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.

scholarly journals Coherent Power Measurements with a Compact Airborne Ka-Band Precipitation Radar

2018 ◽  
Vol 35 (1) ◽  
pp. 3-20 ◽  
Author(s):  
Andrew L. Pazmany ◽  
Samuel J. Haimov
Keyword(s):  
Signal To Noise Ratio ◽  
Power Estimation ◽  
Noise Power ◽  
Signal Power ◽  
Signal To Noise ◽  
Precipitation Radar ◽  
Noise Component ◽  
Ka Band ◽  
Noise Ratio ◽  
Conventional Signal

AbstractCoherent power is an alternative to the conventional noise-subtracted power technique for measuring weather radar signal power. The inherent noise-canceling feature of coherent power eliminates the need for estimating and subtracting the noise component, which is required when performing conventional signal power estimation at low signal-to-noise ratio. The coherent power technique is particularly useful when averaging a high number of samples to improve sensitivity to weak signals. In such cases, the signal power is small compared to the noise power and the required accuracy of the estimated noise power may be difficult to achieve. This paper compares conventional signal power estimation with the coherent power measurement technique by investigating bias, standard deviation, and probability of false alarm and detection rates as a function of signal-to-noise ratio and threshold level. This comparison is performed using analytical expressions, numerical simulations, and analysis of cloud and precipitation data collected with the airborne solid-state Ka-band precipitation radar (KPR) operated by the University of Wyoming.

Microphone array speech enhancement based on optimized IMCRA

2021 ◽  
Vol 69 (6) ◽  
pp. 468-476
Author(s):  
Qiuying Li ◽  
Tao Zhang ◽  
Yanzhang Geng ◽  
Zhen Gao
Keyword(s):  
Power Spectrum ◽  
Speech Enhancement ◽  
Signal To Noise Ratio ◽  
Microphone Array ◽  
Noise Power ◽  
Noise Power Spectrum ◽  
Signal To Noise ◽  
Noise Ratio ◽  
Speech Segments ◽  
Enhancement Algorithm

Microphone array speech enhancement algorithm uses temporal and spatial informa- tion to improve the performance of speech noise reduction significantly. By combining noise estimation algorithm with microphone array speech enhancement, the accuracy of noise estimation is improved, and the computation is reduced. In traditional noise es- timation algorithms, the noise power spectrum is not updated in the presence of speech, which leads to the delay and deviation of noise spectrum estimation. An optimized im- proved minimum controlled recursion average speech enhancement algorithm, based on a microphone matrix is proposed in this paper. It consists of three parts. The first part is the preprocessing, divided into two branches: the upper branch enhances the speech signal, and the lower branch gets the noise. The second part is the optimized improved minimum controlled recursive averaging. The noise power spectrum is updated not only in the non-speech segments but also in the speech segments. Fi- nally, according to the estimated noise power spectrum, the minimum mean-square error log-spectral amplitude algorithm is used to enhance speech. Testing data are from TIMIT and Noisex-92 databases. Short-time objective intelligibility and seg- mental signal-to-noise ratio are chosen as evaluation metrics. Experimental results show that the proposed speech enhancement algorithm can improve the segmental signal-to-noise ratio and short-time objective intelligibility for various noise types at different signal-to-noise ratio levels.

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

scholarly journals Anti-symmetric clustering signals in the observed power spectrum

2021 ◽  
Vol 2021 (12) ◽  
pp. 003
Author(s):  
José Fonseca ◽  
Chris Clarkson
Keyword(s):  
Dark Matter ◽  
Power Spectrum ◽  
Euler Equation ◽  
Large Scale ◽  
Signal To Noise Ratio ◽  
Power Spectra ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Signal To Noise ◽  
Peculiar Velocities

Abstract In this paper, we study how to directly measure the effect of peculiar velocities in the observed angular power spectra. We do this by constructing a new anti-symmetric estimator of Large Scale Structure using different dark matter tracers. We show that the Doppler term is the major component of our estimator and we show that we can measure it with a signal-to-noise ratio up to ∼ 50 using a futuristic SKAO HI galaxy survey. We demonstrate the utility of this estimator by using it to provide constraints on the Euler equation.

scholarly journals Image multiplexing using residue number system coding over MIMO-OFDM communication system

2019 ◽  
Vol 9 (6) ◽  
pp. 4815
Author(s):  
Mohamed Ibrahim Youssif ◽  
Amr ElSayed Emam ◽  
Mohamed Abd ElGhany
Keyword(s):  
Image Quality ◽  
Communication System ◽  
Signal To Noise Ratio ◽  
Image Transmission ◽  
Number System ◽  
Residue Number System ◽  
Signal To Noise ◽  
Residue Number ◽  
Mimo Ofdm ◽  
Noise Ratio

