Glossary of Terms
Analog refers to CCTV – in common parlance this is the older technology in cameras where as digital refers to the new technology.
In reference to CCTV, this refers to systems and components that use the standard NTSC/PAL composite video formats. Digital refers to devices that use pixel formats. The definitions become blurred when you consider that DVRs convert the analog signal into digital form to process the images internally, they convert back to analog to output to other devices. Details aside, many people refer to analog as old technology and digital as the new technology.
Automatic iris (Auto Iris):
This is a lens that auto-adjusts for changing lighting conditions. A built-in motor and amplifier receive signals in lighting changes. Adjustments maintain a consistent video level.
Auto-tracking is when a PTZ camera can automatically detect and follow movement. What constitutes that “movement” can often be adjusted within the internal programming of the camera.
Back focus is a mechanical correction of the sensor relative to the lens used whenever the focal length is adjusted. Basically, it focuses the picture when zooming in and out.
Balun: (Video balun):
A device that lets video travel over twisted paired wire.
This is a device that allows video to travel over twisted pair wire (rather than coax RJ59 cable). This device matches the impedances of the different signals. Balun stands for balanced-unbalanced. A balun is required at the camera and at the receiving device (DVR, monitor, etc.). Baluns can be passive or active (with amplification). Passive distance can be up to 1,000 ft. Active can be up to 3,000 or more. Count on less than half that distance with a DVR.
Standard connector type used by analog (CCTV) for coaxial cable.
This is the standard connector type used in CCTV. It provides an easy snap-on connection for a coax cable. What BNC stands for is less clear. Some say it means British Naval Connector. Others attribute it to the type and the inventor; Bayonet Neil Councilman.
A monitor connected directly to a DVR or NVR, sometimes referred to as a ‘spot monitor.’
This is a secondary monitor connected to a DVR, Multiplexer, etc. This is also called a Spot Monitor. The video displayed is typically a single image. Some units provide multiple outputs. Cameo: Refers to an individual video image in a multi-screen display.
C-Mount /CS-Mount Lenses:
C-Mount/CS-Mounts are used to directly screw lenses onto the camera. They have a fiange focal distance of 12.5 to 22.5mm (spread out in gaps of 5mm using a C-ring spacer). Typically, CS-mounts are designed for smaller formats, 1/2” and down.
Literally, a ‘category-five cable.’ This is the cable used to connect network cameras and their relevant systems. RJ-45 end connectors. Whenever you see “Power over Ethernet” (PoE) being used as a descriptor, this is what they are referring to.
Complementary Metal-Oxide Semiconductor. It’s a computer chip that stores the startup information. You might know it as the information your BIOS uses when you start your computer. The CMOS in the camera industry is usually referred to as the “CMOS Sensor” – a phrase used to separate it from a technology known as CCD (which has mostly been passed-up by this point).
Central Management Software. Remote software packages provided by the DVR/NVR’s manufacturer. Typically, it allows users to view their recorded/recording footage on various platforms. Every manufacturer will have a different name for their proprietary software.
Compression technology. The codec – such as the very ubiquitous H.264 – compresses the video footage into far more manageable file sizes.
A one-channel, low resolution analog video transmission without audio. You might better know it as the ‘yellow’ cable of the red, white, and yellow cabling setup most T.V.’s used until HDMI became prominent.
See: CODEC. The compression is the management of file sizes to make them smaller and easily stored. M-JPEG and H.264 are the most common and known forms of compression.
Covert Cameras and/or Microphones:
The name implies its action – a covert camera is a discreet camera that is intended to be concealed. Microphones can similarly be hidden (e.g., inside of fire detectors). For example, many boardrooms might utilize both technologies.
CVI & TVI:
Composite Video Interface and Transport Video Interface. These are technologies recently developed to bring analog CCTV cameras into the HD world. Please see this article for more information. [attachment]
Day/Night functionality is the camera’s ability to operate in a night-time setting. This is usually done by an IR Cut Filter or IR LEDs.
DNS (Domain Name System):
The Domain Name System is used for IP cameras, also known as network cameras. The DNS puts user-friendly names in place of IP addresses (e.g., an URL).
Dynamic Host Configuration Protocol. This function serves to automatically assign IP addresses to a computer whenever a user logs on. Because all devices on a network require IP addresses, the DHCP is basically the quick and easy way to do it for you. (Alternatively, you can turn it off and do it manually.)
