Geometrics MagArrow User manual

User Guide
For
MagArrow
UAS Deployable Magnetometer
P/N 770-00110-01
Volume 1 - Rev. F
March 2023
COPYRIGHT © 2023

Table of Contents
Table of Contents .....................................................................................................................................2
1.0 The MagArrow.............................................................................................................................. 1
2.0 The MagArrow II ..........................................................................................................................2
3.0 Unpacking the MagArrow .........................................................................................................3
4.0 Recommended Non-Magnetic Lithium Polymer Batteries...............................................4
5.0 Batteries ........................................................................................................................................5
5.1 Installing the Battery .................................................................................................................. 5
5.2 Hot Swapping the Battery .......................................................................................................... 7
6.0 Powering On/Off..........................................................................................................................8
6.1 Restarting the System................................................................................................................9
7.0 LED-Status.................................................................................................................................. 10
8.0 SD Memory Card.........................................................................................................................11
9.0 USB Flash Drive ......................................................................................................................... 12
10.0 Wi-Fi.............................................................................................................................................. 12
11.0 GPS ............................................................................................................................................... 13
12.0 Controlling the MagArrow via Wi-Fi ..................................................................................... 13
12.1 Home Page............................................................................................................................... 14
12.2 Status Page .............................................................................................................................. 16
12.3 Data Page.................................................................................................................................20
12.4 Admin Page.............................................................................................................................. 23
12.5 Help Page.................................................................................................................................24
13.0 Survey Manager –Decimating & Converting Data Files ..................................................25
14.0 Data Format................................................................................................................................26
15.0 Tips on Running a MagArrow Survey ...................................................................................30

15.1 Flight Planning and Preparation ............................................................................................... 30
15.2 Flight Execution........................................................................................................................ 30
16.0 Troubleshooting ........................................................................................................................32
16.1 Magnetometer ......................................................................................................................... 32
16.2 Wi-Fi......................................................................................................................................... 32
16.3 GPS .......................................................................................................................................... 32
16.4 LEDs......................................................................................................................................... 33
16.5 System Boot Internal Light Indicators ...................................................................................... 34
APPENDIX A: MagArrow Specifications...........................................................................................35
APPENDIX B: Embedded Software Updates...................................................................................37
APPENDIX C: Terminology Used with MFAM Based Magnetometers......................................38
APPENDIX D: NTRIP Base Station Correction for RTK Surveys ................................................. 41

rev. 03/23
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1.0 The MagArrow
The MagArrow is a laser-pumped, cesium vapor (Cs133 non-radioactive) total field scalar
magnetometer. The MagArrow’s light weight of 1 kg makes it ideal for use with unmanned aerial
systems (UAS) that can support 2kg+ payloads. Within its aerodynamic carbon fiber housing,
the MagArrow contains:
•MFAM miniature magnetometer
•GPS
•Wireless Connection Point
•SD Memory Card
•USB Drive
•Gyro, Compass, and Accelerometer
•Battery Compartment
The MFAM miniature magnetometer comprises two high-performance cesium sensors attached
to one sensor driver module. The two sensors are used together to eliminate the dead zone and
reduce heading error. Its small weight, low power, and 1000Hz sampling rate make the MFAM a
revolutionary sensor in the geophysical market. See Appendix A for a complete list of product
specifications.

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One MFAM Sensor
The pulse per second (PPS) signal from the GPS synchronizes the sampling rate to ensure 1000
samples are recorded per second. (See Appendix C for a detailed definition of PPS.) Data is saved
to the 32 GB SD memory card, and accessed via Wi-Fi, so the card never needs to be removed.
The USB drive holds the latest MagArrow firmware and can be used for fast field upgrades. The
MagArrow uses non-magnetic lithium polymer batteries for power, which the user must source
locally.
During survey operations, the MagArrow gathers and stores the data in a binary format onto the
SD card (*.magdata). This binary data can then be downloaded onto a PC, tablet, or cell phone
via the system’s on-board Wireless access point. It is recommended to use Chrome Web Browser
and an Android OS (6.1 or newer) device. The MagArrow is not compatible with iOS devices.
Survey Manager Software is provided for converting the binary data into a CSV file for use in
Surfer, Geosoft Oasis Montaj, Quinsy, and other magnetic data processing programs.
2.0 The MagArrow II
The main difference between the MagArrow I and II is the GPS. The MagArrow II uses an upgraded GPS
module with about 50% improvement in the positioning accuracy. It also comes with the external helical
antenna option. The helical antenna is capable of multipath rejection, which improves the GPS accuracy
especially in a crowded environment. We suggest that the helical antenna to be used when the MagArrow
flies < 10m from the ground with 10m line spacing. If the line spacing is > 20m, the internal antenna is
sufficient. A general rule of thumb: Line spacing should be 1-2 times the distance between the
ground and the MagArrow. Anything less won’t reveal more information and anything more will
likely lead to loss of some small features. An external power switch is also added to the MagArrow II. As
a result, the MagArrow II is about 300g heavier (total weight ~1.15kg without the battery) than the
MagArrow I.

