scholarly journals Effects of Frequency Filtering on Intensity and Noise in Accelerometer-Based Physical Activity Measurements

Sensors ◽  
2019 ◽  
Vol 19 (9) ◽  
pp. 2186 ◽  
Author(s):  
Jonatan Fridolfsson ◽  
Mats Börjesson ◽  
Christoph Buck ◽  
Örjan Ekblom ◽  
Elin Ekblom-Bak ◽  
...  
Keyword(s):  
Physical Activity ◽  
Band Pass Filter ◽  
Accelerometer Data ◽  
Frequency Filtering ◽  
Free Living ◽  
Pass Filter ◽  
Cut Points ◽  
Activity Measurements ◽  
Low Pass ◽  
Band Pass

In objective physical activity (PA) measurements, applying wider frequency filters than the most commonly used ActiGraph (AG) filter may be beneficial when processing accelerometry data. However, the vulnerability of wider filters to noise has not been investigated previously. This study explored the effect of wider frequency filters on measurements of PA, sedentary behavior (SED), and capturing of noise. Apart from the standard AG band-pass filter (0.29–1.63 Hz), modified filters with low-pass component cutoffs at 4 Hz, 10 Hz, or removed were analyzed. Calibrations against energy expenditure were performed with lab data from children and adults to generate filter-specific intensity cut-points. Free-living accelerometer data from children and adults were processed using the different filters and intensity cut-points. There was a contribution of acceleration related to PA at frequencies up to 10 Hz. The contribution was more pronounced at moderate and vigorous PA levels, although additional acceleration also occurred at SED. The classification discrepancy between AG and the wider filters was small at SED (1–2%) but very large at the highest intensities (>90%). The present study suggests an optimal low-pass frequency filter with a cutoff at 10 Hz to include all acceleration relevant to PA with minimal effect of noise.

scholarly journals A Biomechanical Re-Examination of Physical Activity Measurement with Accelerometers

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3399 ◽  
Author(s):  
Jonatan Fridolfsson ◽  
Mats Börjesson ◽  
Daniel Arvidsson
Keyword(s):  
Physical Activity ◽  
Motion Capture ◽  
Group Differences ◽  
Band Pass Filter ◽  
Accelerometer Data ◽  
Age Group ◽  
Frequency Filtering ◽  
Frequency Filter ◽  
Step Frequency ◽  
Activity Intensity

ActiGraph is the most common accelerometer in physical activity research, but it has measurement errors due to restrictive frequency filtering. This study investigated biomechanically how different frequency filtering of accelerometer data affects assessment of activity intensity and age-group differences when measuring physical activity. Data from accelerometer at the hip and motion capture system was recorded during treadmill walking and running from 30 subjects in three different age groups: 10, 15, and >20 years old. Acceleration data was processed to ActiGraph counts with original band-pass filter at 1.66 Hz, to counts with wider filter at either 4 or 10 Hz, and to unfiltered acceleration according to “Euclidian norm minus one” (ENMO). Internal and external power, step frequency, and vertical displacement of center of mass (VD) were estimated from the motion capture data. Widening the frequency filter improved the relationship between higher locomotion speed and counts. It also removed age-group differences and decreased within-group variation. While ActiGraph counts were almost exclusively explained by VD, the counts from the 10 Hz filter were explained by VD and step frequency to an equal degree. In conclusion, a wider frequency filter improves assessment of physical activity intensity by more accurately capturing individual gait patterns.

scholarly journals High-Performance RF Balanced Microstrip Mixer Configuration for Cryogenic and Room Temperatures

Electronics ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 102
Author(s):  
Noy Citron ◽  
Eldad Holdengreber ◽  
Oz Sorkin ◽  
Shmuel E. Schacham ◽  
Eliyahu Farber
Keyword(s):  
High Performance ◽  
Schottky Diodes ◽  
Band Pass Filter ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Noise Rejection ◽  
Low Pass ◽  
Hybrid Coupler ◽  
Band Pass ◽  
Simulation Results

A high-performance S-band down-conversion microstrip mixer, for operation from 77 K to 300 K, is described. The balanced mixer combines a 90 degree hybrid coupler, two Schottky diodes, a band pass filter, and a low pass filter. The coupler phase shift drastically improves noise rejection. The circuit was implemented according to the configuration obtained from extensive simulation results based on electromagnetic analysis. The experimental results agreed well with the simulation results, showing a maximum measured insertion loss of 0.4 dB at 2 GHz. The microstrip mixer can be easily adjusted to different frequency ranges, up to about 50 GHz, through the proper choice of microstrip configuration. This novel S-band cryogenic mixer, implemented without resorting to special components, shows a very high performance at liquid nitrogen temperatures, making this mixer very suitable for high-temperature superconductive applications, such as front-ends.

