The Laser Beam Of Green Laser Pointer Is Electricity-saving

The laser beam of  green laser pointer  is electricity-saving
In wireless optical communications, atmospheric absorption, scattering and turbulence effects of the laser spot flash, drift and division, seriously affect the stability and reliability of communication [10-11]. In order to visually and accurately analyze the laser atmospheric communication channel random effect and the effect of error control, the development of the laser through the atmosphere, random channel real-time measurement system, the intention is to obtain experimental data, and its theoretical analysis and system modeling, validation laser communication system adaptable to various channels, in order to further optimize the system performance design, making meaningful exploration. The package method of green laser pointer will be determined in the meeting to be held this afternoon.
Taking into account the atmospheric random channel and various meteorological conditions on atmospheric laser communication link, experiments require long-term, fixed observation, it will set up communication links between the two high-rise, the link between non-blocking material. Cycle on a PC to send a fixed sequence or known data, or data of these sequences is controlled by software through the computer's serial port to send out, will pass over the binary serial number sequence error control coding, then the PPM modulation, the modulator will power signals are converted to optical signals drive the laser emission outside the optical signal through the air channel to reach the light receiving antennas by the photodiode to optical signals into electrical signals. The parameter of 100mW green laser pointer should be added onto the drawing.
Then signal processing (shaping, filtering, amplification), the signal processing PPM demodulation, error control during the decoding, the decoded binary data passed through the serial port computer records. Finally, record the results and send the data bit by bit, the data bits of different statistics, different bits of data bits and the total transmission is the ratio between the error rate was required. Figure 1 Schematic of measurement error. Statistics in a 16 slot in the distribution of errors, showing the basic uniform distribution, there is no slot increase and decrease trends. Adopted July 4, 2007, July 5, August 9, data as samples. The customer has some strict requirements for the parameter of green laser pointer .
Symbol error number 69 120, ie, PPM frame error number 69 120. Eight time slots in front of the number of 32 486 errors, 47%; the number of errors after eight time slots of 36 634, accounting for 53%. The number of errors between adjacent time slots for the 4838, 7%; separated by two time slots for the 6221 number of errors (9%); separated by more than 2 errors in slot number 58 061, accounting for 85 %. Table 1 for different weather conditions, the bit error rate statistics. The results show that: Atmospheric laser communication system basically can work, but run into fog, rain, snow and other inclement weather, the system of communication quality decreased, bit error rate increased, reaching 10 ? 3, close to 10 ? 2, but the use of channel coding techniques, bit error rate after error correction can be achieved basically 10 ? 5. The equipment in the corner is the best one of manufacturing 50mW green laser pointer .
In particular Turbo code and RS (30, 10) this system the two error-correcting codes have better error correction performance, the effect of significantly improving system performance, they are correcting the error rate of the system in 10 ? 5 the following. Rain in the general weather conditions in the system, the average bit error rate remains at 10 ? 4, the use of RS (15, 9) and LDPC codes for atmospheric laser communication systems to improve performance, improve the system bit error rate of 10 ? 6. If the sunny and cloudy days in the case, error correction, the average bit error rate before the system has less than 10 ? 7, the BER after error correction is to achieve a 10 ? 9. The ventilated condition of the warehouse of green laser pointer can ensure the good working status of 200mW green Laser Pointer.