Quickstart Guide for Bull+ Tracker

Preparations

Remove the four case screws and open the device. You will see two sockets for batteries and a slot for an microSD card. The device can be configured either by updating the CONFIG.TXT file on the SD card or by USB connection. After placing the SD card and inserting batteries the device will immediately boot up. During boot the device will wait for the power supply to be fully charged and then, if enabled, wait for the SD card to fully initialize.

Configuration

This is a non-exhaustive list of available configuration parameter that covers the current use cases:

GNSS Mode Selection:

AT+GNSS=1

Values: - 0: off - 1: continuous signal acquisition (high power consumption, continuous position fix) - 2: intermediate signal acquisition (low power consumption, intermediate position fix)

SBAS, Enhanced GNSS Mode

SBAS requires the GNSS module to be continuously powerde on, aka AT+GNSS=1

AT+SBAS=1

Values: - 0: disable - 1: enable

Minimal Position Fix Quality

Configure the minimal quality to accept a gps fix. A lower value means tighter tolerance. Empirically a value of 9 or 10 work well.

AT+EPE_TOL=9

Values: - an integer between 7-12

GNSS Measurement Settings

GNSS measurements are aborted if no signal can be established within a certain time frame. If no signal is detected at all the measurement is stopped after AT+TIMEMIN seconds. If a signal is detected but the fix quality AT+EPE_TOL is not reached the measurement is aborted after AT+TIMEOUT minutes.

AT+TIMEMIN=5 AT+TIMEOUT=2

enable the SDcard

In addition to the wireless transmition of certain data points the device can store more fine grained data on an SD card.

AT+SDCARD=1

Values: - 0: disable - 1: enable

Enable the IMU Sensor

When enabled the IMU sensor data is fed into a welford algorithm and a summary is stored in the POS data log.

AT+IMU=1

Values: - 0: disable - 1: enable

Configuring the IMU sensor

Set the acquisition frequency for the IMU sensor

AT+IMU_FREQ=25

Values, in Hz: - 12 - 25 - 50

enable the IMU log

This requires both the IMU sensor (AT+IMU=1) and SD card (AT+SDCARD=1) to be enabled. When enabled the raw data points from the IMU sensor are recorded to the sd card ind the .IMU file.

AT+IMU_LOG=1

Measurement Periods

There are two main measurement period settings. Every AT+PERIOD minutes one main meassurement will be taken, usually the GNSS position fix. If AT+GNSS=2 is set this will also govern the wakeup pattern between GNSS wake and acquisitions. If the IMU is enabled every AT+SD_PERIOD_SEC seconds a measurement with the averaged IMU data is recorded.

AT+PERIOD=15 AT+SD_PERIOD_SEC=20

LORA Transmission settings

Status packets are sent regularly to observer the current state of the device. Every AT+STAT_PERIOD minutes a status packet is sent. If the packet is not aknowledge by the network it will be stored for later re-transmission. Retransmissions are attempted after AT+TX_STANDBY minutes. When the network is successfully joined the stored packages are sent out one by one with a delay of AT+TX_INTERVAL_SEC seconds between them.

AT+STAT_PERIOD=15 AT+TX_STANDBY=15 AT+TX_INTERVAL_SEC=60