TODAIDESIGN.NET · GLOSSARY · 56 TERMS
CCTV Terminology Glossary: 56 Security Camera Terms Explained
Every CCTV term you need to know — defined in plain English by working installers and integrators. From core hardware (NVR, DVR, PoE) to optical specs (FOV, lux, varifocal), AI analytics (IVS, line crossing, LPR), and standards (ONVIF, IP rating, DORI). Use this reference when reading datasheets, writing tenders, or designing systems.
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A
3 TERMSAnalog CCTV
Traditional surveillance technology that transmits video as an analog signal over coaxial cable to a DVR. Analog cameras are typically lower resolution (D1, 960H) than IP cameras and lack network features like remote viewing, ONVIF compatibility, or built-in analytics. Modern HD-over-coax variants (TVI, CVI, AHD) extend analog systems to 1080p+ without rewiring.
Aspect ratio
The ratio of image width to height. Most modern CCTV cameras use 16:9 (widescreen) for general coverage, 4:3 (legacy) for older systems, or 1:1 (square) for ceiling-mounted multi-sensor cameras. Aspect ratio affects how the field of view maps onto the scene and how much vertical detail is captured.
Auto iris
A motorized lens iris that adjusts the aperture automatically to maintain consistent exposure as ambient light changes. Auto-iris (DC-iris or P-iris) is essential for outdoor cameras facing varying daylight conditions, preventing overexposed mid-day images and underexposed dusk footage. Fixed-iris lenses rely on the camera's electronic shutter and are limited to controlled indoor lighting.
B
4 TERMSBandwidth
Network throughput consumed by camera streams, measured in Mbps (megabits per second). A 4MP H.265 camera at 15 fps typically uses 2–4 Mbps; 4K at 30 fps can exceed 8 Mbps. Total bandwidth budget must account for every camera plus headroom for peak motion. Insufficient bandwidth causes dropped frames, recording gaps, and live-view stuttering.
Bit rate
The volume of compressed video data per second, measured in kbps or Mbps. Higher bit rate means better image quality but more storage and bandwidth. CBR (constant bit rate) gives predictable file sizes; VBR (variable) adapts to scene complexity for better quality at the same average size. Smart codec modes drop bit rate during static scenes.
BLC (Backlight Compensation)
An exposure setting that brightens dark subjects positioned in front of a strong light source, such as a person standing in a doorway with bright sunlight behind them. BLC sacrifices background detail to expose the foreground correctly. For more complex scenes use WDR (Wide Dynamic Range) instead, which preserves both highlights and shadows.
BNC connector
A bayonet-style coaxial connector used to terminate analog and HD-over-coax (TVI/CVI/AHD) camera cables at the DVR. BNC connectors are crimped or twist-on, available in 50Ω (rare in CCTV) and 75Ω (standard). IP camera installations use RJ45 instead.
C
4 TERMSCat5e / Cat6 cable
Twisted-pair Ethernet cabling used to carry IP video and PoE power between cameras and the network switch or NVR. Cat5e supports gigabit Ethernet up to ~100 m; Cat6 adds better noise rejection and is preferred for new installations and longer PoE runs. Outdoor segments require shielded (STP/FTP) variants and UV-resistant jacketing.
CCD sensor
Charge-Coupled Device — a legacy image sensor that produced excellent low-light performance and minimal noise but consumed more power and cost more to manufacture than CMOS. Modern CCTV cameras have nearly all migrated to CMOS, which now matches or exceeds CCD low-light quality thanks to backside-illuminated and Starlight-class sensors.
CMOS sensor
Complementary Metal-Oxide-Semiconductor — the dominant image sensor type in modern IP cameras. CMOS sensors are cheaper to produce, consume less power, and support faster readout for high-resolution and high-frame-rate capture. Premium variants (BSI, stacked, Starlight) deliver low-light performance that rivals or exceeds older CCDs.
Coaxial cable
A shielded copper cable (typically RG-59 or RG-6) that carries analog and HD-over-coax video signals from camera to DVR. Maximum run length is roughly 300 m for standard analog and 500 m+ for HD-TVI/CVI. Coax cannot carry PoE, so each camera needs a separate power feed — a key reason new installs prefer Cat6.
