Everything you need to know about Analog and Digital HD-CCTV, well practically everything.

Understanding the practical difference between CVI, TVI, AHD, SDI, EX/SDI and IP (Megapixel) can be a bit confusing to say the least, so in short we?re going to make it as easy as we can for you.

This article will cover everything you need to know about the differences between ANALOG and DIGITAL HD-CCTV systems, how they work, differ in image quality, and how you can upgrade your current system using the appropriate technology to suit your needs and budget.

What?s available?
CVI, TVI and AHD, use an ANOLOG signal, via frequencies that will allow HD (High Definition) image transmission. These technologies were developed to give systems that use coaxial cable such as D1 and lower, the ability to easily up-grade to HD-CCTV, providing a High Definition resolution.

SDI, EX/SDI and IP Megapixel all use DIGITAL transmission, with SDI and EX/SDI developed to specifically provide Broadcast quality HD-CCTV over Coaxial Cable Infrastructures.
So what?s the real difference between ANALOG and DIGITAL in the world of HD-CCTV?

With analog signals, the longer the cable, the more the ‘quality’ of signal diminishes. This means a lower resolution, or a less detailed image, the further the signal has to travel. A digital signal on the other hand will give you a clear high resolution image right to the point where it reaches its maximum distance, at which point it disappears completely.

Why is this important to know?

If you?re ?retro-fitting? or upgrading your CCTV system, it?s important to know, using inexpensive low quality coaxial cable is no longer viable because your image resolution will suffer. You?ll need high quality cable and connectors to get the best results possible.

Knowing what technology is best for you

Which analog HD-CCTV technology is better? CVI, TVI, or AHD?

The first thing you need to know before choosing the right technology for you is what cabling system you currently have or want to install. Then you can decide which technology best fits that cabling. Needs and budget will have a direct effect on your cabling decision.

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The technologies currently on the market are arguably the same; remember the VHS v Beta wars back in the 1970s. In the end whoever takes the market share will likely end-up being the standard. At the time of writing this paper, TVI is leading but CVI is right on its heels and some would argue AHD is better. When it comes to making your decision, as long as your cabling system supports the technology, which brand you choose to go with will depend on what you think will support you best TODAY and into TOMORROW!

Side Note: Fairfax Electronics only offers HD-CCTV products that are carefully selected and tested for quality and longevity.

Which Digital HD-CCTV Technology is better: SDI, EX/SDI, or IP Megapixel

When it comes to broadcast quality images, at the time of writing this paper, SDI and EX/SDI have only been able to achieve 2.1 megapixels. IP Megapixel on the other hand can currently achieve 20.0 Megapixels and beyond. Cost, storage, and bandwidth make IP megapixel imagers out of reach for many customers but if you have the budget and the need, it?s available.

If it?s a clear close-up image definition you?re after, the more image pixels in a field of view you will need and this is where IP megapixel wins. On the other hand, unless you have a megapixel monitor, the best visible image quality you?re going to get is 1080p on screen.

Currently, SDI and EX/SDI are popular technologies with EX/SDI taking up 90% of the upgrades market. It?s a popular choice, can be employed with copper coaxial cable, is cost effective and offers clear DAY/NIGHT images at 2.1 Megapixels, with true broadcast quality.

The only drawback is that at the time of writing this article, these technologies cannot be used on CAT5e and most authorities on the subject agree they will not be adapted to CAT5e cable.

HD-CCTV Frame Rates ? Know what frame rate your HD-CCTV system can actually handle.

It?s important that you know the Frame Rate your HD-CCTV camera can provide depending on the resolution (SD, HD, FD) you want. There are charts you can print out as a general guide but it?s always important to contact the Manufacturer provided for the right information. You?ll have to look at each device in your system to know what limitations it has and if those are acceptable. As a general rule, the lower the Frame Rate available the lower the cost, although price can of course vary over time.

Fairfax Electronics Recommendations:

Once the existing cabling and existing cameras have been assessed the following is advised by Fairfax Electronics:

First Scenario
If the system has 960H and higher resolution analog cameras, it?s recommended to change the old DVR to a HD-SDI Hybrid type DVR/NVR leaving the old cameras in place. This is a great way to get your client started on HD-CCTV and the new HD SDI DVR will take the 960H image and make it true 960H, close to 1080p. This is a great solution and your client will appreciate that you are trying to save the cost of switching out all the equipment. You can add one 2.1 Megapixel SDI camera connected, giving them motivation and the option to decide if they need more resolution at a later date.

Second Scenario
If anything is lower than 960H, see if the client is willing to rewire, or they have 95% copper coaxial cable. You can also find out if the client wants Broadcast Quality images and have the budget that will allow for it. If this scenario is a good fit, recommend they invest in EX/SDI.

Third Scenario
Anything lower than 960H, has short runs in either coaxial or CAT5e and is watching budget. The recommendation in this situation would be TVI. It appears at the time of writing this paper that established Brands are using TVI to move forward. CVI seems to be the lowest price and AHD has lost ground.

Just as a note, this doesn?t mean that one analog HD-CCTV technology is better than the other, as we mentioned earlier, this is simply a type of format war. However DO beware of UNSUPPORTED products floating around on the market. The best thing to do is choose a reputable company first then the technology, if things do happen to go wrong it?s always good to have responsible support!

About The Author:
Paul Ramos,
CEO, Fairfax Electronics
google.com/+PaulRamos-Entrepreneur?rel=author

Special thanks to:
Greg Bier, CEO of Vitek CCTV,
Jonathan Buchanan of Liberty CCTV, and
Daniel Kim, CCTV Product Engineer for their input.