Beta
×

Welcome to the Slashdot Beta site -- learn more here. Use the link in the footer or click here to return to the Classic version of Slashdot.

Thank you!

Before you choose to head back to the Classic look of the site, we'd appreciate it if you share your thoughts on the Beta; your feedback is what drives our ongoing development.

Beta is different and we value you taking the time to try it out. Please take a look at the changes we've made in Beta and  learn more about it. Thanks for reading, and for making the site better!

Software-Defined Radio For $11

timothy posted more than 2 years ago | from the us-dollars-of-course dept.

Communications 171

Malvineous writes "Don't have $1500 to drop on a USRP? A Linux kernel developer has discovered that a Realtek digital TV tuner chip has an undocumented mode that turns it into a software-defined radio, with a frequency range of 64-1700MHz. The going rate for one of these USB devices can be as low as US$11. If you're unfamiliar with software-defined radio and have 20 minutes to spare, Balint Seeber has a great video introduction."

Sorry! There are no comments related to the filter you selected.

first? (-1)

Anonymous Coward | more than 2 years ago | (#39535875)

First?

better get (-1)

Anonymous Coward | more than 2 years ago | (#39535883)

your f'ing FCC license, freebanders!

Re:better get (0)

Anonymous Coward | more than 2 years ago | (#39535955)

not if they're receiving only. doubtful the thing can transmit.

Re:better get (2)

fuzzyfuzzyfungus (1223518) | more than 2 years ago | (#39536059)

The widgets with this chip are all designed as TV-receiver USB widgets. I'm sure that there are some $11 electronics out there that are... um... totally FCC part 15 compliant; but no intentional radiating is going on.

Re:better get (-1)

Anonymous Coward | more than 2 years ago | (#39536087)

What's the definition of confusion? Saying "Yo Mohammed!" to a bunch of camel-jockey towel-heads.

Re:better get (5, Insightful)

Anonymous Coward | more than 2 years ago | (#39536051)

Don't be a retard.

It's a TV receiver, it has no transmit capability. No FCC license is required to receive (almost) anything with a Class 15 device, which these are. The exception would be cellular telephony, but AFAIK there is no FCC license permitting eavesdropping on those -- you're either the (licensed) carrier who's actually handling the call, or you can't listen.

If you add a transmitter, well, the fact that you're listening via TV dongle obviously doesn't eliminate the licensing and equipment requirements for whatever radio service you're operating in, so a warning specific to this case is unneeded. Anyone "freebanding" or otherwise operating illegally probably knows exactly what they're doing, and if they don't care about what the law says, I very much doubt they care what you say either.

Re:better get (1)

Anonymous Coward | more than 2 years ago | (#39536509)

The FCC put rules into place a long time ago forcing manufacturers of receivers to block analog cellular frequencies from being received by the tuner. I don't see why this gear would be exempted from that.

Granted there are very few analog cell phones out there now days, so it may be a moot point. Maybe the FCC has since rescinded that rule.

Re:better get (1)

Gordonjcp (186804) | more than 2 years ago | (#39536785)

Your old analogue mobile phone frequencies are in analogue TV frequencies in the rest of the world.

I break FCC regulations all day, every day. Why should I care about the "cell phone hole"?

Re:better get (2)

MichaelSmith (789609) | more than 2 years ago | (#39537127)

> The FCC put rules into place a long time ago forcing manufacturers of receivers to block analog cellular frequencies from being received by the tuner

Do those frequencies seriously exist where you live? They were closed ten years ago here in Australia.

receive only? (1, Redundant)

Anonymous Coward | more than 2 years ago | (#39535893)

If it's a TV tuner it probably just has a receiver, no transmitter, right?

Were they running their website on an $11 dongle? (1)

Anonymous Coward | more than 2 years ago | (#39535927)

Because now it's an $0.11 smoking heap of slag...

Getcha google cache here [googleusercontent.com] !

Too long (5, Insightful)

ebcdic (39948) | more than 2 years ago | (#39535929)

I'm unfamiliar with software-defined radio, and I don't want to spent 20 minutes watching a video. I hate this trend of using a video for something that could be explained in text that I could read in a fraction of the time.

Re:Too long (2)

Bananana (1749762) | more than 2 years ago | (#39535939)

yep. and the trend is not limited to April fools' pranks.

Re:Too long (2)

Goaway (82658) | more than 2 years ago | (#39536921)

This has nothing to do with April fools', Slashdot is just late on the uptake as usual.

Re:Too long (0)

hardie (716254) | more than 2 years ago | (#39535953)

Just assume you've used Google to read about software defined radio and aren't interested.

Re:Too long (0)

Anonymous Coward | more than 2 years ago | (#39536859)

Just assume you've used Google to read about software defined radio and aren't interested.

What are the chances that assumption was true for this particular person? :)

Re:Too long (4, Informative)

shish (588640) | more than 2 years ago | (#39535987)

Watching the video now, it appears to be "dump ALL the radio signals to disk, for later analysis", so you can then use software to pick out audio / text / morse code / etc signals

Re:Too long (2, Informative)

trout007 (975317) | more than 2 years ago | (#39535991)

I found this great new site you may be unaware of. It's called Wikipedia. It is kinda of like an online encyclopedia that has brief summaries of almost anything. Check it out I'm sure you will like it.

http://en.wikipedia.org/wiki/Software-defined_radio [wikipedia.org]

Re:Too long (2, Informative)

MinusOne (4145) | more than 2 years ago | (#39536049)

Would it really have been that hard to embed the Wikipedia link in the article? Sure I can look this some up, but someone is trying to explain it to me and its just one stupid link.

Re:Too long (4, Insightful)

LWATCDR (28044) | more than 2 years ago | (#39536647)

Sorry but why complain because someone didn't know you knew what software radio was? This is Slashdot News For Nerds not CNN. If someone posted a story about AMD would you complain that they didn't include a wikipedia link to AMD?
I just don't think that it is outside of reason to expect someone reading slashdot to google something they do not understand.

lowered expectations (-1)

Anonymous Coward | more than 2 years ago | (#39537025)

Sorry but why complain because someone didn't know you knew what software radio was? This is Slashdot News For Nerds not CNN. If someone posted a story about AMD would you complain that they didn't include a wikipedia link to AMD?
I just don't think that it is outside of reason to expect someone reading slashdot to google something they do not understand.

