Surveillance System Considerations

There are a number of factors to consider when setting up an IP-based surveillance system. Network cameras transmit data over your existing IP network, so optimizing bandwidth is important. You’ll also need to think about storage: How long will footage be archived? What type of image quality do you require? Will recording be continuous or triggered by motion? Other key considerations include network security and system scalability. Putting thought into these areas before you set up your system will help to ensure that you have the right equipment and the proper game plan to fulfill your surveillance requirements.

 

Video Storage & Archival

While analog CCTV systems rely on bulky cassette tapes for storage, IP-based surveillance systems are able to store video footage straight to hard disk. This process offers several key benefits, including vastly improved storage capacity, and greatly enhanced searching capabilities. Because the video images are stored digitally, users can quickly sort through archived footage by time and date, and can even add reference tags.

There are a number of factors to consider when calculating the amount of hard disk space required for your specific storage needs.

  • How many surveillance cameras are you operating?
  • Will the cameras be recording continuously or only at certain hours of the day?
  • Will your IP cameras be set to record only when motion is detected?
  • How long will the video footage be stored on the hard disk?
  • What level of image quality is required (this will determine parameters such as frame rate and compression)?

Security

As with any video surveillance system, privacy and security are important factors to consider when setting up an IP-based video solution. Users want to be assured that no one can tap into their video feeds. Those concerns are understandable, but with IP network cameras, it’s quite easy to protect your files from unauthorized viewing and tampering. In most cases, the network camera encrypts the surveillance video before sending it over the network. This helps to ensure that only authorized viewers can access the camera feeds. Most systems also include password protection and different levels of authentication that work to prevent hacking and outside access.

In the case of wireless IP cameras, WPA (WiFi Protected Access) is considered the base level of wireless network protection. With WPA, video is encrypted and the key for each transmitted frame is changed using TKIP (Temporal Key Integrity Protocol). Other advanced security standards found with wireless network cameras include WPA2, AES, and 802.1x authentication.

Another tool for protecting network video feeds is digital watermarking. IP cameras are capable of adding encrypted watermarks into the video stream. The watermarks can include information such as time, location, and user activity, while time stamping can create a trail that shows who has accessed specific video images, and whether any edits have been made to the files.

Network Bandwidth

The amount of bandwidth used by network cameras is determined by several factors, most notably: image resolution, frame rate, and compression ratio.

Resolution

An IP camera’s resolution is determined by pixels. The higher the resolution, the higher the pixel-count, and the greater amount of detail you’ll be able to capture in a video image. It’s important to determine how much detail is enough to meet the requirements of your particular surveillance application. Typically, as the image quality goes up, so does the amount of bandwidth required, so it’s best to find a level that meets your needs while optimizing network bandwidth.

Compression

Video compression is an important tool in helping to ease strain on the network. Compression technologies such as Motion JPEG, MPEG-4, and H.264 allow users to stream and record high-quality video without hoarding bandwidth. H.264 is the latest compression technique, dramatically reducing video file sizes while increasing overall efficiency and lowering storage costs.

Frame Rate

Frame rate is something that can be adjusted within your IP camera, video server, or video management software. By controlling the frame rate, you can greatly reduce bandwidth usage and can eliminate unnecessary frames from traveling over the network. One common technique is to set the surveillance system to increase the frame rate only when motion is detected. Another is to send higher frame rates for local viewing, and lower frame rates over the Internet for remote viewing.

System Scalability

One of the great advantages of IP surveillance is system scalability. With analog surveillance systems, adding new cameras often involves complicated and expensive cabling. But with an IP-based system, it’s as simple as connecting the additional cameras to your existing IP network, the same way you would any other network device. Power over Ethernet (PoE) and wireless network cameras enhance flexibility even further by allowing you to install cameras in locations without a readily available power outlet.

Since a PC server records and manages the video footage in an IP surveillance system, there’s no limit to the size and scope of the installation. Different types of servers can be chosen depending on how many cameras are needed and what frame rate is required

Video Surveillance Management

The network camera is only one piece of the IP surveillance puzzle. Because network cameras transmit data digitally over an IP network, new worlds are opened up in terms of video management. Users can access their cameras from anywhere using a standard web browser, and are provided with advanced tools for monitoring and recording with IP video management software.

