---
title: "Fleet video glossary"
url: "https://dashcamforcars.com/glossary/"
---

# Fleet video glossary

## ACC (accessory or ignition signal)

ACC is the wire that carries power when the ignition is in the accessory or on position. A dashcam uses it to know when the vehicle starts and stops, so it can begin recording, switch to parking monitoring or shut down cleanly.

## ADAS (advanced driver assistance system)

ADAS is software that analyses a road-facing camera and warns the driver of danger ahead. On a fleet dashcam it means forward collision warning, lane departure warning, pedestrian warning and following-distance alerts.

## AHD (analog high definition)

AHD is a camera connection standard that carries 720p or 1080p video over a single cable. MDVR camera inputs are AHD, which is why MDVR accessory cameras are sold as AHD cameras.

## Aviation connector

An aviation connector is a round, screw-locking connector used on MDVR camera cables. It carries video, audio and power in one cable and does not shake loose under vibration.

## BeiDou (BDS)

BeiDou is China's satellite navigation system. Fleet devices that receive both GPS and BeiDou see more satellites, which helps them hold a position fix between tall buildings.

## Bitrate

Bitrate is the amount of data a camera records or streams each second, in kbps or Mbps. A higher bitrate keeps more detail and fills the memory card, or the data plan, sooner. Our recorders' standard bitrate is 4 Mbps for 1080p and 3 Mbps for 720p.

## BSD (blind spot detection)

BSD is a side-mounted camera with software that detects vehicles, cyclists or pedestrians alongside a large vehicle and warns the driver before a turn or a lane change.

## Cat 1 and Cat 4 (LTE categories)

Cat 1 and Cat 4 are speed classes of 4G modems. Cat 1 reaches about 10 Mbps down and 5 Mbps up; our A5, A6 and S202 use it. Cat 4 reaches about 150 Mbps down and 50 Mbps up; our D9 and WD02 use it.

## Channel (CH)

A channel is one camera input on a dashcam or a recorder. A 4-channel MDVR records four cameras at the same time.

## CIF and D1

CIF and D1 are standard-definition video sizes used for low-data streams. CIF is 352 × 288 pixels and D1 is 720 × 576 (PAL). A recorder can keep a CIF or D1 sub-stream for remote viewing alongside the HD recording.

## CVBS (composite video)

CVBS is a standard-definition analog video signal on a single cable. On the WD12 recorder it is the output that drives an in-cab monitor.

## Dashcam

A dashcam is a camera mounted on the windscreen that records while the vehicle is driven, saving video to a memory card in a loop. Fleet dashcams add 4G, GPS and often a second lens for the cabin.

## DMS (driver monitoring system; also DSM, driver status monitoring)

DMS is a cabin-facing camera, usually infrared, with software that watches the driver's face. It alerts on signs of fatigue such as closed eyes and yawning and, depending on the device, on distraction, phone use and smoking.

## FCW (forward collision warning)

FCW is an ADAS alert that sounds when the gap to the vehicle ahead is closing too fast for the current speed.

## G-sensor (accelerometer)

A G-sensor is an accelerometer. A dashcam uses it to detect the sudden change in acceleration of an impact or harsh braking, and to lock that clip so loop recording does not overwrite it.

## GB/T 28181

GB/T 28181 is a Chinese national standard for connecting video surveillance devices to a platform. Our WD12 recorder supports it, so it can send video to GB/T 28181 systems as well as to fleet platforms.

## Geofence

A geofence is a virtual boundary drawn on a map. The fleet platform raises an alert when a vehicle enters or leaves it.

## H.264 and H.265 (AVC and HEVC)

H.264 and H.265 are video compression standards. H.265 was designed to need about half the bitrate of H.264 for the same picture quality, so the same card holds about twice as much footage.

## Hardwire kit

A hardwire kit is a cable that powers a dashcam from the vehicle's fuse box in place of the 12 V socket. It is needed for recording while parked and usually includes a low-voltage cutoff.

## HMW (headway monitoring warning)

HMW is an ADAS alert that warns when the following distance to the vehicle ahead, measured in seconds, drops below a set limit.

## Infrared night vision (IR)

Infrared night vision uses infrared LEDs to light the scene with light the eye cannot see, so a cabin or interior camera still gives a usable picture in darkness.

