What is HD-TVI? What is HD-CVI? What is AHD? What are the differences between analog cameras, HD-TVI, HD-CVI, and AHD cameras?
In this article, we will talk about the differences between HD-TVI, HD-CVI, and AHD, what these technologies do, and which one provides a better image in a CCTV system.
What are HD-TVI, HD-CVI and AHD technologies?
HD-CCTV (High Definition-Closed Circuit Television) is CCTV’s answer to the IP camera’s high definition image quality.
This technology can transmit uncompressed high-definition video over point-to-point coaxial cables. The biggest benefit we saw at the advent of HD-CCTV was the fact that newer HD-CCTV cameras did not need cabling upgrades.
The original coaxial cables from the CCTV era had enough unused data spectrums that they could be used for the new HD-CCTV cameras.
This made it easy to install brand new cameras while not needing to overhaul your entire cabling system. First, we will list what these three types of technologies (HD-CVI, HD-TVI, AHD) have in common and later on, we’ll talk about their differences.
1. HD-TVI, HD-CVI and AHD are all HD analog cameras
All these technologies are called HD-over-coax which is an over-coaxial-cable analog HD video transmission standard developed specifically for the CCTV industry.
The technology provides transmission of HD video as well as audio, and two-way control data over long distances. You can implement an HD system using the same coax cables that your existing analog system is running on. HD-over-Coax installs just like analog cameras and gives you a High Definition image (up to 4K).
These technologies emerged in the video surveillance market in 2010 as an alternative to analog and IP video surveillance solutions. In recent years, HD over coax has grown in popularity with the development of new technologies.
2. All these three technologies are analog (not IP)
High definition over coax technologies converts digital signals to analog signals. The video is transmitted over standard coaxial cable (RG59) and twisted pair cable (CAT5/6), allowing existing coaxial cables to be used to transmit high definition video quality.
The ability to use existing coaxial cable reduces the time and cost associated with transitioning from an old analog system to high definition video. HD over coax cameras install just like standard analog cameras, simplifying system installation with no networking involved.
Many companies manufacture HD-TVI/HD-CVI/AHD recorders that support not just HD CCTV cameras but old traditional analog cameras and IP cameras as well. These recorders are known as hybrid or tribrid recorders.
However, the way these cameras are advertised makes many people think that HD-TVI, HD-CVI, and AHD are not analog cameras, which is wrong. They’re all analog cameras that provide HD images (2MP, 4MP, and even higher).
3. HD-TVI, HD-CVI and AHD cameras work with coaxial cables
Let’s say you need to replace those old grainy CCTV security cameras and intend to install a new crystal clear CCTV system. But it’s gonna be too costly for you to root out and replace the cable network, what do you do?
You go for HD over coax cameras and keep the same old wires. Yes, that’s right, all these HD cameras use coaxial cabling, just like the old traditional cameras.
When it comes to saving time and money, going with an HD-over-coax upgrade is often the easiest option. And while many IP systems are limited in their range by the Ethernet cables transmission distance (about 328 feet), HDoC cameras can, as previously mentioned, transmit in excess of 2000 feet by using coaxial cables. For more information on coaxial cables read the article: Coaxial Cables for CCTV).
4. HD-TVI, HD-CVI, and AHD cameras are cheaper than IP cameras
Generally speaking, HD analog cameras are less expensive than IP cameras. This, of course, depends on the type of camera you choose and its features.
As mentioned above, many newer HD analog cameras are offering more advanced features, so the price will climb depending on what you purchase.
To offer a comparison, a regular 1080P (2MP) HD over coax camera is 2-2.5 times cheaper compared to a regular IP camera. IP cameras are always generally more expensive. If you have a CCTV project, if you go for HD over coax cameras and recorders, the whole project will be much cheaper.
Characteristics of HD over coax technologies
In this section we will discuss the individual characteristics of each of these technologies.
HD-TVI technology
HD-TVI stands for High Definition Transport Video Interface and it was developed by a Japanese company called Techpoint. HD-TVI technology entered the market initially with 720p (HD) and 1080p (Full HD) cameras and recorders.
The Chinese-based company Hikvision is the largest camera manufacturer using this HD-TVI technology with Techpoint chips. Hikvision distributes its products worldwide in different marketing plans, one of them is using its own brand name and the other one is selling OEM products (the third party companies can add their own logos and brand names).
The technology was created in 2014 with the goal to transmit analog signals using coaxial cables at distances up to 500m. In 2016 Hikvision announced the Turbo HDTVI 3.0 technology which is able to deliver 720p resolution images at distances up to 1,200m and 1080p resolution images up to 750m.
The latest version of HD-TVI technology is able to support cameras with high resolution such as 4MP, 5MP and even 4K cameras (8MP).
Another new feature is the PoC (Power over Coax), meaning it’s possible to power up the camera using the same coaxial cable (this feature is almost the same as the PoE in IP cameras). To learn more read the article: What is Power Over Coax for CCTV.
