| Budget Amount *help |
¥10,400,000 (Direct Cost: ¥10,400,000)
Fiscal Year 1985: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1984: ¥9,200,000 (Direct Cost: ¥9,200,000)
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| Research Abstract |
FFT processor as a digital lens: Considering N elements equally spaced linear array of antennas, it gives Fourier components of N/2 for real signals according to Neyquist's theorem. When we use quadrature phase delay lines attached to each antennas, we observe complex signals of N, and obtain Fourier components of N ( real components of N/2 and imaginary components of N/2). Square of complex amplitude of each Fourier component gives the each intensity of electromagnetic radiation of corresponding direction. Thus , we get the radio image of the sky. FFT processor here operates as a lens does in an optical telescope.
The present FFT Processor: Complex eight points FFT processor has been constructed and operating at Waseda University in 1985. This processor aims the evaluation to construct the full system. Benefit of using FFT processor is its capability in extension. In the present system, sixteen A/D converters generate eight complex signals simultaneously at 20 MHz. The FFT processor operates parallely at the same clock. The dynamic range is eight bit. Resulting Fourier components are squared, added, and integrated. Finally these data are tranfered to computer. Twelve butterfly operators are on two boards, and fifty five multiplier-adder C-MOS LSIs( CX-7997 of SONY Corporation, S. Iwase et al 1984) are used. These LSIs are also used as integrators on the other two boards.
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