Digital is the corollary to analog – instead of using analog signals, it uses encoded digital data. This is most often in reference to network/IP cameras, although many CCTV systems can be converted to digital mediums and back again. As far as the quality of the picture goes, digital is almost always superior to analog.
Digital zoom is zooming into a recorded image, instead of physically changing the lens. This feat is accomplished by cropping an image, then expanding it to the original resolution size and using interpolation to handle the new pixel dimensions. Technically, it’s not a real zoom, but a simulacrum of a zoom. The best cameras for this function tend to have very high mega-pixel counts. The more pixels, the easier it is to digitally zoom in.
Digital Signal Processor. The DSP compresses continuous video footage. This function frees the processor to handle other tasks.
Dual stream means the camera can output two video streams simultaneously. This is useful for recording footage while at the same time sending the images over a network.
Digital Video Recorder, the corollary to the NVR (Network Video Recorder. The main purpose of the recorder is to be the ‘brains’ of your system. It is what will (typically) compress and store the footage and give you a point from which you can review the tapes.
Digital Video Disk. Fun fact: the first movie ever released on DVD was Twister.
Dynamic IP Address:
This refers to IP addresses that are automatically assigned to a network device when the user logs on to the system. See DHCP. This is different from a static IP address which does not change.
This is a manufacturer designed hardware platform for a DVR. It may share many functions with a traditional PC platform but it is a proprietary design that is unique to an individual manufacturer.
Default settings on a DVR/NVR/camera’s menu settings. What’s important about the factory defaults is that they are there as a foundation or base point. This gives you the user the ability to tinker around with the menu settings without fear that you’ll screw something up and have a point of no return.
Field of View:
The visible area available to a camera typically via its lens. If you have a smaller lens (e.g., 2.8mm), you will see a much wider field of view. Conversely, a 12mm lens will be far more focused in and technically carry a smaller/more narrow field of view.
Typically, a USB memory device sometimes referred to as a thumb drive. These handy tools allow users to store data on a portable drive which they can then plug into other computers. For DVR/NVR’s, these are frequently used to import firmware updates.
The distance between the secondary principal point in the lens and the plane of the imaging device. The longer the focal length, the narrower is the angle of view (e.g., 12mm lens will be very narrow and focused, but with a longer field of view; a 2.8mm lens will be very wide, but with a shorter field of view).
The combination of two interlaced fields. The frame frequency is half the field frequency.
(File Transfer Protocol): Transfer documents between different types of computers.
This video compression method is an improvement over earlier formats (JPEG, MPEG-4) providing smaller average usable file sizes. See M-JPEG, MPEG-4 and H.264.
The current tip of the spear when it comes to video compression. H.265 will potentially be up to 50% more efficient in handling file sizes and thus storage space. See this article for more information. [attachment]
High Definition Closed Circuit Television. This is CCTV’s answer to network cameras’ high quality imagery. The biggest benefit of HD-CCTV’s arrival is that it did not require any sort of infrastructural update like a transition to IP cameras would. HD-CCTV still runs over the cables that were already running the rest of the analog cameras. The main update needed is a new DVR to handle the higher resolutions – and even then, the newer DVR’s still operate just fine with older analog cameras.
High Definition Multimedia Interface. This is a single cable that provides excellent video quality images.
The initial preset position of a PTZ camera.
DVR/NVR’s which can connect both analog and IP cameras. They are useful when you do not wish to do a total overhaul of your surveillance infrastructure.
A wavelength of light invisible to the human eye. Humans can’t see this light, but cameras can. IR cameras use infrared LEDs to provide excellent night time vision.
IP Protection Standard:
Ingress Protection. The IP protection standard is used to measure how resistant to dust and water a camera is. It is a measure of the ability of an enclosure to resist dust and water. The rating is always listed as two numbers – for example, one of the more common ratings is IP66. Such a camera can withstand inclement weather conditions.
This is the individual address of the computer. IP addresses are 32-bit binary numbers (all ones and zeros). This is fine for computers. Humans need an easier way to express the address. Each binary octet is expressed as a number between zero and 255. An example of an IP address is 192.168.001.001.
These are IP based video cameras using IP networking as their basis rather than the traditional video signal used in broadcast and closed circuit systems. These cameras are both powered by and send data over Ethernet cables.
Refers to cameras that have IR LEDs installed that turn on in low light, providing a usable image in even total darkness. The effectiveness and distance varies widely based on the number of LEDs and overall quality of the camera. In this day and age most cameras come with at least some basic IR or day/night functionality.
