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213 results for “electric field”
Voyager 1 PWS electric field waveform in CDF files
The Voyager 1 Plasma Wave Subsystem (PWS) electric field waveform data set contains all available uncalibrated full resolution 4-bit measurements for the entire mission. The PWS waveform receiver samples the voltage on the 10 m electric antennas at the rate of 28800 samples per second through a 40 Hz to 12 kHz bandpass filter, utilizing an automatic gain control. However, gain information is not returned in telemetry so absolute calibration cannot be done directly. The waveform may be used to identify features such as dust impacts in the time domain or a power spectrum may be derived to show relative amplitudes of spectral elements in the frequency domain.
MMS 3 Digital Signal Processor (DSP) Double Probe (ADP, SDP), Electric Field Power Spectral Density, Level 2 (L2), Slow Mode, 16 s Data
The MMS electric field power spectral density (EPSD) is computed onboard by the Digital Signal Processor (DSP). The fast Fourier transform (FFT) calculation is performed on a digitized version of analog signals from the Axial Double Probe (ADP) and Spin-Plane Double Probe (SDP). This data product is computed in space from individual components that are not synchronized to the 1 second pulse. Therefore, the timing between channels can be inaccurate by a fraction of a second. The samples times are interval start times taken from the x component. The spectra are calculated via a 1024-point FFT algorithm on piecewise continuous sets of waveform data. Nine signals can be processed simultaneously. Six of the twelve DC-coupled E, DC-coupled V, or SCM signals (16384 samples/s) are selected for spectral processing at 100% duty cycle. In addition, the three AC-coupled signals (262,144 kS/s) each can be processed at 6.25% duty cycle. Each of the nine signals has 16, 1024-point FFT operations every second; the field-programmable gate array (FPGA) performs 144 FFTs per second. The FFT is performed by an arithmetic logic unit (ALU), which is controlled by a state machine. Both are hard-coded into the FPGA. The operation starts by applying a 1024-point Hanning window onto a waveform. Next, an FFT is implemented. The FFT is broken into a series of "butterfly" operations performed by the ALU. The result has real and imaginary data. Power spectra are calculated by taking the sum of squares of real and imaginary values (the ALU includes a multiplier), which produces a power spectrum with 512 frequency bins. The frequency bins are then combined to give pseudo-logarithmic frequency spacing (del f)/f. The spectra are reduced to 56 frequency bins with (del f)/f between 6% and 12% when possible. Narrow-band emissions can be fit to an accuracy of (del f)/f ~3%, allowing for an accurate determination of plasma density. The spectra can be averaged in time. The fastest reporting rate of any signal is 16 spectra per second. Reporting rates can be as slow a one spectra every 16 s (averaging 256 spectra). The averaging process has 48-bit accuracy to maximize the dynamic range. The amplitudes undergo a pseudo-logarithmic compression to an 8-bit number representing over 120 dB of dynamic range at ~5% precision.
THEMIS-E: On Board spin fits (FIT) of Electric (EFI) and Magnetic (FGM) field. On-Board Spin-fit electric and magnetic field data
THEMIS-E: On Board spin fits of Electric (EFI) and Magnetic (FGM) fields. This file contains data EFI and FGM that has been despun on-board to 3 second resolution. It stores meta information like the number of points that contributed to each spin and the standard deviation of those points. For the EFI data it also stores variables with the Z component of the EFI data zeroed and the Z component of the EFI estimated using the E.B=0 equality. The need to use an estimated Z axis for the EFI is due to error in measurements from the EFI axial booms. These data are provided in DSL (despun spacecraft L-Z vector), GSM, and GSE coordinates.
THEMIS-A: Probe Electric Field Instrument and Search Coil Magnetometer Instrument, Digital Fields Board - digitally computed Filter Bank spectra and E12 peak and average in HF band (FBK).
