Since the popularity of CMOS image sensor, the traditional analog video surveillance is undergoing tremendous transformation. More and more security camera manufacturers launch new high definition analog solutions, which are, HD-SDI, HD-CVI, HD-TVI, and now HD-AHD. All of them can deliver 720P/1080P high definition images, and transmitting the video over traditional coaxial cable. HD-SDI cameras and HD-SDI DVR are the most expensive HD analog equipment among them, which is the main reason HD-SDI technology doesn’t widely used in HD analog surveillance system. Compared with HD-SDI, the cameras based on other three technologies are very competitive.
We have already written some articles to introduce each of these technologies, and the difference between them. Today, we are going to discuss the difference between HD-CVI cameras and HD-AHD cameras.
The main difference: 1.0 megapixel AHD camera adopts OV9712 + NVP2431H solution, while HD-CVI camera adopts the PO3100K + DH9801 solution. In addition to the difference of solution, the price vary greatly, OV9712 + NVP2431 of AHD camera module only costs US$6.5, and PO3100K + DH9801 camera module costs approximate US$10.
Additionally, AHD camera can connect to CRT display directly, the image can display properly. HD-CVI camera connects to traditional CRT, it doesn’t show images. For video live view/recording/playback, HD-CVI cameras need to work with HD-CVI DVR. It seems, the HD-AHD cameras support 960H output mode, which is very convenient for test and installation. Since the AHD cameras can be backward compatible with all traditional analog equipment. Compared with HD-CVI, it has advantages of great compatibility.
Hit a nutshell, AHD and HD-CVI are very similar. Please note that in order to achieve megapixel definition monitoring (720P), the AHD cameras also need to work with AHD DVR.
Introduction to AHD
During old traditional surveillance system’s upgrading and replacing, can’t balance between achieving high definition surveillance and combining old traditional analog system become headache for users. In standard analog surveillance system, 960H is the highest resolution, to achieve much higher resolution becomes impossible mission for traditional surveillance system since its limitation from its technology.
If adopts all high definition (HD) IP camera, the entire system need to replace, this will not only generate high labor cost, but also significantly increased the project budget.
AHD stands for analog high definition, AHD’s birth, is to solve the transmission distance limitations of existing HD-SDI solution. As one of new HD analog solution, AHD supports video transmission over traditional 75-3 coaxial cable up to 500 meters, and it becomes another alternative for HD analog solution. By the way, it inherits and carries forward advantages of traditional analog solution, video signal are uncompressed, keep all the original video details, to truly achieve high definition uncompressed lossless, no video latency effect.
Similar to other HD analog solutions, through using the progressive scan CMOS image sensor, the AHD camera can deliver 1.0 megapixel, 1.3 megapixel, 2 megapixel resolution, added with ICR filter, the camera achieve true day/night video surveillance; and same like the traditional analog system, AHD products support plug-and-play installation, easy to use.
Introduction to AHD Cameras
Recently, some companies offer AHD analog cameras which deliver 1.0 megapixel and 1.3 megapixel resolution. 1.0 megapixel AHD camera adopts OV9712 + NVP2431H, and 1.3 megapixel adopts SONY IMX238 + NVP2430H chipsets.
AHD chipsets are from Korean company – Nextchip, the company launches AHD chipsets (NVP2430H/NVP2431H) which can work with 1.3 megapixel progressive scan CMOS image sensor. The new HD-AHD chipsets are designed to meet the demands of new trend in CCTV market, it is suitable for both analog HD camera and cost-effective HD-SDI applications. The main concept of NVP2430H is supporting 1.3M CMOS sensor and output I/F as analog 1280H(CVBS/COMET), AHD 1.0(720p) and HD-SDI 720p. NVP2431H is supporting 1.3M CMOS sensor and output I/F as analog 1280H(CVBS/COMET) and AHD 1.0 (720p).
Introduction to AHD DVR
Currently, we still haven’t seen the real products of AHD DVR. Since Nextchip is the AHD solution provider, it also offers AHD codec chipset – NVP6114. NVP6114 is designed to encode and record the video footage from AHD cameras. AHD DVR based on NVP6114 can support 4 channel AHD and 9 channel audio codec. It can work with 1.0 megapixel and 1.3 megapixel AHD cameras, deliver high quality images.
NVP6114 includes 4-Channel AHD1.0 RX and 9-Channel Audio Codec. 4-Channel AHD1.0 RX delivers high quality images. It accepts separate 4 CVBS/COMET/AHD1.0 inputs from Camera and the other video signal sources. It digitizes and decodes NTSC/PAL/COMET/AHD1.0 video signal into digital video signal which represents 8-bit BT.656/BT.656like 4:2:2 byte interleave format with 27/36/54/72/108/144MHz multiplexed. Especially, It is able to use same transmission cable with conventional one for COMET(SD level) and AHD 1.0 (HD level), and they provide the superior image quality by minimizing the interference when separating Y and C. 9-Channel Audio Codec is 8-Channel Voice/1-Channel Mic PCM Codec which handles voice band signals(300Hz~3400Hz) with 8bit/16bit linear PCM, 8bit G.711(u-law, a-law) PCM. Built-in audio controller can generate digital outputs for recording/mixing and accepts digital input for playback. 4-Channel Coaxial Communication Protocol communicates between controller(DVR) and camera on the video signal through coaxial cable. COMET is Composite Video of Enhanced Technology in SD video by NEXTCHIP. AHD is a video transmission technology in HD video by NEXTCHIP.
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