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

Nov. 28 th, Advanced Telescope and Instrument Technology Conference 2 Requirement: Broadband & high resolution  Why broad bandwidth? Δ f/f o = Δv/c  For submillimeter-wave observation

Nov. 28 th, Advanced Telescope and Instrument Technology Conference 3 Requirement: Broadband & high resolution  Why broad bandwidth? Δ f/f o = Δv/c  For high-redshift objects survey 100MHz bandwidth only covers ~300km/s!!! Credit: Young, J. S et al. 1984, ApJ, 287, 153

Nov. 28 th, Advanced Telescope and Instrument Technology Conference 4 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 N 2 H + (J=1-0) : GHz GHz GHz GHz GHz GHz GHz

Nov. 28 th, Advanced Telescope and Instrument Technology Conference 5 Evolvement: From analog to digital  Analog back-end system Filter Bank Spectrometer Acousto-Optical Spectrometer Filterbank & AOS Herschel HiFi

Nov. 28 th, Advanced Telescope and Instrument Technology Conference 6 Evolvement: From analog to digital  Digital back-end system Auto/Cross-Correlation Spectrometer ALMA Correlator, 3bits or 2bits SMA Correlator, 2bits kHz

Nov. 28 th, Advanced Telescope and Instrument Technology Conference 7 FFTS: Principle Autocorrelator/FFT Spectrometer

Nov. 28 th, Advanced Telescope and Instrument Technology Conference 8 Spectral system evolvement at PMO AOS x m telescope at Delingha Single FFTS FFTS x 2 x , ,11

Nov. 28 th, Advanced Telescope and Instrument Technology Conference 9 FFTS: Firmware development Firmware Structure based on AC240 Hardware structure of AC240AC240 Board

Nov. 28 th, Advanced Telescope and Instrument Technology Conference 10 FFTS: Firmware development Parallel pipeline FFT core structure

Nov. 28 th, Advanced Telescope and Instrument Technology Conference 11 FFTS: Firmware development Program language: VHDL Design tool: ISE 9.1 Resource utility

Nov. 28 th, Advanced Telescope and Instrument Technology Conference 12 FFTS: Software development 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 命令组接收 命令解析 数据发送 命令接收 数据发送 Human-computer interaction - Quicklook GUI Data processing – Multithreading （ 9 data processing sub-thread, 2 communication sub-thread ） Data Communication (TCP/IP, 1Gb/s) 、 Data Storage (NFS)

Nov. 28 th, Advanced Telescope and Instrument Technology Conference 13 FFTS: Software development  Quicklook GUI Single FFTS 9-Pixel FFTS BECU case 1 BECU case 2

Nov. 28 th, Advanced Telescope and Instrument Technology Conference 14 FFTS: Performance  Test results Integration Time: ms Dynamic Range: >30dB ADC Full Scale: 1V Stability/Allan-Variance: ~3000s

Nov. 28 th, Advanced Telescope and Instrument Technology Conference 15 FFTS: Performance  Observation results SiO(2-1)

Nov. 28 th, Advanced Telescope and Instrument Technology Conference 16 FFTS: Back-end system integration  Integration with data storage system Gigabits internet 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)

Nov. 28 th, Advanced Telescope and Instrument Technology Conference 17 Future plan  Back-end for dome A telescope  Broadband with high resolution  Low power consumption  High level of integration  High stability  , hardware, firmware & software development 2~2.5 GHz bandwidth, 16 k channels(122 kHz)  >=4 GHz bandwidth, >=32k channels Dome A Telescope

Nov. 28 th, Advanced Telescope and Instrument Technology Conference 18 Thanks for your attention~