  We report on the development of the seven station ARIANNA Hexagonal Radio
Array neutrino detector systems in Antarctica. The primary goal of the ARIANNA
project is to observe ultra-high energy (>100 PeV) cosmogenic neutrino
signatures using a large array of autonomous stations each dispersed 1 km apart
on the surface of the Ross Ice Shelf. Sensing radio emissions of 100 MHz to 1
GHz, each station in the array contains RF antennas, amplifiers, a 2 G-sample/s
signal acquisition and trigger circuit I.C. (the "SST"), an embedded CPU, 32 GB
of solid-state data storage, a 20 Ah LiFePO4 battery with associated battery
management unit, Iridium short-burst messaging satellite and long-distance WiFi
communications. The new SST chip is completely synchronous, contains 4 channels
of 256 samples per channel, obtains 6 orders of magnitude sample rate range up
to 2 GHz acquisition speeds. It achieves 1.5 GHz bandwidth, 12 bits RMS of
dynamic range, ~1 mV RMS trigger sensitivity at >600 MHz trigger bandwidth and
ps-level timing accuracy. Power is provided by the sun and LiFePO4 storage
batteries, and the second-generation stations consume an average of 4W of
power. The station's trigger capabilities reduce the trigger rates to a few
milli-Hertz with 4-sigma thresholds while retaining high efficiency for
neutrino signals.