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To achieve the real time kinematic (RTK) positioning accuracy, NTRIP is needed (we may offer
RTK base station in the future). See Appendix D for more details.
3.0 Unpacking the MagArrow
Your MagArrow is shipped in a rugged black case with safety latches that require you to first
push the button on the latch before raising the latch and opening the lid. To close the latches,
simply push down on them.
To repack for transit, place the MagArrow upside down so it sits securely in the foam. Close all
latches.
The case should also contain:
A. AC Power Adapter
B. USB Drive with User Manual and Survey Manager Software
C. Screwdriver & Drill Bit (JIS#1)
D. Set of 4 Suspension Cords
D
B
C
A

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4.0 Recommended Non-Magnetic Lithium Polymer Batteries
Please note that batteries have not shipped with your MagArrow. You must source the
recommended batteries and battery charger locally. Note that your batteries must have the
XT60 connector.
Geometrics recommends 1800 mAh and 2200 mAh lithium polymer batteries. The Turnigy
batteries listed below have been verified by Geometrics to be non-magnetic, and therefore, the
best option for MagArrow surveys. It is important to do independent testing of the batteries for
abnormal magnetic signatures before use. The batteries should be available from various online
vendors.
https://hobbyking.com/en_us/turnigy-nano-tech-1800mah-3s-65-130c-lipo-pack.html (Turnigy nano-
tech 1800mah 3S 65~130C Lipo Pack)
https://hobbyking.com/en_us/turnigy-nano-tech-2200mah-3s-45-90c-lipo-pack.html (Turnigy
nano-tech 2200mah 3S 45~90C Lipo Pack)
A single 1800 mAh battery will run the MagArrow for about 2 hours; the 2200 mAh, about 2.5
hours. It is recommended to have at least two spare batteries so that one may be charging while
the other is in use.
We recommend a similar battery charger and discharger for use with the MagArrow as below:
https://hobbyking.com/en_us/turnigy-accucell-c150-ac-dc-10a-150w-touch-button-smart-
balance-charger-us-plug.html?___store=en_us

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This is a balanced charger that charges one lithium battery cell at a time. It has a discharge mode
to automatically lower the battery charge state to 30%. IMPORTANT: It is required by law to
reduce the battery charge state of these lithium polymer batteries to 30% before shipment.
5.0 Batteries
5.1 Installing the Battery
On the bottom of the MagArrow, there is a door to the battery compartment where the batteries
will be stored.
A. Remove the battery compartment cover with the provided JIS#1 screwdriver. It is very important
to only use the provided JIS#1 screwdriver or drill bit to tighten or loosen the battery door screws (see
red circles below). Do not use a Phillips Screwdriver.
Battery Compartment Door Removed
B. Proper battery placement inside the battery compartment is as shown in the figure below. The
battery leads must be housed as shown, towards the pointed front of the MagArrow.

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C. Proper Placement of Battery Pack
D. There are two yellow battery connectors and one white cell voltage monitoring connector within
the battery compartment. Locate one of the yellow battery connectors and the white cell voltage
monitoring connector. Plug the lithium battery connector (yellow) into the yellow connector. Note: The
second yellow connector is used when hot swapping batteries. This will allow you to disconnect the
discharged battery without losing power to the magnetometer.
E. After making the power connection, plug the white connector into the white lithium battery
connector. This connection is for monitoring the voltage of the three internal cells of the battery. Be
careful not to connect the white connectors backwards.

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F. Slide the battery into the compartment and carefully tuck the wires alongside the battery.
5.2 Hot Swapping the Battery
For quick battery changes, the new battery pack can be plugged into the second (unused) yellow
battery connector before disconnecting the depleted battery. This method of swapping
batteries does not require shutting the system down, which will save time. See the instructions
below on how to hot swap the battery.
1. Loosen the screws on the battery cover with the JIS#1 screwdriver and remove the cover.