Simultaneous Improvement of Resolving Power and Signal-to-Noise Ratio Using a Modified Hadamard Transform-Inverse Ion Mobility Spectrometry Technique

In Hadamard transform ion mobility spectrometry (HT IMS), the signal-to-noise ratio is always lower for non-modified pseudorandom sequences than for modified sequences. Since the use of non-modified modulating pseudorandom sequences is strategically preferable from a duty cycle standpoint, we investigated the change in the interference signal when transitioning from non-modified modulating sequences to sequences modified by the addition of 1,3,5 and 7 zeros. The interfering signal in HT IMS with modified pseudorandom sequences was shown to be mainly random noise for all the cases except for modifying by incorporation of 1 zero. For standard samples of tetraalkylammonium halides, modulation by non-modified pseudorandom sequences is beneficial in the case of small numbers of averaged spectra (below ∼40 averaged spectra compared to any modified pseudorandom sequences except for 1 zero modified and below ∼200 averaged spectra compared to signal averaging ion mobility spectrometry) and worsens the signal-to-noise ratio in the case of large numbers of averaged spectra. Contrarily, modulation by modified pseudorandom sequences is beneficial for any number of averaged spectra, except for very small ones (below 15 averaged spectra compared to modulation by non-modified sequences). Pseudorandom sequence modified with 1 zero incorporation is beneficial in the case of below ∼400 averaged spectra compared to any modified and non-modified pseudorandom sequences. The signal-to-noise ratio in conventional signal averaging mode ion mobility spectrometry is affected by random noise, whereas the HT IMS with non-modified pseudorandom sequences was demonstrated to be primarily affected by a systematic noise-like artefact signal. Because noise-like artefact signals were found to be reproducible, predicting models for interference signals could be generated to improve signal-to-noise ratio. This is significant because non-modified modulating sequences are limited by their poor signal-to-noise ratio. This improvement would increase the viability of non-modified modulating sequences which are preferred because of their higher sample utilization efficiency.

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Analytical model for the signal-to-noise-ratio of drift tube ion mobility spectrometers

tm - Technisches Messen ◽

10.1515/teme-2021-0013 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Ansgar T. Kirk ◽

Alexander Bohnhorst ◽

Stefan Zimmermann

Keyword(s):

Ion Mobility ◽

Drift Tube ◽

Signal To Noise Ratio ◽

Resolving Power ◽

Operating Point ◽

Optimum Operating ◽

Signal To Noise ◽

Experimental Parameters ◽

Noise Ratio ◽

Optimum Operating Point

Abstract While the resolving power of drift tube ion mobility spectrometers has been studied and modelled in detail over the past decades, no comparable model exists for the signal-to-noise-ratio. In this work, we develop an analytical model for the signal-to-noise-ratio of a drift tube ion mobility spectrometer based on the same experimental parameters used for modelling the resolving power. The resulting holistic model agrees well with experimental results and allows simultaneously optimizing both resolving power and signal-to-noise-ratio. Especially, it reveals several unexpected relationships between experimental parameters. First, even though reduced initial ion packet widths result in fewer injected ions and reduced amplifier widths result in more noise, the resulting shift of the optimum operating point when reducing both simultaneously leads to a constant signal-to-noise-ratio. Second, there is no dependence of the signal-to-noise-ratio at the optimum operating point on the drift length, as again the resulting shift of the optimum operating point causes all effects to compensate each other.

