Globe Tracker GTCU 002 User Manual

GTCU-002

Theory of Operation

December 8, 2014

December 8

, 201

4

GTCU-002 Theory of Operation

Legal Notice .................................................................................................................................................. 3

1 Overview ............................................................................................................................................... 3

2 Main Processor ..................................................................................................................................... 4

3 Wireless Interfaces ............................................................................................................................... 4

3.1 GSM/GPRS Cellular ....................................................................................................................... 5

3.2 Wi-Fi (802.11 b/g/n) ...................................................................................................................... 5

3.3 433 MHz ........................................................................................................................................ 6

3.4 GPS ................................................................................................................................................ 6

4 Wired Interfaces ................................................................................................................................... 6

5 Internal Sensors .................................................................................................................................... 7

5.1 Motion Sensor ............................................................................................................................... 7

5.2 Temperature Sensor ..................................................................................................................... 7

5.3 Voltage Sensing ............................................................................................................................. 7

6 Power Regulation and Control .............................................................................................................. 7

7 GTCM Connection Mid-Plate ................................................................................................................ 8

7.1 SMB Connectors ............................................................................................................................ 8

7.2 DB-9 Connector and Power-On Jumpers ...................................................................................... 8

7.3 LED Indicators ............................................................................................................................... 8

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December 8

, 201

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GTCU-002 Theory of Operation

Legal Notice

This document contains information confidential/proprietary to Globe Tracker International, ApS and
shall not be used for engineering design, procurement or manufacturing in whole or part
without the express written permission of Globe Tracker International, ApS.

1 Overview

This document provides the theory of operation for the Globe Tracker Communications Unit (GTCU).
The GTCU is battery operated and features GSM/GPRS Cellular, Wi-Fi, 433 MHz, and GPS radio
frequency (RF) technologies. The GTCU system consists of the Globe Tracker Communications Module
(GTCM) and the Globe Tracker Antenna Module (GTAM).

The GTCM contains the main PCB, battery, and an internal 433 MHz trace antenna located in the GTCM
end cap. The GTAM contains an antenna array with cellular (GSM) and 433 MHz PCB trace antennas, as
well as Wi-Fi and GPS patch antennas. The GTAM also contains a low noise amplifier (LNA) for the GPS.

The GTCM and GTAM connect via four (4) SMB RF cable assemblies that protrude through sealed
openings in their housings. The GTCM uses a connection plate in the housing for mounting the SMB
connectors, a DB-9 connector for external interfacing, and LED indication.

The GTCU is able to be powered from an internal battery pack or an external input. Units powered
from the internal battery pack are typically in a stand-by power down state to conserve battery energy.

In the simplest configuration for battery powered units, the GTCU will wake-up at pre-defined and
customizable intervals. Upon wake-up the GTCU will power on the various sub-circuits, attempt to
obtain a GPS fix, log any relevant data from its sensors or communication interfaces (typically UART or
433MHz), and transmit data via an appropriate wired or wireless interface if applicable (e.g. UART,
433MHz, Cellular, or Wi-Fi). Units powered externally operate similarly to battery powered units but
may not enter into stand-by mode, and may have increased data acquisition and reporting frequency.

The GTCM main circuit board has the following sub-circuits.

• Main Processor (STM32F2)

o SPI Flash Memory
o JTAG

• Wireless Interfaces

o GSM/GPRS Cellular (Telit GE865-Quad)
o Wi-Fi (802.11 b/g/n) (GainSpan GS1011MIE13)
o 433 MHz Transceiver (Texas Instruments CC1110)
o GPS Receiver (U-Blox IT530M)

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