scholarly journals Non-Foster Matching Circuit Design via Tunable Inductor for VLF Receive Loop Antennas

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Yalong Yan ◽  
Chao Liu ◽  
Huaning Wu ◽  
Yinghui Dong
Keyword(s):  
Circuit Design ◽  
Signal To Noise Ratio ◽  
Low Frequency ◽  
Low Noise ◽  
Loop Antenna ◽  
Fractional Bandwidth ◽  
Loop Antennas ◽  
Better Than ◽  
Loaded Antenna ◽  
Tunable Inductor

This paper presents a non-Foster matching circuit (NFC) for very low frequency (VLF) receive loop antennas. A 1 ⁎ 1 m VLF receive loop antenna was designed with a CMOS switch-based tunable inductor built into the NFC. The NFC can be applied to different VLF loop antennas by adjusting the number and inductance of the cells in the tunable inductor. A loop antenna was matched to the designed NFC with −10 dB S11 fractional bandwidth, marking a 383% improvement as well as enhanced transducer gain (S21) compared to most bands in passive matching (over 15–30 kHz). The noise and received signal-to-noise ratio (SNR) of the matching network were assessed to find that, with a low noise floor level (4 dB) receiver, the SNR of the passive loaded antenna performs better than the non-Foster loaded antenna in VLF.

scholarly journals A Compact Four-Port Coplanar Antenna Based on an Excitation Switching Reconfigurable Mechanism for Cognitive Radio Applications

2019 ◽  
Vol 9 (15) ◽  
pp. 3157 ◽  
Author(s):  
O ◽  
Jin ◽  
Choi
Keyword(s):  
Cognitive Radio ◽  
High Frequency ◽  
Coplanar Waveguide ◽  
Low Frequency ◽  
Loop Antenna ◽  
Ultra Wideband ◽  
Frequency Range ◽  
Uwb Antenna ◽  
High Isolation ◽  
Loop Antennas

In this paper, we propose a compact four-port coplanar antenna for cognitive radio applications. The proposed antenna consists of a coplanar waveguide (CPW)-fed ultra-wideband (UWB) antenna and three inner rectangular loop antennas. The dimensions of the proposed antenna are 42 mm × 50 mm × 0.8 mm. The UWB antenna is used for spectrum sensing and fully covers the UWB spectrum of 3.1–10.6 GHz. The three loop antennas cover the UWB frequency band partially for communication purposes. The first loop antenna for the low frequency range operates from 2.96 GHz to 5.38 GHz. The second loop antenna is in charge of the mid band from 5.31 GHz to 8.62 GHz. The third antenna operates from 8.48 GHz to 11.02 GHz, which is the high-frequency range. A high isolation level (greater than 17.3 dB) is realized among the UWB antenna and three loop antennas without applying any additional decoupling structures. The realized gains of the UWB antenna and three loop antennas are greater than 2.7 dBi and 1.38 dBi, respectively.

scholarly journals Digital signal processsing functions for ultra-low frequency calibrations

ACTA IMEKO ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 374
Author(s):  
Henrik Ingerslev ◽  
Soren Andresen ◽  
Jacob Holm Winther
Keyword(s):  
Signal Processing ◽  
Low Frequency ◽  
Digital Signal ◽  
Low Noise ◽  
Key Comparison ◽  
Low Frequencies ◽  
Dual Channel ◽  
Ultra Low Noise ◽  
Lower Noise ◽  
Better Than

The demand from industry to produce accurate acceleration measurements down to ever lower frequencies and with ever lower noise is increasing. Different vibration transducers are used today for many different purposes within this area, like detection and warning for earthquakes, detection of nuclear testing, and monitoring of the environment. Accelerometers for such purposes must be calibrated in order to yield trustworthy results and provide traceability to the SI-system accordingly. For these calibrations to be feasible, suitable ultra low-noise accelerometers and/or signal processing functions are needed. <br />Here we present two digital signal processing (DSP) functions designed to measure ultra low-noise acceleration in calibration systems. The DSP functions use dual channel signal analysis on signals from two accelerometers measuring the same stimuli and use the coherence between the two signals to reduce noise. Simulations show that the two DSP functions are estimating calibration signals better than the standard analysis. <br />The results presented here are intended to be used in key comparison studies of accelerometer calibration systems, and may help extend current general low frequency range from e.g. 100 mHz down to ultra-low frequencies of around 10mHz, possibly using somewhat same instrumentation.

scholarly journals Statistical moments of power spectrum: a fast tool for the classification of seismic events recorded on volcanoes

