An Analysis of Infrared Spectroscopic Geometries

1997 ◽  
Vol 477 ◽  
Author(s):  
Gregory T. Merklin ◽  
Huihong Luo ◽  
Christopher E. D. Chidsey
Keyword(s):  
Vibrational Mode ◽  
Signal To Noise Ratio ◽  
Signal Strength ◽  
Internal Reflection ◽  
Infrared Spectrometry ◽  
Vibrational Modes ◽  
Signal To Noise ◽  
Transmission Spectroscopy ◽  
Infrared Spectroscopic ◽  
Experimental Geometry

ABSTRACTThe influence of experimental geometry on the signal strength and signal-to-noise ratio of infrared spectrometry has been investigated. In general, it was found that the choice of optimum experimental geometry depended on the orientation of the vibrational mode being investigated. In particular, it has been calculated that internal reflection spectrometry is relatively insensitive to vibrational modes perpendicular to the surface relative to transmission spectroscopy at Brewster's angle, and this has been confirmed by experiment.

scholarly journals Analisis Kualitas Sinyal Jaringan WLAN Terhadap Layout Ruangan di Politeknik Negeri Lhokseumawe

2019 ◽  
Vol 16 (1) ◽  
pp. 7
Author(s):  
Aida Wulandari ◽  
Yassir Yassir ◽  
Hanafi Hanafi
Keyword(s):  
Signal To Noise Ratio ◽  
Signal Strength ◽  
Signal To Noise ◽  
Noise Ratio

Pemanfaatan Wi-Fi dalam sistem komunikasi data berbasis wireless, menjadi pilihan oleh banyak pengguna karena keunggulan mobilitasnya. Dalam sistem komunikasi ini, kualitas signal strength dan SNR menjadi sangat penting dalam mencapai layanan sistem komunikasi yang handal. Kehandalan tersebut dapat diketahui dengan melakukan uji kualitas signal strength dan SNR yang dapat diberikan oleh sebuah perangkat Wi-FI melalui pengukuran. Pengukuran kualitas signal strength dan SNR dilaksanakan pada tiga model ruangan berbeda. Ruang pertama adalah ruang indoor terbuka bertempat di auditorium, ruang kedua adalah ruang semi indoor bertempat di ruang perpustakaan, dan ruang ketiga adalah ruang indoor tertutup bertempat di Gedung 3 Jurusan Teknik Elektro. Sistem menggunakan Wi-Fi yang beroperasi pada frekuensi kerja 2,4 GHz. Pengumpulan data dilakukan pada beberapa titik dalam ruangan dengan memvariasikan jarak antara pemancar dan penerima. Nilai signal strenght pada ruang indoor terbuka tertinggi diperoleh -49 dBm dan terendah -62 dBm, nilai signal strength pada ruang semi indoor tertinggi -51,6 dBm dan terendah 91,2 dBm, dan nilai signal strength pada ruang indoor tertutup -70,4 dBm dan terendah -85 dBm. Nilai SNR tertinggi pada ruang indoor terbuka diperoleh 48 dB dan terendah 38,6 dB, nilai SNR tertinggi pada ruang semi indoor diperoleh 47,2 dB dan terendah 20 dB, dan nilai SNR tertinggi pada ruang indoor tertutup diperoleh 31 dB dan terendah 21,2 dB.Kata-kata kunci: Wi-Fi, Signal Strength, Signal To Noise Ratio, pathloss, frekuensi, WLAN, hardware, sofware

A NEW TECHNIQUE FOR THE STUDY OF SCATTER PROPAGATION IN THE TROPOSPHERE

1957 ◽  
Vol 35 (8) ◽  
pp. 823-830 ◽  
Author(s):  
J. H. Chapman ◽  
W. J. Heikkila ◽  
J. E. Hogarth
Keyword(s):  
Power Spectrum ◽  
Communication System ◽  
Carrier Frequency ◽  
Signal To Noise Ratio ◽  
Signal Strength ◽  
Noise Power ◽  
Signal To Noise ◽  
A New Technique ◽  
Conventional Signal ◽  
Noise Power Density

The power spectrum of the fluctuations in received signal strength on a near-optical U.H.F. circuit has been measured. The sidebands associated with these fluctuations can overlap the information-carrying sidebands of a communication system. When this happens, these sidebands must be taken into account in determining the signal-to-noise ratio of the system. In other words, the fluctuations then have the characteristics of noise, and therefore they are called propagation noise in the present paper. Experiments at a carrier frequency of 500 Mc. have shown that the propagation noise power density usually varies with sideband frequency ƒ (measured from the carrier) as 1/ƒ2, for f in the range 0.1 to 10 c.p.s. Departures from this law have been observed in the regions near 0.1 c.p.s. and 10 c.p.s. The measurement of the power spectrum directly offers several advantages over the conventional signal strength recording method, and these are discussed herein.

