scholarly journals Implementation of a Cross-Spectrum FFT Analyzer for a Phase-Noise Test System in a Low-Cost FPGA

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Patrick Fleischmann ◽  
Heinz Mathis ◽  
Jakub Kucera ◽  
Stefan Dahinden
Keyword(s):  
Phase Noise ◽  
Cross Correlation ◽  
Dynamic Range ◽  
Low Cost ◽  
Test System ◽  
Low Noise ◽  
Noise Levels ◽  
High Quality ◽  
Cross Spectrum ◽  
The Cross

The cross-correlation method allows phase-noise measurements of high-quality devices with very low noise levels, using reference sources with higher noise levels than the device under test. To implement this method, a phase-noise analyzer needs to compute the cross-spectral density, that is, the Fourier transform of the cross-correlation, of two time series over a wide frequency range, from fractions of Hz to tens of MHz. Furthermore, the analyzer requires a high dynamic range to accommodate the phase noise of high-quality oscillators that may fall off by more than 100 dB from close-in noise to the noise floor at large frequency offsets. This paper describes the efficient implementation of a cross-spectrum analyzer in a low-cost FPGA, as part of a modern phase-noise analyzer with very fast measurement time.

scholarly journals Searching for Stochastic Background of Ultra-Light Fields with Atomic Sensors

Universe ◽  
2018 ◽  
Vol 4 (10) ◽  
pp. 99
Author(s):  
Tigran Kalaydzhyan ◽  
Nan Yu
Keyword(s):  
Cross Correlation ◽  
Correlation Method ◽  
Light Fields ◽  
Observation Data ◽  
Main Motivation ◽  
Cross Spectrum ◽  
Space Network ◽  
Stochastic Background ◽  
The Cross ◽  
Atomic Sensors

We propose a cross-correlation method for the searches of ultra-light fields, in particular, with a space network of atomic sensors. The main motivation of the approach is cancellation of uncorrelated noises in the observation data and unique pattern the fields leave on the cross-spectrum, depending on their nature (i.e., scalar, vector or tensor). In particular, we analytically derive a dependence of the cross-spectrum on the angle between two pairs of detectors. We then confirm obtained angular curves with a numerical simulation. We apply the method to the detection of dark matter and gravitational waves.

scholarly journals Analysis of Vibration and Acoustic Signals for Noncontact Measurement of Engine Rotation Speed

Sensors ◽  
2020 ◽  
Vol 20 (3) ◽  
pp. 683 ◽  
Author(s):  
Xuansheng Shan ◽  
Lu Tang ◽  
He Wen ◽  
Radek Martinek ◽  
Janusz Smulko
Keyword(s):  
Embedded System ◽  
Cross Correlation ◽  
Rotation Speed ◽  
Low Cost ◽  
Vibration Signal ◽  
Acoustic Signals ◽  
Correction Method ◽  
Engine Vibration ◽  
Correlation Processing ◽  
The Cross

The non-contact measurement of engine speed can be realized by analyzing engine vibration frequency. However, the vibration signal is distorted by harmonics and noise in the measurement. This paper presents a novel method for the measurement of engine rotation speed by using the cross-correlation of vibration and acoustic signals. This method can enhance the same frequency components in engine vibration and acoustic signal. After cross-correlation processing, the energy centrobaric correction method is applied to estimate the accurate frequency of the engine’s vibration. This method can be implemented with a low-cost embedded system estimating the cross-correlation. Test results showed that this method outperformed the traditional vibration-based measurement method.

scholarly journals A low-noise photonic heterodyne synthesizer and its application to millimeter-wave radar

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Eric A. Kittlaus ◽  
Danny Eliyahu ◽  
Setareh Ganji ◽  
Skip Williams ◽  
Andrey B. Matsko ◽  
...  
Keyword(s):  
Phase Noise ◽  
Millimeter Wave ◽  
Continuous Wave ◽  
Dynamic Range ◽  
Wave Generation ◽  
Low Noise ◽  
Ultra Wideband ◽  
Optical Systems ◽  
Thz Spectroscopy ◽  
Wave Radar

