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, Taiwan2011 Advanced Telescope and Instrument Technology Conference
Nov. 28th, 2011 2011 Advanced Telescope and Instrument Technology Conference 2
Requirement: Broadband & high resolution
Why broad bandwidth?
Δf/fo= Δv/c For submillimeter-wave observation
Nov. 28th, 2011 2011 Advanced Telescope and Instrument Technology Conference 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
Nov. 28th, 2011 2011 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
N2H+(J=1-0) :93.171621GHz93.171917GHz93.172053GHz93.173480GHz93.173777GHz93.173967GHz93.176265GHz
Nov. 28th, 2011 2011 Advanced Telescope and Instrument Technology Conference 5
Evolvement: From analog to digital
Analog back-end system
Filter Bank Spectrometer
Acousto-Optical Spectrometer
Filterbank & AOS4x1GHz@1MHz
HerschelHerschel
HiFi
Nov. 28th, 2011 2011 Advanced Telescope and Instrument Technology Conference 6
Evolvement: From analog to digital
Digital back-end system
Auto/Cross-Correlation Spectrometer ALMAALMA
Correlator, 3bits or [email protected]@244kHz
SMASMA
Correlator, 2bits8x24x82MHz@ 812.5 kHz
Nov. 28th, 2011 2011 Advanced Telescope and Instrument Technology Conference 7
FFTS: Principle
Autocorrelator/FFT Spectrometer
Nov. 28th, 2011 2011 Advanced Telescope and Instrument Technology Conference 8
Spectral system evolvement at PMO
AOS x 313.7m telescope at Delingha
Single FFTSFFTS x 2 x 9
2006,082010,11
Nov. 28th, 2011 2011 Advanced Telescope and Instrument Technology Conference 9
FFTS: Firmware development
Firmware Structure based on AC240
Hardware structure of AC240AC240 Board
Nov. 28th, 2011 2011 Advanced Telescope and Instrument Technology Conference 10
FFTS: Firmware development
Parallel pipeline FFT core structure
Nov. 28th, 2011 2011 Advanced Telescope and Instrument Technology Conference 11
FFTS: Firmware development
Program language: VHDLDesign tool: ISE 9.1
Resource utility
Nov. 28th, 2011 2011 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. 28th, 2011 2011 Advanced Telescope and Instrument Technology Conference 13
FFTS: Software development
Quicklook GUISingle FFTS
9-Pixel FFTS
BECU case 1BECU case 2
Nov. 28th, 2011 2011 Advanced Telescope and Instrument Technology Conference 14
FFTS: Performance
Test results
Integration Time: 32.768msDynamic Range: >30dB
ADC Full Scale: 1VStability/Allan-Variance: ~3000s
Nov. 28th, 2011 2011 Advanced Telescope and Instrument Technology Conference 15
FFTS: Performance
Observation results
SiO(2-1)
Nov. 28th, 2011 2011 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 OTF1Gb/s internet connectionRAID-5 disk array for both high speed and reliability34T bytes storage capacity (data of a month)
Nov. 28th, 2011 2011 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
2011-2012, hardware, firmware & software development• 2~2.5 GHz bandwidth, 16 k channels(122 kHz)
2013-2015• >=4 GHz bandwidth, >=32k channels
Dome A Telescope
Nov. 28th, 2011 2011 Advanced Telescope and Instrument Technology Conference 18
Thanks for your attention~
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