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The Phi does for radio what Apple did for computing
July 8, 2012 3:03 AM   Subscribe

The Phi is a PCIe card which turns your computer into a software-defined radio which "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." While the Phi isn't the first such device available for purchase, it is the first to target hobbyists and eventually consumers, but how will the FCC handle software-defined radio?
posted by reductiondesign (49 comments total) 69 users marked this as a favorite

 
What I thought was really interesting was more from the comments in the article. It turns out, some of the usb tv tuners that are out are basically software defined radios, and people have found how to hook them up to GNU radio, the standard software for SDRs. Hack-a-Day has an article.
posted by zabuni at 3:41 AM on July 8, 2012 [17 favorites]


It's about phreaking time!
posted by mikelieman at 4:11 AM on July 8, 2012 [6 favorites]


Wow, I've been really interested in SDR for ages, but I never felt I could spend $1750 on a USRP2. It looks like it takes serious brainpower to get good at this stuff, and I wasn't sure I could deliver the goods after dropping that much scratch.

But thanks to zabuni's link, well, I can drop $20. That I can do. If I end up not being smart enough to handle it, I won't feel guilty.

So: thanks, zabuni!
posted by Malor at 4:18 AM on July 8, 2012 [2 favorites]


I'm not really getting the Apple analogy, unless you're saying that this is so simple that a person completely unfamiliar with radio electronics can misunderstand how it works.
posted by lodurr at 4:55 AM on July 8, 2012 [1 favorite]


I'm not really getting the Apple analogy, unless you're saying that this is so simple that a person completely unfamiliar with radio electronics can misunderstand how it works.

Did you mean understand how it works? In any case, they're talking about the Apple I which was not exactly user friendly (it required you to build your own power supply!) but it did hit the sweet-spot of being affordable enough for mass home use (mass for the time anyway) and developer friendly enough that people made software for it.

If hardware SDR becomes cheap enough that you can build software radios and expect potential users to buy the hardware and the software is friendly enough that a developer can build things on top of it then it will play a similar role that the Apple I and Apple II did.
posted by atrazine at 5:32 AM on July 8, 2012


There is a huge amount of hype surrounding SDR. Instead of having the traditional components all in the one box, SDR separates out the receiver, signal processing and the transmitter so that they're individual computer controlled devices. They don't even need to be on the same continent if they're linked by the internet.

Many SDR systems have impossibly wide rx/tx bandwidth, which shifts the problem on to the antenna. Most antennas are quite limited in bandwidth, and once you get down to HF and MF they get really big. Good luck setting up all the antennas you'd need.

SDR is the current big thing in amateur radio. FlexRadio make expensive Windows-only boxes. Elecraft's KX3 was the small object of lust at Dayton this year. Even the cheapo $65 TH-UV3R handheld is SDR. But all of them have the limited bandwidth to keep them within the ham bands.
posted by scruss at 5:48 AM on July 8, 2012 [5 favorites]


I'm not really getting the Apple analogy

It turns it into the ultimate hacker's tool. Like the way John Draper hooked an Apple to the Phone system. Using this technology you can hook your computer into the airwaves.
posted by mikelieman at 5:56 AM on July 8, 2012


The effective deregulation of the airwaves could create headaches as careless hobbyists pollute frequency bands that have been reserved for other applications.

They aren't kidding. Anyone listen to 11m (CB radio) lately ?

And it isn't even the racism, misogyny and rampant douchbaggery that is the problem. Start with microphones that add echos and distortion and end with radios that have been modified (poorly) to transmit 100+ watts on a 4 watt band.

There are a couple pirate radio stations around here (well, northern WI) working on 10/11m and I wonder if the FCC even cares anymore.
posted by Pogo_Fuzzybutt at 6:06 AM on July 8, 2012


First to target the hobbyists?.

I'm an SDR fan with a handful of radios - the best of which, the Flex-1500, is in some ways the best receiver I've ever used, and I've used some costing more than twenty times as much. The question of what happens to shortwave (and other areas of the spectrum) now we're getting the tools for true mass anarchy of the air is an interesting one, and I think with luck we'll get a wholesale renaissance.