2020 ◽  
Vol 52 ◽  
pp. 67-74
Author(s):  
Danilo Galluzzo ◽  
Lucia Nardone ◽  
Mario La Rocca ◽  
Antonietta M. Esposito ◽  
Roberto Manzo ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Low Frequency ◽  
Signal Amplitude ◽  
Low Noise ◽  
Seismic Events ◽  
Spectral Moments ◽  
Spectral Parameters ◽  
Seismic Stations ◽  
Event Classification ◽  
Tectonic Earthquakes

Abstract. Spectral analysis has been applied to almost thousand seismic events recorded at Vesuvius volcano (Naples, southern Italy) in 2018 with the aim to test a new tool for a fast event classification. We computed two spectral parameters, central frequency and shape factor, from the spectral moments of order 0, 1, and 2, for each event at seven seismic stations taking the mean among the three components of ground motion. The analyzed events consist of volcano-tectonic earthquakes, low frequency events and unclassified events (landslides, rockfall, thunders, quarry blasts, etc.). Most of them are of low magnitude, and/or low maximum signal amplitude, therefore the signal to noise ratio is very different between the low noise summit stations and the higher noise stations installed at low elevation around the volcano. The results of our analysis show that volcano-tectonic earthquakes and low frequency events are easily distinguishable through the spectral moments values, particularly at seismic stations closer to the epicenter. On the contrary, unclassified events show the spectral parameters values distributed in a broad range which overlap both the volcano-tectonic earthquakes and the low frequency events. Since the computation of spectral parameters is extremely easy and fast for a detected event, it may become an effective tool for event classification in observatory practice.

Design of ECG Signal Acquisition and Processing Circult

2012 ◽  
Vol 236-237 ◽  
pp. 856-861 ◽  
Author(s):  
Jing Ma ◽  
Jun Xu ◽  
Hai Bo Xu ◽  
Yu Wang ◽  
Sheng Xu Yin
Keyword(s):  
Signal To Noise Ratio ◽  
Low Cost ◽  
Low Frequency ◽  
Low Noise ◽  
Cardiac Conduction ◽  
Signal Acquisition ◽  
Ecg Signal ◽  
Physiological Signal ◽  
Heart Study ◽  
Low Pass

ECG signal is, as a vital method performed on the heart study and clinical diagnosis of cardiovascular diseases, an important human physiological signal, containing the human cardiac conduction system of physiological and pathological information. Aiming at the weak low frequency characteristic of ECG signals, the core circuit based on the AD620 and LM324 amplifier is given. After analyzing the major components of the ECG signal and the frequency range of interference, weak ECG signal collected by the electrodes is amplified by the preamplifier circuit, and the interference then is wiped out by using a low-pass filer, a high-pass filer, 50Hz notch filer and back amplifier circuit, finally a right wave of ECG is received. The characteristics of the system features the merits of high input impedance, high CMRR, low noise, less excursion and high SNR(signal to noise ratio), low cost and so on.

scholarly journals Improving the Signal to Noise Ratio of QTF Preamplifiers Dedicated for QEPAS Applications

2020 ◽  
Vol 10 (12) ◽  
pp. 4105
Author(s):  
Piotr Z. Wieczorek ◽  
Tomasz Starecki ◽  
Frank K. Tittel
Keyword(s):  
Operational Amplifier ◽  
Narrow Band ◽  
Signal To Noise Ratio ◽  
Low Frequency ◽  
Electrical Signal ◽  
Low Noise ◽  
Detection Sensitivity ◽  
Noise Amplitude ◽  
Signal To Noise ◽  
Noise Ratio

The signal-to-noise ratio (SNR) is a major factor that limits the detection sensitivity of quartz-enhanced photoacoustic spectroscopy (QEPAS) sensors. The higher the electrical signal level compared to the noise amplitude is the lower the concentration of gases that can be detected. For this reason the preamplifier circuits used in QEPAS should be optimized for low-frequency narrow-band applications. Moreover, special care should be taken when choosing a particular operational amplifier in either a transimpedance or voltage (differential) configuration. It turns out that depending on the preamp topology different operational amplifier parameters should be carefully considered when a high SNR of the whole QEPAS system is required. In this article we analyzed the influence of the crucial parameters of low-noise operational preamplifiers used in QEPAS applications and show the resulting limitations of transimpedance and voltage configurations.