IR Cut Filter:
The IR Cut Filter is designed to reflect or block mid-infrared wavelengths while letting visible light pass through. At night, the filter is removed, letting its light sensitivity drop to lower lux levels.
Internet Service Provider. ISPs provide your connection to the Internet.
Keyboard, Video and Mouse. It is a simple switch device that allows a user to operate multiple computers (PCs, DVRs, NVRs, etc.) from a single monitor.
Local Area Network. A LAN is a group of computers that share a common link to a server.
Liquid Crystal Display. An LCD is a flat-screen slim profile video display.
A LED is a Light Emitting Diode. These are used for producing infrared in cameras.
Live video basically is what it says – it is a live display of what the cameras are showing. This can be done through a video recorder, video management software, or through the internet.
Loop Out is an additional BNC connector attached for the purpose of incoming video being connected to additional devices.
Megapixel is a term used to demonstrate how many actual pixels can fit within a resolution. The actual word “megapixel” means 1-million pixels, though this number is used rather loosely. For better and more demonstrative purposes, MP is often related to a camera’s potential resolution. A camera with 1MP will have around 1-million pixels within the image, but a better way to say it is: the camera has a resolution of 1280×720. Conversely, a camera that has 3,145,728 pixels in its image might be better presented as simply having a resolution of 2048×1536, or 3.2MP. The higher the MP, the higher the resolution.
Motion alarms are triggered by changes in the footage, usually measured by settings the user can tinker with.
The device used to simultaneously project multiple camera inputs, e.g., displaying sixteen videos on your screen at once.
Also known as an “IP” camera. These cameras are recorded through NVR’s and/or Video Management Software. Power over Ethernet (PoE) simplifies the installation of these cameras as you only need one Ethernet cable to plug and play. Both data and then power is sent through the Ethernet line.
Normally Open and Normally Closed. These are the input/outputs and sometimes alarm devices. It’s just a question of whether or not the circuits are already closed and then opened, or already opened and then closed to set off triggers.
National Television Systems Committee is the Americas analog televisions system. This format carries standards of 525 scan lines, a field frequency of 60 Hz, a broadcast bandwidth of 4 MHz, line frequency of 15.75 KHz, frame frequency of 1/30 of a second, and a color subcarrier frequency of 3.58 MHz.
Phase Alternation Line. This is the European standard television system. PAL’s image format is 4:3, 625 lines, 50 Hz and 4 MHz video bandwidth with a total 8 MHz of video channel width.
Pan Tilt Zoom (PTZ):
A functionality in cameras that give the equipment the ability to literally pan around, tilt up and down, and zoom. Most of these devices are controlled by joysticks. As image quality has skyrocketed, the ability to use PTZ has come to be used digitally. Digital PTZ is the ability to pan-tilt-zoom on the image itself, using the pixels to navigate around. This isn’t nearly as high quality as the physical PTZ of moving camera parts around, but as resolutions and megapixels go higher it’s a very solid substitute.
Network Video Recorder. An NVR is a server hardware platform with the manufacturer’s proprietary video recording software installed. Some NVR’s come with switches installed while others simply connect to an external one.
Open Network Video Interface Forum. This is a growing standard for IP camera interface. A non-profit, ONVIF seeks to have interoperability between all network products regardless of manufacturer.
The physical zoom capability of the actual camera’s lens (typically a varifocal lens). This is contrary to digital zoom which simply enlarges the already recorded footage.
On Screen Display. Text and functions that are often tinkered with through the NVR/DVR.
OSI (Open Systems Interconnection), are the rules for network communication that the TCP/IP protocol carries out.
PC based DVR:
Using a PC desktop to be your video recorder. It has all the components of an ordinary PC, including hard-drives and DVD-writers (to burn security footage). PC based DVR’s are flexible because you can easily add and remove hardware as needed. They also work with both analog and network cameras. Problems typically associated with PC based DVR’s are that the units are typically too big and PC’s are quite a bit more vulnerable to hacks and other ways that bring slowdowns (especially if the PC DVR is also being used for other functions).
Software used to review exported DVR video in a standard PC. These are often proprietary to DVR/NVR manufacturers and will need to be installed or will already be pre-installed onto the recorder. Said software’s firmware will typically need to be kept up-to-date. Such updates are often done by inserting thumb/flash drives or simply downloading it if your recorder is PC-based.
