THEMIS-C: 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:

            30 June - 3 July 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.

NASA Contract NAS5-02099, V. Angelopoulos for use of data from the THEMIS Mission, also John Bonnell, Michael Cully, Bob Ergun, and Alain Roux for their work on the FFT and related systems.

FFT Power Spectrum in Particle Burst mode, 16 frequencies for SCM delta-B (parallel to B)

FFT Power Spectrum in Particle Burst, 16 frequencies for SCM delta-B (perp to B)

FFT Power Spectrum in Particle Burst, 16 frequencies for E Field AC Component, Sensors 1 and 2 (spin plane)

FFT Power Spectrum in Particle Burst, 16 frequencies for E Field AC Component, Sensors 3 and 4 (spin plane)

FFT Power Spectrum in Particle Burst, 16 frequencies for E Field AC Component, Sensors 5 and 6 (axial)

FFT Power Spectrum in Particle Burst, 16 frequencies for E Field DC Component, Sensors 1 and 2 (spin plane)

FFT Power Spectrum in Particle Burst, 16 frequencies for E Field DC Component, Sensors 3 and 4 (spin plane)

FFT Power Spectrum in Particle Burst, 16 frequencies for E Field DC Component, Sensors 5 and 6 (axial)

FFT Power Spectrum in Particle Burst, 16 frequencies for EFI E (parallel to B)

FFT Power Spectrum in Particle Burst, 16 frequencies for EFI E (perp to B)

FFT Power Spectrum in Particle Burst, 16 frequenci es for SCM, Axis 1

FFT Power Spectrum in Particle Burst, 16 frequencies for SCM, Axis 1

FFT Power Spectrum in Particle Burst, 16 frequencies for EFI Potential, Sensor 1

FFT Power Spectrum in Particle Burst, 16 frequencies for EFI Potential, Sensor 2

FFT Power Spectrum in Particle Burst, 16 frequencies for EFI Potential, Sensor 3

FFT Power Spectrum in Particle Burst, 16 frequencies for EFI Potential, Sensor 4

FFT Power Spectrum in Particle Burst, 16 frequencies for EFI Potential, Sensor 5

FFT Power Spectrum in Particle Burst, 16 frequencies for EFI Potential, Sensor 6

FFT Power Spectr um in Particle Burst, 32 frequencies for SCM delta-B (parallel to B)

FFT Power Spectrum in Particle Burst, 32 frequencies for SCM delta-B (perp to B)

FFT Power Spectrum in Particle Burst, 32 frequencies for E Field AC Component, Sensors 1 and 2 (spin plane)

FFT Power Spectrum in Particle Burst, 32 frequencies for E Field AC Component, Sensors 3 and 4 (spin plane)

FFT Power Spectrum in Particle Burst, 32 frequencies for E Field AC Component, Sensors 5 and 6 (axial)

FFT Power Spectrum in Particle Burst, 32 frequencies for E Field DC Component, Sensors 1 and 2 (spin plane)

FFT Power Spectrum in Particle Burst, 32 frequencies for E Field DC Component, Sensors 3 and 4 (spin plane)

FFT Power Spectrum in Particle Burst, 32 frequencies for E Field DC Component, Sensors 5 and 6 (axial)

FFT Power Spectrum in Particle Burst, 32 frequencies for EFI E (parallel to B)

FFT Power Spectrum in Particle Burst, 32 frequencies for EFI E (perp to B)

FFT Power Spectrum in Particle Burst, 32 frequencies for SCM, Axis 1

FFT Power Spectrum in Particle Burst, 32 frequencies for EFI Potential, Sensor 1

FFT Power Spectrum in Particle Burst, 32 frequencies for EFI Potential, Sensor 2

FFT Power Spectrum in Particle Burst, 32 frequencies for EFI Potential, Sensor 3

FFT Power S pectrum in Particle Burst, 32 frequencies for EFI Potential, Sensor 4

FFT Power Spectrum in Particle Burst, 32 frequencies for EFI Potential, Sensor 5

FFT Power Spectrum in Particle Burst, 32 frequencies for EFI Potential, Sensor 6

FFT Power Spectrum in Particle Burst, 64 frequencies for SCM delta-B (parallel to B)

FFT Power Spectrum in Particle Burst, 64 frequencies for SCM delta-B (perp to B)

FFT Power Spectrum in Particle Burst, 64 frequencies for E Field AC Component, Sensors 1 and 2 (spin plane).

FFT Power Spectrum in Particle Burst, 64 frequencies for E Field AC Component, Sensors 3 and 4 (spin plane)

FFT Power Spectrum in Particle Burst, 64 frequencies for E Field AC Component, Sensors 5 and 6 (axial)

FFT Power Spectrum in Particle Burst, 64 frequencies for E Field DC Component, Sensors 1 and 2 (spin plane)

FFT Power Spectrum in Particle Burst, 64 frequencies for E Field DC Component, Sensors 3 and 4 (spin plane)

FFT Power Spectrum in Particle Burst, 64 frequencies for E Field DC Component, Sensors 5 and 6 (axial)

FFT Power Spectrum in Particle Burst, 64 frequencies for EFI E (parallel to B)

FFT Power Spectrum in Particle Burst, 64 frequencies for EFI E (perp to B)

FFT Power Spectrum in Particle Burst, 64 frequencies for SCM, Axis 1

FFT Power Spectrum in Particle Burst, 64 frequencies for EFI Potential, Sensor 1

FFT P ower Spectrum in Particle Burst, 64 frequencies for EFI Potential, Sensor 2

