Create a simulated Video Monitoring System

The use of USB cameras for video surveillance systems is no longer new, but this monitoring system is not practical enough because it has limited monitoring scope, the USB camera is limited by the transmission distance of the USB cable (less than 5 meters), so that its monitoring scope is limited to the vicinity of the computer. Secondly, its concealment is too poor, it is hard to imagine that a computer that is on is stuck with an eye-catching camera. It seems that a practical video monitoring system has to be developed.

A usb camera used to simulate a camera. This camera uses the AV Compound interface, which is its advantage, because the market can buy an 8-meter-long AV cable, you can also create a longer AV line. If you use a wireless transmission device, you can extend the transmission distance to several hundred or even several kilometers. Moreover, the AV camera can connect far more devices than the USB camera. televisions, video recorders, DV, and computers can all be used as the receiver of the camera for monitoring or recording. It can be seen that the simulated camera is more suitable for the monitoring system. At present, the simulated camera has withdrawn from the computer accessories market, but it can still be purchased in the security equipment store. In addition, the price is basically the same as that of a digital camera.

This camera works with a cheap PCTV card to meet the needs of video chats. If appropriate software is added, it can be used as a monitoring device.

Device questions required to simulate a video surveillance system

A simple wired video surveillance system requires only one analog camera and one analog acquisition card (the cheapest PCTV card ), if you want to build a wireless video surveillance system, you also need Wireless Audio and video transmitters and wireless receivers.

1. simulate a camera

A simulated camera is a key device in the system. The analog camera works the same as the digital USB camera, but the interface uses the avinterface, that is, the RCA Lotus head (1), which can be directly connected to a computer, TV, video recorder or even DV, use a computer or TV as a monitor, and use a computer, video recorder, or DV to store images. The imaging devices of the analog camera are CMOS and CCD. The cheapest CMOS black and white camera is less than 150 yuan, the CMOS color camera is about four hundred yuan, and the CCD color camera is less than yuan. In general, the imaging quality of CCD is better than that of CMOS, but CMOS has a prominent advantage that CCD does not have, that is, its spectral sensitivity range is 5 ~ higher than that of visible light in near-infrared line segments ~ Because infrared light emitting diodes are used as the lighting source at night, although the human eyes are still dark, the CMOS camera can see clearly! Therefore, the CMOS camera is more suitable for concealed observation at night. In addition, the power consumption of the CMOS camera is much lower than that of the CCD camera, which is more suitable for long-time monitoring.

In order to play a hidden role, this type of camera is also a strange shape, there is a cat-eye style suitable for installation on the anti-theft door, there is a very concealed button shape and screw shape of the camera, there are also spotlights and semi-spherical cameras (2 ). The semi-spherical camera can be installed on the roof, and its monitoring range is five times larger than that of ordinary cameras. Like a camera with a spotlight, it can enable the infrared compensation light source at Low Illumination, you can also perform uninterrupted monitoring in the dark night environment.

2. analog acquisition card

The analog acquisition card is used to receive signals transmitted by a simulated camera, so that images can be received and recorded on a computer. This analog acquisition card has no special requirements. It can be used for acquisition cards with av analog terminals. Simply put, you can use a common PCTV card (3), which can be used to watch TV or connect analog video devices. To perform Multi-Channel Video Monitoring, You need to purchase a Multi-Channel Video Acquisition Card dedicated to video monitoring.

3. Wireless transmitting and receiving devices

Wired video monitoring costs are low, but the restrictions are too large: wiring is required and the transmission range is limited. If wireless devices are used, there will be no such problems. There are two types of wireless monitoring devices: one is to use a wireless camera, which itself carries a wireless transmitter and antenna, and the receiving end receives audio and video signals through a wireless receiver (4 ); one is a dedicated Wireless Audio and Video device, which consists of a wireless transmitter and a wireless receiver.