Recording & Live Monitoring

Some of the key attributes of an IP-based surveillance system involve remote video monitoring and improved recording and storage capabilities.

Remote Monitoring via the Internet

With an IP video surveillance system, video streams can be viewed from any network computer with access to the internet. Since each network camera has a built-in web server and its own IP address, users must simply type the camera’s IP address into the web browser’s address field to view the live video feed.

Monitoring with IP Video Software

Video management software gives users much more flexibility when it comes to viewing and managing their network camera systems. Video management solutions provide tools for simultaneous monitoring of multiple cameras, event management functions, alarm notification, recording, and more. IP video software solutions range from basic programs designed for individual users, to advanced solutions that allow multiple users to access to IP camera system simultaneously from different locations.

Network Video Recording

Typically, video footage from IP cameras is recorded either to a hard drive, uploaded to an FTP server, or stored on a dedicated NVR (Network Video Recorder). For basic applications, the camera’s built-in recording functionality captures video using scheduled or triggered recording, then uploads the video to an FTP server or computer hard drive. Network Video Recorders capture video streams from remote IP cameras and video servers and store the footage on a hard disc. Video management software provides the tools for sophisticated recording and event management. Using IP video software, operators can program for continuous, scheduled, and event-triggered recording.

Motion Detection

Video motion detection is a useful tool that allows you to program your network camera to begin recording, and perform other functions such as sending automated email alerts, when movement is detected within a scene. The functionality comes either built-in with your IP camera, or through video management software.

There are a number of advantages to using motion detection. Since you can limit recording to situations when activity is taking place, motion detection helps to conserve bandwidth, saves storage space, reduces CPU load on recording servers, and also allows for integration with other systems such as alarms and access control systems. The system can be set up so that unless movement is detected, no video is being recorded. It can also be programmed to send video at a low frame-rate until motion is perceived.

A number of actions can be triggered using motion detection. Examples include: saving images before or after an event, delivering video images to specific locations for recording or monitoring, sending email and phone alerts, activating door locks and lights, sounding alarms, and more.

Audio Recording

Many IP camera models offer audio support. Some feature built-in microphones that allow operators to listen in on areas under surveillance, while others provide for two-way audio communication using a microphone and external speaker. Audio is transmitted across your network the same way video footage is, so setting up a surveillance system that captures audio is as simple as hooking up your cameras. Using either a built-in or external microphone, the camera captures the audio, integrates it into the video stream, and streams it over the network for monitoring and recording.

Just like network video, audio footage can be accessed from remote locations. Users can monitor and listen in on areas within range of the cameras, and with a two-way audio setup can even talk to those under the camera’s watch. The cameras can also be programmed to deliver recorded messages informing possible perpetrators that they’re under watch. Another useful function is audio detection. This is the process where a network camera is set to record when the audio level reaches a certain mark. Audio detection can also be used to trigger alarms and send alerts.

Digital Input & Output

Digital input and output ports are available in various network video products, including many IP camera models. Digital input/outputs (or digital I/Os) allow you to connect the camera to external devices such as motion and sound detectors, smoke detectors, doorbells and door locks, glass-break detectors, and of course alarm systems. Communication between the network devices can be managed remotely from a PC with network access, or automatically using the camera’s built-in features.

Digital I/Os can help to limit video transmissions so that video is sent over the network only when one of the network devices is triggered by an event such as motion detection, audio level, or the opening of a door. This process optimizes bandwidth usage and conserves storage space. Digital I/Os also allow for the automatic triggering of specific actions such as capturing and saving images, sending automated alerts via email or phone, and activating lights, alarms, and door locks.

The main function of an IP camera’s input port is to support devices such as sensors and detectors, while the output port allows the camera to trigger external devices and activate specific actions, for instance sirens, alarms, and event-triggers video transfers.

Video Analytics

Video analytics are sophisticated applications and software algorithms that perform analysis of surveillance video as it’s being captured. While there are many potential benefits to using video analytics, the main aim of the technology is to enable surveillance systems to not just capture video footage for post-event investigation, but to actually detect suspicious activity as it happens. In that sense, video analytics serve to provide a form of preventative surveillance.