D
4 TERMSDay/Night camera
A camera with an IR-cut filter that switches between color (day) and monochrome (night) modes. The filter blocks infrared light during the day to preserve color accuracy, then mechanically retracts at low light to let IR illumination reach the sensor. This is standard on virtually all modern outdoor IP cameras.
DDNS (Dynamic DNS)
A service that maps a changing public IP address to a fixed hostname, allowing remote access to NVRs and cameras on residential or small-business connections without static IPs. DDNS is largely being replaced by P2P cloud services (Hik-Connect, EZVIZ, Dahua DMSS) that punch through NAT without port forwarding.
DORI (Detection, Observation, Recognition, Identification)
EN 62676-4 standard defining how far a camera can see for each surveillance task based on pixel density on the subject: 25 PPM for detection, 63 for observation, 125 for recognition, and 250 for identification. DORI distance depends on resolution, sensor size, and focal length — and is the right metric to specify in tender documents instead of generic 'megapixel' claims.
Learn moreDVR (Digital Video Recorder)
Recorder for analog and HD-over-coax cameras. DVRs accept BNC inputs, encode video to H.264/H.265, and store footage on internal HDDs. Modern hybrid DVRs also support a few IP camera channels. Best for retrofitting legacy coax cabling; for greenfield installs use an NVR with PoE.
F
4 TERMSFacial recognition
AI analytics that match a captured face against a database of known identities. Effective facial recognition requires ≥250 PPM on the face (DORI 'Identification' threshold), even lighting, and frontal angles within ±15°. Camera placement at eye level (1.7–2.0 m) over choke points like doorways gives the best results. Subject to GDPR and biometric data regulations in the EU.
FOV (Field of View)
The angle a camera can see, measured in degrees. Determined by lens focal length and sensor size — not by resolution. A 2.8mm lens on a 1/3" sensor gives ~110° horizontal FOV; a 12mm lens gives ~30°. Wider FOV covers more area with less detail; narrower FOV captures more detail at distance.
Learn moreFocal length
The distance in millimeters from the lens optical center to the camera sensor. Shorter focal lengths (2.8–3.6 mm) produce wide-angle views for short-range coverage; longer focal lengths (12–25 mm and beyond) produce telephoto views for long-distance identification. Varifocal lenses let you adjust focal length on-site without swapping the lens.
Learn moreFrame rate (fps)
The number of frames a camera captures per second. 25 fps (PAL) or 30 fps (NTSC) is standard for smooth motion; 15 fps is acceptable for most surveillance and halves storage; 60 fps is reserved for fast-action scenes like LPR or sports. Lower frame rates dramatically reduce storage and bandwidth without sacrificing detection quality for typical use cases.
H
5 TERMSH.264 (AVC)
The dominant video compression standard from ~2010 to ~2020 and still widely supported. H.264 delivers good quality at moderate bit rates and is universally compatible with browsers, mobile apps, and legacy NVRs. New deployments increasingly use H.265 for ~50% smaller files at equivalent quality.
H.265 (HEVC)
Successor to H.264 that compresses video to roughly half the file size at the same visual quality. H.265 is now standard on 4MP+ IP cameras and supported by all current NVRs, but legacy DVRs and older client apps may not decode it. Smart variants (H.265+) further compress static scenes.
HDD (Hard Disk Drive)
Spinning-platter storage in NVRs and DVRs, sized in TB. Use surveillance-grade drives (WD Purple, Seagate SkyHawk) rated for 24/7 write workloads — desktop drives fail prematurely under continuous recording. RAID configurations protect against single-drive failure on critical installs.
HDMI output
Video output on an NVR or DVR that connects directly to a local monitor for live view and playback without a separate computer. Modern NVRs offer dual HDMI for multi-monitor video walls and 4K output to drive large displays.
HD-TVI / HD-CVI / AHD
Three competing standards for transmitting HD video (1080p–8MP) over existing analog coaxial cabling — useful for upgrading legacy installations without rewiring. HD-TVI (Hikvision, ONVIF-affiliated), HD-CVI (Dahua), and AHD (Korean origin) are mutually incompatible at the protocol level, so the camera and DVR must be from the same family.
I
4 TERMSInfrared (IR) illumination
Invisible 850–940 nm light emitted by camera-mounted LEDs to illuminate scenes at night. IR range is specified in meters (e.g. 30 m, 50 m) but real-world distance depends on reflective surfaces, mounting angle, and IR-cut filter behavior. Smart IR adjusts intensity per zone to prevent overexposed close subjects.
