The bandwidth of data links to the ground or to satellite networks is paltry compared to today’s on-board
networking that fast Ethernet links provide. “You only
have a straw as a pipe to the ground or to the satellite,”
Ciufo says. It’s for this reason that today’s on-board
sensor-processing systems must be able
to handle as much
data as possible
on the unmanned
vehicle itself.
“That fabric for PCI
Express and 10-Gigabit
Ethernet can enable a
lot of interesting capabilities in technologies like 3U VPX, but
now we are going much
smaller,” says Curtiss-Wright’s Southworth.
Ultra-small processing
also necessitates the smallest possible I/O, Southworth
says. “We can port things like additional I/O integrated
right in the box,” he adds. “MIL-STD-1553 and ARINC-
439 databuses and CANbus for ground vehicles are
common in these ultra-small-form-factor boxes.
They also have open
slots to support some
add-on interface cards,
which are about the size
of business cards, that
are pre-fitted into these
card slots. With this,
the generic computer
becomes a customizable computer.”
Southworth says customers of Curtiss-
Wright typically know how many extra net-
working and I/O interfaces they need in each
sensor-processing subsystem. “We can inte-
grate that in the boxes we make, and the cus-
tomers will have all the throughput they need.”
One trusted partner of Curtiss-Wright’s for rug-
gedized MIL-STD-1553 and ARINC 429 avionics databus
interfaces is Data Device Corp. (DDC) in Bohemia, N. Y.
One promising data pipe for unmanned sensor pro-
cessing is Universal Serial Bus (USB) 3.0, Southworth
points out. USB 3.0 can transfer data as quickly as
5 gigabits per second. Its successor, USB 3. 1, doubles the
speed, and can transfer data as quickly as 10 gigabits
per second. These data pipes are becoming common on
PC laptop and desktop computers.
“When it comes to ruggedization,
USB 3.0 takes some spe-
cial care,” Southworth
says. “Your cable length
for USB 3.0 will not be
at its full potential, and
you may need shorter
cable runs. You need to make
sure your connector interfaces can
handle the signal from that connection.”
Precision timing
A key component of on-board sensor networking is
precision timing, such that processors and nodes
on the network can be synchronized with nanosecond accuracy.
“Modern processors and communications devices
would come to a halt if they weren’t able to synchronize
their devices,” says Curtiss-Wright’s Southworth.
One accepted industry standard for network pre-
cision timing is the IEEE 1588 precision time
protocol (PTP), which helps synchronize clocks
throughout a computer network. It is designed
for local systems that require accuracies
beyond those attainable using Network Time
Protocol (NTP), as well as for applications that
neither can bear the weight or cost of a sepa-
rate GPS receiver at each node, nor for
which GPS signals are inaccessible.
IEEE 1588 “is an increasing require-
ment in unmanned vehicle Ethernet
networks,” Southworth says. It’s not
just for synchronizing networking
nodes, but also for unmanned vehicle
navigation in areas where signals from
Global Positioning System (GPS) satel-
lites are jammed or otherwise denied.
The military has one program of
record called Mounted Assured Position, Navigation,
and Timing (MAPS), Southworth says. “The goal is to
leverage redundancy in position, navigation, and tim-
ing [PNT] by distributing PNT timing,” he says. “You
The Parvus DuraCOR 312
from Curtiss-Wright Defense
Solutions is an ultra-small
form factor embedded
mission computer built
around the NVIDIA Jetson
Tegra X2 (TX2) integrated in
a miniature rugged chassis
with MIL-grade, high-
density connectors.
Mercury’s Ensemble HDS6603
high-density embedded server
offers more than one tera-
FLOP of general processing
power in an OpenVPX slot.
It has two 1.8-GHz Intel
Xeon E5-2600 v3 processors,
each with 12 cores to deliver
image- and video-processing
power for unmanned vehicles.