Some of the more common surveillance applications that fall under the video analytics umbrella include advanced motion detection, facial recognition, behavioral recognition, audio detection, license plate recognition, and the ability to detect very specific events such as a person leaving behind an object, or acts of graffiti and vandalism.

Video analytics can either be built into the network camera, or work as part of a video management software platform. With the introduction of megapixel IP cameras, this technology has become increasingly popular and effective. While the technology is applicable to a range of applications, it’s most commonly used for surveillance in high-security locations such as banks, airports, and government facilities. Some banks, for instance, now use facial recognition to identify individuals suspected of check fraud and other criminal activities.

Since the technology is relatively new, the various impacts of video analytics are still being weighed. As the technology improves, and more options become available, we can expect to see different forms of video analytics used for everything from preventing crime and speeding up response times, to reducing false alarms and optimizing video storage space.

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Network Camera Considerations

A network camera is essentially a camera and computer in one. These cameras capture and transmit video across an IP network, which allows for both local and remote viewing and video management. IP cameras connect to your existing IP network just like any other network device. The advantages of network cameras over analog equipment include remote monitoring, digital storage, cost-effective installation, flexibility, and scalability should you need to install additional cameras down the road. IP cameras are available in countless makes and models offering limitless surveillance possibilities. Choosing the right network camera setup depends on the specific needs of your surveillance application.

Types of IP Cameras

The variety of network camera models available allows users to install video security solutions fit for any surveillance application. Here are some of the more common IP camera types.

Lens Types

Many IP cameras accept interchangeable lenses for different surveillance applications. When choosing the right camera lens for your specific surveillance needs, there are several factors to consider:

Sensor Size

Network cameras are built with image sensors available in a variety of sizes such as 2/3, 1/2, 1/3, and 1/4-inch sensors. IP camera lenses are designed to work with these sensors, and to get optimal image quality without black corners or lost information, it’s best to use a lens that’s the same size as the image sensor.

Focal Length

The focal length is what determines the horizontal field of view at a certain distance. As the focal length gets longer, the field of view narrows. The lens can offer either manual iris control or automatic iris control. With manual iris control, the lens is set to an average value to be used in varying light conditions. Lenses with automatic iris control, such as DC auto iris lenses, are preferred for outdoor applications, and locations where light can change dramatically throughout the day. The lens is able to adjust as the light changes.

Iris

The role of the iris in the network camera lens is to adjust the amount of light that passes through.

F-number

A lens’s f-number determines the amount of light admitted to the sensor. The smaller the f-number, the more light is admitted to the sensor. For this reason, low f-numbers allow for better image quality in low-light situations.

Security Camera Housings

A variety of IP camera housings are available to ease installation and to help protect network cameras from tampering, vandalism, and harsh conditions such as extreme cold, humidity, dust, moisture, and more.

Vandal-Resistant Housings

For IP cameras placed in vulnerable areas, vandal-proof housings are an excellent option. They’re available for both indoor and outdoor surveillance applications, and typically feature sturdy metal construction, an impact-resistant dome or window, and tamper-resistant screws.

Fixed IP Camera Housings

Designed to offer protection for fixed network cameras, these housings are available for indoor and outdoor surveillance setups. They work to protect and cover network cameras, and come in various forms for mounting on ceilings and walls.

Outdoor Housings

Outdoor network cameras housings are built to be weatherproof, resistant to moisture, and sometimes even feature built-in fans and heaters for both cold and hot environments. The housings come in different sizes to handle different camera types such as fixed IP cameras and PTZ domes, and are also available in vandal-proof versions for hostile environments.

Power over Ethernet (PoE)

Power over Ethernet (or PoE) is a technology that allows LAN-enabled devices, such as network cameras and IP telephones, to be powered over an IP network infrastructure using standard Ethernet cabling. In the case of an IP-based surveillance system featuring PoE cameras, each individual camera transmits data and receives power via a single Ethernet cable, eliminating the need for complicated and expensive cabling because the system operates along an existing network.