IP camera
A digital camera that transmits compressed video over an Ethernet or Wi-Fi network. IP cameras support PoE power, ONVIF compatibility, edge analytics, and resolutions from 2MP to 32MP+. They're the standard choice for new installations, replacing analog cameras that depend on coaxial cabling and dedicated DVRs.
IP rating (Ingress Protection)
Two-digit code describing dust and water resistance. First digit (0–6) covers solids; second (0–9) covers liquids. For outdoor cameras specify at least IP66 (dust-tight, protected from powerful water jets); IP67 adds short-term submersion. Combine with IK rating for impact resistance in vandal-prone zones.
IVS (Intelligent Video Surveillance)
On-camera analytics that detect specific behaviors — intrusion, line crossing, loitering, abandoned objects — and trigger alarms or recordings. Modern IVS uses on-device AI (Hikvision AcuSense, Dahua WizSense) to filter out animals, leaves, and shadows that would otherwise fire false alerts on motion-only systems.
L
4 TERMSLens
The optical assembly that focuses light onto the sensor. CCTV lenses are categorized by focal length (fixed or varifocal), aperture (f-number), and mount type (M12 board mount, CS-mount, C-mount). Lens choice determines field of view and DORI distance — often more important than camera resolution.
Line crossing detection
An IVS rule that triggers an alarm when an object crosses a virtual line drawn on the camera's view, in either direction. Common uses include perimeter alarms, retail entry counts, and one-way corridor monitoring. Line crossing is more reliable than basic motion detection because it ignores stationary scene changes.
LPR / ANPR (License Plate Recognition)
Specialized cameras and analytics that read vehicle license plates. LPR cameras use long-focal-length lenses, faster shutters, and dedicated IR illumination tuned to plate retro-reflectivity. Effective LPR requires careful angle (≤30° off plate normal), correct mounting height, and a dedicated camera per lane — not a general-purpose dome.
Lux
The unit of measured light intensity. Bright sunlight is ~100,000 lux; office lighting ~500 lux; full moon ~0.1 lux; overcast moonless night <0.001 lux. Camera datasheets specify minimum illumination in lux — Starlight-class sensors capture color images down to 0.005 lux, far below traditional cameras that switch to monochrome IR mode much sooner.
M
3 TERMSMegapixel (MP)
Image resolution measured in millions of pixels. 2MP (1920×1080) is HD; 4MP (2560×1440) is the modern minimum for forensic detail; 8MP (3840×2160) is 4K Ultra HD. More megapixels increase storage and bandwidth — match resolution to actual DORI requirements rather than maximum spec.
Motion detection
A basic analytics feature that triggers recording or alerts when pixels change between frames. Pixel-based motion detection generates many false alarms from rain, leaves, headlights, and shadows. AI-enhanced motion detection (Hikvision AcuSense, Dahua WizSense) classifies humans and vehicles to suppress nuisance triggers.
Multiplexer
A legacy device that combined multiple analog camera feeds onto a single recorder or monitor. Multiplexers were standard in pre-DVR systems; modern NVRs handle channel multiplexing internally and the term is now mostly historical.
N
3 TERMSNetwork switch (PoE switch)
A device that connects multiple IP cameras to the NVR over Ethernet and (in PoE-enabled models) also delivers power. Specify total PoE budget (watts) carefully — a 24-port switch with 240W can power ~16 standard PoE cameras but only ~8 PTZ or PoE+ models. Managed switches add VLANs to isolate camera traffic from the corporate network.
Night vision
A camera's ability to capture usable images in low light. Common approaches include IR-LED illumination (monochrome night view), Starlight-class sensors (color in near-darkness), white-light spotlights (full color but visible to subjects), and thermal imaging (no light required at all). Each has trade-offs in range, color fidelity, and visibility.
NVR (Network Video Recorder)
Recorder that captures, stores, and manages video from IP cameras over Ethernet. NVRs handle high resolutions (4K+), built-in PoE for direct camera power, and integrate with on-camera AI analytics. Replacement for legacy DVRs in all new installations except retrofits where existing coax must be reused.