You are expecting some of these slashdotters to stop looking for a reason to bitch about. It's like expecting a bird to stop dropping shit in mid flight. It's ok to expect that from normal, sensible, technologically-savvy people, but these aren't, regardless of what they think of themselves.

Re:Too long - come on! (1)

bdabautcb (1040566) | more than 2 years ago | (#39537207)

Would it really be that hard to hit ctrl-t and type software defined radio? If you are that lazy, in about two mouse clicks more than it would take to hit the link to copy, then paste and search. Sometimes I do not wonder how much influence Snooki has on the 'give me everything now' culture.

Re:Too long (5, Insightful)

Auroch (1403671) | more than 2 years ago | (#39536157)

Actually, I think the point the OP was trying to make was something like ... "Why not just explain it in a sentence or two IN THE F*SKING ARTICLE instead of linking a video or an external source".

Re:Too long (1)

Anonymous Coward | more than 2 years ago | (#39537109)

Actually, I think the point the OP was trying to make was something like ... "Why not just explain it in a sentence or two IN THE F*SKING ARTICLE instead of linking a video or an external source".

Because saying "an approach to move radio functionality from hardware to software" a) doesn't cut it, and b) doesn't say anything that "software-defined radio" doesn't stand for already. Why rehashing something anyone self-proclaimed geek can find with a quick google or wikipedia search, specially rehashing it poorly? Might as well just copy/paste the first two sentences off wikipedia, and for that you might as well *gasp* not do that at all and instead opt to link to the external source. If you look hard enough for something to bitch about, you'll be bound to find it, even if it is inane.

Re:Too long (1)

nurb432 (527695) | more than 2 years ago | (#39536285)

Just using logic alone should explain what a 'software defined radio' might be.

A radio, defined in software instead of hardware..

Re:Too long (3, Funny)

superdave80 (1226592) | more than 2 years ago | (#39536873)

So you've managed to deduce that software defined radio is a radio defined in software? Awesome.

Re:Too long (1)

nurb432 (527695) | more than 2 years ago | (#39536965)

The point was that the OP couldn't figure it out without asking, Not that i didn't know what it was.

But thanks for being an ass, i would hate to think that there were still respectable humans out there.

Re:Too long (0)

hairyfeet (841228) | more than 2 years ago | (#39536665)

I have a good question....why? Are radio chips REALLY expensive or something now? hell all the old analog TV tuners had radios built in and they ended up dropping the feature because nobody used the damned things, so why would you want to do it much more inefficiently in software? this is one of those things like that cassette deck for PCs where i sit there with a serious "WTF?" look on my face because i honestly don't get it. I mean all you are picking up is standard radio, right? no police bands or anything cool like that? hell there are a bazillion free radio station on the net and unlike the clearchannel crapola they play music that doesn't suck.

So I'm sorry if I'm missing something but i really don't get it. Radio is all but dead now anyway, you have tons of free streams, so why care about adding a dying format to your PC?

Re:Too long (3, Informative)

Grieviant (1598761) | more than 2 years ago | (#39536807)

The modern definition of 'radio' refers to any device that uses wireless to transmit / receive an electromagnetic signal. Your wifi modem, bluetooth device, smartphone, TV, etc., are all radios. It's not limited to traditional FM radio from 88-108 MHz. Pretty much all radios are using some form of digital communications these days, as opposed to analog modulation with FM radio. Software defined radio really isn't anything special - the low frequency part of the radio (from IF down to baseband) is handled with a digital signal processor that can be programmed to handle many different formats. It's a natural evolution of digital communications that gets tossed around as a buzzword.

Wikipedia the online encyclopedia (0)

dgharmon (2564621) | more than 2 years ago | (#39537409)

"I found this great new site you may be unaware of. It's called Wikipedia. It is kinda of like an online encyclopedia that has brief summaries of almost anything", trout007

Is this the same Wikipedia that says Windows NT [wikipedia.org] wasn't designed for the Internet?

Re:Too long (-1)

Anonymous Coward | more than 2 years ago | (#39536001)

https://en.wikipedia.org/wiki/Software-defined_radio

Re:Too long (-1)

Anonymous Coward | more than 2 years ago | (#39536027)

No worries. Handing burgers through a window or changing tires require almost no effort to learn. You should be just fine.

Not Searchable. (5, Insightful)

solios (53048) | more than 2 years ago | (#39536037)

Time isn't the issue for me. The issue for me is the fact that video "tutorials" feature voices that frequently grate on my nerves. Worse, the video tutorial cannot be quickly searched for the relevant information.

Seriously. I can find out if a text tutorial is relevant to the issue at hand in seconds. With video tutorials, I've typically closed the tab before the "host" finishes talking about how great he is, how great the software is, and what the tutorial is going to cover.

Re:Not Searchable. (2)

ColdWetDog (752185) | more than 2 years ago | (#39536231)

I agree and feel like complaining this morning.

Come on, world. Shaky, unedited cell phone cam 'videos' are only slightly worse than slick, over prepared 'tuts' with dippy techo music in the background and pointless transitions (yeah, the ones on the very bottom of the picklist that nobody has used since 1981).

Just write it down. Show a static picture if you need to. Video is for things that move, not talking heads, not pointing fingers.

Now, if you don't mind. I shall take a nap. That was exhausting.

Re:Not Searchable. (0)

Anonymous Coward | more than 2 years ago | (#39536269)

This was my big problem with Joomla too - you need 2 hours and goddamn popcorn and soda just to get through the basic how to's.

A video may be worth a thousand words, but technical video documentation is only worth one click.

Re:Not Searchable. (0)

Anonymous Coward | more than 2 years ago | (#39536319)

...over prepared 'tuts' with dippy techo music in the background...