TRAVELING SIGNAL‐TO‐NOISE RATIO AND SIGNAL POWER ESTIMATES

Geophysics ◽  
1967 ◽  
Vol 32 (3) ◽  
pp. 485-493 ◽  
Author(s):  
S. M. Simpson
Keyword(s):  
Seismic Noise ◽  
Signal To Noise Ratio ◽  
Signal Strength ◽  
Noise Removal ◽  
Statistical Properties ◽  
Signal Power ◽  
Signal To Noise ◽  
Direct Estimation ◽  
Noise Ratio

Undesirable seismic noise of a nondeterministic type must be destroyed by making use of its statistical properties. Averaging of one sort or another provides methods for performing this noise removal. Our purpose here is to present a method for direct estimation of signal strength versus seismogram time, with stepout as a parameter. After describing the method and its expected behavior to some extent, we illustrate its application to a set of three noisy records.

scholarly journals Design of Enhanced Rotation Locked Loop for Roll Angle Estimation of Rotating Vehicle in a Weak GPS Signal Environment

Sensors ◽  
2018 ◽  
Vol 19 (1) ◽  
pp. 80
Author(s):  
Hun Im ◽  
Deok Lim ◽  
Sang Lee
Keyword(s):  
Computer Simulations ◽  
Signal To Noise Ratio ◽  
Signal Strength ◽  
Roll Angle ◽  
Weak Signal ◽  
Signal To Noise ◽  
Angle Estimation ◽  
Signal Environment ◽  
Noise Ratio

In order to estimate the roll angle of a rotating vehicle, an enhanced rotation locked loop (RLL) algorithm is proposed in this paper. The RLL algorithm estimates the roll angle by using the property that the power of the GPS signal measured at the receiver of a rotating vehicle changes periodically. However, in case the received GPS power is decreased, the performance of the conventional RLL algorithm degrades, or it cannot estimate the roll angle anymore, therefore, for operating the RLL algorithm in a weak signal environment, this paper designs a method to increase the signal-to-noise ratio (SNR) by overlapping multiple GPS signals’ correlator outputs and a method to compensate the decreased response of a rotation discriminator at low-signal strength. Through computer simulations, the performance of the proposed algorithm is verified and it is shown that the roll angle can be estimated stably even at a weak signal environment down to 29 dB–Hz of C/N0.

scholarly journals Detection of Particulate Matters with a Field-Portable Microscope Using Side-Illuminated Total Internal Reflection

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2745
Author(s):  
Haechang Yang ◽  
Sanghoon Shin ◽  
Dongmin Seo ◽  
Jaewon Park ◽  
Sungkyu Seo
Keyword(s):  
Total Internal Reflection ◽  
Detection System ◽  
Signal To Noise Ratio ◽  
Low Cost ◽  
Internal Reflection ◽  
Dust Particles ◽  
Halogen Lamp ◽  
Signal To Noise ◽  
Portable Detection ◽  
Transmission Microscope

Field-portable observation and analysis of particulate matter (PM) is required to enhance healthy lives. Various types of the PM measurement methods are in use; however, each of these methods has significant limitations in that real time measurement is impossible, the detection system is bulky, or the measurement accuracy is insufficient. In this work, we introduce an optical method to perform a fast and accurate PM analysis with a higher-contrast microscopic image enabled by a side-illuminated total internal reflection (TIR) technique to be implemented in a compact device. The superiority of the proposed method was quantitatively demonstrated by comparing the signal-to-noise ratio of the proposed side-illuminated TIR method with a traditional halogen lamp-based transmission microscope. With the proposed device, signal-to-noise ratios (SNRs) for microbeads (5~20 µm) and ultrafine dust particles (>5 µm) increased 4.5~17 and 4~10 dB, respectively, compared to the conventional transmission microscope. As a proof of concept, the proposed method was also applied to a low-cost commercial smartphone toy microscope enabling field-portable detection of PMs. We believe that the proposed side-illuminated TIR PM detection device holds significant advantages over other commonly used systems due to its sufficient detection capability along with simple and compact configuration as well as low cost.