The Filter Bank is part of the Digital fields board and provides band-pass filtering for EFI and SCM spectra as well as E12HF peak and average value calculations. The Filter Bank provides band-pass filtering for less computationally and power intensive spectra than the FFT would provide. The process is as follows: Signals are fed to the Filter Bank via a low-pass FIR filter with a cut-off frequency half that of the original signal maximum. The output is passed to the band-pass filters, is differenced from the original signal, then absolute value of the data is taken and averaged. The output from the low-pass filter is also sent to a second FIR filter with 2:1 decimation. This output is then fed back through the system. The process runs through 12 cascades for input at 8,192 samples/s and 13 for input at 16,384 samples/sec (EAC input only), reducing the signal and computing power by a factor 2 at each cascade. At each cascade a set of data is produced at a sampling frequency of 2^n from 2 Hz to the initial sampling frequency (frequency characteristics for each step are shown below in Table 1). The average from the Filter Bank is compressed to 8 bits with a pseudo-logarithmic encoder. The data is stored in sets of six frequency bins at 2.689 kHz, 572 Hz, 144.2 Hz, 36.2 Hz, 9.05 Hz, and 2.26 Hz. The average of the coupled E12HF signal and it's peak value are recorded over 62.5 ms windows (i.e. a 16 Hz sampling rate). Accumulation of values from signal 31.25 ms windows is performed externally. The analog signals fed into the FBK are E12DC and SCM1. Sensor and electronics design provided by UCB (J. W. Bonnell, F. S. Mozer), Digital Fields Board provided by LASP (R. Ergun), Search coil data provided by CETP (A. Roux). Table 1: Frequency Properties. Cascade Frequency content of Input Signal Low-pass Filter Cutoff Frequency Freuency Content of Low-pass Output Signal Filter Bank Frequency Band 0* 0 - 8 kHz 4 kHz 0 - 4 kHz 4 - 8 kHz 1 0 - 4 kHz 2 kHz 0 - 2 kHz 2 - 4 kHz 2 0 - 2 kHz 1 kHz 0 - 1 kHz 1 - 2 kHz 3 0 - 1 kHz 512 Hz 0 - 512 Hz 512 Hz - 1 kHz 4 0 - 512 Hz 256 Hz 0 - 256 Hz 256 - 512 Hz 5 0 - 256 Hz 128 Hz 0 - 128 Hz 128 - 256 Hz 6 0 - 128 Hz 64 Hz 0 - 64 Hz 64 - 128 Hz 7 0 - 64 Hz 32 Hz 0 - 32 Hz 32 - 64 Hz 8 0 - 32 Hz 16 Hz 0 - 16 Hz 16 - 32 Hz 9 0 - 16 Hz 8 Hz 0 - 8 Hz 8 - 16 Hz 10 0 - 8 Hz 4 Hz 0 - 4 Hz 4 - 8 Hz 11 0 - 4 Hz 2 Hz 0 - 2 Hz 2 - 4 Hz 12 0 - 2 Hz 1 Hz 0 - 1 Hz 1 - 2 Hz *Only available for 16,384 Hz sampling.
THEMIS-D: On Board spin fits (FIT) of Electric (EFI) and Magnetic (FGM) field. On-Board Spin-fit electric and magnetic field data
THEMIS-D: On Board spin fits of Electric (EFI) and Magnetic (FGM) fields. This file contains data EFI and FGM that has been despun on-board to 3 second resolution. It stores meta information like the number of points that contributed to each spin and the standard deviation of those points. For the EFI data it also stores variables with the Z component of the EFI data zeroed and the Z component of the EFI estimated using the E.B=0 equality. The need to use an estimated Z axis for the EFI is due to error in measurements from the EFI axial booms. These data are provided in DSL (despun spacecraft L-Z vector), GSM, and GSE coordinates.
