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First Fully Digital Radio Transmitter Built Purely From Microprocessor Tech
Zothecula writes For the first time in history, a prototype radio has been created that is claimed to be completely digital, generating high-frequency radio waves purely through the use of integrated circuits and a set of patented algorithms without using conventional analog radio circuits in any way whatsoever. This breakthrough technology promises to vastly improve the wireless communications capabilities of everything from 5G mobile technology to the multitude devices aimed at supporting the Internet of Things (IoT).
The 1620 was an all digital machine built of discrete transistors. As an undergraduate, we wrote programs that caused the machine to alternate between two loops at a variable rate. The computer radiated so many harmonics that this could be heard all across the AM band where no strong station existed. We programmed it to play (mostly) classical music, "Flight of the Bumblebee" was the perennial favorite. Any truly all digital transmitter will generate harmonics outside of the allowable FCC band, so at the very least they need a really good analog bandpass filter on the output.
The article says: "The Pizzicato digital radio transmitter consists of an integrated circuit outputting a single stream of bits, and an antenna ".
That doesn't sound like 'Purely from Microprocessor Tech' to me. It sounds like a strap-on peripheral chip, which is not at all 'Purely microprocessor.'
Most of the people commenting on this story have no clue about signal processing or radios. It is quite possible to feed a "stream of bits" to an analog filter and create a clean analog signal. This is effectively what 1-bit delta-sigma data converters do, and it is close to what Class-D audio amplifiers do. The trick is indeed doing this with wide bandwidth signals and sufficient oversampling to have good signal quality. To get wide bandwidth at 5GHz, they probably are running the sampling rate in the GHz range to get a few 10's of MHz bandwidth and picking off (filtering/selecting) a harmonic at 5GHz. An antenna and matching network are a type of filter network. There's a lot of innovation in these areas, and it's annoying to see uniformed /.'ers dumping on an area they don't understand.
The posts here I'm referring to are mindlessly dumping on the whole idea or possibility of there either being anything novel here or that it would actually work. Similar techniques are quite common in signal processing and audio, and we've been approaching all-digital radio technology incrementally for about 20 years now. The biggest novelty here is that they're claiming to be effectively all digital at 5GHz. While "Microprocessor Tech" may be an annoying marketing buzzword or mangling of terminology, the digital techniques and circuitry are valid, some of them are probably novel, and there are indeed many similarities to digital processing circuits found in microprocessors, as the original press release states. There's hype in their release about "no traditional radio parts," where there's likely to be at least an antenna match, but that's not the level of detail these folks are writing about here. Disappointing for a technology oriented site.