FFT Power Spectrum in Particle Burst, 64 frequencies for EFI Potential, Sensor 3

FFT Power Spectrum in Particle Burst, 64 frequencies for EFI Potential, Sensor 4

FFT Power Spectrum in Particle Burst, 64 frequencies for EFI Potential, Sensor 5

FFT Power Spectrum in Particle Burst, 64 frequencies for EFI Potential, Sensor 6

FFT Power Spectrum in Wave Burst, 16 frequencies for SCM delta-B (parallel to B)

FFT Power Spectrum in Wave Burst, 16 frequencies for SCM delta-B (perp to B)

FFT Power Spectrum in Wave Burst, 16 frequencies for E Field AC Component, Sensors 1 and 2 (spin plane)

FFT Power Spectrum in Wave Burst, 16 frequencies for E Field AC Component, Sensors 3 and 4 (spin plane)

FFT Power Spectrum in Wave Burst, 16 frequencies for E Field AC Component, Sensors 5 and 6 (axial)

FFT Power Spectrum in Wave Burst, 16 frequencies for E Field DC Component, Sensors 1 and 2 (spin plane)

FFT Power Spectrum in Wave Burst, 16 frequencies for E Field DC Component, Sensors 3 and 4 (spin plane)

FFT Power Spectrum in Wave Burst, 16 frequencies for E Field DC Component, Sensors 5 and 6 (axial)

FFT Power Spectrum in Wave Burst, 16 frequencies for EFI E (paral lel to B)

FFT Power Spectrum in Wave Burst, 16 frequencies for EFI E (perp to B)

FFT Power Spectrum in Wave Burst, 16 frequencies for SCM, Axis 1

FFT Power Spectrum in Wave Burst, 16 frequencies for EFI Potential, Sensor 1

FFT Power Spectrum in Wave Burst, 16 frequencies for EFI Potential, Sensor 2

FFT Power Spectrum in Wave Burst, 16 frequencies for EFI Potential, Sensor 3

FFT Power Spectrum in Wave Burst, 16 frequencies for EFI Potential, Sensor 4

FFT Power Spectrum in Wave Burst, 16 frequencies for EFI Potential, Sensor 5

FFT Power Spectrum in Wave Burst, 16 frequencies for EFI Potential, Sensor 6

FFT Power Spectrum in Wave Burst, 32 frequencies for SCM delta-B (parallel to B)

FFT Power Spectrum in Wave Burst, 32 frequencies for SCM delta-B (perp to B)

FFT Power Spectrum in Wave Burst, 32 frequencies for E Field AC Component, Sensors 1 and 2 (spin plane)

FFT Power Spectrum in Wave Burst, 32 frequencies for E Field AC Component, Sensors 3 and 4 (spin plane)

FFT Power Spectrum in Wave Burst, 32 frequencies for E Field AC Component, Sensors 5 and 6 (axial)

FFT Power Spectrum in Wave Burst, 32 frequencies for E Field DC Component, Sensors 1 and 2 (spin plane)

FFT Power Spectrum in Wave Burst, 32 frequencies for E Field DC Component, Sensors 3 and 4 (spin plane)

FFT Power Spectrum in Wave Burst, 32 frequencies for E Field DC Component, Sensors 5 and 6 (axial)

FFT Power Spectrum in Wave Burst, 32 frequencies for EFI E (parallel to B)

FFT Power Spectrum in Wave Burst, 32 frequencies for EFI E (perp to B)

FFT Power Spectrum in Wave Burst, 32 frequencies for SCM, Axis 1

FFT Power Spectrum in Wave Burst, 32 frequencies for EFI Potential, Sensor 1

FFT Power Spectrum in Wave Burst, 32 frequencies for EFI Potential, Sensor 2

FFT Power Spectrum in Wave Burst, 32 frequencies for EFI Potential, Sensor 3

FFT Power Spectrum in Wave Burst, 32 frequencies for EFI Potential, Sensor 4

FFT Power Spectrum in Wave Burst, 32 frequencies for EFI Potential, Sensor 5

FFT Power Spectrum in Wave Burst, 32 frequencies for EFI Potential, Sensor 6

FFT Power Spectrum in Wave Burst, 64 frequencies for SCM delta-B (parallel to B)

FFT Power Spectrum in Wave Burst, 64 frequencies for SCM delta-B (perp to B)

FFT Power Spectrum in Wave Burst, 64 frequencies for E Field AC Component, Sensors 1 and 2 (spin plane)

FFT Power Spectrum in Wave Burst, 64 frequencies for E Field AC Component, Sensors 3 and 4 (spin plane)

FFT Power Spectrum in Wave Burst, 64 frequencies for E Field AC Component, Sensors 5 and 6 (axial)

FFT Power Spectrum in Wave Burst, 64 frequencies for E Field DC Component, Sensors 1 and 2 (spin plane)

FFT Power Spectrum in Wave Burst, 64 frequencies for E Field DC Component, Sensors 3 and 4 (spin plane)

FFT Power Spectrum in Wave Burst, 64 frequencies for E Field DC Component, Sensors 5 and 6 (axial)

FFT Power Spectrum in Wave Burst, 64 frequencies for EFI E (parallel to B)

FFT Power Spectrum in Wave Burst, 64 frequencies for EFI E (perp to B)

FFT Power Spectrum in Wave Burst, 64 frequencies for SCM, Axis 1

FFT Power Spectrum in Wave Burst, 64 frequencies for EFI Potential, Sensor 1

FFT Power Spectrum in Wave Burst, 64 frequencies for EFI Potential, Sensor 2

FFT Power Spectrum in Wave Burst, 64 frequencies for EFI Potential, Sensor 3

FFT Power Spectrum in Wave Burst, 64 frequencies for EFI Potential, Sensor 4

FFT Power Spectrum in Wave Burst, 64 frequencies for EFI Potential, Sensor 5

FFT Power Spectrum in Wave Burst, 64 frequencies for EFI Potential, Sensor 6