How software-defined radio could revolutionize wireless

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In 1976, two shaggy-haired college dropouts founded a company called Apple to manufacture personal computers. The company's prospects looked so poor that the third co-founder relinquished his 10 percent stake in the company for $800 that same year. It simply wasn't clear why anyone would want the firm's Apple I computer. It was so under-powered that it couldn't perform many of the functions of mainframes and minicomputers that were already on the market. And most consumers had no interest in having a computer in their homes.

Today, of course, Apple is the world's largest company. What was important about the Apple I wasn't the meager capabilities of the original version, but the promise it held for rapid innovation in the coming decades.

Now, a company called Per Vices hopes to do for wireless communication what Apple did for computing. It is selling software-defined radio gear called the Phi that, like the Apple I, is likely to be of little interest to the average consumer (it was even briefly priced at the same point as the Apple I, $666.66, but has since been placed at $750). But the device, and others like it, has the potential to transform the wireless industry. This time, the revolution will depend on hackers enabled to manipulate radio signals in software.

The versatility of software-defined radio

Traditional radio chips are hard-wired to communicate using one specific protocol. For example, a typical cell phone has several different chips to handle a variety of radio communications: one to talk to cell phone towers, another to contact WiFi base stations, a third to receive GPS signals, and a fourth to communicate with Bluetooth devices. In contrast, software-defined radio hardware works with raw electromagnetic signals, relying on software to implement specific applications.

This makes software-defined radio devices tremendously versatile. With the right software, a single software-defined radio chip could perform the functions of all of those special-purpose radio chips in your cell phone and many others besides. It could record FM radio and digital television signals, read RFID chips, track ship locations, or do radio astronomy. In principle it could perform all of these functions simultaneously. Software-defined radio hardware also enables rapid prototyping of new communications protocols.

Software-defined radio will make it possible to use the electromagnetic spectrum in fundamentally new ways. Most radio standards today are designed to use a fixed, narrow frequency band. In contrast, software-defined radio devices can tune into many different frequencies simultaneously, making possible communications schemes that wouldn't be feasible with conventional radio gear.

Most significantly, the widespread adoption of software-defined radio hardware could undermine the FCC's control over the electromagnetic spectrum itself. Right now, the FCC largely focuses on limiting the transmission frequencies of radio hardware. But this regulatory approach is likely to work poorly for software-defined radio devices that aren't confined to any specific frequency.

The effective deregulation of the airwaves could create headaches as careless hobbyists pollute frequency bands that have been reserved for other applications. But it's also likely to usher in an era of unprecedented radio innovation as millions of people have the opportunity to experiment with technologies that, until recently, were the exclusive domain of well-funded industrial labs.

The pioneers

Software-defined radio has had political undertones since its inception. A decade ago, some early software radio enthusiasts became interested in the "broadcast flag" debate then raging in Washington. Hollywood wanted to force consumer electronics companies to detect and comply with metadata in HDTV broadcasts that would signal what consumers were allowed to do with television content.

Eric Blossom, founder of a software project called GNU Radio, hoped that implementing an HDTV receiver in software and releasing it as open source would demonstrate the futility of this approach. Even if the government forced his project to implement the broadcast flag, he argued, anyone could tweak the source to disable the broadcast flag code and then re-compile it.

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