scholarly journals Simple Simulated Inductor, Low-Pass/Band-Pass Filter and Sinusoidal Oscillator Using OTRA

2016 ◽  
Vol 07 (03) ◽  
pp. 83-99 ◽  
Author(s):  
Raj Senani ◽  
Abdhesh Kumar Singh ◽  
Ashish Gupta ◽  
Data Ram Bhaskar
Keyword(s):  
Pass Band ◽  
Band Pass Filter ◽  
Pass Filter ◽  
Sinusoidal Oscillator ◽  
Low Pass ◽  
Band Pass

scholarly journals Implementation of Low, High and Band Pass Filters using Verilog HDL

2019 ◽  
Vol 9 (2) ◽  
pp. 5178-5182
Keyword(s):  
Communication Networks ◽  
Detailed Knowledge ◽  
Band Pass Filter ◽  
Verilog Hdl ◽  
Pass Filter ◽  
Essential Components ◽  
Low Pass ◽  
Band Pass ◽  
High Pass ◽  
Descriptive Language

Filters are some of the highly essential components used for operating in most electronic based circuits. Filters are most important and widely used to block some portion of signals according to frequency. Having a detailed knowledge of various filters. A designer will be able to design an efficient communication networks, by varying the cut off frequencies. Filters are required in computer, mechanical and some other fields too. As days passed by the usage of active and passive filters has gradually increased in the market. There are various types of Filters available, in which we are going to perform the simulation of Low pass, High Pass and Band pass Filter using Verilog Hardware Descriptive Language and Xilinx ISE 13.1 as a simulation tool. This paper provides a detailed explanation, circuit diagram, advantages, disadvantages, applications, working of Verilog code and simulation result of Low pass, High pass and Band pass filter. Using Verilog Hardware Descriptive language its simpler to understand and execute the functionality of filters then using other tools like MATLAB, Microcontroller, Microprocessor.

scholarly journals CMOS CDBA-Based Inverse Filter Structure

2020 ◽  
Vol 9 (3) ◽  
pp. 2226-2231
Keyword(s):  
Cmos Technology ◽  
Experimental Results ◽  
Band Pass Filter ◽  
Inverse Filter ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Filter Structure ◽  
Low Pass ◽  
Band Pass ◽  
High Pass

This paper presents a voltage-mode(VM) tunable multifunction inverse filter configuration employing current differencing buffered amplifiers (CDBA). The presented structure utilizes two CDBAs, two/three capacitors and four/five resistors to realize inverse low pass filter (ILPF), inverse high pass filter (IHPF), inverse band pass filter (IBPF), and inverse band reject filter(IBRF) from the same circuit topology by suitable selection(s) of the branch admittances(s). PSPICE simulations have been performed with 0.18µm TSMC CMOS technology to validate the theory. Some sample experimental results have also been provided using off-the-shelf IC AD844 based CDBA.

A NEW TUNABLE FLOATING CMOS FDNR AND ELLIPTIC FILTER APPLICATIONS

2010 ◽  
Vol 19 (08) ◽  
pp. 1641-1650 ◽  
Author(s):  
FIRAT KAÇAR
Keyword(s):  
Integrated Circuit ◽  
Current Mode ◽  
Band Pass Filter ◽  
Mos Transistors ◽  
Pass Filter ◽  
Elliptic Filter ◽  
Low Pass ◽  
Band Pass ◽  
Fifth Order ◽  
A Current

A new tunable CMOS FDNR circuit is proposed. The circuit is based on the transcapacitive gyrator approach with both transcapacitive stages realized by MOS transistors configuration. This FDNR element lends itself well to the design of low-pass ladder filters and its use will result in a more efficient integrated circuit implementation than filters that simulate floating inductors utilizing resistive gyrators. The applications of FDNR to realize a current-mode fifth-order elliptic filter and current mode sixth-order elliptic band-pass filter are given. The proposed FDNR is simulated using CMOS TSMC 0.35 μm technology. Simulation results are given to confirm the theoretical analysis.

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