MMS 4 Digital Signal Processor (DSP) Double Probe (ADP, SDP), Electric Field Power Spectral Density, Level 2 (L2), Fast Mode, 2 s Data
The MMS electric field power spectral density (EPSD) is computed onboard by the Digital Signal Processor (DSP). The fast Fourier transform (FFT) calculation is performed on a digitized version of analog signals from the Axial Double Probe (ADP) and Spin-Plane Double Probe (SDP). This data product is computed in space from individual components that are not synchronized to the 1 second pulse. Therefore, the timing between channels can be inaccurate by a fraction of a second. The samples times are interval start times taken from the x component. The spectra are calculated via a 1024-point FFT algorithm on piecewise continuous sets of waveform data. Nine signals can be processed simultaneously. Six of the twelve DC-coupled E, DC-coupled V, or SCM signals (16384 samples/s) are selected for spectral processing at 100% duty cycle. In addition, the three AC-coupled signals (262,144 kS/s) each can be processed at 6.25% duty cycle. Each of the nine signals has 16, 1024-point FFT operations every second; the field-programmable gate array (FPGA) performs 144 FFTs per second. The FFT is performed by an arithmetic logic unit (ALU), which is controlled by a state machine. Both are hard-coded into the FPGA. The operation starts by applying a 1024-point Hanning window onto a waveform. Next, an FFT is implemented. The FFT is broken into a series of "butterfly" operations performed by the ALU. The result has real and imaginary data. Power spectra are calculated by taking the sum of squares of real and imaginary values (the ALU includes a multiplier), which produces a power spectrum with 512 frequency bins. The frequency bins are then combined to give pseudo-logarithmic frequency spacing (del f)/f. The spectra are reduced to 56 frequency bins with (del f)/f between 6% and 12% when possible. Narrow-band emissions can be fit to an accuracy of (del f)/f ~3%, allowing for an accurate determination of plasma density. The spectra can be averaged in time. The fastest reporting rate of any signal is 16 spectra per second. Reporting rates can be as slow a one spectra every 16 s (averaging 256 spectra). The averaging process has 48-bit accuracy to maximize the dynamic range. The amplitudes undergo a pseudo-logarithmic compression to an 8-bit number representing over 120 dB of dynamic range at ~5% precision.
Van Allen Probe B Electric Field and Waves Suite (EFW) Burst Mode 1 (512 Samples/sec) Electric and Magnetic Fields, Waveform, in Spacecraft Spin (UVW) Coordinates, Level 1 (L1), 1.95 ms Data
The EFW Burst Modes provide targeted Measurements over Brief Time Intervals of 3-D Electric Fields, 3-D Wave Magnetic Fields, and Spacecraft Potential. There are two EFW Burst Modes: BURST1 (B1), Medium-Rate 512 samples/s nominal and BURST2 (B2), Higher-Rate, 16384 samples/s nominal. The Burst 1 Mode Data includes three components of the Electric Field (E12_B1, E34_B1, E56_B1), six Components of the Spacecraft-Sensor Potential (V1_B1 through V6_B1), and three Components of the AC Magnetic Field (SCM_U_B1, SCM_V_B1, SCM_W_B1 from the EMFISIS Search Coil Magnetometer). The Burst 2 Mode Data returns a similar Complement of Electric Field (E_12ac_B2, E34ac_B2, E56ac_B2), Search Coil (SCM_B2, SCM_2B2, and SCM_B2 again from the EMFISIS Search Coil Magnetometer) and Single-ended Potential Measurements (V1ac_B1 through V6ac_B2) with the exception that in the Default Mode the Single-ended Potential and Electric Field Signals are AC coupled with a higher Gain. All Quantities are in "uvw" Coordinates where "u" and "v" are the Sensor Coordinates rotating with the Spacecraft and "w" points along the Spacecraft Spin Axis. Burst Waveform CDF Files are available. The three Data Types available are the Electric Field "E" the Searchcoil Magnetic Field "MSC" and Antenna Potential "V". The Suffix on each of these is either "B1" or "B2". B1 or Burst 1 is the Human-in-the-Loop Burst Type, meaning that both Collection and Playback (for arbitrary Lengths of Time) are requested on the Ground. B2 or Burst 2 is automatically telemetered as short Bursts based on an onboard Triggering Algorithm, typically set to trigger on large Amplitude Signals near 1 kHz. Sample Rates for B1 and B2 can and are changed depending on varying Science Goals.