O
1 TERMONVIF
Open Network Video Interface Forum — the industry standard that lets cameras and recorders from different manufacturers interoperate. ONVIF Profile S covers basic streaming; Profile T adds H.265 and edge analytics; Profile G covers recording and playback. Always verify ONVIF profile support before mixing brands.
P
4 TERMSPTZ (Pan-Tilt-Zoom)
A motorized camera that can pan horizontally, tilt vertically, and zoom optically under operator control or scheduled tour. PTZs cover large open areas with one camera but only watch one direction at a time — a static dome covers the rest. Auto-tracking PTZs follow detected motion automatically.
Pixel density (PPM)
The number of camera pixels covering one meter of subject at a given distance, measured in pixels per meter (PPM). Pixel density determines what surveillance task is achievable — 25 PPM for detection, 63 for observation, 125 for recognition, 250 for identification (per EN 62676-4). The right PPM target drives camera selection and placement.
Learn morePoE (Power over Ethernet)
Power and data delivered over a single Cat5e/Cat6 cable, eliminating separate camera power supplies. PoE 802.3af provides 15.4W (standard cameras), PoE+ 802.3at provides 30W (PTZ, IR-heavy domes), and PoE++ 802.3bt provides 60–90W (heated outdoor PTZ). Maximum cable run is ~100 m per segment.
Progressive scan
A capture mode that records full frames in a single pass, eliminating the interlacing artifacts (combing on moving subjects) of older interlaced cameras. All modern IP cameras use progressive scan; you'll only encounter interlaced video in legacy analog systems.
R
3 TERMSRAID storage
Redundant Array of Independent Disks — combines multiple HDDs for fault tolerance or capacity. RAID 1 (mirror) survives one drive failure; RAID 5 survives one out of 3+ drives with better capacity efficiency; RAID 6 survives two failures. Use RAID for critical-loss installations; for typical surveillance, simple multi-disk recording with hot-swap drives is often sufficient.
Resolution
The number of pixels captured per frame, expressed as width × height (e.g. 1920×1080 = 2MP) or shorthand (1080p, 4K). Higher resolution increases pixel density (PPM) at a given distance — more detail per meter — but multiplies storage and bandwidth. Choose resolution to meet DORI targets, not as a marketing tier.
RJ45 connector
The 8-pin modular connector used to terminate Ethernet cabling at IP cameras, network switches, and NVRs. Outdoor camera RJ45s should be inside weatherproof junction boxes or use shielded outdoor connectors with rubber boots to prevent corrosion.
S
5 TERMSSDVR (Standalone DVR)
A self-contained DVR appliance with built-in storage, power supply, and HDMI output — designed for plug-and-play deployment without a separate PC. Most modern surveillance recorders are sold in this form factor.
Sensor size
The physical dimensions of the camera image sensor, expressed in inch fractions (1/3", 1/2.8", 1/1.8", 2/3"). Larger sensors capture more light per pixel for better low-light performance and depth of field, but cost more. Sensor size also affects effective field of view for a given lens — a 2.8mm lens covers a wider angle on a 1/2" sensor than on a 1/3".
Smart IR
Adaptive infrared illumination that reduces LED intensity for close subjects to prevent the white-out effect of overexposed faces near the camera. Smart IR is now standard on premium outdoor cameras and dramatically improves usable IR range and image quality at all distances.
Starlight
Marketing term for sensors that produce usable color images in extremely low light (typically below 0.01 lux), without resorting to IR or monochrome modes. Starlight-class sensors are essential for license plate capture at night, color identification of clothing or vehicles, and any scene where color information is forensically important.
Storage calculation
Estimating the total HDD capacity needed for a planned retention period. Storage = (bit rate × seconds × number of cameras) / 8, then divided by compression efficiency. As a rule of thumb, a 4MP H.265 camera at 15 fps uses ~30 GB per day; 30 days × 16 cameras × 30 GB ≈ 14 TB total.
Learn moreT
1 TERMThermal camera
A camera that detects long-wave infrared heat radiation rather than visible light, producing images based on temperature differences. Thermal cameras work in total darkness, fog, and smoke — ideal for perimeter detection over hundreds of meters where visible cameras would fail. Resolution is lower (320×240 or 640×480) and cost significantly higher than visible-light models.