Could be worse. Could be Creed [youtube.com] .

Re:Not Searchable. (0)

Anonymous Coward | more than 2 years ago | (#39536325)

videos suck ass, the MTV / stupid passive-participation crowd have won out.

but how did you NOT see that coming?

Re:Not Searchable. (0)

Anonymous Coward | more than 2 years ago | (#39536897)

Right on!

Fucking tired of where I work saying "Oh, that was covered in the 2 hour video of the meeting, did you not watch it?" No, I fucking didn't. The first 10 minutes were worthless and I have work to do, I don't have 2 hours to watch that worthless video for one little piece of information. I'd be happy to do it the stupid way if I weren't on salary...

Last time they forced me to do it, I took notes and wrote a nice text document on the presentation.

Re:Not Searchable. (2)

jamesh (87723) | more than 2 years ago | (#39537085)

Time isn't the issue for me. The issue for me is the fact that video "tutorials" feature voices that frequently grate on my nerves. Worse, the video tutorial cannot be quickly searched for the relevant information.

Seriously. I can find out if a text tutorial is relevant to the issue at hand in seconds. With video tutorials, I've typically closed the tab before the "host" finishes talking about how great he is, how great the software is, and what the tutorial is going to cover.

Is the term "tl;dw" in common use? It would apply to any video over about 30 seconds (or any porn video over 60 minutes).

Re:Too long (0)

Anonymous Coward | more than 2 years ago | (#39536091)

There is a Wiki link in there, if you're too lazy to read the text that you could read in a fraction of the time, don't complain if the video isn't edited to your likeing...

Re:Too long (1)

swalve (1980968) | more than 2 years ago | (#39536135)

It is easier to think about in the transmit mode of operation, and then receive is just the opposite. Alright, you know how you can take digital data on your computer and convert it into sounds coming out of your sound card? Same thing but with higher (faster) radio frequencies. Reversing it for receive means that you hook up your "microphone" (antenna) to the line-in, and tell it to record. Using the raw "wave" file, you can filter out the signal you want, and then process that signal to get the data out.

Re:Too long (4, Interesting)

Alsee (515537) | more than 2 years ago | (#39536141)

In a "normal" radio-using device you have an electronic circuit to detect or create an exact sort of signal at a particular frequency range. For example you have one sort of circuit to detect FM tpy signals and a completely different circuit to detect AM radio signals, and a TV has circuitry that transforms exact-TV-format signals into the needed picture and sound signals. The advantage of these specific electronics is that they are cheaper and use less power.

A software defined radio picks up (or transmits) radio waves basically as a graph. A digitized wave form. A software defined radio uses a CPU to examine (or create) the radio wave. This means that simply by loading in the right software you can detect (or create) absolutely any sort of signal at all. You have one circuit that can handle up AM, FM, TV, cellphone signals, wifi signals, or anything. They can also use advanced digital methods to eliminate various kinds of noise.

The downside of software defined radio is that the circuitry needs to be bigger, faster, and more power-hungry to handle fast computation.

Software defined radio has the government worried and paralyzed. The government is used to individually regulating the frequencies and power levels and signal characteristics of each kind of radio-using device. An AM/FM radio specifically does not pick up police or cell phone frequencies, and things like CBs and walkie-talkies and cellphones and baby monitors all have specific power levels and specific frequencies they can broadcast on, and they only broadcast in specific radio formats. And those limits are hard-baked into the devices by their exact circuitry. Software defined radio throws that entire idea out the window. A software defined radio is going to have some inherent power limit based on the exact hardware, and some minimum and maximum frequency range based on the hardware, but generally it can handle a very broad range from low frequency bands to high frequency bands, and they can send/detect absolutely any radio format over that entire range, and they can do it at full power. There's no way to regulate "don't detect police/cell frequencies", and no way to regulate "don't broadcast FM on what is supposed to be an AM band", and there is no way to regulate different power levels on different bands. Once you sell a software defined radio, the end user can load in any software they want.

Software defined radio is revolutionary. It is incredibly flexible. And that flexibility is exactly the "problem" for government regulators.

-

Re:Too long (5, Interesting)

bmo (77928) | more than 2 years ago | (#39536311)

Software defined radio has the government worried and paralyzed. The government is used to individually regulating the frequencies and power levels and signal characteristics of each kind of radio-using device. An AM/FM radio specifically does not pick up police or cell phone frequencies, and things like CBs and walkie-talkies and cellphones and baby monitors all have specific power levels and specific frequencies they can broadcast on, and they only broadcast in specific radio formats. And those limits are hard-baked into the devices by their exact circuitry. Software defined radio throws that entire idea out the window. A software defined radio is going to have some inherent power limit based on the exact hardware, and some minimum and maximum frequency range based on the hardware, but generally it can handle a very broad range from low frequency bands to high frequency bands, and they can send/detect absolutely any radio format over that entire range, and they can do it at full power. There's no way to regulate "don't detect police/cell frequencies", and no way to regulate "don't broadcast FM on what is supposed to be an AM band", and there is no way to regulate different power levels on different bands. Once you sell a software defined radio, the end user can load in any software they want.

Anyone with the technical knowledge can do any of these tasks in hardware, for not a lot of money. There are entire libraries of books and technical articles on how to broadcast/receive on any band, even "forbidden" ones like 800MHz cellular. I remember an article in Popular Communications for a down-converter you could build to listen to 800MHz back in the early 90s that simply screwed into the BNC of your scanner in line with the antenna.

BFD.

>implying it's somehow illegal to listen to bands outside of AM/FM

What the hell are you talking about? Beyond the Cellular legislation, any and all bands are open for reception. It's your right to intercept radio waves on whatever spectrum and you don't need a license to do so. You only need a license to transmit on licensed spectrum.

>cannot regulate power levels and bands

As if they weren't able to regulate for the past 80 years?

Protip: If you are transmitting 1kw, and transmitting in a band you shouldn't be in, it won't be the feds who track you down, it will be the licensed operators who will find you and turn your ass in to the feds and they'll be happy to do so.

