EYTraker V9 LTE: 1 May 2024
Introduction
The
original EYTraker was first introduced in 2006 and
has since then been through a few iterations and redesigns based on new platforms
and technology. I will do a writeup on the evolution of the design in the near future.
The
latest revision of the EYTraker V9 is based on the SIMCom Cat 1 LTE/GPS engine A7670E module that is available
from Makerfabs as a complete voice and data LTE
solution. The unit also features a SAMD21 low-power microcontroller using
the 32-bit ARM® Cortex® processor with power and battery management included. The
compatibility of this microcontroller with Arduino IDE makes it ideal to
develop a robust tracking system. The previous EYTraker
designs were based on the GSM 2G network that has since become oversubscribed
and unreliable with even indications that the 2G networks will be
decommissioned to free up frequency spectrum for 4G. The new unit is fully LTE
or 4G capable that increases the tracking reliability of the unit.
Apart
from a few external components, the unit requires very little additional
changes to allow it to function as a stable tracking platform. The features of
the EYTraker V9 includes the following:
·
5V
supply via the USB-C connector with a LM2596 used to ensure a wide range of
input voltages.
·
Ignition
voltage sense + Ignition status
·
LiPo
Battery and USB Bus voltage sense
·
Accurate
GPS positioning + max speed per sector
·
Hourly
engineering data payloads to APRS
·
Internal
unit temperature
·
Full
Watchdog and hard reset in software to ensure reliable online time
·
Functions
with MTN or Vodacom SIM cards
The
design of the EYTraker V9 is based on off-the-shelf
components that allows for quick configuration of the unit. The basic design is
based on the A7670E module PCB and a LM2595 buck boost converter set to 5V
feeding the USB-C connector. A small 3.8V 800mA LiPo battery provides about 2
hours of backup power in case of a power disconnect. There are 2 status SMD
LEDs with current limiting resistor (330 ohm), on Pin D8 and D9, that show the status
of the tracker at any given time, a jumper on D13 for hard reset in software
and the ignition sense with a voltage divider (220K and 1M resistors) and
smoothing cap (1 uF) on pin A0.
A
very simple design supported by stable firmware on the SAMD21 that has been
tested extensively.
The
unit is housed in a plastic enclosure (110mm (L) x 60mm (W) x 24mm (H)) with an
external power connector, GPS SMA pigtail and GSM SMA pigtail to allow the
connection of external GPS and GSM antennas. The option exist
to use an internal GPS antenna if required. The complete unit draw 80 mA on
average.
Although
the unit firmware is open source, it is not freely available due to the risk of
access of non-amateur users to the APRS network. I will only share the Arduino
IDE format firmware via email and if your amateur radio callsign is confirmed.
The
unit connects to the South African APRS-IS server at http://www.aprs-za.com:14501 with full position reports and engineering
data available at aprs.fi.
Please
send me an email if there are any questions or you want a copy of the
firmware.
73,
Hennie, ZS6EY