Software-Defined Radio: the Apple I of Broadcast? 153
benfrog writes "A company called Per Vices has introduced software-defined radio gear that Ars Technica is comparing to the Apple I. Why? Because software radio can broadcast and receive nearly any radio signal on nearly any frequency at the same time, and thus could 'revolutionize wireless.' The Per Vices Phi is one of the first devices aimed at the mass hobbyist market to take advantage of this technology."
USRP is expensive (Score:5, Informative)
The USRP is really cool, but stupidly expensive. Some really cool stuff is happening with the RTL2832 based TV dongles, though. These are $20 devices that can be used to receive from ~64-1700 MHz (or DC-30ish with a little tweaking). So far, much of the info is here [reddit.com]
The USRP would be cool if current PCB layouts and schematics were available or if the development effort went to a system that wasn't just making Ettus a profit. A truly open development platform would really benefit the SDR community.
Re:News Release (Score:5, Informative)
gnuradio just wasn't sexy enough, I guess. Not enough like arduino on the tip of everyone's tongue.
The device [pervices.com] in TFA is a piece of hardware designed to support gnuradio(it might support other things as well; but a gnuradio interface is explicitly mentioned in the device specs).
Gnuradio is just the software side. Traditionally, the USRP has been the peripheral of choice. Not cheap; but configurable for a wide range of frequencies and probably the most mature. A sound card(with appropriate external circuitry bringing things down to audio frequencies, of course) is also an option, and certain flavors of DVB TV receiver dongles are the new hotness in the cheap seats.
This "Phi" device lacks some of the versatility of the classier USRP gear; but it is cheaper and offers a very fast interface to the host computer...
Unlike 'Arduino', where the term refers more or less interchangeably to both the software development environment and to a variety of atmega-based microcontroller boards, Gnuradio is just the software side. There is no 'gnuradio' hardware per se, as there is with Arduino. The USRP is probably the closest to being that; but it is pricey enough to be out of the hands of a great many hobbyists.
so? old hat. (Score:5, Informative)
hams have had SDR for a decade more or less. and software-controlled radio back a little longer. and I seem to remember a win95 radio card that slid into an AT slot back in the mid or late 90s...
The FCC heavily regulates SDRs (Score:5, Informative)
A few of the relevant obstructions in the form FCC regulations and laws are: 47 USC 2.501, 47 USC 302, 47 USC 605, 47 CFR 2.944, 47 CFR 15.3 (dd).
47 CFR 2.944:
Software defined radios.
(a) Manufacturers must take steps to ensure that only software that has been approved with a software defined radio can be loaded into the radio. The software must not allow the user to operate the transmitter with operating frequencies, output power, modulation types or other radio frequency parameters outside those that were approved. Manufacturers may use means including, but not limited to the use of a private network that allows only authenticated users to download software, electronic signatures in software or coding in hardware that is decoded by software to verify that new software can be legally loaded into a device to meet these requirements and must describe the methods in their application for equipment authorization.
(b) Any radio in which the software is designed or expected to be modified by a party other than the manufacturer and would affect the operating parameters of frequency range, modulation type or maximum output power (either radiated or conducted), or the circumstances under which the transmitter operates in accordance with Commission rules, must comply with the requirements in paragraph (a) of this section and must be certified as a software defined radio.
(c) Applications for certification of software defined radios must include a high level operational description or flow diagram of the software that controls the radio frequency operating parameters.
[70 FR 23039, May 4, 2005]
The penalty for a violation is forfeiture, a fine of up to $10,000, and up to one year in federal prison. See 47 USC sec. 501 This applies to person who purchase the radios as well as persons who sell them. See 47 USC sec. 500 et. seq.
Various internet sources assert that SDRs are "test equipment" and excluded under 47 CFR 15.3 (dd), which reads:
(dd) Test equipment is defined as equipment that is intended primarily for purposes of performing measurements or scientific investigations. Such equipment includes, but is not limited to, field strength meters, spectrum analyzers, and modulation monitors.
I find it difficult to believe the FCC would classify the various SDRs as test equipment, but we will probably find out soon enough.
http://www.law.cornell.edu/cfr/text/47/2.944 [cornell.edu]
http://www.law.cornell.edu/uscode/text/47/501 [cornell.edu]
Before you downvote me because you don't like the laws; consider this: I posted this information because we must change these laws rather than suffer them.
Obnoxious Apple Namedropping (Score:2, Informative)
Re:Eh? (Score:5, Informative)
Not really.
There are large blocks of spectrum already set aside for use of personal radio devices. Just about anything goes in those bandwidths, subject only to power limitations and staying inside of the spectrum block.