## IO alarm input

An IO alarm input is a wire input that tells the recorder when something switches, such as a panic button, a door or a tipper body. The event can trigger a recording and an alert on the platform. Our WD02 has two and our WD10 has four.

## JT/T 1078

JT/T 1078 is the Chinese transport-industry standard for vehicle video, the companion to JT/T 808. It defines how a vehicle terminal sends live video, recorded video and audio to a monitoring platform.

## JT/T 808

JT/T 808 is a Chinese transport-industry standard that defines how a vehicle terminal talks to a monitoring platform: registration, position reports, alarms and commands. A device and a platform that both support it, set to the same edition (2011, 2013 or 2019), can work together without a custom integration.

## LDW (lane departure warning)

LDW is an ADAS alert that sounds when the vehicle drifts across a lane marking above a set speed.

## Loop recording

Loop recording is continuous recording in short files, typically of one, three or five minutes. When the card is full, the oldest file is overwritten, so the camera never stops recording. Locked event clips are kept.

## Low-voltage cutoff

A low-voltage cutoff switches a hardwired dashcam off when the vehicle battery falls to a set voltage, commonly between 11.6 V and 12.4 V on a 12 V vehicle, so parked recording cannot leave the vehicle unable to start.

## LTE band

An LTE band is a radio frequency range used for 4G. Carriers in different countries use different bands, so a 4G device must support the bands of the local carrier to connect. Our A18, for example, covers bands 1 and 3 only.

## Main stream and sub-stream

The main stream and the sub-stream are the two encodings a recorder makes of each camera. The main stream is the full-quality video saved to the card. The sub-stream is a smaller copy for live viewing over 4G; on our recorders it uses about 40 to 60 MB per camera per hour.

## MDVR (mobile digital video recorder)

An MDVR is a recorder installed in a vehicle that records four or eight cameras at the same time to a hard disk or SD cards. With 4G and GPS it sends video, location and alerts to a platform.

## OTA update (over the air)

An OTA update is a firmware update delivered to the device over its mobile or Wi-Fi connection, with no workshop visit.

## Parking monitoring (parking mode)

Parking monitoring is recording, or watching for impacts, while the vehicle is parked with the ignition off. It needs constant power, normally from a hardwire kit with a low-voltage cutoff.

## Passenger counting (automatic passenger counting, APC)

Passenger counting uses sensors above a vehicle's doors to count people boarding and leaving. Stereo (binocular) cameras measure depth, which separates people who enter together.

## PCW (pedestrian collision warning)

PCW is an ADAS alert that warns when a pedestrian is detected in the vehicle's path. On our ADAS Camera it is active below 50 km/h.

## Resolution

Resolution is the number of pixels in each video frame. 720p is 1280 × 720, 1080p (Full HD) is 1920 × 1080 and 2K, as used for dashcams, is 2560 × 1440, which is 1.78 times the pixels of 1080p.

## RS232 and RS485

RS232 and RS485 are serial ports for connecting accessories to a recorder, such as a fuel sensor, a card reader or a pan-tilt camera.

## SOS button (panic button)

An SOS button is a button the driver presses in an emergency. The device sends an alert with the vehicle's position to the fleet platform.

## Supercapacitor

A supercapacitor stores enough power for a camera to finish writing the last video file if the supply is cut in a crash, so the file is not corrupted. It tolerates heat better than a battery. Our D9 and D2 use one.

## TF card (microSD card)

A TF card is the small memory card used in dashcams, now called microSD; TransFlash was the original name. Dashcams need a card of Class 10 or faster, and a high-endurance card lasts longer under continuous recording.

## Two-way voice (intercom)

Two-way voice is a microphone and a speaker in the dashcam that let a dispatcher talk with the driver over the mobile connection. Our D9, WD02, A5, A3, A6, A18 and S202 have it.

## Video telematics

Video telematics is fleet tracking that combines vehicle location and driving data with camera video, so an event such as harsh braking arrives with the clip that shows what happened.

## WDR (wide dynamic range)

WDR is image processing that balances the bright and the dark areas of one picture, such as headlights at night or a low sun, so details are not lost.