ICE PLASMA WAVE ELECTRIC FIELD MEASUREMENT DATA
The Plasma Wave Data were submitted to National Space Science Data Center after the Principal Investigator's death (Scarf) by S. Chang of TRW. For the electric field data, the time interval submitted was Sept 9 - 14, 1985 was included. That information, as well as an explanation of the reformatted data is detailed.
MMS 2 Digital Signal Processor (DSP) Double Probe (ADP, SDP), Electric Field Power Spectral Density, Level 2 (L2), Fast Mode, 2 s Data
The MMS electric field power spectral density (EPSD) is computed onboard by the Digital Signal Processor (DSP). The fast Fourier transform (FFT) calculation is performed on a digitized version of analog signals from the Axial Double Probe (ADP) and Spin-Plane Double Probe (SDP). This data product is computed in space from individual components that are not synchronized to the 1 second pulse. Therefore, the timing between channels can be inaccurate by a fraction of a second. The samples times are interval start times taken from the x component. The spectra are calculated via a 1024-point FFT algorithm on piecewise continuous sets of waveform data. Nine signals can be processed simultaneously. Six of the twelve DC-coupled E, DC-coupled V, or SCM signals (16384 samples/s) are selected for spectral processing at 100% duty cycle. In addition, the three AC-coupled signals (262,144 kS/s) each can be processed at 6.25% duty cycle. Each of the nine signals has 16, 1024-point FFT operations every second; the field-programmable gate array (FPGA) performs 144 FFTs per second. The FFT is performed by an arithmetic logic unit (ALU), which is controlled by a state machine. Both are hard-coded into the FPGA. The operation starts by applying a 1024-point Hanning window onto a waveform. Next, an FFT is implemented. The FFT is broken into a series of "butterfly" operations performed by the ALU. The result has real and imaginary data. Power spectra are calculated by taking the sum of squares of real and imaginary values (the ALU includes a multiplier), which produces a power spectrum with 512 frequency bins. The frequency bins are then combined to give pseudo-logarithmic frequency spacing (del f)/f. The spectra are reduced to 56 frequency bins with (del f)/f between 6% and 12% when possible. Narrow-band emissions can be fit to an accuracy of (del f)/f ~3%, allowing for an accurate determination of plasma density. The spectra can be averaged in time. The fastest reporting rate of any signal is 16 spectra per second. Reporting rates can be as slow a one spectra every 16 s (averaging 256 spectra). The averaging process has 48-bit accuracy to maximize the dynamic range. The amplitudes undergo a pseudo-logarithmic compression to an 8-bit number representing over 120 dB of dynamic range at ~5% precision.
MMS 2 Digital Signal Processor (DSP) Double Probe (ADP, SDP), Electric Field Power Spectral Density, Level 2 (L2), Slow Mode, 16 s Data
The MMS electric field power spectral density (EPSD) is computed onboard by the Digital Signal Processor (DSP). The fast Fourier transform (FFT) calculation is performed on a digitized version of analog signals from the Axial Double Probe (ADP) and Spin-Plane Double Probe (SDP). This data product is computed in space from individual components that are not synchronized to the 1 second pulse. Therefore, the timing between channels can be inaccurate by a fraction of a second. The samples times are interval start times taken from the x component. The spectra are calculated via a 1024-point FFT algorithm on piecewise continuous sets of waveform data. Nine signals can be processed simultaneously. Six of the twelve DC-coupled E, DC-coupled V, or SCM signals (16384 samples/s) are selected for spectral processing at 100% duty cycle. In addition, the three AC-coupled signals (262,144 kS/s) each can be processed at 6.25% duty cycle. Each of the nine signals has 16, 1024-point FFT operations every second; the field-programmable gate array (FPGA) performs 144 FFTs per second. The FFT is performed by an arithmetic logic unit (ALU), which is controlled by a state machine. Both are hard-coded into the FPGA. The operation starts by applying a 1024-point Hanning window onto a waveform. Next, an FFT is implemented. The FFT is broken into a series of "butterfly" operations performed by the ALU. The result has real and imaginary data. Power spectra are calculated by taking the sum of squares of real and imaginary values (the ALU includes a multiplier), which produces a power spectrum with 512 frequency bins. The frequency bins are then combined to give pseudo-logarithmic frequency spacing (del f)/f. The spectra are reduced to 56 frequency bins with (del f)/f between 6% and 12% when possible. Narrow-band emissions can be fit to an accuracy of (del f)/f ~3%, allowing for an accurate determination of plasma density. The spectra can be averaged in time. The fastest reporting rate of any signal is 16 spectra per second. Reporting rates can be as slow a one spectra every 16 s (averaging 256 spectra). The averaging process has 48-bit accuracy to maximize the dynamic range. The amplitudes undergo a pseudo-logarithmic compression to an 8-bit number representing over 120 dB of dynamic range at ~5% precision.