The only reason why Joe Trucker doesn't get turned in with his 1kw linear on CB is because he's a moving target. Anyone else sitting in his basement throwing shitty harmonics up and down the bands can be found.

Also, software defined radios are not amplifiers. You are conflating one technology with another.

The amount of wrong in your post is staggering.

--
BMO

Re:Too long (5, Interesting)

girlintraining (1395911) | more than 2 years ago | (#39536507)

The only reason why Joe Trucker doesn't get turned in with his 1kw linear on CB is because he's a moving target

Actually, it's because the government just doesn't give a sh*t about CB radio frequencies. But given that it uses an incredibly simple modulation scheme, it can easily be traced and tracked in realtime. All you need to catch "Joe Trucker" is three antennas spaced one wavelength or more apart and you can get a fix on their position. They may be a moving target, but they're moving along a fixed path: The road. Find a guy heading northwest in the same direction as the highway and you just hop on the road a few exits up and join the flow of traffic. He'll talk again, and when he does... oh look, it's the guy 50 feet in front of you in the left lane... *flips on lights* Goodbye 1kW transmitter, goodbye trucker.

Be more concerned about frequency hopping mobile devices that use a PRNG to communicate with another device over a range of frequencies and encoding techniques... That requires a LOT more equipment to sort out where the signal is coming from. Actually, that's pretty much what the military does... o_o

LOL (1)

ArchieBunker (132337) | more than 2 years ago | (#39537203)

You really think it happens like that?

Re:Too long (1)

illtud (115152) | more than 2 years ago | (#39537593)

Be more concerned about frequency hopping mobile devices that use a PRNG to communicate with another device over a range of frequencies and encoding techniques... That requires a LOT more equipment to sort out where the signal is coming from. Actually, that's pretty much what the military does... o_o

Yes, thanks in no small part to Heady Lamarr [wikipedia.org] . Now that's a factoid.

Re:Too long (1)

BobNET (119675) | more than 2 years ago | (#39537771)

That's Hedley!

Re:Too long (0)

Anonymous Coward | more than 2 years ago | (#39537725)

"...goodbye trucker..."

OMG I don't want them to kill him! Just take his amp!!!

Re:Too long (0)

Anonymous Coward | more than 2 years ago | (#39536335)

Yeah, everyone follows laws regarding CB modifications and power limits. And no one uses off the shelf scanners to listen to police traffic. I don't feel like this is a problem for the government for a couple reasons:

1) SDR can't do much that a large amalgamation of current radios can do. Just easier, nothing new here.
2) Most SDRs have wimpy TX power
3) Most amateur and commercial radios can be modified to go out of band or over power, depending on what band you're in, none of this is new.

SDR is just an easier more flexible way to do things we've already been doing for years, and soon enough, more cheaply. I say bring it on.

Re:Too long (5, Interesting)

Anonymous Coward | more than 2 years ago | (#39536501)

What the hell are you talking about?

1) The hard bit of any radio, especially important for transmission, is low noise band filtering, precise tuning and mixing to convert to/from AF. This all involves a lot of careful analog design and cannot be replaced by the S of SDR. Sure, the oscillator can use DDS, but that's not going to be done by wasting your computer's CPU cycles and it wouldn't make any difference anyway;

2) For analog modes, it's arguably easier to build a circuit than write decoding software. For digital modes, you're either running software on your desktop/laptop or you're running software on the radio's CPU. The only relevant questions are a) whether the modulation is documented - the answer is usually "yes" except for military; b) the keys for any encryption are available to you - if not, being able to implement an SDR makes not a hoot of difference;

3) Yes, you can do some fine DSP with a modern CPU but only an idiot thinks this is a substitute for a good antenna and (per 1) front-end.

SDR is the e-m equivalent of the "winmodem" in dial-up days: yes, you have the opportunity for a lot more versatility, but only by creating something dumb and offloading the work to a less power-efficient general purpose computer which may or may not have something better to do.

Re:Too long (3, Insightful)

ChrisMaple (607946) | more than 2 years ago | (#39537755)

SDR makes possible "brick wall" filters that aren't practical with analog circuits, and that are more stable over temperature and time than is possible with analog circuits. Software doesn't drift. Physical inductors have limited "Q", crystals and mechanical resonators have "spurs", and so forth and do on.

Re:Too long (0)

Anonymous Coward | more than 2 years ago | (#39536525)

"There's no way to regulate "don't detect police/cell frequencies",

Because it's perfectly legal to listen in on any frequency. Getting around the encryption used to obscure the content (law enforcement comms) might be a different issue.

"and no way to regulate "don't broadcast FM on what is supposed to be an AM band"

Really. Then how come there -is- such regulation, and how come it is in fact being enforced?

Government is paralyzed? (1)

Anonymous Coward | more than 2 years ago | (#39536803)

SDR has the *paralyzed the government*? Really?

I would think if anything has paralyzed the government is the inability of our two political parties to come to consensus on more mundane issues such as budgeting and taxation.

Re:Too long (0)

Anonymous Coward | more than 2 years ago | (#39536149)

Jesus all kinds of increasingly lazy people around here go to wikipedia

Re:Too long (3, Informative)

Polo (30659) | more than 2 years ago | (#39536151)

I found this particular video showed me what you could do in a visual way I wouldn't have picked up by reading about it.

Yes, I agree that sometimes you can't watch a video where you could read text though.

Re:Too long (0)

jimmerz28 (1928616) | more than 2 years ago | (#39536243)

As accustomed to ultra-consumption as we are 20 minutes to learn something new in an area you're (at least I was) totally unfamiliar with isn't all that much time.

Plus the video is rather well done and informative.

Challenge Accepted (5, Informative)

Gordonjcp (186804) | more than 2 years ago | (#39536315)

In a conventional radio receiver, you start by filtering off the wanted signal with a broad filter, mixing it with another locally-generated signal (the Local Oscillator) to make a lower Intermediate Frequency (IF), then filtering the IF to extract a single "channel" of information. Then you demodulate this, possibly after mixing it down to an even lower IF.

