CCTV Basis (Pan/tilt, Housing, Encoder)

Pan/tilt and Housing

Pan/tilt is a kind of platform unit holding camera to pan or tilt turning. Inner pan/tilt has two motors, one of which supports pan turning and the other supports tilt turning. Pan turning angle is 350°; but tilt turning angle can be ±45°, ±75° and ±35°. Pan & tilt angle can be adjusted by phase switcher. Pan/tilt types include below:

Indoor pan/tilt and outdoor pan/tilt

Indoor pan/tilt payloads slight, without rain proof function. Outdoor pan/tilt payloads strong and with rain proof function, even some wonderful pan/tilts also support heating function.

Payload

In order to match installation of different camera and housing, pan/tilt payload should not be always sameness. We should select suitable pan/tilt according to the total weight of camera and housing. Indoor pan/tilt holds light weight, as well as has small volume and self-weight. Whereas for outdoor pan/tilt, due to holding housing (all-weather model most) and camera, the payload, the volume and self-weight requires higher demand.

Current indoor pan/tilt loads almost 1.5kg~7kg and outdoor pan/tilt loads almost 7kg~50kg. Besides, there are micro-pan/tilts, such as micro-pan/tilts mounted inside dome hosing or all-weather housing with camera.

Control mode

Common pan/tilts are motorized pan/tilts by wire. Control line has 5 input ports: ne is common port for power supply; the other 4 ports (up/down/left/right) are control ports. For example, connecting power supply to common port and "up" port, pan/tilt makes camera upraised, so do others. Even some pan/tilts build in a relay kit. Thus pan/tilt includes 6 input ports: one is common port of power supply; other 4 ports handle up/down/right/left; the last port refers to auto rotate. If power supply connects to common port and "auto" port, pan/tilt will make camera auto rotates up/down/left/right.

Power voltage currently are 24V (DC) or 220V (AC). Pan/tilt consumption relies on payload, that is to say the consumption is proportional to payload.

Today, there are also 6V (DC) indoor pan/tilt with built-in battery, which is IR controlled remotely. Most pan/tilts still adopt linear control. When pan/tilts are few and near to control center, they can be directly signal-controlled. Whereas when pan/tilts are many and far to control center, it is usual for control signal to be firstly transmitted to decoder and then sent out to control pan/till turning.

We should select pan/tilt with port that has control-input port and video-in/out port, even fixed position and rotate position are linked by control-input line and video-in/out line. Such pan/tilt will not ruin after long-term using. Thus pan/tilt is more suitable for outdoor environments.

Housing ensures camera work normal in dusty, rainy and hot conditions. Housing includes two types. One is indoor housing which is cheap and simple in structure. Such housing mainly prevents camera falling dust and being destroyed, like anti-burglar or anti-destroy. However outdoor housings almost support all-weather working. That is to say no matter blow, rain, snow, hot or cold, camera can normally work. So this kind of housing supports cooling, heating, rain-proof and snow-proof function. Meantime, in order to guarantee camera normal work in poor weather, it is common to mount a wiper in the front of glass window.

The good all-weather housing now adopts semi-conductor heating and cooling. This kind of housing builds in semi-conductor which can auto cooling or heating, low consumption.

Encoder

In detail CCTV system, encoder belongs to front-end devices. It usually mounts near to camera with pan/tilt and motorized lens. There are multi-core cables connecting to pan/tilt and lens, besides a communication-line (STP or UTP) connects to monitoring server.

In same system there are many decoders. Every decoder has dialing switcher which determines the ID number in system. We must set dialing switcher ahead of using decoder. When setting, dial switcher must accord with camera number. Otherwise it appears operation confusion. For example, when camera signal connects to DVR sever first input channel (CAM1), the accordant decoder number should be 1. Otherwise, it is very possible that monitor displays no pan/tilt rotation and lens action, even thinks this decoder as breakdown.

Common decoders have self-checking functions which refer to directly manage dialing switcher rather than managed by remote host server. Testing pan/tilt & motorized lens normal or not, by this way, in order to judge wiring right or not. Meantime, lens can be selected among 6V, 8V, 10V and 12V in order to suit lens power.

Decoder usually equips communication indicator. When communication is normal, indicator opens. Thus it is easy to determine whether communication is right or not between decoder and host server.