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Development of FFTS for Radio Astronomy

Development of FFTS for Radio Astronomy. Sheng Li , Zhen-Hui Lin, Ji Yang Wen-Ying Duan, Qi-Jun Yao, Sheng-Cai Shi Purple Mountain Observatory, Chinese Academy of Sciences. Nov. 28 th , 2011 Sun-Moon Lake, Taiwan 2011 Advanced Telescope and Instrument Technology Conference.

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Development of FFTS for Radio Astronomy

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  1. Development of FFTS for Radio Astronomy Sheng Li, Zhen-Hui Lin, Ji Yang Wen-Ying Duan, Qi-Jun Yao, Sheng-Cai Shi Purple Mountain Observatory, Chinese Academy of Sciences Nov. 28th, 2011 Sun-Moon Lake, Taiwan 2011 Advanced Telescope and Instrument Technology Conference

  2. Requirement: Broadband & high resolution • Why broad bandwidth? Δf/fo= Δv/c • For submillimeter-wave observation

  3. Requirement: Broadband & high resolution • Why broad bandwidth? Δf/fo= Δv/c • For high-redshift objects survey 100MHz bandwidth only covers ~300km/s!!! Credit: Young, J. S et al. 1984, ApJ, 287, 153

  4. N2H+(J=1-0) : 93.171621GHz 93.171917GHz 93.172053GHz 93.173480GHz 93.173777GHz 93.173967GHz 93.176265GHz Requirement: Broadband & high resolution • Why high frequency resolution? • For observe fine structure of molecular lines • For knowing the kinematics characteristics of objects Credit: Schnee, S. et al. 2005, ApJ, 624, 254

  5. Evolvement: From analog to digital • Analog back-end system Herschel Filter Bank Spectrometer HiFi Acousto-OpticalSpectrometer Filterbank & AOS 4x1GHz@1MHz

  6. ALMA Evolvement: From analog to digital • Digital back-end system Auto/Cross-Correlation Spectrometer Correlator, 3bits or 2bits 8x2GHz@15.625MHz 8x250MHz@244kHz Correlator, 2bits 8x24x82MHz@ 812.5 kHz SMA

  7. FFTS: Principle Autocorrelator/FFT Spectrometer

  8. AOS x 3 13.7m telescope at Delingha Spectral system evolvement at PMO Single FFTS FFTS x 2 x 9 2010,11 2006,08

  9. FFTS: Firmware development AC240 Board Hardware structure of AC240 Firmware Structure based on AC240

  10. FFTS: Firmware development Parallel pipeline FFT core structure

  11. FFTS: Firmware development Program language: VHDL Design tool: ISE 9.1 Resource utility

  12. 命令组接收 • 命令解析 • 数据发送 • 设备初始化 • 图形界面创建 • 子线程创建 • 频谱及状态显示 • 标准源观测 • 谱线OTF观测 • 谱线5点观测 • 命令接收 • 数据发送 FFTS: Software development • Human-computer interaction - Quicklook GUI • Data processing – Multithreading • （9 data processing sub-thread, 2communication sub-thread） • Data Communication (TCP/IP, 1Gb/s) 、Data Storage (NFS)

  13. Single FFTS BECU case 2 FFTS: Software development • Quicklook GUI 9-Pixel FFTS BECU case 1

  14. FFTS: Performance • Test results ADC Full Scale: 1V Stability/Allan-Variance: ~3000s Integration Time: 32.768ms Dynamic Range: >30dB

  15. SiO(2-1) FFTS: Performance • Observation results

  16. FFTS: Back-end system integration • Integration with data storage system • 20~40 MB/s data transfer rate with OTF • 1Gb/s internet connection • RAID-5 disk array for both high speed and reliability • 34T bytes storage capacity (data of a month) Gigabits internet

  17. Dome A Telescope Future plan • Back-end for dome A telescope • Broadband with high resolution • Low power consumption • High level of integration • High stability • 2011-2012, hardware, firmware & software development • 2~2.5 GHz bandwidth, 16 k channels(122 kHz) • 2013-2015 • >=4 GHz bandwidth, >=32k channels

  18. Thanks for your attention~

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