Research on the Signal Transmitting Device for Downhole Wireless Electromagnetic Short Transmission System
On the basis of ground simulation test platform for downhole data wireless electromagnetic short-distance transmission,the test of signal transmission amplitude-frequency property was completed. It was determined that the frequency band of 1 ~ 7 kHz is the band in which signal transmission is relatively stable and the attenuation is slight. Meanwhile,it was found that signal transmission through amplitude modulation is liable to external disturbance and thus of remarkable fluctuation. Finally,the new scheme of transmitting signals through frequency modulation was determined. The signal transmitting device was designed according to the two schemes which were based on function generator ICL8038 and microcontroller respectively. The calibration test was completed. The test findings show that the designed signal transmitter operates stably,with a precise collection of data. This research has laid a solid foundation for the further study of downhole data wireless electromagnetic short transmission system.
Connecting people across the Digital Divide is as much a social effort as a technological one. We are developing a community-centered approach to learn how interaction techniques can compensate for poor communication across the Digital Divide. We have incorporated the lessons learnt regarding Social Intelligence Design in an (abstract) device called the SoftBridge. The device allows information to flow from endpoints through adapters (getting converted if necessary), and out to destination endpoints. Field trials are underway with two communities in South Africa, disadvantaged deaf users and an isolated rural community. First lessons learned show that we have to design user interfaces that allow users to understand and cope with delay (latency) as a necessary consequence of our approach.