The wireless transmitter (5) provides an av interface for analog camera access. Generally, it transmits audio and video signals at a frequency of 2 to 4 GHz. This type of product has many specifications, and the price is mainly divided by power. The price of 50 MW small transmitters is about 200 ~ 300 RMB (receiving range: 50 ~ 100 m), 1800 MW high-end products, the price is around 500 yuan (receiving range ~ 1000 meters ). The transmit power and environment determine the signal transmission distance. If you want to obtain a further transmission distance, you can also use a targeted antenna at the transmitting end and the receiving end, which can prolong the transmission distance several times. The receiver has two types of small receiver desktop receivers, where the desktop can be set in the specified 2 ~ Automatically switch between the four channels and set the automatic switch time. The price for a common small receiver is 160 ~ About 180 yuan, while the desktop receiver costs 100 yuan.

Figure 1 simulated camera

Figure 2 four cameras

Figure 3 A common video capture card

Figure 4 wireless cameras

Figure 5 wireless transmitters

Monitoring System Installation

The installation of the monitoring system is not complex. In addition to the hardware system, you also need suitable monitoring software.

1. Installation of Wired Monitoring System

The installation of the wired monitoring system is very simple. Most analog cameras use AV composite terminals, and the analog acquisition card also has the corresponding AV terminals, you only need to connect them with a proper length of av (6 ). When installing the camera, you should be aware of the hidden location, so that it cannot be easily discovered, or you will lose the meaning of monitoring.

2. Installation of wireless monitoring devices

The installation of wireless monitoring equipment is similar to that of Wired monitoring equipment. The transmitters and receivers are equipped with av, conversion wires, and regulated power supplies. You only need to connect them one by one. The connection method is 7.

3. Monitoring Software

Monitoring software can use "Superman Monitoring Alarm System" (: http://www.skycn.com/soft/16414.html), this is a set of monitoring, static image shooting, video and other functions in one of the professional monitoring software, the image change alarm function can be used as the receiver software in our monitoring system.

(1) set the video source

When the software runs for the first time, the "video source" dialog box is displayed. On the "Capture source" tab, select the video device as the PCTV card (8), and then select the video source as the composite video (avinterface ).

(2) Set resolution

On the main interface of the software, click the "video format" button (9). In the displayed "video format" dialog box, set the resolution of the monitoring and video, for manual monitoring, the resolution can be set to a maximum of 640 × 480. For video recording, the CPU processing capability is required, because the PCTV card is a soft acquisition card, the encoding in the video depends entirely on the CPU, and the resolution can be reduced.

(3) set the video compression format

Select the video compression button, select the video compression format in the video compression dialog box, usually Xvid, DivX, ffdshow MPEG-4 encoding format, this greatly saves hard disk space while ensuring video quality. The encoding bit rate can be set to around 640 Kbps when the resolution is 480 × 320, and 240 kbps when the encoding bit rate is 500 ×.

(4) Select a capture method

The software can capture videos, alarms, photos, and dynamic recordings. You can select the "video" mode when you steal a video. When someone monitors the video, you can select the "alarm" mode. When the image changes, the system automatically generates a beep to effectively detect the intruder; dynamic recording is suitable for unattended monitoring for a long time. It only performs video recording when the image changes, greatly reducing the disk usage.

After the mode is selected, you can set the Frame Rate of the video. The Frame Rate of the video in the mode is determined by the CPU. To achieve the real-time effect, you can generally set the frame rate to 25 ~ 30fps. In addition, the software interface has settings such as detection sensitivity, duration of each segment, and file name. These settings can be used at a glance.

In fact, this simulated video monitoring system is widely used in more than anti-theft monitoring. It can also be used in fields such as news unannounced visits, judicial forensics, aerial photography, adventure entertainment program shooting, and robot vision systems, it is widely used. If you are interested, you may wish to DIY a set. (Head-heavy)

Figure 6 wired Monitoring System

Figure 7 wireless monitoring system

Figure 8 set the Video Source System

Figure 9 set the resolution of the captured image