MMS 3 Digital Signal Processor (DSP) Double Probe (ADP, SDP), Electric Field Power Spectral Density, Level 2 (L2), Fast Mode, 2 s Data
The MMS electric field power spectral density (EPSD) is computed onboard by the Digital Signal Processor (DSP). The fast Fourier transform (FFT) calculation is performed on a digitized version of analog signals from the Axial Double Probe (ADP) and Spin-Plane Double Probe (SDP). This data product is computed in space from individual components that are not synchronized to the 1 second pulse. Therefore, the timing between channels can be inaccurate by a fraction of a second. The samples times are interval start times taken from the x component. The spectra are calculated via a 1024-point FFT algorithm on piecewise continuous sets of waveform data. Nine signals can be processed simultaneously. Six of the twelve DC-coupled E, DC-coupled V, or SCM signals (16384 samples/s) are selected for spectral processing at 100% duty cycle. In addition, the three AC-coupled signals (262,144 kS/s) each can be processed at 6.25% duty cycle. Each of the nine signals has 16, 1024-point FFT operations every second; the field-programmable gate array (FPGA) performs 144 FFTs per second. The FFT is performed by an arithmetic logic unit (ALU), which is controlled by a state machine. Both are hard-coded into the FPGA. The operation starts by applying a 1024-point Hanning window onto a waveform. Next, an FFT is implemented. The FFT is broken into a series of "butterfly" operations performed by the ALU. The result has real and imaginary data. Power spectra are calculated by taking the sum of squares of real and imaginary values (the ALU includes a multiplier), which produces a power spectrum with 512 frequency bins. The frequency bins are then combined to give pseudo-logarithmic frequency spacing (del f)/f. The spectra are reduced to 56 frequency bins with (del f)/f between 6% and 12% when possible. Narrow-band emissions can be fit to an accuracy of (del f)/f ~3%, allowing for an accurate determination of plasma density. The spectra can be averaged in time. The fastest reporting rate of any signal is 16 spectra per second. Reporting rates can be as slow a one spectra every 16 s (averaging 256 spectra). The averaging process has 48-bit accuracy to maximize the dynamic range. The amplitudes undergo a pseudo-logarithmic compression to an 8-bit number representing over 120 dB of dynamic range at ~5% precision.
MMS 4 Electric Double Probe (EDP) Axial Double Probe, Spin Plane Double Probe (ADP-SDP) Three-Dimensional HMFE Electric Field, Level 2 (L2), Burst Mode, 0.01525878906 ms Data
Electric Double Probe, Three-Dimensional HMFE Electric Field, Level 2, Burst Mode, Level 1B AC Electric Field Data
THEMIS-E: On Board Fast Fourier Transform (FFT) power spectra of Electric (EFI) and Magnetic (SCM) field measurements, for particle and wave burst survey modes.