Power over Ethernet allows for flexible camera installation as cameras can be placed in areas where power outlets aren’t readily available. This means users can actually install the cameras where they’re needed, not just where the AC sockets are. Power is supplied directly from the data ports that the cameras and other network devices are connected to. Users can also install Wireless LAN access points for even greater flexibility.

Another benefit of PoE technology is it enables easy installation of UPS (uninterruptible power supplies) for video surveillance applications requiring 24-hour surveillance that will continue even during power outages.

Wireless Connectivity

Wireless network cameras are primarily used in situations where the installation of extra cabling in a building could cause damage, or in locations where cameras need to be frequently repositioned. Basically, we’re talking about video surveillance installations where a wired solution is impractical, or installations requiring the mobility that a wireless solution provides.

The most common modes of wireless communication are wireless LANs and wireless bridges. A wireless LAN is just what it sounds like – a wireless local area network. Wireless LANS are typically setup indoors and cover short distances. The standards for this type of wireless network are usually well defined so products from different vendors can operate together on the same network.

Wireless bridges are used to connect buildings or multiple sites together using a point-to-point data link that allows data to travel long distances at high speeds.

Megapixel Resolution

Megapixel cameras take video surveillance to the next level by providing much higher resolution than traditional security cameras. The improved resolution not only results in clearer video images, it also significantly increases the camera’s field of view without any loss in image detail. In fact, a single megapixel camera can monitor areas that would ordinarily require multiple surveillance cameras. Consider how many cameras it takes to monitor locations such as casinos, parking lots, construction sites, and retail stores. In a parking lot, for instance, it’s now possible for a single megapixel camera to cover the entire area. And because of the high resolution and greater image detail, surveillance operators can zoom in on specific portions of the recorded scene to identify individuals and license plate numbers. It’s all about enhancing the quality of the recorded images, as well as providing high-definition live video streams.

Megapixel IP cameras are especially useful for surveillance applications where details are critical for identification purposes. Banks, airports, and other high-security areas are good examples, as are retail locations requiring point-of-sale monitoring. But with camera prices dropping as the technology becomes more readily available, the use of magapixel cameras for all types of surveillance applications is sure to increase steadily in the coming years.

Video Compression Standards

In the world of IP cameras, the main aim of video compression is to optimize network bandwidth and storage capacity by reducing video files sizes. The catch, however, is to maintain high-quality video images. A number of compression technologies are currently available in different network camera models, each aiming to provide the best possible compression ratio for specific video management functions.

Motion JPEG

A common compression standard available with most network cameras is Motion JPEG. By using Motion JPEG, a network camera is able to present video as a series of individual JPEG images. The frame rate can be adjusted, and any frame rate at or above 16 frames per second is considered full motion video.

MPEG-4

MPEG-4 is another very common compression technology found in IP cameras. With MPEG-4 the bit-rate of images is lowered to meet whatever level of image quality is required for a specific surveillance application.

H.264

H.264 is latest video compression standard. It improves upon Motion JPEG and MPEG-4 in significantly reducing digital file sizes without compromising image quality. The benefits of H.264 include reduced storage and bandwidth costs, higher resolution and frame rate, and improved megapixel camera performance.

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Intro to IP Video

IP video technology provides flexible, scalable, and cost-effective surveillance solutions suitable for a wide range of industries and applications. With an IP-based video surveillance setup, users can monitor and record video remotely using an IP network as the system’s backbone. IP video installations can be deployed in any environment, and offer many benefits previously unavailable with analog CCTV systems.

Benefits of Network Video

IP-based video surveillance has improved the effectiveness of video security by leaps and bounds over the analog CCTV equipment we’ve grown so accustomed to over the years. Today’s IP video surveillance solutions use an IP network, rather than complicated cabling setups, as the backbone for delivering information. This allows for flexible, cost-effective installation, remote video monitoring, improved storage, and a host of other benefits.

Remote Video Monitoring

With an IP-based surveillance system, users can view live network camera feeds in real-time from any computer with Internet access. Network cameras can capture and transmit high-quality video images over any IP network or the Internet, where the footage can be viewed remotely using a computer or, in some cases, cell phones and other handheld devices. Additionally, the recorded surveillance footage can be stored at remote locations.

