Analog CCTV Systems

Intro to CCTV Surveillance Systems

Intro to Analogue CCTV Surveillance

Though most of our attention these days is focused on the transition to IP video technology, it’s important to note that analogue CCTV solutions can still be highly effective for many surveillance applications, especially those on a budget. With traditional CCTV, the video signal is processed and transmitted in analogue format for local viewing from one central monitoring location. But that doesn’t mean you can’t use analogue cameras in an IP-based surveillance environment. Using IP video encoders and other equipment such as digital video recorders and hybrid DVRs makes it possible to leverage your existing analogue cameras while migrating into the world of digital surveillance.

 

Analogue CCTV Security Cameras

What is a CCTV Camera?

In its truest form, a CCTV (or closed-circuit television) camera is an analogue video camera that transmits signals via coaxial cable to a single central location for monitoring, recording, and video analysis. While the recent trend is a push towards IP network cameras, CCTV cameras are still widely used, and offer a cost-effective answer to many common surveillance scenarios.

CCTV technology has been around since the 1940’s, and became a major player in the security industry around 1970. The technology is tried and true, and there are CCTV camera models for virtually any surveillance application. The two main categories of CCTV cameras are fixed cameras and pan/tilt/zoom models which can rotate horizontally and vertically to cover more area.

 

CCTV Pros and Cons

Pros and Cons of Analogue Surveillance

These days, there’s a lot to think about when putting together a video surveillance system. And the first question on most people’s minds is “Do I go with traditional analogue cameras, or IP network cameras?” There are pros and cons to both choices. Let’s focus our attention on analogue CCTV cameras.

Pros of analogue CCTV

  • Lower initial cost – In most cases, analogue cameras cost less up front than IP network cameras.
  • Wide-spread compatibility – Mixing and matching camera models and surveillance equipment form different manufacturers is easy with an analogue CCTV setup.
  • Lower initial cost – Analogue cameras tend to handle low-light situations better than IP cameras on average, though IP camera technology is improving in this regard.

Cons of analogue CCTV

  • Expensive cabling – For large-scale surveillance applications, analogue cameras require complicated cabling schemes that can be quite expensive and also challenging to install.
  • Limited features – Many of the advanced features now available with IP cameras (for instance: megapixel resolution, digital zoom, and video analytics), aren’t available in analogue CCTV models.

 

CCTV Surveillance System Components

Components of a CCTV System

There’s a lot that goes into a successful CCTV installation. While the cameras get most of the attention in the beginning, you also have other concerns, such as viewing, recording, and archiving the video footage, and the equipment required for carrying out those tasks. Here’s a look at the basic components of a typical CCTV system.

Cameras

Security cameras are the starting point for most CCTV systems. There are endless possibilities when choosing CCTV cameras and lenses – everything from fixed models designed for monitoring very specific locations, to day/night cameras, and powerful PTZ domes for patrolling large areas.

Monitor

In a traditional CCTV setup, operators view footage from a central location on a monitor very much like a TV, but with higher lines of resolution for better picture quality. Monitors can be dedicated (meaning they display video from a single camera), or call-up (meaning operators can access multiple cameras at the same time).

Cable

With an analogue system, coaxial cable is required for transmitting video footage from the cameras. This is one of the drawbacks of analogue CCTV, as the cable can be expensive and difficult to install, especially for larger camera networks, and those were cameras must be positioned in difficult locations.

DVR

Most modern CCTV systems incorporate DVRs (digital video recorders) which enable operators to reap some of the benefits of a network-based surveillance setup. DVRs convert the analogue footage to digital, which helps to extend storage capacity, makes it much easier to search archived footage, and also allows users to stream video over a network for remote viewing from multiple locations.

 

Types of CCTV Security Cameras

CCTV Camera Types

Fixed

Fixed CCTV cameras point in a single direction, which makes them perfect for monitoring very specific areas of interest. They’re also preferred for applications where it’s beneficial to install cameras in clearly visible locations. For this reason, fixed cameras are quite effective not only for capturing footage of suspicious activity, but also for deterring criminals and vandals from carrying out their acts in the first place. The direction of the camera is set during installation. Many cameras also accept interchangeable lenses and housings, so you have the flexibility to meet a wide variety of surveillance needs.

PTZ

PTZ cameras are ideal for wide-area surveillance. They give operators the ability to remotely control pan, tilt, and zoom functions to follow activity and to zoom in for detailed monitoring. This is an area where analogue CCTV cameras fall behind their IP camera counterparts. With IP cameras, the pan/tilt/zoom functions are controlled manually or automatically and delivered over a single network cable, while analogue cameras require additional wiring to perform similar functionality.

 

Understanding CCTV Image Resolution

Measuring CCTV Image Quality

Understanding TVL Resolution

The image detail of an analogue CCTV camera is usually conveyed in a form of measurement called TVL (or TV Lines). Think of the video picture as being composed of active horizontal lines. These lines are delivered to a monitor or recording device in two off-set fields. One field contains even-numbered lines while the other contains odd-numbered lines. The viewer sees a complete picture because the lines are interlaced. Since the picture has a 3×4 aspect ratio, the amount of detail you can measure in 3/4 of the picture’s width determines the horizontal TVL resolution. Generally, most standard CCTV cameras offer a TVL resolution of around 380, while high-resolution cameras will deliver something closer to 540 TVL.