On the other hand, the crystal set I built out of four bits of random stuff... that's one of the best radios I've ever used to. For other reasons.
posted by Devonian at 6:29 AM on July 8, 2012 [1 favorite]


OK. So, can I replace my cable company with this device? If so, I am very interested.
posted by Benny Andajetz at 6:59 AM on July 8, 2012


Is GNU Radio the beginning and end of open source software radio hacking? Or are there other open projects with significant community?
posted by Nelson at 7:32 AM on July 8, 2012


Even the cheapo $65 TH-UV3R handheld is SDR. But all of them have the limited bandwidth to keep them within the ham bands.

My cheapo Baofeng UV-3R, another SDR, covers the entire VHF/UHF bands transmit/receive. It could easily be used to interfere with public service since it does DCS along with CTCSS (but not P-25). The FCC's enforcement model does not comprehend non-hams having easy access to frequency-agile transmitters. Self-regulation only works when the vast majority wish to follow the rules, it fails when that majority does not.
posted by tommasz at 7:33 AM on July 8, 2012


Am I the only one who is slightly concerned about the RFID reader aspect of this? I wonder how secure the RFID powered pay pass option on my bank card would be if RFID readers were commonly available for example.
posted by peppermind at 7:54 AM on July 8, 2012


Am I the only one who is slightly concerned about the RFID reader aspect of this? I wonder how secure the RFID powered pay pass option on my bank card would be if RFID readers were commonly available for example.

If the bank card's security depends on RFID readers being hard-to-get, then it's not really secure, is it? True information security always depends on a cryptographic component with a properly-protected key.
posted by Slothrup at 8:02 AM on July 8, 2012


RFID readers are already commonly available, peppermind.
posted by teraflop at 8:03 AM on July 8, 2012


FWIW, this is the most significant thing to happen in radio since Armstrong's work in the early 1900's. It is bound to have wide ranging implications.

The other really significant thing (IMO) that happened was the FFT, which enabled OFDM to come to be.

OFDM enables mobile data radio, substantially free from destructive multipath propagation issues and is math in action. The elegance of the FFT and its contribution to modern life are under appreciated.

Other stuff is in the pipes, of course.
posted by FauxScot at 8:10 AM on July 8, 2012 [1 favorite]


FFT fixed link.
posted by FauxScot at 8:13 AM on July 8, 2012


It turns out, some of the usb tv tuners that are out are basically software defined radios

Well, that's $20 I didn't realize I was going to spend 5 minutes ago. But seriously, thanks for the link, zabuni, that looks super-cool and I can't wait to start playing with it.
posted by jcreigh at 8:16 AM on July 8, 2012


Woah, that "cheapo $65 TH-UV3R" would appear to do everything that my old Kenwood TH-78A did, and the Kenwood was around $300 in 1994 dollars, IIRC.

I think I want one.

Is there a cheap SDR that will let me do 6 meters? I always wanted to play around with that band, but could never afford an elaborate base station and 6M HTs weren't very good.
posted by snuffleupagus at 8:28 AM on July 8, 2012


SDR is just a different way to create (or receive) the signal. It's not magic, any more than a computer sound card is magic.
posted by gjc at 8:44 AM on July 8, 2012 [1 favorite]


Maybe I should put my call sign in my profile on here... I've had a Soft66LC2 (2.5-30Mhz) for about a year but haven't had time to play with it as much as I'd like.

I got burned by one of the "bad" eBay sellers ("Oh, we're out of stock!" then they turned around and sold what was previously an $11 P160 device for $55+) a few months back and got disgusted and forgot about the RTL-SDR project for a while.

Just picked up a pair of "DVB-T USB Starter Set"s (USB dongle, USB extension cable, antenna connector adapters) from NooElec for $80 total. Looking forward to playing with them.

Heh, and I have a UV-3R sitting on my desk under a pile of cables a couple feet away...
posted by mrbill at 9:12 AM on July 8, 2012


Like Devonian mentioned, none of the newfangled stuff will be as fun as it was powering up a Ten-Tec 1253 regenerative shortwave receiver that I built up from a pile of parts and hearing Radio Taiwan.
posted by mrbill at 9:22 AM on July 8, 2012 [1 favorite]


I have a feeling that SDR might totally fascinate me, if only I could find a more simplified starting point toward understanding precisely what the hell it actually is.

