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Quad-Mag Board for CubeSat Applications�

Brady Strabel

Mark Moldwin

Lauro Ojeda

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Oversampling with Multiple Commercial Sensors

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Fluxgate Magnetometer from the Magnetospheric Multiscale Mission (from Russel et. al., 2016)

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→ High manufacturing costs

→ Relatively large size

→ Substantial power draw

→ Extremely low noise

Traditional Magnetometers

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PNI RM3100 next to United States quarter for size comparison (from Regoli et. al., 2018)

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→ Low manufacturing costs

→ Extremely small size

→ Minimal Power Consumption

→ Relatively high noise

Commercial Off-The-Shelf Magnetometers

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Fully Assembled Quad-Mag Board Top

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Fully Assembled Quad-Mag Board Bottom

System Design

  • Four independent RM3100 magnetometers (purple)
  • MSP430FR5949 Microcontroller
  • Simple UART controller-to-host interface

Quad-Mag Serial Communication Format

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System Characterization

  • Quad-Mag placed in a zero Gauss chamber inside a μ-metal lined copper room
  • Individual RM3100 magnetometers cycle count set to 400 (~65 Hz sampling rate)
  • Meda uMag fluxgate magnetometer used to calibrate and remove offsets in each RM3100

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Zero Gauss Chamber (left) and Copper Room (right) used for testing (from Regoli et al., 2018)

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Quad-Mag Resolution Testing Data Overlayed at 65 Hz

Resolution @ 65 Hz

  • Ten-minute warm-up period to let sensor measurements settle
  • Data are recorded for 30 seconds
  • Standard deviation taken as resolution at the given frequency

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Performance Characteristics

Axis

X

Y

Z

Resolution (nT) @ 65 Hz

4.74

4.71

5.34

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Quad-Mag Resolution Testing Data Overlayed at 1 Hz

Resolution @ 1 Hz

  • Ten-minute warm-up period to let sensor measurements settle
  • Data are recorded for 10 minutes
  • Down-sampled through typical approach of low-pass filtering and decimating

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Performance Characteristics

Axis

X

Y

Z

Resolution (nT) @ 1 Hz

1.04

0.82

0.83

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Quad-Mag Overlayed Power Spectral Density

Noise Floor

  • Ten-minute warm-up period to let sensor measurements settle
  • Data are recorded for ten, 1-Hour intervals
  • The average of the ten intervals is taken

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Performance Characteristics

Axis

X

Y

Z

Noise Floor (pT)

3.77

3.37

3.29

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Quad-Mag Stability Testing

Stability

  • Ten-minute warm-up period to let sensor measurements settle
  • Data are recorded for 38 hours
  • Bin size set to ¼ least significant bit

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Performance Characteristics

Axis

X

Y

Z

Kurtosis Index

-2.963

-2.943

-2.949

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Quad-Mag Interference Testing Unpopulated Board at 65 Hz

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Quad-Mag Interference Testing Populated Board at 65 Hz

Interference – Mutual Sensor Influence

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Quad-Mag Interference Testing Unpopulated Board at 65 Hz

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Quad-Mag Interference off Board at 78 Hz

Interference – Board Influence

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Quad-Mag Performance Characteristics

Summary of Quad-Mag Characterization

  • Standalone RM3100 magnetometer has 2.2 nT resolution @ 1Hz
  • Quad-Mag increases resolution to 1.04 nT @ 1Hz
  • Exceeds theoretically estimated improvement by ~10%
  • Large disparity between resolution of individual magnetometers and coils
  • Take newly established resolution as an upper limit

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Future Directions

  • Launch on CubeSat missions to demonstrate reliability and improve Technology Readiness Level
  • Apply recently developed UBSS algorithms to clean spacecraft noise

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References

  1. Leuzinger and Taylor, 2010
  2. Regoli et. al., 2018. Investigation of a Low-Cost Magneto-Inductive Magnetometer for Space Science Applications
  3. Regoli et al., 2018. Four Magnetometer Board for CubeSat Applications
  4. Russel et. al., 2016
  5. Strabel et. al., 2022

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