title: A high-efficiency real-time digital signal averager for time-of-flight mass spectrometry.
abstract: BACKGROUND
  Analog-to-digital converter (ADC)-based acquisition systems are widely applied in time-of-flight mass spectrometers (TOFMS) due to their ability to record the signal intensity of all ions within the same pulse. However, the acquisition system raises the requirement for data throughput, along with increasing the conversion rate and resolution of the ADC. It is therefore of considerable interest to develop a high-performance real-time acquisition system, which can relieve the limitation of data throughput.
  
  
  METHODS
  We present in this work a high-efficiency real-time digital signal averager, consisting of a signal conditioner, a data conversion module and a signal processing module. Two optimization strategies are implemented using field programmable gate arrays (FPGAs) to enhance the efficiency of the real-time processing. A pipeline procedure is used to reduce the time consumption of the accumulation strategy. To realize continuous data transfer, a high-efficiency transmission strategy is developed, based on a ping-pong procedure.
  
  
  RESULTS
  The digital signal averager features good responsiveness, analog bandwidth and dynamic performance. The optimal effective number of bits reaches 6.7 bits. For a 32 µs record length, the averager can realize 100% efficiency with an extraction frequency below 31.23 kHz by modifying the number of accumulation steps. In unit time, the averager yields superior signal-to-noise ratio (SNR) compared with data accumulation in a computer.
  
  
  CONCLUSIONS
  The digital signal averager is combined with a vacuum ultraviolet single-photon ionization time-of-flight mass spectrometer (VUV-SPI-TOFMS). The efficiency of the real-time processing is tested by analyzing the volatile organic compounds (VOCs) from ordinary printed materials. In these experiments, 22 kinds of compounds are detected, and the dynamic range exceeds 3 orders of magnitude.
authors.affiliation: School of Electronic Science and Engineering, National University of Defense Technology, Changsha, Hunan, China.
authors.forename: Yinan
authors.initials: Y
authors.lastname: Wang
authors.forename: Hui
authors.initials: H
authors.lastname: Xu
authors.forename: Qingjiang
authors.initials: Q
authors.lastname: Li
authors.forename: Nan
authors.initials: N
authors.lastname: Li
authors.forename: Zhengxu
authors.initials: Z
authors.lastname: Huang
authors.forename: Zhen
authors.initials: Z
authors.lastname: Zhou
authors.forename: Husheng
authors.initials: H
authors.lastname: Liu
authors.forename: Zhaolin
authors.initials: Z
authors.lastname: Sun
authors.forename: Xin
authors.initials: X
authors.lastname: Xu
authors.forename: Hongqi
authors.initials: H
authors.lastname: Yu
authors.forename: Haijun
authors.initials: H
authors.lastname: Liu
authors.forename: David D-U
authors.initials: DD
authors.lastname: Li
authors.forename: Xi
authors.initials: X
authors.lastname: Wang
authors.forename: Xiuzhen
authors.initials: X
authors.lastname: Dong
authors.forename: Wei
authors.initials: W
authors.lastname: Gao
mesh_terms: D013058:Mass Spectrometry / Q000295:instrumentation* / Q000379:methods*; D013997:Time Factors; D055549:Volatile Organic Compounds / Q000032:analysis
chemical_list: D055549:Volatile Organic Compounds