In a software-defined radio, you convert directly down to a much lower frequency (audio frequency, even), but - and this is the clever bit - you do it with two local oscillators, 90 degrees out of phase. This gives you a complex sample, a pair of samples representing In-phase and Quadrature, or the real and imaginary components of your signal.

From there you can apply digital signal processing techniques to extract the wanted signal, show an FFT of the chunk of band you're capturing, and so on. This lets you do very sharp filtering, because you're no longer constrained by the physical realities of trying to implement electronic filters with practical components.

Shameless plug - if you want to try SDR out, go here:
https://github.com/gordonjcp/lysdr [github.com]
Follow the instructions in the README, then either post a reply or bug me in irc.freenode.net ##electronics for further instructions.

Re:Challenge Accepted (3, Interesting)

YoopDaDum (1998474) | more than 2 years ago | (#39536869)

What you described is the difference between an old two stages RF architecture going from the target frequency to a base band signal through an intermediate frequency and a direct conversion / zero IF RF architecture. All recent RF chips for wireless are zero IF nowadays.

But SDR usually refers to the digital processing part. Some modem implementations use custom digital logic to do the processing. A SDR approach will use a big DSP (vector DSP even) to do the processing in software. Although typically some heavy parts like the FEC and FFT (for OFDM/OFDMA) can still be done with custom hardware for better efficiency.

In any case, the dream of a purely generic hardware is still only a dream. We can have flexible software modem (if you're not too concerned about die size and power efficiency), we have also wide band radios. But in front of that you still require a RF front-end (FE), comprising filters (not to be blinded by adjacent channels in Rx, or not to kill adjacent channels in Tx) and power amplifier in the transmission side. And there's no much flexibility there. You can have wide-band PAs, but it's limited and efficiency will suffer (so burn more power, heat more than a narrow band PA). And filters are not configurable. If you want to support many bands combinations, you end up with many different filters and a switch.

So the post is too optimistic. You may be able to toy a bit with this hardware, but don't expect making anything solid (product quality) based on that. Still for hacking and the fun / learning value, why not?

Re:Challenge Accepted (2)

pakar (813627) | more than 2 years ago | (#39537655)

You should probably do a bit more fact-checking before saying stuff like that..

http://www.linuxfordevices.com/c/a/News/Embedded-Linux-powers-first-handheld-software-radio/ [linuxfordevices.com]
http://www.electronicsweekly.com/Articles/17/12/2007/42781/intel-targets-wimax-with-software-radio-device.htm [electronicsweekly.com]

There are already chips that do direct-if conversion for DVB-T.. It's not a generic chip they use but a specialized that will have a high-speed ADC and then have hardware that do the 'tuning' to the wanted frequency...

So... There is stuff already doing this on a large scale...

If you want something that works with any type of protocol then you need some type of generic CPU that can be loaded with software that can be reprogrammed, and this is probable something that don't exist outside some specific circles, but it do exist and is available commercially. This stuff is usually done on FPGA's to reduce the powerusage and get good performance....

Re:Too long (0)

Anonymous Coward | more than 2 years ago | (#39536617)

God damn. Mod parent up!!!

Re:Too long (1)

Gothmolly (148874) | more than 2 years ago | (#39536737)

No kidding. Are people too illiterate to read a 1 page article?

Re:Too long (3, Insightful)

DrVomact (726065) | more than 2 years ago | (#39536995)

I'm unfamiliar with software-defined radio, and I don't want to spent 20 minutes watching a video. I hate this trend of using a video for something that could be explained in text that I could read in a fraction of the time.

Amen, brother. I figured that my aversion to video "tutorials" or "reviews" or whatever was just cranky old me being out of touch with the rest of the world again, so I wasn't going to say anything. But yeah, I am very sick of people talking and mugging for the camera instead of just writing a couple of clear concise paragraphs. The written word is random access. I can quickly skim a few paragraphs to see if this is what I'm looking for, I can read a lot faster than some fool can talk, and I if I just need one particular piece of information I can find it much more quickly in a written document than a video. I reserve particular disgust for people who try to demonstrate complex procedures, but have no idea about lighting or camera angle, so that the critical stuff is always done either in murky darkness or hidden behind the guy's hand.

Videos suck time. You have to sit in front of the monitor and watch while some guy natters on about whatever the subject is. Even if the video truly contains important reference information, you can't just watch it once, then later quickly go back to the critical part that you forgot. You have to try to find the right place to start playing the video. Again. You can't search a video for key-words. You can't print a video for later reference, or print a page to give to a friend who has a similar problem, and needs just a bit of key information. You can just send him the link, and invite him to waste his time.

What I truly fear is that the trend to videos is just another sign of cultural degeneration: it is part of the decline of literacy, of regard for the written word, and of the analytical thought that is possible only by means of the written word. So I don't look for a reversal of this trend any time soon. It's just going to get worse, along with everything else.

Re:Too long (0)

Anonymous Coward | more than 2 years ago | (#39537669)

What I truly fear is that the trend to videos is just another sign of cultural degeneration: it is part of the decline of literacy, of regard for the written word, and of the analytical thought that is possible only by means of the written word. So I don't look for a reversal of this trend any time soon. It's just going to get worse, along with everything else.

Page views and ad revenue. The average viewer wants to passively receive information from an audiovisual medium. This has worked well for movies, music, and TV since the time they were invented/perfected/mass distributed.

The 'fringe element' know their time is valuable and opt for text based solutions to get the information they want or need. They uses all sorts of adblock to speed up their browsing to increase their 'mental bandwidth'. It is all but impossible for advertisers to make money from this group of people so they focus on the other, larger group who aren't inclined to shift themselves to the other group because it is 'too complicated'.

CAPTCHA: stuffed (the advertising that fills commercial television. :P [about 20 minutes/hour in 2012 (>_); )

Re:Too long (0)

Anonymous Coward | more than 2 years ago | (#39537327)

> I'm unfamiliar with software-defined radio, and I don't want to spent 20 minutes watching a video. I hate this trend of using a video for something that could be explained in text that I could read in a fraction of the time.