On Board Fast Fourier Transform (FFT) power spectra of Electric (EFI) and Magnetic (SCM) field measurements for particle and wave burst survey modes. Spectra are produced only in Particle Burst and Wave Burst modes; only a preselected four of the signals listed in Table 1 are input at any time. Data fed through the FFT while not in Particle or Wave Burst modes is automatically disgarded. The FFTs (Cooley-Tukey algorithm) are conducted as an integral part of the power spectrum calculation by the Field Programable Gate Arrays (FPGAs). A CORDIC algorithm is used for sine/cosine calculations. The data has raw resolution of 1024 pts for 8,192 sample/sec signals and 2048 pts for 16,384 sample/sec signals (EAC measurements only). Signals at 8,192 samples/sec are handled by 1024-point FFTs, while those at 16,384 samples/sec go through 2048-point FFTs. Past and current signal configurations for specific spacecraft are listed bellow in Table 2. The spectra are arranged into log spaced frequency bins in steps of 16, 32, or 64. Cadence is adjusted to keep packet size constant (i.e. increasing the fequency resolution by a factor of 2 decreases the sampling rate by 1/2). The frequency bins cover a range of 0 Hz to 4 kHz. Table 1: FFT Input Signals. Signal Description SCMX, SCMY, SCMZ: Three axis magnetic fiend from SCM V1 through V6: Probe-spacecraft voltage for all six EFI sensors E12DC, E34DC, E56DC: DC-coupled electric field measured from opposing EFI sensors E12AC, E34AV, E56AC: AC-coupled electric field measured from opposing EFI sensors E12HF: High frequency electric field from EFI Table 2: Spacecraft specific configurations. All probes were initially set to use EDC34, EDC56, SCM2, and SCM3 signals for both particle and wave burst modes. Output was set to 16 frequency bins at 4 Hz. Configuration Changes: 23-27 June 2008: Particle burst spectra on all probes reconfigured to 64 bins at 1 Hz. Table 3: Instrument-Spacecraft Physical Configuration Instrument Alignment in Spacecraft Geometric coordinates (SPG). See THEMIS website for coordinate system details and mechanical drawings. EFI boom 1: Along positive X-axis EFI boom 2: Along negative X-axis EFI boom 3: Along positive Y-axis EFI boom 4: Along negative Y-axis EFI boom 5: Along positive Z-axis EFI boom 6: Along negative Z-axis SCM: *The SCM uses an instrument specific set of axes; an orthogonal system centered instrument with the X-axis 12.1 degrees from the SPG X-axis.
MMS 3 Electric Double Probe (EDP) Axial Double Probe, Spin Plane Double Probe (ADP-SDP) Electric Double Probe, High-Frequency Electric Field Spectra, Level 2 (L2), Survey Mode, 16 s Data
Electric Double Probe, High-Frequency AC Electric Field Spectra, Level 2, Survey Data, Level 1B AC Electric Field Data
MMS 2 Electric Double Probe (EDP) Axial Double Probe, Spin Plane Double Probe (ADP-SDP) Three-Dimensional HMFE Electric Field, Level 2 (L2), Burst Mode, 0.01525878906 ms Data
Electric Double Probe, Three-Dimensional HMFE Electric Field, Level 2, Burst Mode, Level 1B AC Electric Field Data
MMS 1 Electric Double Probe (EDP) Axial Double Probe, Spin Plane Double Probe (ADP-SDP) Three-Dimensional HMFE Electric Field, Level 2 (L2), Burst Mode, 0.01525878906 ms Data
Electric Double Probe, Three-Dimensional HMFE Electric Field, Level 2, Burst Mode, Level 1B AC Electric Field Data
Van Allen Probe A Electric Field and Waves Suite (EFW) Burst Mode 1 (512 Samples/sec) Electric and Magnetic Fields, Waveform, in Spacecraft Spin (UVW) Coordinates, Level 1 (L1), 1.95 ms Data
The EFW Burst Modes provide targeted Measurements over Brief Time Intervals of 3-D Electric Fields, 3-D Wave Magnetic Fields, and Spacecraft Potential. There are two EFW Burst Modes: BURST1 (B1), Medium-Rate 512 samples/s nominal and BURST2 (B2), Higher-Rate, 16384 samples/s nominal. The Burst 1 Mode Data includes three components of the Electric Field (E12_B1, E34_B1, E56_B1), six Components of the Spacecraft-Sensor Potential (V1_B1 through V6_B1), and three Components of the AC Magnetic Field (SCM_U_B1, SCM_V_B1, SCM_W_B1 from the EMFISIS Search Coil Magnetometer). The Burst 2 Mode Data returns a similar Complement of Electric Field (E_12ac_B2, E34ac_B2, E56ac_B2), Search Coil (SCM_B2, SCM_2B2, and SCM_B2 again from the EMFISIS Search Coil Magnetometer) and Single-ended Potential Measurements (V1ac_B1 through V6ac_B2) with the exception that in the Default Mode the Single-ended Potential and Electric Field Signals are AC coupled with a higher Gain. All Quantities are in "uvw" Coordinates where "u" and "v" are the Sensor Coordinates rotating with the Spacecraft and "w" points along the Spacecraft Spin Axis. Burst Waveform CDF Files are available. The three Data Types available are the Electric Field "E" the Searchcoil Magnetic Field "MSC" and Antenna Potential "V". The Suffix on each of these is either "B1" or "B2". B1 or Burst 1 is the Human-in-the-Loop Burst Type, meaning that both Collection and Playback (for arbitrary Lengths of Time) are requested on the Ground. B2 or Burst 2 is automatically telemetered as short Bursts based on an onboard Triggering Algorithm, typically set to trigger on large Amplitude Signals near 1 kHz. Sample Rates for B1 and B2 can and are changed depending on varying Science Goals.
