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How Does A Car Camera Work?
Jun 08, 2018

The bus camera monitors every moment outside the car at all times, protecting the safety of passengers and providing strong evidence for the site. The working principle of the car camera, you know?

According to a certain resolution, the points on the image are collected in an interlaced manner. When a certain point is scanned, the grayscale of the image at the point is converted into a voltage value corresponding to the grayscale by the image sensor chip. Then this voltage value is output through the video signal. The car camera continuously scans one line of the image, and the output is a continuous voltage signal. The undulation of the voltage signal reflects the gray level change of the line image.

When one line is scanned, the video signal terminal outputs a level lower than the minimum video signal voltage (for example, 0.3V) and remains for a while. This is equivalent to having a voltage "groove" immediately after each line of image signals. This "groove" is called a line sync pulse, which is a sign of line feed scanning. Then, after skipping one line (because the on-board camera is interlaced), a new line starts to be scanned, and so on, until the video signal of the field is scanned, and then a blanking zone appears again. There are several composite blanking pulses in this area, one of which is far wider (ie, longer than the duration) of other blanking pulses, called the field synchronization pulse, which is a sign of the scan change field. The field sync pulse marks the arrival of a new field, but the field blanking zone happens to cross the end of the previous field and the beginning of the next field. In the past, the video signal of the next field is really arrival.

The onboard camera scans 25 images per second, each of which is divided into odd and even two fields. After the odd field and then even field, 50 images are scanned every second. Only odd-numbered lines in the image are scanned in the odd field, and even-numbered lines are scanned in the even field.


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