I chose to reply here instead of one reply to all the morons that pass by and say "Google it!".

First, what's the big idea about opening a tech site and having to google the subject? What kind of tech site is this?

Second, it's okay being unfamiliar with something. If someone understands SDR what are the chances the guys groks Biology? We have lots of kinds of smart dudes over here but you cannot assume everyone has to know what you happen to know...

Moreover, after that insanely basic video about TVs a few days ago, what is the deal with an "introductory" video talking about kinds of different signals? wtf?

And finally, I'd like to have great sound quality and online digital is more than enough... sorry for those without fiber at home, but there's still internet on radio. So what really is SDR useful for? For the common user -- and I understand this would require some bureaucracy -- mp3/ogg streaming over normal SW might be enough.

Re:Too long (1)

foniksonik (573572) | more than 2 years ago | (#39537369)

I highly recommend the video. You could not describe it effectively with words even combined with static images.

Re:Too long (1)

squiggleslash (241428) | more than 2 years ago | (#39537863)

It's a radio that instead of being tunable to the bit of spectrum you want to receive (eg. "200KHz at 88.9MHz, encoded using FM" - that's what your (analog) car radio's tuner is designed to do) , instead receives and digitally encodes an extremely large, fixed, block of spectrum. You then use software to extract the signal(s) you're actually interested in.

The major advantage of the system is that it's highly configurable - in theory, the same receiver can be used to receive and decode FM radio, ATSC TV, Wi-fi, GSM, UMTS, etc, as long as the receiver covers the part of the spectrum those signals are transmitted on.

Disclaimer: I'm not an expert, but I figured what I know to be more useful than being required to plow through a Wikipedia article on the subject.

WTF is that Acronym? (2, Funny)

Anonymous Coward | more than 2 years ago | (#39535933)

How difficult would it have been to type Universal Software Radio Peripheral to avoid the obvious confusion with the Ukrainian Socialist-Revolutionary Party?

quantity (1)

nten (709128) | more than 2 years ago | (#39535951)

I use USRPs, I like USRPs. There are many, many things you can do with a USRP that you could never do with one of these (if you spent some extra and got a daughterboard, otherwise its a brick). However, there are some things you could do with 100 of these that you could never do with a single, similarly priced USRP. I did not order 100, but I did get some. I'm thinking a beagle bone, might make a nice friend for it.

Re:quantity (1)

Auroch (1403671) | more than 2 years ago | (#39536167)

Beagle bone + USRPs? I'd google that, but it sounds like I'd find some nasty rule 34 images out there... Unless you mean beagle BOARD ...

Re:quantity (0)

Anonymous Coward | more than 2 years ago | (#39536249)

I haven't played w/ this setup, but the openHPSDR setup is slick!

Re:quantity (1)

Anonymous Coward | more than 2 years ago | (#39536513)

Yep, this is very true.

I assume the 3.2 M/s limit comes from the chipset's design being centered around a TV channel (and presumably there's a bandpass filter in there as well), but lost samples suggests it's saturating the USB bus or something. In any case, a series of USB 3.x hubs would certainly permit connecting a farm of these to one PC.

I'm a ham (albeit one with no real SDR experience... yet), so I can see loads of applications, but a lot of them really want a fairly sophisticated tx setup to go with. One good application might be the gnarliest FM broadcast receiver setup ever -- it's receive-only, and decent antennas are dead-simple and dirt-cheap to make, so it's easy to throw, say, 28 receiver/antenna modules up, and use it as 7 arrays (88 to 108 =20MHz, so 7x 3MHz subbands) to receive the entire FM broadcast band, and phase the 4 antennas in each array (in software) to get directional selectivity. Then you can stream any or all stations over your LAN to various speakers around the house. Perfect for NYC or such places, where the band is jampacked...

A smaller version might be suitable for mobile applications -- 3 antennas fit easily enough on your average car (stock antenna plus two mag-base whips on the trunk), and while you'd "only" get all the stations in one 3MHz strip, you could easily follow a single station (or, y'know, several stations in that 3MHz band, if cacophony's your thing), even on a highway commute crossing the centerline between two transmitters on the same channel.

Naturally, there's less-legal (GSM snooping) options, and maybe some nifty tricks for the scanner guys listening to trunked (yay software radio!) or multiple systems.

Of course the bandwidth just covers the 1.25m/222MHz band, and there's certainly nothing wrong with a SDR receiver to monitor various frequencies while using a hardware radio to transmit (maybe routing the frequency your transmitter's on to the right channel, and mixing the others to the left).

Re:quantity (0)

Anonymous Coward | more than 2 years ago | (#39537637)

a series of USB 3.x hubs would certainly permit connecting a farm of these to of PCs

Sadly, USB 2.0 (or 1.1 ...) over USB 3.0 doesn't work like that. For 100% backward compatibility, a USB 2.0 device opens a complete point to point channel talking only USB 2.0 all the way to the root hub. I'm not certain if a single 2.0 device hugging the entire bandwidth will practically prevent USB 3.0 traffic from flowing at full speed, but I suspect so.

google cache link (2)

Nyder (754090) | more than 2 years ago | (#39535963)

https://webcache.googleusercontent.com/search?q=cache:fRixFRVwNjoJ:sdr.osmocom.org/trac/wiki/rtl-sdr+&cd=1&hl=en&ct=clnk&gl=us [googleusercontent.com]

funny thing about this google cache link though, it's trying to load stuff from sdr.osmocom.org, which is currently slashdotted, so not sure if google knows what cache means anymore...

yes, sorry, https because that's how i roll baby...

