MAGGEX FRRMAGGEX FRREvan AnzaloneEvan Anzalone

Louisiana State UniversityLouisiana State University

5/23/2005 NSBF, Palestine, TX5/23/2005 NSBF, Palestine, TX

PurposePurpose

• Measure magnitude of the geomagnetic field as a function of altitude

• Check accuracy of World Magnetic Model over a large altitude range

• Look for spatial and temporal variations in magnetic field

Expected FieldExpected FieldField Strength vs. Height

489.0

490.0491.0

492.0493.0

494.0

495.0496.0

497.0498.0

499.0

0 10 20 30 40

Height (km)

|B|

(mG

)

Cou

rtes

y: I

GR

F M

odel

Payload OverviewPayload Overview

• Based on standard BalloonSat package:– BasicStamp 2p24, 4 channel ADC, RTC, 256kbit

EEPROM– Each reading is 80 bits– Take reading every 5 seconds

• Outer box: 18 x 15 x 10.5 cm• Batteries: 8 x 1.5 V e2 Lithium Batteries

3000mAh– 2 for RTC backup, 6 for electronics

• Power needed: 60 mA ~4 hours, 240 mAh• Weight: 423.7 g

Sensor PackageSensor Package

• Donated by Precision Navigation Corp.

• PNI ASIC 11096 Driver, Sen-L Sensor– low power, temperature-independent

measurements, resolution used ~ .042 mG/count

– Driver returns 16 bit signed integer “count” of change in frequency between forward and reverse bias frequency measurements

– 3 sensors arranged orthogonal

Operations DesignOperations Design

• Read time from RTC

• Read measurement of temperature from sensors on voltage regulator

• Individually send commands to ASIC to take three orthogonal field measurements

• Store all information to EEPROM

• Pause until next reading

CertificationsCertifications

• Vacuum: – Stable operation independent of pressure

• Temperature:– Readings independent of temperature change– Insulation proven to keep temperature at

operation level

• Electronics/Software:– Proven operation in lab, electronics/software

at very mature stage of use

Interference TestingInterference Testing

• Other BalloonSat’s– No effect at inter-payload distance

• Payload Electronics– Small effect, ~.1 mG, within error, steady

• GPS Beacons– No effect due to radio beacon, even when

antenna placed near to sensor

Data Analysis ProcedureData Analysis Procedure

• Offload data from EEPROM to PC

• Obtain location data

• Put location data into modified World Magnetic Model Code

• Compare Model to actual readings to see local variations

Final PreparationsFinal Preparations

• Install fresh batteries

• Seal inner package

• Paint outer package

• Seal outer package (near time of attachment to flight-line)