Linear frequency modulation photoacoustic radar: Optimal bandwidth and signal-to-noise ratio for frequency-domain imaging of turbid media

2011 ◽  
Vol 130 (3) ◽  
pp. 1313-1324 ◽  
Author(s):  
Bahman Lashkari ◽  
Andreas Mandelis
Keyword(s):  
Frequency Domain ◽  
Frequency Modulation ◽  
Signal To Noise Ratio ◽  
Linear Frequency Modulation ◽  
Turbid Media ◽  
Signal To Noise ◽  
Optimal Bandwidth ◽  
Linear Frequency ◽  
Noise Ratio

High precision linear frequency modulation ranging system based on semiconductor laser

2018 ◽  
Vol 32 (11) ◽  
pp. 1850136 ◽  
Author(s):  
Mingyuan Xue ◽  
Cunxiao Gao ◽  
Linquan Niu ◽  
Shaolan Zhu ◽  
Na Guo ◽  
...  
Keyword(s):  
Semiconductor Laser ◽  
High Precision ◽  
Frequency Modulation ◽  
Signal To Noise Ratio ◽  
Linear Frequency Modulation ◽  
Repetition Frequency ◽  
Laser Ranging ◽  
Signal To Noise ◽  
Linear Frequency ◽  
Noise Ratio

Based on the linear frequency modulation (LFM) of semiconductor laser, a laser ranging system is built. The ranging precision of the system is about micron dimension with the repetition frequency of 100 kHz and a distance of 1–10 m. We analyzed the ranging precision experimentally. As the bandwidth increases, the ranging precision becomes higher and higher. When the bandwidth is fixed, as the distance increases, the signal-to-noise ratio (SNR) will decrease, which reduces the precision.

scholarly journals Thermal barrier coating debonding defects detection based on infrared thermal wave testing technology under linear frequency modulation heat exitation

2019 ◽  
Vol 23 (3 Part A) ◽  
pp. 1607-1613
Author(s):  
Yuanlin Liu ◽  
Guojin Zhao ◽  
Yongzhi Du ◽  
Yang Zhang
Keyword(s):  
Light Source ◽  
Frequency Modulation ◽  
Thermal Wave ◽  
Signal To Noise Ratio ◽  
Linear Frequency Modulation ◽  
Thermal Barrier ◽  
Signal To Noise ◽  
Linear Frequency ◽  
Barrier Coating ◽  
Testing Technology

Thermal barrier coating debonding defects detection based on infrared thermal wave testing technology under linear frequency modulation heat excitation was studied. The principle the infrared thermal wave testing technology under linear frequency modulation was presented. The effects of different light source power and Chirp modulation frequency on signal-to-noise ratio were compared and analyzed. The results show that, defects can be more easily detected with the bigger power of light source, and the signal-to-noise ratio can be increased by using lower initial and termination frequencies.

scholarly journals PERFORMANCE EVALUATION OF SINGLE CARRIER FREQUENCY DOMAIN EQUILIZER (SC-FDE) OVER IMPULSIVE NOISE CHANNEL

2019 ◽  
Vol 11 (2) ◽  
pp. 270-277
Author(s):  
Hussein Abdullah Leftah ◽  
Husham Lateef Swadi
Keyword(s):  
Frequency Domain ◽  
Carrier Frequency ◽  
Communication Systems ◽  
Impulsive Noise ◽  
Signal To Noise Ratio ◽  
High Signal ◽  
Signal To Noise ◽  
Single Carrier ◽  
Noise Ratio ◽  
Error Floors

Impulsive noise is considered as one of the major source of disturbance in the state-of-the-art multicarrier (MC) communication systems. Therefore, several techniques are being constantly proposed to eliminate the effect of such noise. In this work, a time domain matrix interleaved is compiled with a single carrier frequency domain equalizer (SC-FDE) is proposed to reduce the deleterious effects of impulsive noise. A mathematical model for the proposed scheme is also presented in this paper. Simulation results show that the proposed technique superiors the interleaved multicarrier system where the proposed scheme can completely avoid the error floors not only at high signal-to-noise ratio (SNR) but also at heavily distributed impulsive noise. The bit-error-rate (BER) of the alternative proposed scheme decreases as the signal-to-noise ratio (SNR) increases whereas the BER of the standard system suffers from error-floors with a constant BER at about 10-3 for about 8 dB SNR for medium and heavily impulsive noise.

Frequency Domain Design Method of Wavelet Basis Based on Pulsar Signal

2020 ◽  
Vol 73 (6) ◽  
pp. 1223-1236
Author(s):  
Sihai You ◽  
Hongli Wang ◽  
Yiyang He ◽  
Qiang Xu ◽  
Lei Feng
Keyword(s):  
Wavelet Transform ◽  
Frequency Domain ◽  
Design Method ◽  
Signal To Noise Ratio ◽  
Frequency Domain Analysis ◽  
Time Of Arrival ◽  
Frequency Noise ◽  
Wavelet Basis ◽  
Signal To Noise ◽  
Noise Ratio

During pulsar navigation, the high-frequency noise carried by the pulsar profile signal reduces the accuracy of the pulse TOA (Time of Arrival) estimation. At present, the main method to remove signal noise by using wavelet transform is to redesign the function of the threshold and level of wavelet transform. However, the signal-to-noise ratio and other indicators of the filtered signal need to be further optimised, so a more appropriate wavelet basis needs to be designed. This paper proposes a wavelet basis design method based on frequency domain analysis to improve the denoising effect of pulsar signals. This method first analyses the pulsar contour signal in the frequency domain and then designs a Crab pulsar wavelet basis (CPn, where n represents the wavelet basis length) based on its frequency domain characteristics. In order to improve the real-time performance of the algorithm, a wavelet lifting scheme is implemented. Through simulation, this method analyses the pulsar contour signal data at home and abroad. Results show the signal-to-noise ratio can be increased by 4 dB, the mean square error is reduced by 61% and the peak error is reduced by 45%. Therefore, this method has better filtering effect.

Signal-to-noise ratio enhancement in frequency-modulation spectrometers by digital signal processing

1994 ◽  
Vol 19 (2) ◽  
pp. 144 ◽  
Author(s):  
Haris Riris ◽  
Clinton B. Carlisle ◽  
Russell E. Warren ◽  
David E. Cooper
Keyword(s):  
Signal Processing ◽  
Digital Signal Processing ◽  
Frequency Modulation ◽  
Signal To Noise Ratio ◽  
Digital Signal ◽  
Signal To Noise ◽  
Noise Ratio
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