themis/gbo engineering peer review 1 ucb, oct. 17, 2003 ground magnetometer gbo design

THEMIS/GBO Engineering Peer Review 1 UCB, Oct. 17, 2003

GROUND MAGNETOMETER

GBO DESIGN


Ground Magnetometer – GBO Design

Sub-System Features

GPS Receiver Antenna and Electronics Integrated into one package

May be located >30M from host (RS232 signals)

NTP compatible (<1msec time accuracy)

Flxugate Magnetometer ±72KnT dynamic range @ 0.03nT Resolution (~22 bits)

Offset DAC system for 72 4KnT ranges per axis

2 Vectors per second data rate

Low Power < 2W

Small Size 22cm x 13cm x 5cm

Ruggedized All Weather Sensor Design

USB interface for data retrieval and firmware upload



GPS Receiver Block Diagram

GBO Magnetometer To Fluxgate Sensor

Antenna Heater

To Power SupplyPower ControlRS232 bidirectional

Survival Heater and Thermistor

GPS Power

RS232 bidirectional

USB InterfaceGBO Data System

GPS Receiver

Up to 30M cable length

Up to 50M cable length

12VDC



FEEDBACKFEEDBACK

FEEDBACKFEEDBACK

FEEDBACKFEEDBACK

UCLA Sigma-Delta

Fluxgate Magnetometer

MAGCLOCKS

MAGCLOCKS

SHIFT & INTERNALLOGIC CLOCKS

SHIFT & INTERNALLOGIC CLOCKS

FEEDBACKLATCH

FEEDBACKLATCH

DATA FORMATING& OUTPUT

REGISTERS

DATA FORMATING& OUTPUT

REGISTERS

DIGITALNOISE SHAPING

FILTER

DIGITALNOISE SHAPING

FILTER

XILINX XC2S50

DRIVECIRCUIT

DRIVECIRCUIT

SYNC.Demodulator

SYNC.Demodulator

3 AXIS SENSORASSEMBLY

3 AXIS SENSORASSEMBLY

INTEGRATORINTEGRATOR


SYNC.Demodulator

SYNC.DemodulatorINTEGRATOR


INTEGRATOR

SYNC.Demodulator

SYNC.DemodulatorINTEGRATOR


INTEGRATOR

SYSTEM CLOCKSYSTEM CLOCK

OffsetDAC

OffsetDAC

OffsetDAC

OffsetDAC

OffsetDAC

OffsetDAC

OFFSETDAC

OUTPUTREGISTERS

OFFSETDAC

OUTPUTREGISTERS

SensorHeater

SensorHeater

ElectronicsHeater

ElectronicsHeater


xdt

Integrator 1

Comparator

1-bit

DAC

xdt

Integrator 2

FPGA

Digital

Decimation

Filter

21-bits

x(n)

x(t)

y(t)- -Fs:fs

32:1

Fs y(n)

Fluxgate

Sensor

AC

Coupling

Input

Amplifier

Synch

demodulator

xdt

IntegratorBand-Pass

Filter

Feedback

Resistor

Analog-to-Digital

Converter

ADC16-24 bits

Second Order Sigma-Delta Modulator



Fluxgate

Sensor

AC

Coupling

Input

Amplifier

Synch

demodulator

xdt

Integrator 1

xdt

Integrator 1 Comparator

1-bit

DAC

Feedback

Resistor

FPGA

2FO

DQ

FO/2

1

1

-

Comb Filter

Decimate 32IIR FilterIIR Filter Decimate 75

18-bits2Hz Data

2nd Order Fluxgate Magnetometer

-

2nd Order Fluxgate Magnetometer



UCLA GBO MAGNETOMETER SYSTEM OVERVIEW


PIC18F452

Micro-Controller

GPS Serial Interface

DB

15FU

SB

COM PORT

USB Interface

USB Interface

DB

9F

PPS Timing Interface

PPS Timing Interface

GPS Heater & Power Interface

GPS Heater & Power Interface

TCXOTCXO

XC2S50

FPGA

FPGA FLASH

FPGA FLASH

Power Regulation

+/-15V +5V

Power Regulation

+/-15V +5V

DIN

-5F

Axis 1Axis 1

Axis 2Axis 2

Axis 3Axis 3

DB

25F

DriveDrive

Sensor Heater

Sensor Heater


UCLA GBO Magnetometer Chassis - Mechanical


DB15F – GPS Receiver

DB9F – GBO Data System

USB Type B – GBO Data System

21.6cm

DB25F – Fluxgate Sensor

DIN 5F – +12V Power Input

5.1cm

12.7cm


UCLA GBO Magnetometer Sensor - Mechanical

DB25M

~100cm


12.7cm

50Meters (Max)



Ground Magnetometer Fluxgate Sensor

~100cm



Ground Magnetometer Fluxgate SensorSub Components



Ground Magnetometer - Electrical

Input Voltage: (9 – 18)VDC

Input Current: GPS system 100ma.Magnetometer 150ma.Sensor Heater 600ma.Electronics Heater 100ma.


GBO Magnetometer Data Timing

Sampling determined by TCXO (<10ppm aging)

Time Tagging determined by GPS (<100μsec) GPS

GPS Time Quality Factor Logged

Time Recalculated Periodically Typ. Hourly

Re-Synchronization at Programmable Rate Optional




Sigma-Delta Fluxgate Magnetometer Test Data


GBO Magnetometer Data Products

Data Inputs Include: Configuration File (UCLA_GBO_ssss_Vxx_xx.INI)

uP Firmware File (UCLA_GBO_ssss_Vxx_xx.UPF)

FPGA Firmware File (UCLA_GBO_ssss_Vxx_xx.GAF)

Data Outputs Include: Mag Vector Data (ssssdddddd_MAG_hh_cc.RMD)

Mag Housekeeping Data (ssssdddddd_MAG_hh_cc.HKD)

Magnetometer Log Data (ssssdddddd_MAG_hh_cc.LOD)

Mag Calibration Data (UCLA_GBO_ssss_Vxx_xx.CAL)




GBO Magnetometer Vector Data File Format

[File Preamble(I32)] [File Name(string “ssssdddddd_MAG_hh_cc.RMD”)]

[Nominal Vector Interval in msec (I32)]

[Time of next data point(string “mmddyyyy-hh:mm:ss-mmm”)]

[Number of vectors to follow N (I32)] [Vector 1 (3xI32)] [Vector 2 (3xI32)] ……

….. [Vector N-1 (3xI32)] [Vector N (3xI32)]

[Time of next data point(string “mmddyyyy-hh:mm:ss-mmm”)]

[Number of vectors to follow N (I32)] [Vector 1 (3xI32)] [Vector 2 (3xI32)] ……

….. [Vector N-1 (3xI32)] [Vector N (3xI32)]

[File Postamble(I32) ]


GBO Data System Software Features

Magnetometer Setup using LabView Program Real time display of three axis time series data

Real time display of three axis Power Spectra

Operator control of Magnetometer settings including, Heaters, Offset DACs, and operating modes

Autonomous Operations using C++ Program Command Line execution

Initialization controlled via Configuration file




Ground Magnetometer GBO Schedule

themis/gbo engineering peer review 1 ucb, oct. 17, 2003 ground magnetometer gbo design

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