We know that LED displays are afraid of heat and water, and the impact of heat on the performance of LED displays is fatal, directly affecting the stability of the display process and the service life of the display. Therefore, in order to reduce the impact of heat on the display, we need to understand the heat dissipation characteristics of the display, and then make a reasonable heat dissipation design for the display. In view of the heat dissipation of the LED display, this paper has carried out the calculation of the director, in order to play a certain role in the research and development of the LED display and the engineering installation of the LED display. First, the calculation of the heat dissipation of the LED display 1, condition setting Let the pixel spacing of the LED display be P (unit: mm), the area of ​​the LED display screen be S (unit m2), the brightness of the LED screen is L screen (unit cd/m2), and the input power of the LED display screen is W screen. (Unit W). It is assumed that the light intensity of the RGB lamp bead used is IR, IG and IB (unit cd), and the corresponding input powers are WR, WG and WB (unit W). 2. Calculation of optical radiation power of pixels composed of RGB Calculate the optical radiation power that can be generated at each pixel point during white balance. The calculation can be as follows: Because the intensity ratio of RLED, GLED, and BLED is about 3:6:1 when the display is white balanced, for a screen with a brightness of L (unit cd/m2) in the case of a white screen, each pixel Light intensity I pixel = L screen (cd / m2) ÷ points / m2 ÷ η (η is the system loss of light, generally about 0.9); then R, G, B accounted for the light intensity values ​​are: When the LED display screen reaches the white balance with the brightness of the L screen, the input electric power of the R, G, BLED lamps can be approximated as follows: The electro-optical conversion efficiencies of the above R, G, and BLED lamp bead chips are ηr, ηg, and ηb, respectively (the efficiency of converting the electric energy into light energy by the electro-optical conversion efficiency LED chip ). Then, the optical power radiated by each of the above RGB LEDs is: 3. Calculation of total radiant power of the entire LED display screen Due to the number of pixels in the display = the area of ​​the display / the square of the pixel spacing = Therefore, the optical power radiated by the LED display: W screen LED light = display pixel number × optical power generated per pixel = Thermal power generated by LED display LED lights: W screen LED heat = display pixel number × thermal power generated per pixel
The PufangTech`s wireless data modem is used to replace standard RS232 and RS485 serial communication cables. It provides a transparent connection between source and destination terminal and requires no knowledge of the data it is transmitting and the data can be simply sent and received with minimal delay.
With 12.5KHz channel spacing, the over-air transmission adopts different modulation scheme to meet various air rates. For air rate below 1200 bps, modulation scheme of FSK is used. For air rate of 1200, 2400 or 4800bps, MSK or FFSK modulation scheme is used. At 8000bps air rate, GMSK modulation scheme is adopted and at 9600bps air rate, the modulation is 4-level FSK. With 25KHz channel spacing, GMSK modulation scheme can support air rate of 16000bps and 4-level FSK can support 19200bps.
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