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Ion multiplexing: Maximizing throughput and signal to noise ratio for ion mobility spectrometry

TrAC Trends in Analytical Chemistry ◽

10.1016/j.trac.2019.03.014 ◽

2019 ◽

Vol 116 ◽

pp. 340-345 ◽

Cited By ~ 5

Author(s):

Tobias Reinecke ◽

Cameron N. Naylor ◽

Brian H. Clowers

Keyword(s):

Ion Mobility Spectrometry ◽

Ion Mobility ◽

Signal To Noise Ratio ◽

Signal To Noise ◽

Noise Ratio

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Signal-to-Noise Ratio and Astronomical Fourier Transform Spectroscopy

Symposium - International Astronomical Union ◽

10.1017/s0074180900034793 ◽

1988 ◽

Vol 132 ◽

pp. 71-78

Author(s):

J. P. Maillard

Keyword(s):

Fourier Transform ◽

Signal To Noise Ratio ◽

Resolving Power ◽

High Resolution Spectroscopy ◽

Signal To Noise ◽

Array Detectors ◽

Noise Ratio ◽

The Fourier Transform ◽

Large Telescopes ◽

Very High

The multiplex properties of the Fourier Transform Spectrometer (FTS) can be considered as disadvantageous with modern detectors and large telescopes, the dominant noise source being no longer in most applications the detector noise. Nevertheless, a FTS offers a gain in information and other instrumental features remain: flexibility in choosing resolving power up to very high values, large throughput, essential in high–resolution spectroscopy with large telescopes, metrologic accuracy, automatic substraction of parasitic background. The signal–to–noise ratio in spectra can also be improved: by limiting the bandwidth with cold filters or even cold dispersers, by matching the instrument to low background foreoptics and high–image quality telescopes. The association with array detectors provides the solution for the FTS to regain its full multiplex advantage.

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Signal-to-noise ratio enhancement of a Hadamard transform spectrometer using a two-dimensional slit-array

Applied Optics ◽

10.1364/ao.56.007188 ◽

2017 ◽

Vol 56 (25) ◽

pp. 7188 ◽

Cited By ~ 3

Author(s):

Mingbo Chi ◽

Yihui Wu ◽

Fang Qian ◽

Peng Hao ◽

Wenchao Zhou ◽

...

Keyword(s):

Signal To Noise Ratio ◽

Hadamard Transform ◽

Two Dimensional ◽

Signal To Noise ◽

Noise Ratio

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The Effect of a Single Defective Mask Element on the Multiplex Advantage in Hadamard Transform Spectroscopy

Applied Spectroscopy ◽

10.1366/0003702894203372 ◽

1989 ◽

Vol 43 (2) ◽

pp. 278-283 ◽

Cited By ~ 8

Author(s):

Stephen A. Dyer ◽

Jin Bae Park

Keyword(s):

Output Signal ◽

Signal To Noise Ratio ◽

Hadamard Transform ◽

Signal To Noise ◽

Noise Ratio ◽

Defective Element ◽

Output Snr

The effect of a single defective mask element on the output signal-to-noise ratio (SNR) for a stationary-mask Hadamard transform (HT) spectrometer is investigated. The decrease in output-SNR from that of an HT spectrometer having a perfect mask is found to be dependent on the amount of energy impinging on the defective element. A method of compensating for the defective mask element is presented. The method is computationally inexpensive and can be fully automated.

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Resolution performance of Wiener filters

Geophysics ◽

10.1190/1.1441517 ◽

1983 ◽

Vol 48 (7) ◽

pp. 887-899 ◽

Cited By ~ 17

Author(s):

S. H. Bickel ◽

D. R. Martinez

Keyword(s):