Power over Ethernet, literally the use of an Ethernet cable to power a camera.
Point of Sale. This usually refers to data captured from an exchange at a cash register. Point of Sale data is useful for surveillance over a cash register to catch employee theft.
DVR’s can be set to record only when an alarm is triggered. However, footage can often be recovered just prior to the alarm recording being set off. This footage is often referred to as “pre-alarm” footage.
Similar to the pre-alarm setting, the post-alarm setting is how much time is spent actually recording after the alarm has been triggered.
Usually used in reference to PTZ cameras – the preset is a predetermined position that the camera can be swung to aim at. Presets are useful for when you want to quickly attain footage of a number of areas.
Digital shields placed over viewed areas to prevent the camera operator from seeing them.
The command set used to control one device from another. When you see a lot of options for camera controls, the protocol is the software element of that design. The cables or wires, such as RS-422, would be the hardware element.
Pan-Tilt-Zoom cameras are cameras that can, in essence, pan, tilt, and zoom. They are typically controlled with an actual joystick system.
Redundant Array of Independent Drives. There are a few different RAID setups, some increasing the speed of the hard drive while others utilize drives to protect you from hard drive failure
How many hours of footage a DVR/NVR can take before beginning to overwrite previous data.
Camera resolution is measured by its megapixel count.
This is the hardware device that provides a gateway to the Internet.
Scene illumination and Lux:
Lux is a measurement of illumination. You will most often see this in reference to what lux levels a camera can still draw night vision from. For comparison, 120,000 lux would be like standing outside on a bright, cloudless day. 1,000 lux would be your typical overcast day. Sub-1 lux is extremely dark storm clouds. 0.25 lux is a full moon, and 0.01 would be a quarter. For best results, the ratio of the lightest to the darkest areas should not be more than a factor of two.
Viewing multiple cameras on a single monitor screen. Typical formats are full variations of 16×9 or 4×3. Lesser known ones would be 2×2, 3×3, 4×4 and any number of multiple screen divisions.
A device that can take two cameras and combine their views onto a single screen.
Serial Advanced Technology Attachment, a cable that connects hard drives to the motherboard. Usually used in reference to how many hard drives a DVR or NVR can hold.
Search is for finding data in a recorded database. There are a number of ways to search including by time/date, alarm triggers, and even by movement or abandoned object detections.
Dual cable of RG-59 and an 18 gauge wire suitable for providing 12VDC or 24VAC power. With this setup, there is no need for a locally installed AC outlet at the camera location. Power is usually provided from a power distribution box at the control end.
Static IP Address:
A manually entered IP address. In large networks, IP addresses are usually automatically assigned by DHCP.
Thermal cameras detect heat. Light signatures are contrasted against a black and white background, making any moving objects with heat very easy to spot.
Another name for a USB drive. Useful for transporting data around, but also installing firmware onto DVRs and NVRs.
A ‘tour’ of either a number of cameras, or of a PTZ’s swinging from preset to preset. Think of it as like a guard touring around, but instead of the guard physically being there he’s just watching the screens.
See thumb drive. Useful for transporting data around and installing firmware onto DVRs and NVRs.
Up-The-Coax. A new analog technology that allows users to remotely set the camera’s OSD (On-Screen Display).
A lens that can have its focal length manually or automatically adjusted. The advantage of a lens like this is that it gives you the flexibility to zoom in or out to your heart’s content.
Use of changes in the footage to provide data or reactions out of the camera. For example, auto tracking, motion detection, missing objects, people count, etc.
This term refers to cameras that were once an active part of the system (connected to a DVR) and the video signal has been lost. This provides an alarm to alert the operator to the video lost situation. This loss could be due to vandalism or to a component failure. Most likely it is due to a bad cable connection.
Video Management Software. Software used to manage your camera’s recorded footage. Sometimes comes through a manufacturer’s proprietary software or through an external software company.
Video Motion Detection:
A camera’s ability to detect motion. PTZ’s can often go a step further and track the motion. Motion detection can also be connected to alarm settings.
Wide Dynamic Range. This technology solves the issue of strongly contrasted lighting conditions, such as natural sunlight cutting into an indoor office-lit setting. Often, this contrast will wash out a camera’s image, but wide dynamic range evens out the conditions to make for a much clearer picture.
A camera set up that does not use wires, sometimes referred to as “wi-fi.”