Some info from the page (5, Informative)

Nyder (754090) | more than 2 years ago | (#39535975)

rtl-sdr

DVB-T sticks based on the Realtek RTL2832U can be used as a cheap SDR, since the chip allows transferring the raw I/Q samples to the host, which is officially used for DAB/DAB+/FM demodulation. The possibility of this has been discovered by the V4L/DVB kernel developer Antti Palosaari.
Specifications

The RTL2832U outputs 8-bit I/Q-samples, and the highest theoretically possible sample-rate is 3.2 MS/s, however, the highest sample-rate without lost samples that has been tested so far is 2.8 MS/s. The frequency range is highly dependent of the used tuner, sticks that use the Elonics E4000 offer the best range (64 - 1700 MHz).
Supported Hardware

So far, the following devices are supported:

        ezcap EzTV668 USB 2.0 DVB-T/DAB/FM stick (Elonics E4000 tuner) (sources: AliExpress, Dealextreme)
        ezcap EzTV666 USB 2.0 DVB-T/DAB/FM stick (Elonics E4000 tuner, picture Download)
        Hama nano DVB-T stick (Elonics E4000 tuner)
        Terratec NOXON DAB/DAB+ USB-Stick (Fitipower FC0013 tuner)

People over at reddit are collecting a list of other devices that are compatible.

Other sticks based on the RTL2832U might be added in the future as well.

Re:Some info from the page (0)

Anonymous Coward | more than 2 years ago | (#39536145)

CDN cache

http://sdr.osmocom.org.nyud.net/trac/wiki/rtl-sdr

Re:Some info from the page (2)

Formalin (1945560) | more than 2 years ago | (#39536701)

The only one from the page with a link is $19.50 (dealextreme).

Where is the $11 one the summary refers to?

eBay (3, Informative)

ArchieBunker (132337) | more than 2 years ago | (#39537239)

But the sellers have sold out days ago along with all the other retailers. Looks like one is left and they ship direct from Hong Kong so expect a few weeks wait. I'm kinda pissed about only finding out now.

I've been toying with the idea of getting an entry level SDR for a while just to see what all is out there on the airwaves. This USB tuner chip appears to do the same thing as the $100+ Funcube Dongle.

Jerri Elsworth on FPGA-based SDR (0)

Anonymous Coward | more than 2 years ago | (#39536119)

FYI

http://www.youtube.com/watch?v=0UBKw7F9Mck

subreddit dedicated to the RTL-SDR project (2)

citizenr (871508) | more than 2 years ago | (#39536397)

http://www.reddit.com/r/RTLSDR [reddit.com]

has all the info, list of tuners that work, tutorials and more.

Cool!...only (0)

Anonymous Coward | more than 2 years ago | (#39536415)

...has anyone found any ATSC tuners with a similar mode? (writing from USA).

Re:Cool!...only (1)

Jimbookis (517778) | more than 2 years ago | (#39536669)

No but what do you care if you are in the USA? You won't be using this dongle for TV, just SDR. There are plenty of Chinese sites and eBay vendors who will sell you this from China and have it at your door within 2 weeks.

Been there, done that (5, Informative)

ctrl-alt-canc (977108) | more than 2 years ago | (#39536429)

A few years ago, together with a friend, we reverse engineered a DVB-T usb pen by Hauppauge, and we were able to extract the raw data stream skipping the demodulation process. We did it since we wanted to test if it the device could be used as a DSP IF strip in a homemade spectrum analyzer. The device worked, but the analog IF strip we wanted to replace was actually drawing circles around its digital replacement, so we abandoned the project. 8 bit of resolution and an hardware designed for a very specific purpose couldn't bring us too far, as we feared.
It is nice to see that somebody else was capable to reverse engineer these devices, but as you can see from their results, they aren't actually that good. I saw somewhere that a USB pen for DVB had to hit the market, and its ADC has been announced to be 12 bit wide.This could be an interesting device to hack for SDR applications, hoping it isn't vaporware...

Re:Been there, done that (-1)

Anonymous Coward | more than 2 years ago | (#39537339)

Orly? This sound like a case of "put up or shut up", because this is a real project and it works, and people are actually using it, while all you have is a story.

Links Slashdotted (1)

utkonos (2104836) | more than 2 years ago | (#39536627)

Here [googleusercontent.com] is a link to the GNU Radio site in Google's cache. And here [googleusercontent.com] is the link to osmocom, also from Google's cache.

That would be a *receive-only* SDR (0)

Anonymous Coward | more than 2 years ago | (#39536653)

And a USRP has a reconfigurable FPGA, which provides a whole lot more processing horsepower than your PC streaming samples over USB.

But cool none-the-less.

Reality check (0)

Anonymous Coward | more than 2 years ago | (#39536697)

Your cell phone and modem are basically software defined radios.

The idea with modern radio is to get the RF signal down to a frequency where it can be digitized and then do everything else in software. I have often said that, if you tried to implement a 3G cell phone in circuitry rather than software, it would occupy a rather large room.

Is the government really having a fit over sdr? Not so much. For one thing, they can't do much about it. The hardware isn't too hard, as long as you aren't trying to stuff it in a small package. You don't even need high speed a/d converters for the most part. The gnuradio system uses the sound card in your computer. http://www.ettus.com/ [ettus.com]

The other thing is that most interesting signals are encrypted.

If you want to play, gnuradio-companion is great. You don't need to mess with code because you can drag and drop blocks in an interactive gui. Check out Sharlene Katz's sdr project page. You don't need hardware because you can run the software with files. http://www.csun.edu/~skatz/katzpage/sdr_project/sdrproject.html [csun.edu]

Slashdot (1, Insightful)

Higgins_Boson (2569429) | more than 2 years ago | (#39536761)

Has become a haven for cowards who think that "I disagree" and "troll" are the same thing.

This site has gone so far down hill that it's now underground and slowly suffocating to death.

Let it die off already... especially if this is how it is allowed to run.

Missing the point? (1)

lpt1 (46613) | more than 2 years ago | (#39536829)

What everybody seems to be missing that worries regulators/spectrum enforcers is that this opens the way for the radio equivalent of script kiddies.

Sure, you could disassemble your Radio Shack scanner, desolder this, resolder that, jumper the other, and receive whatever you wanted.

Now, you download this, dbl click that, agree to a EULA, and you're done. Better yet, a fairly simple data wipe of that directory, and there's no evidence.

