81. What are the classifications of cameras?
A: By color: color camera and black and white camera
B: According to the system: PAL system and NTST system
82. What is the imaging principle of the camera?
The image of the subject is focused on the CCD chip through the lens, and the CCD accumulates a corresponding proportion of charge according to the intensity of the light. Under the control of video timing, the charges accumulated by each pixel are shifted out point by point, and after filtering and amplifying processing, the video signal output is formed. Connect the video signal to the video input of a monitor or TV to see the same video image as the original image.
83. What are the main parameters of the camera?
A: CCD target surface size B: Signal-to-noise ratio C: Minimum illumination D: Sharpness
84. How to choose the lens?
In order to obtain the desired photographic results, there are six basic elements that should be paid attention to when choosing a lens:
A: The size of the subject
B: Detail size of the subject
C: object distance
D: focal length
E: The size of the target surface of the CCD camera
F: Resolution of lens and camera system
85. What are the types of lenses?
Classification according to application:
A: Wide-angle lens: The viewing angle is more than 90 degrees, the observation range is large, and the near image is distorted.
B: Standard lens: The viewing angle is about 30 degrees, and the range of use is wide.
C: Telephoto lens: The viewing angle is within 20 degrees, and the focal length can reach tens of millimeters or hundreds of millimeters.
D: Zoom lens: The focal length of the lens is continuously variable, and the focal length can be changed from wide-angle to telephoto. The longer the focal length, the larger the image.
E: Pinhole lens: used for concealed observation, often installed in places such as ceilings or walls.
86. What are the functions and classifications of protective cover?
The protective cover is an important component in the monitoring system. It is a key protective device that enables the camera to still be used normally in the presence of dust, rain, high and low temperature, etc.
Shields are generally divided into two categories:
A: Indoor protective cover. Its main function is to prevent the camera from falling ash and have a certain safety protection effect.
B: Outdoor protective cover. This kind of protective cover is generally an all-weather protective cover, that is, no matter bad conditions such as wind, rain, snow, high temperature, low temperature, etc., the camera installed in the protective cover can work normally. Therefore, the protective cover has the functions of cooling, heating, rainproof and snowproof. At the same time, in order to enable the camera to capture images normally in rainy and snowy weather, a controllable wiper is generally installed in front of the glass window of the all-weather protective cover. In addition, there are hemispherical and spherical protective covers, which have built-in universal adjustable brackets and are beautiful in appearance.
87. What should I do if the squadron duty room cannot switch control with the sentry monitoring sub-machine?
A: Check whether the production and connection between the RJ-45 connector of the sentinel monitoring slave and the control host are good.
B: If you can't talk to all the outposts, check the control panel section.
C: If you cannot communicate with a certain post, check the monitoring sub-machine part.
88. When the monitoring sub-machine is talking with the host, the sound from the duty room is low, how to adjust it?
If this phenomenon occurs in a single sub-machine, adjust the P1 potentiometer in the sub-machine board; if all the sub-machines are small, adjust the P2 potentiometer on the main board. (Clockwise direction)
89. The client cannot establish a connection with the server. What is the reason for the failure of the server?
A: The telephone line is faulty or connected incorrectly.
B: The modem is faulty or connected incorrectly.
C: The remote transmission module is faulty or the power supply is incorrect.
D: The main board of the AV controller is faulty.
90. What are the requirements for the server-side telephone line for remote connection?
The analog telephone line of the telecommunications bureau, the transmission rate is not less than 10K, and the sound is blocked when it is less than 15K.