MMS 1 Digital Signal Processor (DSP) Double Probe (ADP, SDP), Electric Field Power Spectral Density, Level 2 (L2), Fast Mode, 2 s Data
The MMS electric field power spectral density (EPSD) is computed onboard by the Digital Signal Processor (DSP). The fast Fourier transform (FFT) calculation is performed on a digitized version of analog signals from the Axial Double Probe (ADP) and Spin-Plane Double Probe (SDP). This data product is computed in space from individual components that are not synchronized to the 1 second pulse. Therefore, the timing between channels can be inaccurate by a fraction of a second. The samples times are interval start times taken from the x component. The spectra are calculated via a 1024-point FFT algorithm on piecewise continuous sets of waveform data. Nine signals can be processed simultaneously. Six of the twelve DC-coupled E, DC-coupled V, or SCM signals (16384 samples/s) are selected for spectral processing at 100% duty cycle. In addition, the three AC-coupled signals (262,144 kS/s) each can be processed at 6.25% duty cycle. Each of the nine signals has 16, 1024-point FFT operations every second; the field-programmable gate array (FPGA) performs 144 FFTs per second. The FFT is performed by an arithmetic logic unit (ALU), which is controlled by a state machine. Both are hard-coded into the FPGA. The operation starts by applying a 1024-point Hanning window onto a waveform. Next, an FFT is implemented. The FFT is broken into a series of "butterfly" operations performed by the ALU. The result has real and imaginary data. Power spectra are calculated by taking the sum of squares of real and imaginary values (the ALU includes a multiplier), which produces a power spectrum with 512 frequency bins. The frequency bins are then combined to give pseudo-logarithmic frequency spacing (del f)/f. The spectra are reduced to 56 frequency bins with (del f)/f between 6% and 12% when possible. Narrow-band emissions can be fit to an accuracy of (del f)/f ~3%, allowing for an accurate determination of plasma density. The spectra can be averaged in time. The fastest reporting rate of any signal is 16 spectra per second. Reporting rates can be as slow a one spectra every 16 s (averaging 256 spectra). The averaging process has 48-bit accuracy to maximize the dynamic range. The amplitudes undergo a pseudo-logarithmic compression to an 8-bit number representing over 120 dB of dynamic range at ~5% precision.
Effects of ultrasound and pulsed electric field on solvent extraction of bioactive substances from Chlorella
<p>Ultrasound (US) and pulsed electric field (PEF) treatments are widely used to disrupt living cells to enhance the extraction of bioactive compounds. The aim of the present work was to compare them for processing fresh water green alga <em>Chlorella </em>spp</p>
MMS 1 Electric Double Probe (EDP) Three-Dimensional Electric Field, Level 2 (L2), Slow Mode, 0.125 s Data
Electric Double Probe, Quick-Look Three-Dimensional Electric Field, Level 2, Slow Survey Data
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