AN HTS FILTER SUBSYSTEM FOR 800MHz MOBILE COMMUNICATION SYSTEM

2005 ◽  
Vol 19 (01n03) ◽  
pp. 419-422 ◽  
Author(s):  
Z. S. YIN ◽  
B. WEI ◽  
B. S. CAO ◽  
X. B. GUO ◽  
X. P. ZHANG ◽  
...  
Keyword(s):  
Mobile Communication ◽  
Low Noise ◽  
Low Noise Amplifier ◽  
Electronic Control ◽  
Fractional Bandwidth ◽  
Hts Filter ◽  
Electronic Control System ◽  
Noise Amplifier ◽  
Mgo Substrate ◽  
Better Than

In this paper, we present a high temperature superconducting (HTS) Filter subsystem, which consists of a 14-pole HTS filter, a low noise amplifier (LNA), a Stirling Cooler and an electronic control system. The HTS filter has a 2.1% fractional bandwidth at 814MHz. It was fabricated on MgO substrate which was double sides coated with YBCO thin films. The insertion loss of the HTS filter is less than 0.2 dB , the gain of the subsystem is 22 dB at 60K . In this subsystem, the out-of-band rejection is better than 70 dB and the steepness of the band-edges is larger than 25 dB/MHz at 60K .

The Effects of Frequency Response on Speech Perception for Cochlear Implant Users

2003 ◽  
Vol 14 (10) ◽  
pp. 582-591 ◽  
Author(s):  
Alexandra Weatherby ◽  
Katherine R. Henshall ◽  
Colette M. McKay
Keyword(s):  
Speech Perception ◽  
Cochlear Implant ◽  
Cochlear Implants ◽  
High Frequency ◽  
Signal To Noise Ratio ◽  
Low Frequency ◽  
Frequency Range ◽  
Speech Processor ◽  
Minimal Difference ◽  
Better Than

The aim of this study was to investigate the effects on speech perception of manipulating filter gains in a cochlear implant speech processor. Five implantees, who use the CI22 implant and Spectra processor manufactured by Cochlear Ltd, participated. Four experimental maps were created that were identical to their clinical map except for the profile of gains across the filters. Experimental gain profiles had rising or falling gains across the frequency range, or emphasized or de-emphasized the middle frequencies, relative to the clinical map. Perception of CNC (consonant-vowel-consonant) words at 70 dB SPL was significantly better with the clinical map than with all experimental maps, whereas at the lower level (60 dB SPL) there was minimal difference between the maps, with the low-frequency emphasis map giving significantly better scores than the high-frequency emphasis map. Perception of sentences at 70 dB SPL with a signal-to-noise ratio of +10 dB was better with the high-frequency emphasis map than with the low-frequency emphasis map. None of these best-conditions, however, were statistically better than the clinical map. The results highlighted the importance of signal audibility for speech perception with cochlear implants.

High-Temperature Anisotropic Magnetoresistive (AMR) Sensors

2015 ◽  
Vol 12 (4) ◽  
pp. 205-211 ◽  
Author(s):  
Bharat B. Pant ◽  
Lucky Withanawasam ◽  
Mike Bohlinger ◽  
Mark Larson ◽  
Bruce W. Ohme
Keyword(s):  
Bias Voltage ◽  
Closed Loop ◽  
Oil And Gas ◽  
Signal To Noise Ratio ◽  
Low Frequency ◽  
Low Noise ◽  
Measurement Variability ◽  
Magnetic Field Sensors ◽  
Voltage Range ◽  
Increasing Temperature

Magnetic field sensors are employed in downhole oil and gas well drilling applications for azimuth sensing, orientation/rotation sensing, and magnetic anomaly detection. As the wells get deeper there is demand from industry to increase the operating temperature from ~175°C to ~225°C and higher. We have extended the operating regimen of silicon-based anisotropic magnetoresistive sensors to higher temperatures to address this demand. The low-frequency minimum detectable field of these sensors monotonically increases with increasing temperature. At room temperature it is 2.2 μG/√Hz@1 Hz reaching a value of 26 μG/√Hz@1 Hz at 225°C. Signal and noise density both increase with increasing sensor bias voltage such that low-frequency signal-to-noise ratio does not vary in the bias voltage range of 2.5–10 V. We achieve excellent linearity of transfer function in the ±0.8 Gauss range in a closed-loop configuration. Deviation from linearity increases monotonically with increasing temperature but remains &lt;0.002% of full scale or 29 μGauss at 225°C. Using low-noise electronics, closed loop operation of a typical sensor shows 1 – σ measurement variability of 21 μGauss at 220°C. By a combination of averaging and closed-loop operation, an input step from 0 to 75 μGauss is replicated at the output to within 0.1 μGauss at 225°C. Initial measurements suggest survivability of these sensors at 225°C to 2,000 h.

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