Scalability

Expanding a network surveillance system is as simple as connecting additional IP cameras to the IP network. IP cameras can be placed anywhere along the network, and there’s no need for expensive and complicated cabling. Simply connect the camera like you would any other network device.

Improved Storage Capabilities

Since network cameras capture digital video images, large amounts of footage can be stored on servers and network video recorders, where archived video can be quickly accessed and searched. Compare this type of setup to analog systems where video was stored on VHS cassette tapes, and it’s easy to see the benefits of a digital surveillance system.

What is an IP Camera?

An IP camera captures and sends video footage over an IP network, allowing users to view, record, store, and manage their video surveillance images either locally or remotely over the network infrastructure. The camera can be placed wherever there’s an IP network connection. It has its own IP address and unlike a webcam, doesn’t require a connection to a PC in order to operate.

Along with streaming video footage, network cameras can include a number of additional functionalities, such as pan/tilt/zoom operation, motion detection, audio surveillance, integration with alarms and other security systems, automated alerts, intelligent video analytics, and much more. Many IP cameras can also send multiple streams of video, using different compression technologies for live viewing and archiving.

IP cameras offer flexible installation, ease of use, higher-quality images, stability, and scalability as new cameras can be added to the network at any time.

What is NVR software?

Video management software is a key component of any video surveillance solution. It’s the software that provides the tools for monitoring and analyzing surveillance footage, as well as recording. While a standard web browser often allows for remote viewing, dedicated video management software is required for viewing and managing multiple cameras at once.

The most basic IP video software provides live viewing, recording, and retrieving of video footage. More advanced NVR software platforms offer simultaneous viewing of multiple cameras, and multiple recording modes (including continuous, scheduled, and triggered recording). Other features may include the ability to handle large image files with high frame rates, fast search capabilities, pan/tilt/zoom control, audio support, and remote access via web browser as well as cell phones and other handheld devices. Some software programs also support intelligent surveillance using sophisticated video analytics such as facial recognition and advanced motion detection.

 

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DVR Recording & CCTV Video Management

DVRs make it possible for users to convert analog 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 analog 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.

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).

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 analog video feeds and converts them to digital. It’s a cost-effective way to bring an analog CCTV system into the modern world, and provides some of the same benefits as IP video, but in a more budget-friendly solution.

Benefits of DVR Recording

DVR recording is a great way to migrate your analog CCTV into a digital surveillance solution. This is a low-cost option that brings a number of benefits to those who already own analog 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 analog 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 analog tape can be a time-wasting nightmare. With DVRs, your footage is converted from analog 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.

Converting from Analog 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 analog 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 analog security cameras you already have on hand.

Hybrid Analog/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 analog 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 analog 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 know as a server) digitizes analog 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 analog 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 analog CCTV cameras and IP network cameras. This level of flexibility isn’t available with traditional DVRs, which only connect to analog cameras. Hybrid DVRs ease the transition from analog 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 analog cameras when necessary.

 

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Intro to Analog CCTV Surveillance

Though most of our attention these days is focused on the transition to IP video technology, it’s important to note that analog 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 analog format for local viewing from one central monitoring location. But that doesn’t mean you can’t use analog 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 analog cameras while migrating into the world of digital surveillance.

What is a CCTV Camera?

In its truest form, a CCTV (or closed-circuit television) camera is an analog 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.

Pros and Cons of Analog 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 analog cameras, or IP network cameras?” There are pros and cons to both choices. Let’s focus our attention on analog CCTV cameras.

Pros of analog CCTV

  • Lower initial cost – In most cases, analog 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 analog CCTV setup.
  • Lower initial cost – Analog cameras tend to handle low-light situations better than IP cameras on average, though IP camera technology is improving in this regard.

Cons of analog CCTV

  • Expensive cabling – For large-scale surveillance applications, analog 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 analog CCTV models.

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 analog system, coaxial cable is required for transmitting video footage from the cameras. This is one of the drawbacks of analog 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 analog 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.

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 analog 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 analog cameras require additional wiring to perform similar functionality.

Measuring CCTV Image Quality

Understanding TVL Resolution

The image detail of an analog 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 analog CCTV systems today use a DVR as the recording medium. This allows the analog 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 analog-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.

 

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