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Detailed emission signal of wireless video doorbell
2011-03-04 08:36:23
Same wireless visible Talkback doorbell. Differentiating by emission signals can be divided into: analog signal and digital signal transmission in two ways. Classified according to the communication protocol: 2.4GHZ, Bluetooth, WIFI three.


Analog signal transmission: refers to audio and video signals on a 2.4GHZ carrier modulation is carried in by a continuous, wireless transmission to the receiver, and then restored to the original audio/modem, video signal. Wireless video doorbell when using the analog signal transmission, transmitting and receiving system as a whole is simulation approach to implementation, number 4-8. Simulated transmission mode, transmitter power 10dBm.
Mainly has the following issues:
1. transport about 100 meters from the open territory, farther if you want to transfer, you need to increase the transmission power;
2. the wall is relatively weak;
3. emission band less vulnerable to similar products of interference, image appears snowflakes, and discontinuous;
4. analog transmission products, complex production process, there is a need to adjust the component parameters in the production process, it is difficult to ensure consistent production;


Digital signal transmission: means audio, and video signal by module conversion into digital signal (second into system code), modulation to digital of 2.4GHZ of carrier Shang; (using jump frequently spectrum extended technology, to band into several a jump frequency channel (hop channel), in once connection in the, radio transceiver device by must of code sequence constantly to from a channel "jump" to another channel).
Digital signal transmission has the following characteristics:
1. wireless frequency-hopping communication protocol: a total of 83 communication channels, the use of AFH Adaptive frequency hopping the way you work, with channel replaces mechanism, data to the mechanism;
2. frequency hopping mode: software automatically divided into a number of general frequency table 83 channels, each frequency using table is composed of around 30 channels, software randomly one of general frequency table to FH;
3. replace channel: when a channel is in General a frequency table when there is interference, the software will be automatically replaced with the interference of frequency, channel hopping to not be interference of FH;
4. data: when a packet is sent in the process, was interfered with, resulting in receiving recognition for the port does not function properly, then took over the end will require the launching end and then resend packets by interference.
5. strong wireless communication: wireless communications privacy: every machine using the code of communication, the software will randomly generate a random code, only two random coding same machine to communication. This random code without any rules.
6. transmission distance open territory around 300, transmit power 100MW, within the scope of the certification;
7. the wall is relatively weak;
8. digital products, the production process is simple, no adjustment of components in the production parameters, production of high consistency;
9. image quality clear, there is no snow;

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