Can someone help an old man out? Maybe with a link to a more basic, introductory article on the subject?
posted by DirtyOldTown at 12:08 PM on July 8, 2012


I ordered one of the $20 rtl-sdr usb sticks a few weeks ago and spent the intervening shipping time getting the gnuradio suite compiled on my mac. Now that everything has arrived and is running, I'm at a total loss, though I do have several tabs of tutorials and documentation open. It's one of those things where if you don't know the basics of radio, the documentation refers you to several thick books before you get started.
posted by crawl at 12:28 PM on July 8, 2012


Are there any cheap USB dongle to pick up shortwave and frequencies below 64Mhz?
posted by pashdown at 1:39 PM on July 8, 2012


So it suddenly is a lot cheaper to create an IMSI catcher and intercept GSM calls? Now all we need is some very public and embarrassing intercepts and perhaps we can get decent crypto on cell phones?
posted by DreamerFi at 2:16 PM on July 8, 2012


The RTL-SDR buzz showed up last week on one of the sailing forums I frequent. The boaters are interested in its possible use for receiving ship and weather data signals. So I've ordered one and I believe it's about halfway to North America by now.

Dirty Old Town - ground zero for uptodate info on the RTL-SDR projects is here. And, here's a nice overview of RTL-SDR with the dongles.

SDR, especially if available on a cheapie USB stick, means to me that some esoteric functions (like RF spectrum analysis) that normally require expensive hardware can now be done on the cheap in software. for $20 and some time downloading software... hell yeah it's a great toy learning opportunity.

Note that these dongles have crappy front ends and lame antennas, so serious radio performance might require some effort or investment in antennas and RF preamps.

I was into radio as a geeky youth (while waiting for the Internets) and I've built and used a few shortwave receivers. SDR is an interesting new facet of radio technology, but I don't think it brings anything that will halt or slow down the decline of ham radio and international shortwave listening as hobbies or useful media.

Back in the day Late at night, when you slowly tuned across an international shortwave broadcast band, you'd try to tune in between the big and close stations that you already logged months ago, in the hopes of grabbing something new. Something would fade in, and it's weak yet clear... and you have to keep tweaking the tuning to stay on it, and if you're lucky the signal is still audible at the top of the hour when you hope for a clear station id.

Nowadays, your frequency-synthesizing digital-readout radio tunes in 100Hz jumps. When you find a new station, you take note of the frequency, and you visit a couple of websites with up-to-date schedules for all the shortwave broadcasters, and the time plus the frequency will immediately ID the station. A station which brobably broadcasts on the Internet too, without all that tuning or fading. Or, just download the podcast for later.

The number of countries doing broadcast shortwave to North America is dropping. CBC just shut down their shortwave arm (RCI).

Ain't the same. -sigh-


pashdown: Are there any cheap USB dongle to pick up shortwave and frequencies below 64Mhz?

It's possible to make a front-end mixer that would 'up-convert' frequencies below 64 MHz to within the acceptance range of the cheapie dongles.
posted by Artful Codger at 8:10 PM on July 8, 2012


If the bank card's security depends on RFID readers being hard-to-get, then it's not really secure, is it?

True dat.
posted by flabdablet at 9:53 PM on July 8, 2012


The cheapest way to get started with SDR is websdr, a collection of SDR stations around the world that let you tune up to 3 KHz of your own private passband on their receivers via a Java applet. The applet only implements CW, AM, and SSB (both USB and LSB), but that's enough to get started with most of HF. PSK31 would be awesome, but they don't have it right now.

73, NY3U
posted by autopilot at 5:23 PM on July 9, 2012 [2 favorites]


Very belatedly, I was checking into the Phi's user manual, and I spotted something of interest: there is no warranty whatsoever on the hardware. According to them, once you have it in your hands, they wash their hands of all further responsibility. If it never works at all, or breaks in the first week: too bad, so sad.