The FCC is all for this type of use. The FCC is also fully in favor of reallocation spectrum when the situation and demand changes, which is why analog TV is a thing of the past.
There is precedent for this.
Re:The FCC heavily regulates SDRs (Score:5, Informative)
There is basically no regulation on SDRs.
Receivers - well, you have normal receive rules, though the cellphone one is pretty much invalid these days as no one uses AMPS anymore.
Transmitters - the rule basically says if you have a software transmitter, that software better only allow transmission on the licensed bands.
There aren't any special rules other than "don't transmit where you're not licensed to". The rule for software options is basically ensuring that the user cannot misprogram their transmitter and operate out of band and interfere with other licensed services.
It's the same as an old style transmitter - care should be taken so users cannot readily change the operating frequency and power so they create interference.
And yes, the fines are like that because they apply to unlicensed transmitters as well - if you're transmitting on a band you're not supposed to, you, the user can find your equipment confiscated and fined.
The law is perfectly adequate - manufacturers need to ensure their SDR cannot be used out of the licensed bands (and power envelopes). It's an "SDR" rule because in an old style transmitter, the output stages normally dictate that you can't transmit out of band anyhow without retuning. But since an SDR can be free to transmit on any band without limitation, the software must ensure it's within the license and the user can't trivially modify it to be out of spec.
SDRs are everywhere - the modern cellphone, wifi radio, bluetooth, etc., they're all SDRs internally. These normally have very specific front ends and filters so even if you could set them out of band, they are out of tune and don't transmit squat.
It's a fair rule and prevents frequency anarchy (and frequencies are set aside for various uses).
Re:News Release (Score:5, Informative)
(And, indeed, this does seem to have spurred greater interest among people who weren't in for a USRP; but were interested. The fact that SDR involves substantially more nontrivial math than many arduino projects probably limits the mass appeal some, though.)
Re:Pirate radio? (Score:4, Informative)
Technical Specifications and Support [pervices.com]:
Nope ... RX/TX. If you'd read the article by the way, it should have been clear they wanted a SDR that goes both ways. Of course it doesn't really have an amplifier to speak of, so you can't just hook up an antennae to it and expect to work the world. Especially if you want to output multiple signals in multiple bands, as mentioned in the article, things can get very hairy at the transmission end. By the way, good, distortion free, broadband amplifiers aren't cheap as well and come with their own set of problems.
The idea might be nice, an 'open source' spectrum, and for the receiving end it's all fine and dandy. I'm not a proponent, of security through obfuscation/obscurity, so regulation of waves receiving: Governments, just grow up!
But even at low power conditions, for certain frequencies, you don't want to have transmission capabilities in the wrong hands (read: someone who hasn't at least got a a HAM Radio license. A degree in Electronics, Electromechanics, Physics might suffice as well... if it has covered the correct subjects). Things can turn out very nasty even at low power situations. Things like GPS will stop working, or other satellite signals jammed. Many satellites only transmit at an order of 10-100 watts. The amount of signal left when received on earth is miniscule. A little more power and things like Wifi and RC toys/remote controlls/bluetooth will be affected. Digital broadcasting is next I think... including mobile phones and portophone systems there isn't nearly as much robustness in there as there was with the old analogue signals... As they digitized the signals, they could cut bandwith and power requirements... Nice for energy savings and miniaturization of systems but it does mean it can be jammed easier, even if there is overhead in the protocol for error correction. Well .. you'll get the picture.
While I agree this sounds like a better deal for radio enthousiasts than the Ettus USRP and I'll be itching to get my hands on one of these, color me sceptic about the whole low power broadband broadcast 4 noobs vibe the Per Vices founders seem to transmit.
73. PG8W.
Re:Only half of the widget... (Score:3, Informative)
You can fudge quite a bit on a receiving antenna, not so much with a transmitting antenna...
None of the uses in the quote you objected to require a transmitting antenna.
True. That's a good point. However, consider the enormous range of those services:
RFID: 120 KHz - 10 GHz (Generally below 2.4 GHz, with LF and UHF tags being common)
FM Broadcast: 88 MHz - 108 MHz
DTV: 55 MHz - 700 MHz (Three bands, ~55-85, ~175-210, ~470-700)
Radio Astronomy: 13 MHz - 0.8 THz or something equally nuts way up there (The VLA receives below 50 GHz)
That's way outside the scope of getting an antenna to fudge on receive. We're talking wavelengths from ~1.5 MILES to under half a millimeter !
Unless Scotty beams down and hands us an antenna from the future, TFA's mega-broadband SDR described as doing all that at the same time is science fiction. I'll buy that SDRs could possibly handle that kind of bandwidth sometime soon, but there's no way we're going to see a practical antenna system shipping with it.