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Bus monitoring analog camera selection and installation guide

(V1.0)

Disclaimer

Our company reserves the right to modify this manual at any time, and the contents are subject to change without notice. This manual does not assume any form of warranty, including but not limited to the implied warranties of merchantability and fitness for a particular purpose of the product. The errors contained in this manual or the incidental or consequential damages resulting from the use of this manual are not responsible.

This guide is a general recommendation for the selection and installation of surveillance cameras for 3G DVR bus-type car tachographs. Some adjustments should be made depending on the installed model and vehicle environment.

Attention: The cameras described in this guide refer to the analog camera with built-in pickup.

First, the camera selection

1) clarity

For color surveillance cameras, 420 TVL (TV line) are medium resolution surveillance cameras, and 480 TVL and above are high resolution surveillance cameras. The higher the clarity, the higher the price. For better image quality, we recommend using a camera of 480 TVL and above.

2) Focal length

The focal length is the distance between the lens and the photosensitive element. By changing the focal length of the lens, you can change the magnification of the lens and change the size of the captured image. Because car cameras usually use fixed-focus cameras, customers need to choose the right focal length camera according to their needs. The larger the focal length of the lens, the larger the magnification, the closer the zoom can be, the smaller the range of the picture, the more detailed the details of the distant view; the smaller the focal length of the lens, the smaller the magnification, the wider the range of the picture, the more visible Big scene. Commonly used lenses are 3.6mm, 6mm, 8mm, etc. The 3.6mm lens shooting angle is about 90°, the 6mm lens shooting angle is about 60°, and the 8mm lens shooting angle is about 45°.

3) Signal to noise ratio

It is required to select a camera with a signal-to-noise ratio greater than 48 dB. When the ambient illumination is insufficient, the image of the surveillance camera with higher signal-to-noise ratio becomes clearer.

4) Night Vision

In order to obtain visual effects at night, it is necessary to turn on the infrared fill light at night. The selected lenses are all infrared light, and the color of the pictures taken during the day is naturally disturbed by the infrared light. If you don’t want infrared light, use a color lens that is not transparent to infrared light, the picture will be vivid and clear, but you can’t take pictures in the dark.

In principle, the car camera uses a 15-meter infrared integrated dome camera with a 15 meter night vision distance, which automatically turns on the infrared light when low illumination.

5) Power supply

The power supply is 12VDC, and the maximum current of a single camera (infrared light) requires less than 400mA.

6) Interface

In order to ensure a high-reliability connection in a harsh environment, the interface of the AV and power supply is in principle selected from the female plug of the aviation plug.

Second, the camera installation specification

1 Keep away from the heat source on the vehicle and the source of electromagnetic interference. At the same time, pay attention to waterproof, and the installation position should be protected from human damage.

2 Determine the number of installations for the installed vehicles. Position them as far as possible in a wide range of viewing angles, and try to avoid “blind areas”.

3 Please pay attention to the installation position. After adjusting the angle, tighten the lens or apply glue to prevent the lens from loosening.

4 The installation position is convenient and fixed, avoiding artificial rotation and damage to the camera, affecting the monitoring effect; installing in a place with sufficient light, avoiding installation in a dark place, enabling the infrared function to be turned on for a long time, shortening the life of the camera.

5 The installation position should be at the upper part of the carriage to avoid vandalism. If the vehicle has a lower body, the two sides of the carriage and the front and rear positions of the carriage should be installed.

6 It is recommended that each passenger bus be installed with 3-4 lenses in accordance with the condition of the door. The following is a schematic diagram of the lens installation position: (mainly considering the deployment of single and double doors)

Schematic diagram of the installation of the front door of the single door

Double door installation diagram

Third, the use of recommendations

1. If you want to get a wide range of shooting, but the requirements for detailed images are not high, it is recommended to use a 3.6mm lens camera, such as shooting inside the car;

2. If the shooting range is not high and the detailed image is required, if you need to take the front license plate, it is recommended to use a 6mm or 8mm lens camera;

Example: The picture below shows a picture taken simultaneously with a 6mm lens and an 8mm lens. Under the same conditions, the picture of the car before the 8mm lens is more clear, but the picture taken by the 6mm lens has a larger angle and more content, and can completely capture the right front vehicle, while the 8mm lens can only capture parts.

6mm lens monitoring effect

8mm lens monitoring effect

3. When there is insufficient external light at night, the camera will turn on the infrared light (night vision), because the vehicle’s headlights will also turn on. At this time, when the front license plate is photographed, the shooting effect will be poor due to the windshield reflection, as follows The figure shows. Therefore, it is recommended to turn off the infrared light (night vision) function of the camera when using it in this case, and rely on the vehicle’s own light source or external light source such as street light to shoot. That is to say, when taking pictures through the glass, you cannot turn on the infrared light of the camera (night vision).

Because the reflective front license plate was photographed as white

4. If you make your own patch cord or extension cord to dock with the camera and pickup, you need to pay attention to the following:

1) Connect the video cable of the camera to a video coaxial cable with a characteristic impedance of 75 ohms to prevent interference from external signals;

2) To connect the audio adapter cable of the pickup, it is necessary to use a single-core shielded cable to prevent interference from external signals;

3) The power cable of the single-channel camera needs to use at least 22-gauge wire. The power cable length is ≤15m. Multiple camera power supplies cannot be connected to one set of power cables.

4) All wires must be flame retardant.

5. The camera of the tachograph is a camera-acoustic integrated structure, and the aviation plug interface contains the connection of video, audio and power. If you want to choose and install the pickup separately, you need to use an active pickup, power supply 12V.