For a $850 device, I find this absolutely unacceptable, and would suggest that this, perhaps, might not be your wisest investment.
posted by Malor at 3:05 PM on July 15, 2012


I finally got the Ezcap receiver from DealExtreme today. I haven't actually done anything with it yet, but I wanted to let folks know that DX is A) real, and B) very slow. They didn't ship the order until the 20th, and it finally came today. It comes Registered mail, so you have to either accept delivery in person, or leave a signed note in your mailbox.

Just sort of a heads-up. If the thread doesn't close, I may post more about my experimentation with it, but delivery, at least, was successful.

It appears that a good antenna that will actually cover the full range of this thing is kind of involved to build -- zabuni's Hackaday link, in turn, links to plans for a 'discone' antenna that looks promising. But, for now, I'm just going to go grab a $15 TV antenna from Radio Shack that they say works well for terrestrial broadcasts. It looks like satellite signals will need the discone.... apparently this is because satellite feeds change their polarity all the time, as they're staying in the same orientation while flying overhead in a circular path around the Earth. So it looks like it's spinning from the perspective of the ground. Thus, you want a receiving antenna with 'circular' polarity. Regular vertical and horizontal antennas, it seems, will lose lock on a weak satellite signal. I'm not real clear on how polarities work, just that they exist, and that you want to match your source for best reception.

I didn't realize that circular polarity was even possible, so chalk that up as Thing One I learned about radio. But I am completely clueless on how it works. Vertical and horizontal made sense, because that's just the direction that the photons are vibrating in, so aligning your antenna with their vibration means you catch more of them. I have no idea how something that's fundamentally linear can be polarized into a circle.
posted by Malor at 3:43 PM on July 27, 2012


I have no idea how something that's fundamentally linear can be polarized into a circle.

One way to think about it is to imagine it as the superposition of two linearly polarized waves that are 90 degrees out of phase.

To elaborate on that a bit, suppose we've got a bog-standard 3-d Cartesian coordinate system. So let's say that a plane wave is travelling in the z-direction. The electric and magnetic field components are always perpendicular to the direction of travel, so we can describe as being in the x-y plane. Also, since there is a strict relationship between the electric and magnetic fields in a self-propagating wave, let's just forget about the magnetic field for now, and only consider the electric field, since if we want to know about the magnetic field we can figure out what it must be from the electric field.

Now pick some arbitrary location in space. We can describe the electric field at this point by considering it to be the sum of the electric field in the x and y directions. More specifically, the x and y components will be sine waves with magnitudes and a relative phase.

So let's try to think about this. Let's say that our x-direction is parallel to the ground. That means that "horizontal" polarization in this case would be if the y-component had a magnitude of zero, so then the E-field is just whipping back and forth in the x-direction, tracing out a line along the x-axis as time progresses.

Conversely, if the x-component had a magnitude of zero, the E-field would trace out a line bobbing up and down along the y-axis as a function of time. This would be "vertical" polarization.

Okay, so what about the case where the x and y components are both non-zero? What kind of shape will our E-field vector trace out? This is where it gets a bit tricky.

Let's first consider the case where the x and y components are "in phase", meaning that their sine waves reach their zeros, maximums, minimums, etc., at the exact same time. What would happen then?

Say that the x component has a magnitude of 2 and the y component has a magnitude of 1. Since the components are in-phase, we know that the E-field at minimum will be (-2, -1), at maximum (2, 1) and at zero (0, 0). You may notice that these points are co-linear, and this is not a coincidence: If the x and y components are in-phase, the result is still a linear polarization, it's just at some weird angle relative to the horizon instead of perfectly vertical or horizontal.

Alright, but what if they aren't in phase? Let's say that the x and y components are equal in magnitude and the x component is leading the y by 90 degrees.

Again, let's walk through what this means. Starting arbitrarily with the y component at 0 and increasing, this means the x component is at its maximum and just starting to decrease. (Remember what a sine wave plot looks like?). This means that our E-field starts out at (1, 0).