Consider if this hack did apply to a transmit capable device:
Would you be comfortable with script kiddies being able to transmit on your local fire dept/ambulance freqs?
Do you really think a script kiddie will respect freq allocations? Even emergency ones?

Now, consider trying to track down every l33t teen kid who runs the software. Make enforcement a nightmare when you go from a couple of thousand complaints a year to tens of thousands a month.

knowing he did that with an 11 dollar TV card (1)

FudRucker (866063) | more than 2 years ago | (#39536851)

makes me mad at companies like WinRadio and RF_Limited and Icom etc... that charge damn near 1000 bucks and more for a computer controlled shortwave radio or wideband radio when i know they probably have maybe 50 to 150 bucks in hardware

i wont ever buy one of those high dollar software defined radios or software controlled radios knowing they are not worth what they are asking, i will sooner buy a cheap portable like a sangean for about a hundred bucks

Re:knowing he did that with an 11 dollar TV card (1)

Jimbookis (517778) | more than 2 years ago | (#39536901)

Steady on - those companies have been making SDR since last century. No, what they do isn't so novel anymore since commodity widgets that are repurposed came out in the last year or so. You'll find though that they make hardware that is mature and is intended to be parts of larger systems that are reliable and have a long working life. They do need to get their skates on and make something comparable to RealtekDSR for price and performance. Anyway I have my ezyTV dongle sitting here waiting to get a big aerial attached.

Re:knowing he did that with an 11 dollar TV card (5, Informative)

Anonymous Coward | more than 2 years ago | (#39536953)

You realize that if a significantly-sized company is selling you a radio for $1K that has $150 worth of parts in it, for an item that isn't mass-market consumer
    (and ICOM/Kenwood/Yaesu radios intended for the HAM market aren't "mass market", compared to, for example, cell phones), that they are on the edge of
    *losing money*. I've run two different manufacturing businesses in the last 20 years, and really, if you only look at the raw BOM costs of something, and don't
    factor in all the other costs of bringing a reliable product to market, you'll go out of business.

Many of the so-called "high dollar" SDRs out there are "high dollar" for fairly good reasons. They are typically sold into markets where economies of manufacturing scale don't really apply, they often have feature sets that are *vastly* larger than what we're seeing in these "rtl-sdr" devices, and they tend to use higher-quality components. These DVB-T devices, for example, use a master clock that is good to about 100PPM--which for radios is rather seriously crappy. They won't have features like a DDC (usually FPGA resident) for fine-tuning the RX signal. The 8-bit resolution may be fine for some applications, but for others requiring higher dynamic range, that 8-bit resolution will be a killer. Plus many of the "high dollar" SDR devices offer TX chains as well as RX chains, and all the other comments apply for the TX chain as well.

But one of the big things about "high dollar" SDR devices is that they're primarily designed as *development platforms* for developing SDR applications across a wide "spectrum" of fields of endeavour. So they include large FPGAs, those FPGAs allow you to perform part/all of your DSP algorithms at insane speeds inside the FPGA--speeds/sample-rates that would be impractical for a host-software implementation. Large/fast FPGAs are expensive, and that cost has to be passed on. Further, the "high dollar" SDRs typically offer bandwidths into/out-of the host at much higher sample rates than 3.2Msps. Yes, 3.2Msps, RX-only, 8-bit resolution, no-fancy features is entirely-adequate for a lot of different hobbyist work. But it's inadequate for a lot of other types of work for which the so-called "high dollar" SDRs are supremely-well suited.

Re:knowing he did that with an 11 dollar TV card (2, Informative)

Anonymous Coward | more than 2 years ago | (#39537195)

Jesus tapdancing christ, a finished product is more than the sum of its parts - you sound like the people who whine because Apple's making $x "profit" based on $sale_price - $parts_price.

1) Much higher quality hardware filters for the band and for the particular AF signal required, giving the sort of selectivity needed for amateur levels of power;
2) Low noise amps, again essential for amateur levels;
3) DDS or PLL tuners accurate to a few Hz at worst, not ones which vary by at least 100Hz on the tuned frequency;
4) Well-documented open or semi-open RS232/USB interface;
5) Higher resolution ADC;
6) DSP running on-board rather than wasting the CPU cycles of your far hotter desktop/laptop;
7) Good, local vendor support for a small market keen to get the most use out of a well-built product, rather than zero vendor support for a consumer market buying a throwaway item;
8) Sometimes an on-board UI.

Finally, you're ignoring that "Icom etc" make transceivers, whereas this is firmly receiver-only. And a shitty receiver is one thing, but someone operating a transmitter with shitty parts isn't only being a dick to fellow spectrum users but may be breaking the law.

Re:knowing he did that with an 11 dollar TV card (0)

Anonymous Coward | more than 2 years ago | (#39537249)

Same people who whine about price also complain about the movement of domestic engineering jobs to cheaper parts of the world. They want their cheap electronics, *and* they want their jobs to stay here. Hmmmm.

Ask Slashdot: Mesh Networks? (3, Interesting)

Bob9113 (14996) | more than 2 years ago | (#39537397)

Help a noob out; I'm just poking around on Wikipedia reading about SDRs and software defined antennas. These sound kind of like a magic pill to solve decentralized mesh networking. Stick an SDA on the roof, wire it up to an SDR, seek some marker signal identifying a freenet mesh node, focus in directional point-to-point comm to anyone in range who is running a compatible sda/sdr/router.

Does that about sum it up, or am I just being an over-excited noob?

Re:Ask Slashdot: Mesh Networks? (2, Informative)

Anonymous Coward | more than 2 years ago | (#39537479)

AMPRnet has been around since the late '70s, various forms of packet radio existing before and after. The first TCP/IP stack I ever used was KA9Q.

1) lack of bandwidth;
2) legality of high power transmissions for non-hams;
3) legality of encrypted transmissions for hams.

YouTube pays $$$ (0)

Anonymous Coward | more than 2 years ago | (#39537809)

The poster makes $$$ every time his video is viewed. This is the reason his info is in the video.

Load More Comments
Slashdot Login

Need an Account?

Forgot your password?