling, long-distance and non-compression transmission, but somehow we are ignoring an important and also practical factor — the infrastructure. After all, the analogue solution has its advantages, such as the vast existing market, stability, reliability and recognition from the customer. However, despite its advantages, its average image quality can’t contend with today’s HD demand anymore. But Dahua Technology is about to introduce a solution— Dahua in-house transmission technology HDCVI (High Definition Composite Video Interface). As the name says, it is for HD data transmission, which is an over-coaxial-cable analog HD video transmission standard, developed in-house. The technology renders two HD video formats—1920H (1920×1080) & 1280H (1280×720) by progressive scanning.
Firstly, the HDCVI was specially designed for authentic analogue HD transmission with max. definition of 1280H (1280×720) and 1920H (1920×1080), which is far better than the current 960H (960x576) generation products. Due to the fact that the chroma signal of CVBS is on the carrier wave of 4.43MHz, which is within the brightness range, the signal crosstalk problem has yet to be solved despite the separation processing on the back-end. However, the HDCVI can successfully remove this obstacle with the new modulation tech adopted, and ensure a high separation ratio in modulating the brightness and chroma and maximising the resolution and visual effect.
Secondly, the current “CVBS products” need extra cabling, components and installation, such as audio cable and built-in modules or external devices to realise audio and reverse control. But HDCVI again solves the problem by compounding the video/audio/PTZ signals together while standardising the two-way transmission format, ensuring the compatibility of the products while simplifying the installation and maintenance.
Lastly, comes the cost. HDCVI has an advantage in installation and costs concerning accessories and maintenance, as it reserves the conventional analogue system structure.
HDCVI versus HD-SDI
Even with the cableΦ75-5 and the latest compression technology under HDCCTV alliance, its max transmission distance is about 300 meters, theoretically. But the HDCVI’s minimum transmission distance is 500 meters with cableΦ75-3. In addition the HD-SDI signal is easily interfered, especially in a high-frequency environment, which can easily exert a bad effect on the image. On the contrary, HDCVI has a strong anti-interference capability & solid interface protection.
HDCVI versus IP
As HDCVI is regarded as the upgraded version of the previous analogue system, it naturally evades the disadvantages of an IP solution.