Now let's move 45 degrees later on our sine waves. One is increasing, and the other is decreasing, but they happen to have the same value. This puts us at (0.707, 0.707). (Recall: sin(45 degrees) = sqrt(2)/2 =~ 0.707)

Moving 45 degrees later (90 degrees relative to our start), the x component is now zero, and still decreasing, and the y component is at is maximum and just starting to decrease. This means our position is (0, 1).

You can see where this is going. We're tracing out a circle. Hopefully this should seem somewhat familiar if you've taken trig: sin and cos are 90 degrees out of phase, and trace out a circle.

Anyway, I hope that helps. I suck at explaining things, and it's complicated, and I don't fully understand it myself, so any confusion you feel is probably my fault.

BTW, if the phase difference is some random angle instead exactly 0 or 90 degrees, the E-field will trace out an ellipse and is said to be elliptically polarized.
posted by jcreigh at 4:53 PM on July 27, 2012 [3 favorites]


It would be nice if they specified Noise Figure. I'm having a hard time thinking of things I would actually do with an SDR. Perhaps it would be nice just to have a really cheap spectrum analyzer.

I have a feeling that SDR might totally fascinate me, if only I could find a more simplified starting point toward understanding precisely what the hell it actually is.

Can someone help an old man out? Maybe with a link to a more basic, introductory article on the subject?


You could start with wikipedia of course. As I understand it, SDR is basically just implementing the back end of a radio receiver in software. (radio meaning any terrestrially "over-the-air" transmitted signal like TV, FM, WLAN, Bluetooth, RFID). So provided the hardware front end and antenna can tune in the correct RF frequency and capture the full signal bandwidth with sufficient SNR, you could demodulate and decode any of the signals with the right software. The software for many of these standards has been developed as open source by other hobbiests or is available some other way, presumably. In the past you would need specific hardware to tune in a specific modulation, but with this device a fairly high performance "quadrature" ADC is placed at the IF stage to digitize the signal which is then streamed over the PCIe bus to the host memory of a PC where it can be demodulated, decoded, etc. Of course many of these signals are encrypted so along with all of the necessary software you'd have to have the right decryption keys. As this Phi device appears to have a transmitter, you could transmit signals as well (but not very far without another amplification stage and large antenna). For something like digital video there is actually a heck of a lot of software necessary to get from DVB-T (OFDM)/ATSC (8VSB) modulation to transport stream to mpeg decoded video frames and raw audio.
posted by Golden Eternity at 5:48 PM on July 27, 2012


Malor: I got my SDR-capable USB thingie with antenna just over a week ago. I found it on ebay for $19, including postage, and it took just over two weeks to arrive from Hong Kong. Sounds to me like DX doesn't carry stock, they just order when they have demand.

For software I'm currently using SDRSharp, til I have a free Linux box to try the GNU-Radio stuff. SDRSharp was very easy to set up and get working, and it's operation is pretty simple, and fun, with the "spectrum analyzer" display plus the waterfall. I've wasted more than a few hours bouncing up and down the band - listening to airplanes, marine, pagers, etc etc.

Plan on acquiring a few different antennae if you want the best performance out of the thing across its whole spectrum. I found some nice VHF/UHF rabbit ears at a surplus joint for $5 (HDTV-ready!!), and it clearly makes a difference on the lower end (60 to maybe 300 MHZ). On SDRSharp, you can see that the signals are higher with one antenna vs another. The tiny supplied antenna is decent at the higher frequency end.

Rather than having to source a euro RF connector, I've cut the supplied antenna's lead about 6" from the plug, soldered a phono (aka 'RCA') female plug on it, and now I just have to adapt any antenna lead to phono male.

It's big fun for $20. Lots to try, lots to learn. The spectrum analysis display alone is worth getting one.