HD-TVI is an open platform technology, giving manufacturers the technology necessary to produce their own HD-TVI product lines.
Even with the introduction of other technologies, HD-TVI has attracted over 100 manufacturers to design and distribute their own HD-TVI product lines. With so many manufacturers adopting the HD-TVI technology, a wide variety of camera housings is available along with additional features, such as remote focus and remote zoom lens control.
Key features:
- 300-500m coax cable distance
- 720p up to 60fps, 1080p up to 30fps
- PTZ control signals transmitted over coaxial
- No transmission delay
HD-CVI technology
HD-CVI stands High Definition Composite Video Interface. Launched in 2012 by the privately owned Chinese company Dahua, HD-CVI technology has hit the market to revolutionize the use of high-resolution analog cameras.
This technology was a breakthrough for CCTV cameras as it brought HD images and allowed for high-definition analog images to travel well over four hundred and even five hundred meters of cable. (Once an image is traveling far enough, it begins to need boosts to help it get through.)
The first cameras were models with 720p and 1080p resolution. By 2014 the company was already launching the HD-CVI 2.0 version of the technology that continued to advance each year with the launch of new products with high resolutions and the possibility of using cables with greater distances.
Dahua manufactures the cameras themselves and also licenses the use of the technology by other companies around the world. In the HD-CVI version 3.0 the company announced resolutions of up to 4K (8MP) and the PoC (Power over Coax) technology that allows sending power, data, and video through the traditional coaxial cable.
Key features:
- 300-500m coax cable distance
- 720p up to 60fps, 1080p up to 30fps
- PTZ control signals transmitted over coaxial
- No transmission delay
AHD technology
AHD stands for Analog High Definition and was developed by the Korean company Nextchip. AHD technology has brought the 720p and 108op high-resolution analog cameras to market. AHD is interesting because most of its distribution has come in the form of no-name brands.
However, it was recently adopted by Samsung, making the technology considerably more legitimate as far as mainstream markets and long-term sustainability go. HD-AHD cameras are very cheap and are intended to occupy the low-end market.
AHD technology can achieve the reliable transmission of ultra-long distance (500 meters) high-definition video signal on the existing analog transmission line.
It adopts advanced Y/C signal separation and simulation filtering technology, which can effectively reduce the color noise in the high-frequency areas, image reducibility is better. Compared with the traditional high definition products, AHD manufacturers claim better image quality and compatibility, but in practice that’s doubtful.
When purchasing an AHD camera you’ll find the under three naming rules: AHD-L, AHD-M, and AHD-H that represent Low, Medium, and High resolutions respectively. The AHD-M has a 720p resolution and the AHD-H has 1080p resolution.
Key features:
- 300-500m coax cable distance
- 720p up to 60fps, 1080p up to 30fps
- PTZ control signals transmitted over coaxial
- No transmission delay
HD-TVI, HD-CVI, and AHD picture comparison
The images below show how these three technologies compare to each other. These tests were conducted by the Dan Clinton of Clinton Electronics. The cameras were tested out on default settings and all of them were running on a Sony chipset.
Moving vehicle during the day
A casino table and dollar bills
Parked cars during the day
Color palette test
Low light environment. Note the artifacts.
Varifocal cameras fully zoomed in (12 mm)
Video compression did not affect the tests due to the use of an external recorder device for all cameras.
Where to buy HD-TVI, HD-CVI, and AHD cameras?
You can visit the manufacturer’s official site to look for local resellers or dealers. Or you can check on Amazon. Keep in mind that many HD CCTV cameras support all these three technologies at the same time. Sometimes these cameras are called 3in1 or 4in1 HD over coax cameras.
Summary of the Three
You may have noticed that none of the technical specs really differentiate from each other. There are minute differences in what chips or image sensors they’re using, but ultimately for the end-user, there’s not enough to make a point of it. Now if you were to ask the individual vendors and manufacturers they’d probably have enough to fill your ear for days.
What concerns you as a customer is a split in how these technologies encode their videos or, to be more specific, in their DVRs (Digital Video Recorder).
While IP cameras can encode from the camera itself, as IP cameras are essentially tiny computers, HD-CCTV sends their data to DVRs for encoding. The problem is that each technology must use its own DVR. You cannot cross an HD-CVI camera with an HD-TVI DVR, for example. This is important as it means the consumer will be sticking with the technology they purchase first.
Generally speaking, while these cameras have few technical differences, you are likely to see quality issues depending on who you are buying them from. A no-name cheapo brand is definitely going to be more interested in cutting costs to ship out a low-cost product.
You don’t just magically cut manufacturing costs, quality is going to be taking a hit somewhere. For you, the customer, you just need to keep in mind that you get what you pay for. If you’re seeing giant gaps in pricing between similar products then you also need to be looking at who is manufacturing the product.
