Digital Surveillance Systems
When we talk about digital systems in video surveillance, we're referring to how information is captured, processed, and transmitted as a series of numbers instead of continuous signals.
In digital systems, binary code rules. Everything boils down to "1s" and "0s" — where "1" represents a high-level signal, and "0" a low-level one. Fun fact: the "low" signal doesn’t necessarily mean zero volts, just something lower than a set threshold. For example, CMOS components running on 5 volts might define anything from 0 to 1.5 volts as a "0" and anything from 3.5 to 5 volts as a "1."
Why is this important? Because while digital cameras and DVRs (digital video recorders) are commonplace, they all use some analog tech internally before converting the signal into binary form.
Is IP Surveillance Really "Digital"?
Let’s clear up a common myth: saying "IP cameras are digital, and analog ones aren’t" isn’t entirely correct. Even analog systems record footage digitally when storing it on a hard drive. The same goes for IP cameras. They process brightness and other video properties in analog form before converting it to digital data.
The real difference is how the video gets transmitted. With IP surveillance, the data moves across networks in binary form (see Figure 1 on the right). In analog systems, the transmission remains analog (Figure 1 on the left).
What About "HD" Analog Systems?
Modern "analog" systems aren't truly analog in the old-school sense. Today's HD analog formats include:
- AHD
- TVI
- CVI
These formats deliver high-definition images while sticking to traditional cabling methods, making them cost-effective and easy to upgrade. So, instead of calling IP systems "digital," it’s better to use the term network-based or IP-based since they rely on networking protocols to transmit data.
Digital Tech Is Everywhere
No matter what kind of surveillance setup you use, digital tech plays a role. Even DVRs and cameras marketed as "analog" have some level of digital processing. That means the term "digital" doesn’t help much when choosing equipment. Be specific. Are you after a network-based (IP) or high-definition (HD) system? The right terms will make it easier to find what you need.
Pro Tip for Buying Digital Equipment
If you're searching for a "digital DVR," relax—you can grab almost any DVR because they're all digital these days. But beyond that, there are endless variations of IP recorders and cameras. So, knowing your exact needs is crucial.
For example, just saying you need an "outdoor camera" is too vague. Is it for long-distance coverage? Do you need night vision or motion alerts? The more specific you are, the better your results will be.
The Big Takeaway
Using "digital surveillance systems" as a blanket term is outdated and unclear. It’s time to drop it in favor of clearer, more accurate language:
- IP systems for network-based surveillance
- HD systems for high-definition analog options
You'll save yourself a lot of confusion and get better advice when shopping or discussing your setup with pros.