Caveat - SDRSharp, even though it's supposed to be relatively efficient, still requires lots of CPU time to operate. on my 6-year-old 3 MHz P4 (WinXP), it was taking about 50% of my cpu's time... 40% if I hid the display. I was disappointed to find that my netbook with an ATOM N455 couldn't run SDRSharp without audio glitching. So much for portability, unless i buy a real laptop. I wonder if a small cheap DSP dev board would be able to be the platform for this dongle. (so many toys, so little time...)

jcreigh - nice explanation of circular polarization.
posted by Artful Codger at 8:35 PM on July 27, 2012 [1 favorite]


Well, after all that, the fucking Ezcap dongle no longer comes with the good tuner. The one I got came with the Fitipower FC0013:

Found 1 device(s):
0: ezcap USB 2.0 DVB-T/DAB/FM dongle

Using device 0: ezcap USB 2.0 DVB-T/DAB/FM dongle
Found Fitipower FC0013 tuner
Supported gain values (4): -6.3 7.1 19.1 19.7

posted by Malor at 4:14 PM on July 28, 2012


Malor, apparently that's happened to a lot of people, although this guy got DealExtreme to refund his money.

I also ordered mine from DealExtreme, which I haven't received yet, but I suspect mine will also be a repackaged EzTV-645 with the FC0013. Hopefully I'll be able to work something out with DX if that is the case.
posted by jcreigh at 7:03 PM on July 28, 2012


From the compatible hardware list on Reddit, there are several compatible units with the FC0013 tuner. The real magic is the Realtek RTL2832U.

Did you fire up your unit with software to determine if it works? If I understand correctly, the FC0013 tuner doesn't get above 900 MHz.

For the record, here's what I bought, it's got the E4000 tuner, and apparently there's still quite a few on auction.
posted by Artful Codger at 8:08 PM on July 28, 2012


Yeah, I ordered a different one from NooElec on Ebay, which explicitly said it had the E4000 tuner and would ship from New York, so hopefully I'll have a better one to play with soon.
posted by Malor at 1:24 AM on July 30, 2012


OK, so I did a little more digging on my wrong order, and it turns out DealExtreme actively screwed me. It was not my mistake, it was deliberate fraud on their part.

My original email that I got for the order says this:

Description:Ezcap EzTV668 DVB-T Digital TV USB 2.0 Dongle with FM/DAB/Remote Controller , Item #:92096
Unit price:$19.60 USD
Qty:2
Amount:$39.20 USD


(I ordered a spare, just in case)

But now if I go look at the order, and click on the linked web page for what I supposedly ordered, now it's the 645, which has the crap Fitipower tuner, and isn't working correctly with the Linux software.

I was thinking I had screwed up. But I didn't. I ordered exactly the right thing, and they changed the webpage to make it look like I'd ordered something else.

Dealextreme has engaged in active fraud here. It's not a huge dollar figure, but it's fraud. You should not deal with them.
posted by Malor at 3:03 AM on July 30, 2012


Hmmm. From what I've read, it seems some "Ezcap EzTV668" cases were stuffed with #645 pc boards, so maybe DX were themselves screwed by their supplier...? So they now have a pallet of 645's to move. I notice that the DX webpages don't mention the chipset... did they, before?

It's cool (and also a little bit sad) that electronics, especially small functional blocks like these, are almost a commodity now, with several suppliers able to provide essentially the same functionality... and for peanuts. It was sort of neat to see the market dynamics unfold: as soon as suppliers twigged to the SDR potential, the prices shot up from $10 to $20 and more, and the actual chip IDs became the selling point. Meanwhile, dongles without the desirable chips get depressed in price.

For giggles I found a DVB-T dongle on ebay for around $10, and I asked them what chipset it used... and they wouldn't tell me. Anyway, ebay still has several suppliers with the RTL2832U/e4000 chipsets. I found some for about $16.50, ordered one yesterday, and the nice people tell me it hit the Hong Kong mail today.

So, other than the lower top end (900MHz vs 1.7GHz), how's the performance of the 645? Does it work at all? Did you try it with the SDR# software on Windoze? (I haven't fired mine up in Linux yet). The bulk of the 'easy' radio fun is below 900MHz anyway.
posted by Artful Codger at 10:37 AM on July 30, 2012


Well, my email says that I ordered a 668, but the web page now says that I ordered a 645, so it was obviously changed ex-post-facto. I haven't heard back from them yet on my request for a refund, but my overall determination of whether or not this happened in good faith will hinge on how they respond.