Time Constant ◽

Matched Filter ◽

Signal To Noise Ratio ◽

Wiener Filter ◽

Resolving Power ◽

General Definition ◽

Resolution Time ◽

Signal To Noise ◽

Temporal Separation ◽

Noise Ratio

To improve the resolution of seismic events, one often designs a Wiener inverse filter that optimally (in the least‐squares sense) transforms a measured source signature into a spike. When this filter is applied to seismic data, the bandwidth of any noise which is present increases along with the bandwidth of the signal. Thus the signal‐to‐noise ratio is degraded. To reduce signal ambiguity it is common practice to prewhiten the Wiener filter. Prewhitening the filter improves the output signal‐to‐ambient noise ratio, but at the same time it reduces resolution. The ability to resolve the temporal separation between events is determined by the resolution time constant which we define as the ratio of signal energy to peak signal power from the filter. For unfiltered wavelets the resolution time constant becomes the reciprocal of resolving power recently described by Widess (1982). For matched filter signals the resolution time constant can be regarded as the inverse of the frequency span of the signal. Although it is satisfying that the resolution time constant definition agrees with other measures of resolution, this more general definition has two major advantages. First, it incorporates the effect of filtering; second, it is easily generalized to incorporate the effects of noise by assuming that the filter is a Wiener filter. For a given amount of noise the Wiener filter is a generalization of the matched filter. Marine seismic wavelets demonstrate how reducing the noise level improves the resolution of a Wiener filter relative to a matched filter. For these wavelets a point of diminishing return is reached, such that, to realize a further small increase in resolution, a large increase in input signal‐to‐noise ratio is required to maintain interpretable information at the output.

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High Sensitivity Snapshot Spectrometer Based on Deep Network Unmixing

Sensors ◽

10.3390/s20247038 ◽

2020 ◽

Vol 20 (24) ◽

pp. 7038

Author(s):

Hui Xie ◽

Zhuang Zhao ◽

Jing Han ◽

Lianfa Bai ◽

Yi Zhang

Keyword(s):

Neural Network ◽

Light Intensity ◽

Signal To Noise Ratio ◽

High Sensitivity ◽

Hadamard Transform ◽

High Signal ◽

Signal To Noise ◽

Compact Structure ◽

Reconstructed Signal ◽

Noise Ratio

Spectral detection provides rich spectral–temporal information with wide applications. In our previous work, we proposed a dual-path sub-Hadamard-s snapshot Hadamard transform spectrometer (Sub-s HTS). In order to reduce the complexity of the system and improve its performance, we present a convolution neural network-based method to recover the light intensity distribution from the overlapped dispersive spectra, rather than adding an extra light path to capture it directly. In this paper, we construct a network-based single-path snapshot Hadamard transform spectrometer (net-based HTS). First, we designed a light intensity recovery neural network (LIRNet) with an unmixing module (UM) and an enhanced module (EM) to recover the light intensity from the dispersive image. Then, we used the reconstructed light intensity as the original light intensity to recover high signal-to-noise ratio spectra successfully. Compared with Sub-s HTS, the net-based HTS has a more compact structure and high sensitivity. A large number of simulations and experimental results have demonstrated that the proposed net-based HTS can obtain a better-reconstructed signal-to-noise ratio spectrum than the Sub-s HTS because of its higher light throughput.

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A Very Reduced Upper Limit on the Interstellar Abundance of Beryllium

Symposium - International Astronomical Union ◽

10.1017/s0074180900167014 ◽

2000 ◽

Vol 198 ◽

pp. 432-434

Author(s):

Guillaume Hébrard ◽

Martin Lemoine ◽

Roger Ferlet ◽

Alfred Vidal-Madjar

Keyword(s):

Equivalent Width ◽

Signal To Noise Ratio ◽

Resolving Power ◽

Signal To Noise ◽

Interstellar Absorption ◽

Upper Limit ◽

Noise Ratio

We present the results of observations of the λ3130Â interstellar absorption doublet of 9Be ii in the direction of ζ Per. The data were obtained at the Canada-France-Hawaii 3.6m telescope using the Gecko spectrograph at a resolving power ∼ 110000 and a signal-to-noise ratio ∼ 2000. The 9Be ii lines are not detected and we obtain an upper limit on the equivalent width W ≤ 30μÂ. This upper limit is 7 times below the lowest upper limit ever reported hitherto. The derived interstellar abundance is (9Be/H) ≤ 7 × 10—13; it corresponds to an upper limit δBe ≤ —1.5 dex on the depletion factor of 9Be.

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