AbstractMicrowave photonics offers transformative capabilities for ultra-wideband electronic signal processing and frequency synthesis with record-low phase noise levels. Despite the intrinsic bandwidth of optical systems operating at ~200 THz carrier frequencies, many schemes for high-performance photonics-based microwave generation lack broadband tunability, and experience tradeoffs between noise level, complexity, and frequency. An alternative approach uses direct frequency down-mixing of two tunable semiconductor lasers on a fast photodiode. This form of optical heterodyning is frequency-agile, but experimental realizations have been hindered by the relatively high noise of free-running lasers. Here, we demonstrate a heterodyne synthesizer based on ultralow-noise self-injection-locked lasers, enabling highly-coherent, photonics-based microwave and millimeter-wave generation. Continuously-tunable operation is realized from 1-104 GHz, with constant phase noise of -109 dBc/Hz at 100 kHz offset from carrier. To explore its practical utility, we leverage this photonic source as the local oscillator within a 95-GHz frequency-modulated continuous wave (FMCW) radar. Through field testing, we observe dramatic reduction in phase-noise-related Doppler and ranging artifacts as compared to the radar’s existing electronic synthesizer. These results establish strong potential for coherent heterodyne millimeter-wave generation, opening the door to a variety of future applications including high-dynamic range remote sensing, wideband wireless communications, and THz spectroscopy.

Systems. An Analog High-Performance Transfer-Stabilized Fiber-Optic Transmission System for Baseband Video Signals

1984 ◽  
Vol 5 (3) ◽  
Author(s):  
L. P. de Jong ◽  
E. H. Nordholt
Keyword(s):  
High Performance ◽  
Dynamic Range ◽  
Automatic Gain Control ◽  
Low Cost ◽  
Gain Control ◽  
High Dynamic Range ◽  
Optical Signal ◽  
Transmission System ◽  
Low Noise ◽  
Noise Current

SummaryA low-cost video baseband transmission system using analog light-intensity modulation with an 850 nm LED compensated for nonlinearity is presented. A very low- noise current amplifier at the input of the receiver and a high-dynamic range automatic gain control provide a transmission system that can accomodate more than a 20 dB difference in optical losses without any adjustment. At the receiver input, a 100 nW (- 40 dBm) optical signal is required for surveillance transmission quality. The transmitter delivers an optical signal power of - 18 dBm to a 50 pm graded-index fiber. The differential gain and phase of the system lie below 2% and 1°, respectively.

Studies of high-frequency seismic noise in eastern Kazakhstan

1988 ◽  
Vol 78 (5) ◽  
pp. 1744-1758
Author(s):  
J. Berger ◽  
H. K. Eissler ◽  
F. L. Vernon ◽  
I. L. Nersesov ◽  
M. B. Gokhberg ◽  
...  
Keyword(s):  
High Frequency ◽  
Dynamic Range ◽  
Power Spectra ◽  
Test Site ◽  
Average Frequency ◽  
Low Noise ◽  
Noise Model ◽  
Site Conditions ◽  
Noise Levels ◽  
Ground Acceleration

Abstract Three seismographic stations have been established in the region of the principal underground nuclear weapons test site in the republic of Kazakhstan in the Soviet Union. Instrumentation includes both surface and borehole seismometers with a bandwidth of 100 Hz and a system dynamic range of 180 dB. Power spectra of the regional ambient ground acceleration peak between 4 and 6 Hz, and are, on average, frequency independent above 10 Hz, where levels are approximately equal to 10−15 to 10−16 (m sec−2)2Hz−1. Kazakh noise levels are roughly equivalent to those observed by the Regional Seismic Test Network between 1 and 20 Hz, and about 10 to 20 dB higher than the very low noise model for Lajitas, Texas, in the same band. Noise observed by the borehole sensors is about 10 dB less than that observed by the surface instruments above about 20 Hz under low wind conditions at two of the three Kazakh sites; borehole improvement is greater under high winds. The third Kazakh site, Karasu, is characterized by much higher surface noise levels (15 to 20 dB higher than the borehole levels from 4 to 40 Hz) under both low or high wind conditions, which is attributed to amplification by local site conditions and the exposed terrain. Power spectra of individual runs of ambient vertical ground acceleration measured down the borehole show that high-frequency slopes (between 10 and 80 Hz) vary between f−0.60 and f0.22, depending on wind and site conditions.

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