Revisiting the atmosphere of HD 209458b with HARPS-N, CARMENES and ESPRESSO

2020 ◽  
Author(s):  
Núria Casasayas-Barris ◽  
Enric Palle ◽  
Monika Stangret ◽  
Guo Chen ◽  
Fei Yan ◽  
...  
Keyword(s):  
High Resolution ◽  
Time Evolution ◽  
Transmission Spectrum ◽  
State Of The Art ◽  
Signal To Noise Ratio ◽  
Light Curves ◽  
High Resolution Spectroscopy ◽  
Transmission Spectra ◽  
Signal To Noise ◽  
Transmission Spectroscopy

<p>HD 209458b was the first transiting planet discovered, and the first for which its atmosphere, in particular Na I, was detected. With time, it has become one of the most studied planets, with a large diversity of atmospheric studies using low- and high-resolution spectroscopy. Here, we present the analysis of high-resolution transmission spectroscopy of HD 209458b using a total of five transit observations with HARPS-N and CARMENES spectrographs. In contrast to previous studies where atmospheric Na I absorption is detected, we find that, for all of the nights, either individually or combined, the transmission spectra can be explained by the combination of the centre-to-limb variation and the Rossiter-McLaughlin effect. Thus, the transmission spectrum reveals no detectable Na I absorption in HD 209458b. This is also observed in the time-evolution maps and transmission light curves, but at lower signal-to-noise ratio. Other strong lines such as Hα, Ca II IRT, the Mg I triplet region, and K I D1 are analysed, and are also consistent with the modelled effects, without considering any contribution from the exoplanet atmosphere. New ESPRESSO observations, with state-of-the-art stability and considerably larger signal-to-noise, confirm the results of our study and will also be shown.</p>

EVALUATION OF TWO EFFICIENT TARGET TRACKING ALGORITHMS FOR MATCHED-FIELD PROCESSING WITH HORIZONTAL ARRAYS

1995 ◽  
Vol 03 (04) ◽  
pp. 311-326 ◽  
Author(s):  
MICHAEL J. WILMUT ◽  
JOHN M. OZARD ◽  
PETER BROUWER
Keyword(s):  
Target Tracking ◽  
Signal To Noise Ratio ◽  
Signal Strength ◽  
Detection Performance ◽  
Performance Difference ◽  
Source Position ◽  
Acoustic Source ◽  
Signal To Noise ◽  
Matched Field Processing ◽  
Tracking Algorithms

A tracking algorithm may be used to reduce the ambiguity of the positions of a moving underwater acoustic source. The objective of this paper is to evaluate two efficient target tracking algorithms suitable for use with Matched-Field Processing (MFP). The detection after tracking algorithms described here are applicable to targets moving linearly at constant speed and depth that produce low Signal-to-Noise Ratio (SNR) signals at the receivers. The input to the tracker consists of the positions of the largest Bartlett statistics or peaks on the MFP ambiguity surfaces. Even at very low SNRs, these largest peaks usually include the match at or near the source position sufficiently often that the detection performance of our efficient tracker rivals that of an exhaustive tracker. In this paper efficient algorithms are developed and evaluated based on examining either the sum of the uniformly weighted Bartlett array outputs or the sum of the Bartlett array outputs weighted by predicted received signal strength. This sum is evaluated along a set of linear tracks that connect the largest peaks. Detection performance is shown to be better for the signal-strength weighted tracker. The performance difference is largest for tracks along a constant bearing from the array.

Determination of the Best Emulsion for the Microscopy of Crystals

1981 ◽  
Vol 39 ◽  
pp. 32-33
Author(s):  
David A. Grano ◽  
Kenneth H. Downing
Keyword(s):  
Spatial Frequency ◽  
Information Transfer ◽  
Signal To Noise Ratio ◽  
Experimental Situation ◽  
Photographic Emulsion ◽  
Modulation Transfer ◽  
Signal To Noise ◽  
Frequency Space ◽  
Noise Ratio

The retrieval of high-resolution information from images of biological crystals depends, in part, on the use of the correct photographic emulsion. We have been investigating the information transfer properties of twelve emulsions with a view toward 1) characterizing the emulsions by a few, measurable quantities, and 2) identifying the “best” emulsion of those we have studied for use in any given experimental situation. Because our interests lie in the examination of crystalline specimens, we've chosen to evaluate an emulsion's signal-to-noise ratio (SNR) as a function of spatial frequency and use this as our critereon for determining the best emulsion.The signal-to-noise ratio in frequency space depends on several factors. First, the signal depends on the speed of the emulsion and its modulation transfer function (MTF). By procedures outlined in, MTF's have been found for all the emulsions tested and can be fit by an analytic expression 1/(1+(S/S0)2). Figure 1 shows the experimental data and fitted curve for an emulsion with a better than average MTF. A single parameter, the spatial frequency at which the transfer falls to 50% (S0), characterizes this curve.

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