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The Journey of Radios From Hardware to Software
Posted by
Zonk
on Sat Sep 22, 2007 10:15 PM
from the wave-of-the-future dept.
from the wave-of-the-future dept.
An anonymous reader writes "The New York Times is carrying a story all about the process of replacing radios with software. The article tells the tale of Vanu Bose, son of the man who started the Bose company, and his quest to bring software to what was previously a hardware-only enterprise. He met a lot of resistance in the 90s to his ideas, because processor technology was not up to the task. Now that technology has caught up with Vanu, his software (and other products like it) are increasingly replacing now-outdated hardware components. 'Well-established companies like Motorola and Ericsson now use elements of software-defined radio for their base stations. But Mr. Bose was the first to come to market with software that could handle multiple networks with the same equipment. Software radio appears to offer an elegant solution to what has been a vexing problem: how to have a single handset, like a cellphone, communicate across multiple networks. For instance, the G.S.M. standard, for global system for mobile communications, is used broadly in Europe, and most notably in the United States by AT&T.'"
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An interesting idea (Score:4, Interesting)
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Re:An interesting idea (Score:5, Informative)
Well, yeah. Square wave outputs do tend to generate alllll sorts of harmonics. But it does technically work. If I were serious about it, I'd at least add a capacitor across the output, to make some attempt at filtration.
The "schematic" involved an 8-pin microprocessor, with two outputs each connected to a 1k resistor. The other ends of both resistors were connected to the antenna. Not very efficient, but as a proof of concept, it was a cool toy. Tuning was completely via software (tweak the timing loop to provide the correct waveform.)
You want pictures? Happy to oblige. (The idea was to see just how simple a transmitter I could make...)
http://www.intellectualism.org/electronics/schematic.jpg [intellectualism.org]
http://www.intellectualism.org/electronics/Closeup.jpg [intellectualism.org]
Parent
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Why do you have two outputs from the IC?
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Re:An interesting idea (Score:4, Informative)
Bottom line - the harmonics can be taken care of by wave-shaping, i.e. you take the output load configuration into equation as you design the radio.
Parent
Obvious Next Step (Score:2)
Re:Obvious Next Step (Score:4, Insightful)
Parent
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Re:Obvious Next Step (Score:4, Insightful)
Parent
Software radios are awesome! (Score:2, Offtopic)
It's the multiplexing (Score:5, Informative)
It's not that a single software-defined radio is all that important. It's that you can do the transforms on the incoming waveform and then extract N different channels with one signal processing system. That's what's been making cellular base stations go for almost two decades. (All the hard work is on the receive side; transmission is easy.)
First generation cellular base stations (i.e. AMPS) had one big analog card per channel, each heavily shielded from its neighbors. The amount of hardware required was huge, and cell sites tended not to be fully populated with channel cards, so they were easy to overload.
Then things started to go digital, with combinations of analog and DSP components processing the signal. Both GSM and CDMA inherently assume digital processing, and in early systems, hard-wired special purpose components were used. As CPUs get faster, there's a steady trend toward using general purpose CPUs.
It's still rare to actually process RF directly in software. Usually, there's a local oscillator and mixer to down-convert the desired band to a working IF frequency, which is then digitized and processed. So it's only necessary to digitize at maybe 10-100MHz, not up in the gigahertz range.
For lower bands, though, a true software RF receivers [rfspace.com] are available. These just suck up everything from 0 to 30MHz and digitize it. An attached PC does all the hard work.
Maybe use block frequency converters? (Score:3, Interesting)
didn't someone ... (Score:2, Interesting)
Re:didn't someone ... (Score:4, Interesting)
That's an oversimplification, but it may be what you were thinking of.
Parent
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Nyquist apply to the signal you want to process. If you want to do your filtering in the digital domain you will first have to capture both your wanted signal and the signals you seek to suppress. Otherwise you have your selectivity in your hard-ware and not in your software.
The function of "ADC with lots of front-end bandwidth" is what the hardware in the RF front-end is doing in a traditional radio system.
In GSM you must be able to detect your own signal at say -108dBm while you have a blocker at 0d
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If your radio is entirely based on software, then you'll need to do the filtering and de-modulation using digital filters and that will handle the "entire" wave and will actually nee
Two Words (Score:5, Informative)
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Even if you're not an amateur radio operator, it's worth checking out if you're interested in SDR. And the banquet speaker this year is Bruce Perens of Debian and OSI fame.
http://www.tapr.org/dcc [tapr.org]
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I figure in a few more years we'll get cheap SDR.
Re:Two Words (Score:4, Informative)
You can use a capture card with a BT878 chip as a cheap entry into SDR and GNU Radio. See Here [domenech.org]
The card I have didn't require any kind of modifications, and I've successfully captured signals all the way up to about 400kHz directly from the air simply using a long wire, including digital radio (the unfortunately named DRM [wikipedia.org]) signals.
Parent
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Three Letters (Score:2)
http://www.dslreports.com/forum/r18623835-FCC-says-freeopen-source-software-radio-drivers-are-OK/ [dslreports.com]
I read this and... (Score:2)
I read this and end up believing that my next radio will be delivered to me as a software printout on a sheet of paper.
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I read this and end up believing that my next radio will be delivered to me as a software printout on a sheet of paper.
