[Discuss-gnuradio] Salon - Radio Free Software

[Tim Pozar]

http://www.salon.com/tech/feature/2002/12/18/gnu_radio/index.html

Radio Free Software

Call them hackers of the last computing frontier: The GNU Radio
coders believe that any device with a chip should be able to do,
well, anything.

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By Sam Williams

Dec. 18, 2002  |  It's the vision that elicited a beatific smile
from Alan Turing, a Bela Lugosi-like cackle from John von Neumann,
and a cannabis-tinged giggle from 1970s-era PC creators: Imagine a
universal machine, a computation device capable of mimicking the
functionality of any other machine.

OK, now imagine the looks of terror on the faces of existing machine
makers. Imagine if the only thing stopping your handheld PDA from
simultaneously being a GPS receiver, phone, radio or miniature TV
was your willingness to download and install some free software
program.

For Eric Blossom, founder of the GNU Radio project, the vision plays
itself over and over again, like a Mbius film strip. An electrical
engineer by trade, Blossom knows better than most the thin barriers
that separate one person's garage-door opener from another person's
global positioning satellite receiver. He also knows the proprietary
barriers that hinder technological innovation. Rather than curse
those walls, Blossom has decided to gut the floor plan entirely
with the help of free software. Sony, Philips and Nokia be damned.

"We're pretty much turning all hardware problems into software
problems," Blossom says. "We want to facilitate evolution in the
radio arena."

Turning hardware problems into software problems is, of course, an
old trick. Since the days of Univac, computer programmers have
written software to mimic the functionality of everything from
mechanical calculators to videocassette recorders. Wireless
communication devices -- radios, cellphones, televisions, etc. --
are merely the latest target, especially now that most carry
sophisticated microprocessors. With device manufacturers jealously
guarding hardware specs, however, the challenge to an independent
programmer is stiff. To get the GNU Radio project started, Blossom
has set his sights on a simple target: PC-based AM/FM radio.

"Radio has always been this dedicated hardware universe, a closed
system really," says Blossom. In other words, it was just the kind
of private party that free software was meant to crash. "Besides,
we had prove we could deliver on the basic idea," Blossom says.

So far, the GNU Radio project has made good on its promise. Blossom
and development partner Matt Ettus have developed a software program
that can make a PC receive two radio stations simultaneously. The
only additional hardware components needed are a low-cost R.F.
tuner, to pull the radio waves out of the air, and an analog-to-digital
converter to convert each signal into digital samples.

Playing two stations at once may seem like a geeky pastime, but GNU
Radio's goals get more ambitious over the long term. At its most
basic level, GNU Radio is an attempt to do for radio-software
developers what the original GNU Project did for Unix developers
-- that is, provide a common set of nonproprietary tools that can
be ported from one device to the next.

Step back a little, however, and GNU Radio changes shape. Viewed
against the backdrop of digital "convergence," the marketing term
for pouring data and communications functionality into a single
device, GNU Radio becomes a steppingstone to the ultimate hybrid
device: a handheld PC that can be converted into a walkie-talkie
one minute and an HDTV the next.

"We're bringing the free-software ethic to radio," Blossom says.
"Who knows what's going to come out of it?"

But that's not all: Even more intriguing is GNU Radio's political
component. A look at recent Hollywood-backed legislation reveals a
growing antipathy on the part of content providers toward modifiable
consumer technology. Such laws, if passed, would limit the ability
of hardware manufacturers to consort with software programs that
let a user turn his or her home PC into a digital television or
TiVo-style recorder.

Viewed against this backdrop, GNU Radio is a hacker's version of
the preemptive strike. Rather than wait for Washington to set limits,
the project is working to undermine existing device barriers.

"It shows pretty starkly what's at stake: that computer technology
can empower people to do new and interesting things," says Edward
Felten, a Princeton computer science professor whose Web site,
Freedom To Tinker, has been offering periodic updates on the project.
"And yet it is the very power and adaptability of that technology
that people are most afraid of."

According to Blossom, the GNU Radio project grew out of a seven-year
stint working on cellphone security. Early on, Blossom discovered
the dirty little secret of the cellphone industry: Most digital
cellphone manufacturers ship their devices with weakened encryption
to stay in the good graces of the government and rely on secondary
methods -- proprietary hardware, arcane software protocols -- to
frustrate amateur snoopers.

"Contrary to what the cellphone operators were saying," Blossom
says, "digital cellular phones could be easily intercepted by an
adversary with the right equipment."

