  Location tracking with global navigation satellite systems (GNSS), such as
the GPS, is used in many applications, including the tracking of wild animals
for research. Snapshot GNSS is a technique that only requires milliseconds of
satellite signals to infer the position of a receiver. This is ideal for
low-power applications such as animal tracking. However, there are few existing
snapshot systems, none of which is open source. To address this, we developed
SnapperGPS, a fully open-source, low-cost, and low-power location tracking
system designed for wildlife tracking. SnapperGPS comprises three parts, all of
which are open-source: (i) a small, low-cost, and low-power receiver; (ii) a
web application to configure the receiver via USB; and (iii) a cloud-based
platform for processing recorded data. This paper presents the hardware side of
this project. The total component cost of the receiver is under $30, making it
feasible for field work with restricted budgets and low recovery rates. The
receiver records very short and low-resolution samples resulting in
particularly low power consumption, outperforming existing systems. It can run
for more than a year on a 40 mAh battery. We evaluated SnapperGPS in controlled
static and dynamic tests in a semi-urban environment where it achieved median
errors of 12 m. Additionally, SnapperGPS has already been deployed for two
wildlife tracking studies on sea turtles and sea birds.