V
5 TERMSVideo compression
An algorithm that reduces video file size by removing redundant data between frames. H.264 (AVC) is the legacy standard; H.265 (HEVC) cuts file size by ~50% at equivalent quality. Smart codec modes (Smart 264/265, H.265+) further compress static scenes. Newer H.266 (VVC) and AV1 are emerging in high-end and edge-AI cameras.
Vandal-proof (IK rating)
Impact resistance specification for camera enclosures, rated IK00–IK10. IK10 (the highest civilian level) withstands a 5 kg mass dropped from 40 cm — sufficient for stairwells, parking decks, and public restrooms. Combine with IP rating for outdoor vandal-prone installations.
Varifocal lens
A lens with adjustable focal length, allowing the installer to fine-tune field of view on-site without swapping the lens. Manual varifocals are adjusted with a small screwdriver during installation; motorized varifocals (sometimes called 'motorized lens' or 'MFZ') can be re-zoomed remotely from the NVR or VMS interface.
VMS (Video Management System)
Software that manages live monitoring, recording, playback, and analytics across many cameras and recorders — typically running on a server or cloud platform. Examples: Milestone XProtect, Genetec Security Center, Hikvision HikCentral, Axis Camera Station. Used for installations larger than a single NVR can handle (hundreds to thousands of cameras).
VCA (Video Content Analysis)
Umbrella term for analytics that interpret video content — motion classification, object detection, behavior recognition, people counting, heat mapping, and license plate reading. Modern VCA runs on the camera (edge AI) for low latency and reduced bandwidth, sending only metadata and event clips to the recorder.
W
2 TERMSWDR (Wide Dynamic Range)
An exposure technology that captures detail in both bright highlights and dark shadows of the same frame — essential for scenes with mixed lighting like a doorway facing the sun, a car park entrance, or a shop window. True WDR (sensor-level, dual exposure) is far superior to digital WDR (DWR/DSP-based) and is specified in dB (120 dB+ is excellent).
Wireless (Wi-Fi) camera
A camera that connects to the network over Wi-Fi instead of Ethernet, eliminating the need for data cabling — though power still requires either a nearby outlet or solar/battery setup. Wireless cameras work for residential and small-business installations but are less reliable than wired PoE for professional surveillance: Wi-Fi congestion, range limits, and security risks (weak WPA configurations) make Ethernet the standard for serious deployments.
Frequently asked
CCTV terminology — common questions
What does FOV mean in CCTV?
FOV (Field of View) is the angle a camera can see, measured in degrees. A wider FOV (e.g. 110° from a 2.8mm lens) covers more area but with less detail at distance. A narrower FOV (e.g. 30° from a 12mm lens) shows less area but captures finer detail. FOV is determined by lens focal length and sensor size — not by resolution.
What is the difference between NVR and DVR?
An NVR (Network Video Recorder) records video from IP cameras over Ethernet, while a DVR (Digital Video Recorder) records from analog cameras over coaxial cable. NVRs handle higher resolutions (4K and beyond), support PoE for camera power, and integrate with modern AI analytics. DVRs remain common in legacy installations or budget retrofits where existing coax cabling can be reused.
What is PoE in security cameras?
PoE (Power over Ethernet) delivers both data and DC power to an IP camera through a single Cat5e/Cat6 cable, eliminating the need for a separate power supply at each camera location. Standard PoE (802.3af) provides 15.4W, PoE+ (802.3at) up to 30W, and PoE++ (802.3bt) up to 90W for PTZ and heated dome cameras. Maximum cable run is roughly 100 meters per segment.
What does IP rating mean for outdoor cameras?
IP (Ingress Protection) ratings describe how well a camera enclosure resists dust and water. The first digit (0–6) covers solids; the second (0–9) covers liquids. For outdoor surveillance look for at least IP66 (dust-tight, protected against powerful water jets); IP67 adds short-term submersion. Combine with an IK (impact) rating like IK10 for vandal-resistant zones.
What is DORI distance in CCTV?
DORI (Detection, Observation, Recognition, Identification) is the EN 62676-4 standard that defines how far a camera can see for each task based on pixel density on the subject. The thresholds are 25 PPM for detection, 63 for observation, 125 for recognition, and 250 for identification. DORI distance depends on resolution, sensor size, and focal length — two cameras with identical FOV can have very different DORI ranges.
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