I haven't been able to get the radio working under Linux at all, although I haven't put a lot of time into it. The Windows software it came with works for FM radio okay, so I know it's at least partially working, but the Linux software I've tried doesn't get a signal from it at all. And the Windows software won't do US TV reception, as far as I can tell.
posted by Malor at 6:40 PM on July 30, 2012


And the Windows software won't do US TV reception

Dude, none of the SDR-capable dongles will do US digital TV. They aren't compatible with the North American DTV system. Most of the vendors are very up-front with this.

The whole point is to gain access to a very capable software-controlled tuner and demodulator.

For TV I have ... a TV.
posted by Artful Codger at 7:29 PM on July 30, 2012 [1 favorite]


I've ordered four from NooElec by now, and always gotten exactly what I ordered and they all work great, FYI.
posted by mrbill at 2:06 AM on July 31, 2012


The whole point is to gain access to a very capable software-controlled tuner and demodulator.

Yes, I understand that. However, since the software I'm using doesn't seem to like these dongles, I was seeing if I could use them under Windows instead. As it turns out, they're only good for FM radio, using the software that comes with them.

none of the SDR-capable dongles will do US digital TV.

I don't think this is worth underlining and getting in my face about. Everything I said was factual reporting on what I was seeing. The sites are selling them as "HDTV decoders", so acting like I'm an idiot for being surprised that they won't do US HDTV is way off base and uncalled for.
posted by Malor at 1:39 AM on August 2, 2012


I was in everyone's face about that, because if you missed that fact, others might have missed it as well. The magic dongles don't do digital TV in North America.

I now notice that DealExtreme don't seem to point that out, so I better understand how you and others might have missed it. So... my apologies.

Just trying to help (everyone).
posted by Artful Codger at 4:46 PM on August 2, 2012


So my order from NooElec is taking a long time. I ordered on Saturday, I believe. EBay said that the expected receive date was yesterday, Thursday. I got an email from EBay on Sunday saying my order shipped. Then I got an email from NooElec on Monday saying my order shipped.

So I went to track the package today, because I didn't get it yet, and as it turns out, they only transmitted electronic shipping info on Monday. They didn't actually ship the package until yesterday, the day it was supposed to actually arrive.

Not the end of the world or anything, but kinda scummy.
posted by Malor at 11:23 PM on August 2, 2012


(yesterday, meaning Thursday -- this is quite early Friday morning. So they didn't ship it until the morning of the day it was supposed to arrive.)
posted by Malor at 11:24 PM on August 2, 2012


So I've RMA'd my EzTB645, and supposedly I'll get my money back plus return shipping. We'll see.

Regarding the performance of the 645, I was able to pick up FM broadcast stations with the crappy included antenna, but not much of anything else. I tried to tune to some local repeater frequencies, but I didn't pick up anything, although that could easily be operator error.

One thing I did see that concerned me was a little bit of a peak in the signal at the tuned frequency and some nearby harmonics that was always there regardless of the selected frequency, which made me think that it had to be noise from the receiver.
posted by jcreigh at 9:43 PM on August 3, 2012


One thing I did see that concerned me was a little bit of a peak in the signal at the tuned frequency and some nearby harmonics that was always there regardless of the selected frequency, which made me think that it had to be noise from the receiver.

I have seen this too - a bump around the center of the range, and what seems to be constant , evenly-spaced signals, and I have one of the 'good' ones (e4000/RTL2832). I've read somewhere that the bump in the center is DC offset, and any persistent peak that's at the same point to either side of center is most likely some interference picked up after the tuner, at the next stage input. Also, any broad, consistent, regularly-spaced bumps are likely some sort of outside digital interference - hash from the PC, etc.

I wouldn't be overly concerned. The things were designed to be cheap TV receivers, not lab instruments. There are some simple things that can be tried to improve their performance. Most important is better antennae, so you have stronger signals. I believe I reduced hash from the computer just by using a USB extension cable to get the thing further away from the PC. Once I get my second unit in, I'm going to try more invasive tricks, such as better RF rejection at the USB jack, and shielding the whole unit.
posted by Artful Codger at 5:29 AM on August 4, 2012


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