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Classification of LED display signal transmission is analysed

Date: 2015-06-18
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  The LED display has been widely used in each big commercial plaza, the location of the bustling commercial center, and all kinds of foot traffic, such as railway station, subway, shopping malls, etc.Due to the different areas of the display effect, its diversity and complexity, the audio and video signal transmission is stable, reliable, fluency is also put forward higher requirements.Single play, or the LED display of network broadcast and other occasions LED display signal using the transmission way of diversification.Common LED display signal into the wired signal transmission cable, GPRS, 3 g and 4 g wireless way to convey the wireless signal.How much do you know that about the LED display signal transmission?
  
  First, the classification of LED large screen signal transmission:
  
  1, wireless transmission: first rely on wireless signals to the frequency of different categories, such as long wave, medium wave, short wave, microwave, etc.Cell phone signal is a kind of wireless access method, a lot of use of mobile phones in 900 MHZ GSM operation frequency.Television signals varieties more, such as cable television: general transmission of analog signals, digital television is the transmission of digital signal;Satellite TV signals are digital LED display signal.
  
  2, cable transmission, and can be divided into analog signals, digital signals transmission, digital optical signal transmission.
  
  Second, LED electronic display screen signal transmission project:
  
  In addition to the signal attenuation, affect another element of the signal transmission is that the signal reflection.Impedance mismatches and the impedance don't have to be the RS - 485 bus signal reflection of the two primary reasons.Impedance mismatch, impedance don't match first horse is 485 chip and the impedance mismatch between communications lines.Lead to reflection because in communications lines free, all communications lines signal at sixes and sevens, once such reflection signal triggered the 485 chip to lose into the contrast, occurs fault signal.Our usual solution is to RS - 485 bus line A and B plus must value bias resistors, then up and down, separation this can prevent clutter signal not know beforehand.Impedance is not string, is with the light from one medium into another medium as a result of reflection is similar.Signal in the cable impedance is very small, but at the end of a transmission line and signal in the local will lead to the shot.To eliminate the reflection of the most commonly used method, is at the end of the cable a jumper and the characteristic impedance of the cable termination resistors of the same range.
  
  Three, how to ensure the LED electronic display screen security functions of signal transmission process:
  
  We can draw up a brief of the RS - 485 communication protocol, shorter when communication interval, using environmental trouble hour, one-way communication function will be able to complete the project, but most of the use of the environment are not all so this ideal.In is, to formulate a set of perfect communication protocol is particularly important.Specific measures, to transmit data of the subcontract, after every packet data, plus the frame head and tail frame to the data package, in the frame stay a byte as check word.Under a machine after their accounting check byte as compared with PC transmit to check byte, announced to the upper machine instructions, is from the beginning to send just the packet data is then issued under a packet of data is under a pack of a pack again after the samples, until the stop.After such a check retransmission mechanism, we can reduce the probability of error, make communication system normal operation.
  
  Therefore, in the process of transmission signal, with the increase of interval.So, in order to ensure that the LED screen playback, LED display performance relative to other advertising communication way, LED display of the transmission medium selection is particularly important.
Copyright:2005 - 2015 ShenZhen Meiyad Optoelectronics Co. Ltd
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