Typing in program listings? I thought that had pretty much died out by the end of the 1980s, and thank God for that. It was a PITA back then, can you imagine how long it would take you to type in software nowadays? If we generously assume that one can fit a 16KB BASIC listing onto one A4/legal-sized page, a 16MB program (pretty small by today's standards) would require 1000 pages!
(Meanwhile, a double-layer DVD's worth of data would need roughly half a million pages, so you'd need a small truck to deliver
Cell Phones (Score:2, Interesting)
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gnuradio (Score:2)
if anyone's interested, more here:
http://www.gnu.org/software/gnuradio/doc/exploring-gnuradio.html [gnu.org]
and a bunch of links on wikipedia:
http://en.wikipedia.org/wiki/Gnuradio [wikipedia.org]
Not the first time I noticed this (Score:3, Interesting)
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Emergency Communications (Score:3, Interesting)
The DoD's new Software-based Radio (Score:4, Interesting)
That's a direct quote from the Wikipedia article (which looks like it's pretty accurate), located here: http://en.wikipedia.org/wiki/JTRS [wikipedia.org]
I'm in the Army, and buddies of mine have played with it and can attest that "it's pretty cool"
You should see the aerial.. (Score:2)
The aerials for these things are mostly ignored but are nothing short of impressive.
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Software radio scaners (Score:2, Interesting)
http://groups.yahoo.com/group/gnu_radio_scanner/ [yahoo.com]
This is a group looking to build on the GNU Radio blocks.
GNU Radio (Score:2)
Software replacing hardware... (Score:5, Interesting)
There are just two big problems that have made software control a non-starter.
First is customization. Put a spring in the mechanics of an engine, and I can replace it with a shorter/longer/stronger/weaker spring. I can heat it up to weaken it, grind it down, etc... With software, you are given a black box, binary-only, with no documentation on how it works, and definitely no common interface to access and modify it. So every time car companies add another function to their cars' onboard computers, and take away mechanical systems, there's extreme resistance, as buyers know they're out of the loop, and if they want to adjust anything, or if something should go wrong, they can only take it to the select few company-blessed shops, which have paid the necessary bribes to get enough info to do just a few basic things with the onboard computer. And you're entirely screwed if you want more changes than that, because the company doesn't WANT you to, and without man millions of dollars on the line, you're not even a blip on their radar.
Despite what many believe, cost is almost never a problem. For low cost products, low-end micro-controllers can be found for pennies, and even cheaper are the basic I/O elements like thermistors, power meters, transistors, relays, etc. Yet even the dirt cheap processors sold today can do many millions of calculations per second, far faster than could be needed for damn near any products.
Second, and perhaps more important, is reliability. Computer hardware is EXTREMELY reliable. You can go buy a dirt cheap commodity CPU, RAM and MOBO, and be pretty damn sure it will run for 20 years without a SINGLE error. The only big exception to this is power supplies... a marginal one, not supplying enough power will cause a crash, but that generallyonly happens in the case of the cheapest no-name junk. What's more, go up a small step to a high quality MOBO, ECC RAM, redundant PSUs, UPS, etc., and you'll never ever see a hardware-induced glitch.
The reliability problem comes ENTIRELY from poor software, and mostly commonly available kernels, at that. People don't want to believe that, but the facts are that computers are 100% pure math machines, and math is 100% accurate. A computer will do exactly what you tell it to do, but most people are trying to program their computer through several million lines of indirection... If you write, in hex, a simple loop with a bit of processing, a computer will run it error-free, from here until doomsday, but programing a complex system in hex is much too hard, and human programmers aren't perfect enough to do so.
The only real possibility to ensure reliability with reasonable development time is something very much like a micro-kernel. You need a tiny bit (a few hundred KBs) of EXTREMELY-thoroughly audited code, that can very strictly manage memory, do strict input and bounds checking, carefully manage communications between independent modules of code, instantly tear-down and restart any bit of code which shows the slightest signs of an error, and also strictly ensuring real-time operation.
I'm not endorsing any product here. The fact is nothing like this exists. That is why we aren't seeing mechanical systems having components being replaced by software as quickly as they can be redesigned. Open source operating systems
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Re:A little too much feature creep. (Score:4, Insightful)
This is about radios in a variety of communication devices. Like cell phones. And cell phone towers. Especially cell phone towers. Not so much your Sony Walkman et al.
Parent
Looking in the wrong section. (Score:3, Interesting)
Why does it have to "not look like crap?" Why can't it look like you didn't overspend on sony quality?
Now.. whatever happened to mass-produced small crystal radios? Those'd be interesting for hurricane kits, especially if they could tune the broadcast FM band (but obviously not as an FM receiver. You can still hear FM with an AM reciever, it just doesn't sound all that great. Voice is fine, though.)
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Mod parent up (Score:2, Informative)
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No highs, no lows, gotta be Bose.
Re:Bose blows (Score:5, Funny)
Only midrange! Must be Bose.
Parent
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Ok, I'll bite.
I worked years ago in the Audio department at a best buy. I don't know the current state of home electronics, but I know what the mid-range state of electronics was about, oh, 8 years ago.
If Bose is not a quality audio solution, then who is? Are we back to Sony, Pioneer?
I'd rather have EITHER of those brands of speakers over bose. Any day. We also sold Cerwin Vega and JBL and yamaha, and I'd rather have any of those. The only brand that I'd buy bose over was "KLH", which was our generic h
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As for paying no royalties, I guess it's not the same as owning the patent. I wonder how it works