The Bit Error Rate Research Of Space X-ray Communication

Space development has played an increasing important role in civil and military use. As a result, a great number of researches have been focused on communication security field. The traditional communication methods, such as microwave and laser wave, cannot meet the requirement of space communication at certain extent because of their own restrictions. In contrary, applying X-ray as the carrier can not only realize information transitive against the electromagnetic shielding, but also set the tone for the future space communication field.X-ray communication, known as XCOM, was presented by NASA at 2007 which has been regarded as the next generation space communication method. Besides, the XCOM experiment has been put on their schedule. Domestically, the idea using X-ray as the communication carrier was firstly put forward by our team at 2011. After that, the X-ray vacuum communication demo system which based on the grid-controlled transmitting tube and MCP detector has been implemented. The idea of X-ray communication was tested and verified at the moment when the sound re-generated by the receiver side. The experience accumulated on X-ray transmitting and receiving will play an important role in the future space communication applications.This paper aims at find out how the modulation method influences the communication system performance by fulfilling two different digital pulse modulation methods, OOK and PPM. Specifically, the power function based on several transfer stages is given, as well as the X-ray space noise model based on the Poisson distribution. Finally, we can get the bit error rate specification under different conditions as well as the relationship between optic power and error rate. Currently, the bit error rate can be maintained around 10-4(OOK) and 10-5(PPM) level separately.As for the experiment design, in order to achieve better communication performance, the X-ray focus/ align system which can reduce the power loss dramatically was introduced into this demo system. Based on current condition, sound signal successfully passed the 10 meter vacuum tube. In addition, experiment data accorded with the theory calculation at a large extent. Finally, reasons of restricting the communication system perfor mance are also listed for the future improvement. Currently, the experiment result indicates that X-ray demo system will achieve 8.7km/1Mbps vacuum communication if the tube power large than 30 W.In summary, the idea applying X-ray as communication carrier can meet the special requirement of multivariate space environment. Therefore, it is important and meaningful to cultivate this brand new field.