Lightning Research Group of Osaka University (LRG-OU) has been developing the VHF Broadband Digital Interferometer (DITF) to image precise lightning channels and monitor lightning activity widely. The feature of the DITF is its bandwidth (from 25MHz to 100MHz) and implicit redundancy for esti-mating VHF source location. LRG-OU considers to installing the DITF on a satellite taking advantage of its high resolution and the compactness of the system, and joins the SOHLA (Space Oriented Higashi-Osaka Leading Associate) satellite project. The SOHLA satellite is planed to be a low altitude satellite about several hundred kilometers from the ground, and the locations accuracy of 0.01 radian may provide us the sufficient and unique opportunity to discriminate between the active and non-active thunderclouds by space-based observations. As a pilot study a small satellite, SOHLA-1, is being manufactured. LRG-OU proposes the BMW (Broadband Meas-urement of Waveform for VHF Lightning Impulses ) to examine the feasibility of the DITF by receiving VHF lightning impulses in space. To finalize the specifications of the amplifier and analog-to-digital converter (ADC), numerical analysis for propagation characteristic of wideband EM wave in the ionosphere is done. Now BMW has been ready and the integrated system test of SOHLA-1 in on going. The most part of the onboard DITF has been designed as well. SOHLA-1 is expected to be launched in 2008.
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