<p>Image transmission over Orthogonal Frequency-Division Multiplexing (OFDM) communication system is prone to distortion and noise due to the encountered High-Peak-to-Average-Power-Ratio (PAPR) generated from the OFDM block. This paper studies the utilization of Residue Number System (RNS) as a coding scheme for digital image transmission over Multiple-Input-Multiple-Output (MIMO) – OFDM transceiver communication system. The use of the independent parallel feature of RNS, as well as the reduced signal amplitude to convert the input signal to parallel smaller residue signals, enable to reduce the signal PAPR, decreasing the signal distortion and the Bit Error Rate (BER). Consequently, improving the received Signal-to-Noise Ratio (SNR) and enhancing the received image quality. The performance analyzed though BER, and PAPR. Moreover, image quality measurement is achieved through evaluating the Mean Squared Error (MSE), Peak Signal to Noise Ratio (PSNR), and the correlation values between the initial and retrieved images. Simulation results had shown the performance of transmission/reception model with and without RNS coding implementation.</p><p> </p>

Study on Fast Algorithm for SNR and Method for Threshold Confirmation

2013 ◽  
Vol 427-429 ◽  
pp. 1718-1722
Author(s):  
Lin Sun ◽  
Ran Wei ◽  
Fu Ting Bao ◽  
Xian Zhang Tian
Keyword(s):  
Power Spectrum ◽  
Fast Algorithm ◽  
Human Gene ◽  
Signal To Noise Ratio ◽  
Average Power ◽  
Threshold Value ◽  
Computational Experiments ◽  
Rigorous Derivation ◽  
Signal To Noise ◽  
Average Power Spectrum

To reduce the amount of computing resources, a fast algorithm of the average power spectrum and signal-to-noise ratio was presented based on rigorous derivation of the formula. Also, it proved the rule gained from computational experiments. Besides, a method called fitting-optimization to determine the classification threshold value was proposed. It improves the accuracy by about 7% for human gene.

scholarly journals Probing the high-z IGM with the hyperfine transition of 3He+

2020 ◽  
Vol 497 (1) ◽  
pp. 572-580 ◽  
Author(s):  
Shivan Khullar ◽  
Qingbo Ma ◽  
Philipp Busch ◽  
Benedetta Ciardi ◽  
Marius B Eide ◽  
...  
Keyword(s):  
Power Spectrum ◽  
Signal To Noise Ratio ◽  
Neutral Hydrogen ◽  
Noise Power ◽  
Large Collection ◽  
X Ray ◽  
Hyperfine Transition ◽  
The One ◽  
X Ray Binaries ◽  
Insight Into

ABSTRACT The hyperfine transition of 3He+ at 3.5 cm has been thought as a probe of the high-z IGM, since it offers a unique insight into the evolution of the helium component of the gas, as well as potentially give an independent constraint on the 21 cm signal from neutral hydrogen. In this paper, we use radiative transfer simulations of reionization driven by sources such as stars, X-ray binaries, accreting black holes and shock heated interstellar medium, and simulations of a high-z quasar to characterize the signal and analyse its prospects of detection. We find that the peak of the signal lies in the range ∼1–50 μK for both environments, but while around the quasar it is always in emission, in the case of cosmic reionization a brief period of absorption is expected. As the evolution of He ii is determined by stars, we find that it is not possible to distinguish reionization histories driven by more energetic sources. On the other hand, while a bright QSO produces a signal in 21 cm that is very similar to the one from a large collection of galaxies, its signature in 3.5 cm is very peculiar and could be a powerful probe to identify the presence of the QSO. We analyse the prospects of the signal’s detectability using SKA1-mid as our reference telescope. We find that the noise power spectrum dominates over the power spectrum of the signal, although a modest signal-to-noise ratio can be obtained when the wavenumber bin width and the survey volume are sufficiently large.

Power spectral analysis of the diaphragm electromyogram

1983 ◽  
Vol 54 (6) ◽  
pp. 1579-1584 ◽  
Author(s):  
T. K. Aldrich ◽  
J. M. Adams ◽  
N. S. Arora ◽  
D. F. Rochester
Keyword(s):  
Power Spectrum ◽  
Signal To Noise Ratio ◽  
Normal Subjects ◽  
Chronic Obstructive ◽  
Signal To Noise ◽  
Low Frequencies ◽  
Mean Values ◽  
The Mean ◽  
Noise Ratio ◽  
Diaphragm Fatigue

We studied the power spectrum of the diaphragm electromyogram (EMG) at frequencies between 31 and 246 Hz in four young normal subjects and five patients with chronic obstructive lung disease (COPD). Diaphragm EMGs were analyzed during spontaneous breathing and maximum inspiratory efforts to determine the effect of signal-to-noise ratio on the power spectrum and if treadmill exercise to dyspnea was associated with diaphragm fatigue. We found that the centroid frequencies of the power spectra (fc) were strongly correlated (r = 0.93) with ratios of power at high frequencies to power at low frequencies (H/L) for all subjects. Of the two indices, H/L had the largest standard deviation expressed as a percentage of the mean. The mean values of both of these decreased significantly after exercise, fc from 100.2 to 97.3 and H/L from 1.07 to 0.97. Signal-to-noise ratios were higher in maximal inspiratory efforts and after exercise in normal subjects and higher in COPD patients. The signal-to-noise ratio was correlated negatively with fc and H/L, indicating that these indices of the shape of the power spectrum are influenced by signal strength and noise levels as well as muscle function. We conclude that the fc and H/L index similar qualities of the power spectrum, that they are partially determined by the signal-to-noise ratio, and that, in some cases, exercise to dyspnea is associated with apparently mild diaphragm fatigue.

Sign in / Sign up

Export Citation Format

Share Document