Effects of Digital Conversion on Image Quality

Most analogue CCTV systems today use a DVR as the recording medium. This allows the analogue signals to be digitized for recording and for delivery over the network. While a DVR solution is a cost-effective alternative to IP video, and provides users with valuable benefits such as digital storage and remote accessibility, there are drawbacks. One is a slight drop-off in image quality. Simply put, it’s harder to retain image quality in this type of setup because of the various analogue-to-digital conversions that take place from the camera to the recorder. Cabling distance also plays a role, as the further the video signals travel, the weaker they become. Still, a DVR-based solution is a very good option for users looking to reap some of the benefits of digital IP surveillance while using lower-cost CCTV cameras.

 

CCTV System Management and DVR Recording

DVR Recording & CCTV Video Management

It wasn’t long ago that most surveillance systems used VCRs to record individual video streams. The footage was recorded either continuously or triggered by an event, and recorded on cassette tape usually at a rate of 25 frames per second. Back in the day, this seemed like an advanced solution. But now we know, regardless of what type of surveillance cameras you’re using, storing video footage on cassette tapes is not a very effective strategy. The tapes take up space, can’t hold very much information, and they’re incredibly difficult to search through if you need to pinpoint video images of a specific event.

Enter the digital video recorder (DVR).

DVRs make it possible for users to convert analogue CCTV video to digital, allowing for remote monitoring, greater storage capacity, and quick and easy searches. Think of the DVR as a cost-effective solution for those not yet ready to move to a full-on IP surveillance setup. Digital video recorders allow you to bring your analogue CCTV cameras into the modern age. When footage is converted to digital, new worlds open up in terms of how you can view and manage your video feeds.

 

What is a DVR?

What is a Digital Video Recorder?

A Digital Video Recorder (DVR) contains software, video storage, and a computer hard disk all in a single unit. The DVR accepts analogue video feeds and converts them to digital. It’s a cost-effective way to bring an analogue CCTV system into the modern world, and provides some of the same benefits as IP video, but in a more budget-friendly solution.

 

Advantages of Digital Video Recorders

Benefits of DVR Recording

DVR recording is a great way to migrate your analogue CCTV into a digital surveillance solution. This is a low-cost option that brings a number of benefits to those who already own analogue cameras, or aren’t yet ready to make the move to a fully IP-based surveillance system.

Remote Monitoring

In the past, conventional CCTV systems could only transmit video to a single monitoring station, but that’s not the case when you’re using a DVR. Most digital video recorders now allow you to access your camera footage remotely over the internet. By connecting your analogue cameras to a DVR, you can monitor video feeds in real time from any computer with internet access, and even from compatible cell phones or handheld PDAs.

Digital Storage

Not long ago, most surveillance systems could only record to VHS cassette tape. Recording to tape has many drawbacks. For one, the tapes are bulky and take up a lot of space. Additionally, trying to search the recorded footage on analogue tape can be a time-wasting nightmare. With DVRs, your footage is converted from analogue to digital, so you can store significantly more video without the clutter, and it’s much faster and easier to sort through archived footage.

Video Compression

To make the most of available storage capacity, DVRs provide a number of different compression technologies. Common compression formats include Motion JPEG, MPEG-4, and H.264. With video compression, your files sizes are reduced as much as possible without compromising image quality.

Secure Connectivity

Most digital video recorders offer password protection so only authorized users are able to access the video footage from remote locations.

 

The Transition from CCTV to IP Video

Converting from Analogue to IP Surveillance

It’s no secret that the future of video surveillance is in IP-based solutions, but that doesn’t mean you need to throw out your existing analogue cameras as you make the transition. Cutting-edge surveillance equipment such as hybrid DVRs and video encoders allow you to build a future-proof IP surveillance network while retaining the analogue security cameras you already have on hand.

Hybrid Analogue/IP Systems

There’s a difference between a DVR-based system and a hybrid surveillance system. With a standard DVR setup, you’re limited to using only CCTV cameras. The analogue video signals are sent to a DVR where the footage is then converted to digital. In a hybrid system, you have the option of using both IP network cameras and analogue cameras, all operating together on the same network. This is typically done by using video encoders and servers, or a hybrid DVR.

Video Encoders & Servers

A video encoder (also known as a server) digitizes analogue video signals so they can be sent directly over an IP network. This enables users to view live video images using a standard web browser or with video management software on any local or remote computer with network access. Best of all, the digitized footage from the analogue cameras is traveling along the same IP network as any new IP cameras you add, so you can view footage from all your cameras the same way.

Hybrid DVRs

Hybrid DVRs are unique in that they can support both analogue CCTV cameras and IP network cameras. This level of flexibility isn’t available with traditional DVRs, which only connect to analogue cameras. Hybrid DVRs ease the transition from analogue to IP surveillance. Since they support both camera types, you don’t have to restrict your camera options. This makes it easy to move towards an IP-based solution while still using lower-cost analogue cameras when necessary.

 

 

 

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