IEEE Spectrum February, 2010 - 6

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wavelength this long is that it
can penetrate such obstacles
as concrete walls and work
in environments with large
amounts of metallic clutter.
This, the Dash7 advocates
contend, is more of a problem
for ZigBee, which employs
868 MHz, 915 MHz, or most
popularly, 2.4 gigahertz, the
last of which is also used for
many Wi‑Fi networks. Using
"2.4 GHz is really nasty in
environments with a lot of
metal," says Pat Burns, vice

president of marketing and
licensing for Savi Technology,
the Mountain View, Calif.,
company that first devised
the Dash7 technology.
Jon Adams, Freescale
Semiconductor's director
of business development
for wireless connectivity
operations and a former
vice chairman of the ZigBee
Alliance, is, however,
skeptical. "Wavelength is
only part of the equation,"
he says, adding that if the

A Critical Perspective
on Climategate

The disclosure of e‑mails and other
documents by scientists at the University of
East Anglia, in England, has aroused wide
consternation. The University of Alabama's
John R. Christy [above], an atmospheric
scientist who has taken a contrarian view
of the world's recent temperature history,
comments on the significance of the
British work and the implications of the
climate scandal. See http://spectrum.ieee.
org/energy/policy/critical‑perspective‑
on‑climategate.
10

NA * Ieee SpecTRum * FebRuARy 2010

only way for a radio signal to
pass into or out of a room is
through a window, a shorter
wavelength may, in fact, work
better. "I think some of what
we're hearing about Dash7 is
market positioning," he says.
The search for a market for
Dash7 isn't new. Savi began
developing this technology
two decades ago, intending it
initially as a way for parents
to keep track of their kids
during family outings. But
that application proved a
dud. According to Burns,
advisors told Savi's founders,
recent graduates of Stanford,
"You guys have to do a reboot
and find a different business
model." So they shifted
plans, and following the
first Gulf War, they began
selling active RFID tags
to the U.S. Department
of Defense for tracking
shipments of war materials.
The U.S. military
embraced this radio tagging
system and has been
employing it increasingly.
This, of course, has been a
boon for Savi. But in 2006,
the Defense Department
pressured Savi to license
its patents to several other
companies so that the military
wouldn't be dependent on a
single supplier. In January
of 2009, the DOD awarded
a US $428 million contract
for Dash7 RFID devices,
software, and services to four
companies: Savi, Northrop
Grumman, Systems &
Process Engineering
Corp., and Unisys.
In a move to expand its
reach into the commercial
sector, Savi joined with other
companies to form the Dash7

Alliance this past March. Savi
also liberalized its licensing
arrangements in October,
removing up‑front fees and
reducing royalties to as little
as 5 cents per tag, which,
according to Burns, has made
dozens of companies eager to
use Dash7 in their equipment.
One is RFind Systems,
of Kelowna, B.C., Canada,
which began more than
four years ago to develop
RFID tags that broadcast
their positions whenever
they are moved. Customers
might use this system
to locate pallets within
a factory or cars on a
dealer's lot, for example.
According to Sharon
Barnes, RFind's chief
executive officer, the
company's original tags
employed a proprietary
protocol to communicate
with one another and to
determine their location with
respect to a small set of fixed
tags. Now RFind is adopting
Dash7 to do the same.
The new technology has
clearly helped this company
refine its product line, but
Dash7's general claims for far
less power use than ZigBee
depend on the details of
how the particular wireless
network is set up. And its
promise of better range, too,
hinges on the environment
in which it is used. But
one uncontested attribute
of Dash7 is that its name
has a clear and sensible
derivation: It's a catchy
contraction for ISO 18000‑7.
That's something that
neither Wi‑Fi, nor Bluetooth,
nor ZigBee can boast.
-David Schneider
specTrum.ieee.org

phillip gentry/the UniverSity of alabama in hUntSville

Number of bits in the RSA encryption code recently cracked by scientists from europe and Japan. The attack required
the equivalent of 2000 cpu cores working for a full year to find the prime factors of a large number. The scientists say
that today's 1024-bit codes could be vulnerable within the decade.

http://www.spectrum.ieee http://specTrum.ieee.org

Table of Contents for the Digital Edition of IEEE Spectrum February, 2010