That realization soon led to a larger realization: If a device could
be mimicked by the right equipment, it could also be mimicked with
software. Blossom began taking an active interest in software-defined
radio, or SDR, an engineering subfield dedicated to transporting
circuit-based tasks into the realm of software.

"You can think of it as a set of building blocks," Blossom says.
"Mixers, phase lock loops, filters: All the things you build into
an ordinary radio device can be built using software. You just need
a way to tie them all together."

In early 2000, Blossom began working on the PC radio-software kit.
Frustrated by the proprietary nature of most SDR projects, Blossom
began looking for ways to import the "free software" ethic into the
SDR development community. He broached the idea of a free-software
SDR project to John Gilmore, GNU Project veteran and co-founder of
the Electronic Frontier Foundation. Gilmore subsequently ran the
idea by GNU Project founder Richard Stallman, who agreed to take
the project under the GNU aegis.

"We'd been doing the project for a while and were still kicking
around for a name," says Blossom. "So it helped us on two fronts."

Renamed GNU Radio, the project's political implications became clear
a few months later. Faced with an FCC-imposed deadline to convert
all television content to digital content by 2007, Hollywood studios,
together with information technology companies and consumer electronics
manufacturers, have been wrangling over how to prevent a widescale,
Napster-style redistribution of digital movies. The tentative
solution, put forward by a joint committee last winter, is to embed
an invisible software signal or "broadcast flag" within the content
of every digital broadcast, making it possible to record but not
redistribute digitally broadcast television programs.

Such hobbling of recording devices is an old trick, as any person
who has tried to duplicate a Macrovision-protected VHS tape knows.
Unlike past efforts, however, the broadcast flag would be entirely
software based, giving those who know software intimately the ability
to develop a quick workaround. To work effectively, the standard
would require new federal regulations requiring that all consumer
devices not only comply with the standard but also restrict the
amount of tinkering an end-user would be able to do with a legally
owned device.

Noting that the GNU General Public License absolutely forbids any
restriction on a user's right to modify, Brad Kuhn, executive
director of the Free Software Foundation, the organization that
oversees the GPL, says such a regulation would amount to a marketwide
ban on GPL-protected software.

"There's no feasible way we could develop devices that adhere to
the mandate of the broadcast flag," says Kuhn. "We could add a
no-record feature, but anybody along the distribution chain would
have complete freedom to remove it."

Faced with this potential challenge, Blossom and Ettus began writing
a software tuner capable of translating digital television signals.
They released an alpha version in early November, less than a year
later.

Ettus, a fellow electrical engineer, sees the overall speed of the
GNU Radio project as a clear indicator of how "empowering" the
software-driven radio approach can be.

"To create a new HDTV chip from scratch would take probably 50
engineers, one to two years, and a $12 million investment," says
Ettus. "Taking the software route, it's been less than a year and
it's been mostly the two of us, and I'm working only in the evenings."

For the FSF, such comments lay the groundwork for a bold political
strategy. No longer content with matching proprietary developers,
the Boston-based organization hopes to use the GNU Radio project
as a prime example of innovation that will be crushed by any
congressional legislation or FCC regulation that seeks to limit
device functionality, at least on the receiving end. Put another
way: If the GNU Radio team can develop a proof of concept before
the FCC gets a chance to rule on the "broadcast flag" proposal, the
FSF and its allies in the consumer and small-business community
will have seized the high ground in the subsequent legal battle
over innovative fair use.

"From our point of view, GNU Radio is the technological proof that
interesting things can be done and that those things can also be
taken away," says Kuhn.

Since backing GNU Radio project, the FSF has sought ways to build
the momentum. Earlier this year, the organization launched the
Digital Speech Project, a Web site that keeps track of ongoing
congressional debates that could, potentially, have an impact on
innovation and fair use. The project seeks to build a "grass-roots
coalition" of students, musicians, artists and software developers
to repeal the 1998 Digital Millennium Copyright Act.

"At FSF, we have little choice but to enter this battle and take
an active role," writes Kuhn via e-mail. "We also know that we can't
win this fight alone; we need allies."

As for Blossom, he hopes GNU Radio opens the way to even more
innovation. The reality of a universal device may still be a ways
off, but as the free-software tools pile up, developers and consumers
will have that much more to work with.

"Technology ought to be useful to people," Blossom says. "Ultimately,
this will put a lot of technology decisions in the user's hands,
which should speed up innovation considerably. That doesn't mean
every user has to be a software developer, but it does mean the
freedom to innovate is there."