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Group Kickstarting a High-Bandwidth Software Defined Radio (SDR) Peripheral

Soulskill posted about a year and a half ago | from the name-it-for-some-flavor-of-pie dept.

Technology 140

TwineLogic writes "Many Slashdot readers have been enjoying the availability of $20 USB radios which can tune in the range of 50MHz-2GHz. These devices, while cheap, have limited bandwidth (about 2MHz) and minimal resolution (8-bit). Nuand, a new start-up from Santa Clara, wants to improve on that. Their Kickstarter proposal for bladeRF, a Software Defined Radio transceiver, will support 20MHz bandwidth and 12-bit samples. The frequency range to be covered is planned as 300MHz-3.6Ghz. In addition to the extended spectrum coverage, higher bandwidth, and increased resolution, the bladeRF will have an on-board FPGA capable of performing signal processing and an Altera processor as well. SDR hobbyists have been using the inexpensive receivers to decode airplane data transmission giving locations and mechanical condition, GPS signals, and many other digital signals traveling through the air around us. This new device would extend the range of inexpensive SDRs beyond the spectrum of 2.4GHz Wi-Fi. In addition, the peripheral includes a low-power transmitter which the experimenter can use without needing a 'Ham' license."

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300 mhz and up? (3, Insightful)

fyngyrz (762201) | about a year and a half ago | (#42774429)

Mmmpf. HF is where all the fun is. :)

Re:300 mhz and up? (1)

drwho (4190) | about a year and a half ago | (#42774505)

Get a downconverter. You know, a 400 mhz oscillator, a mixer, and some filters.

Re:300 mhz and up? (5, Funny)

GrahamCox (741991) | about a year and a half ago | (#42774531)

Do you know how hard it is to make a stable 400 millihertz oscillator?

Re:300 mhz and up? (1)

WWJohnBrowningDo (2792397) | about a year and a half ago | (#42774605)

How hard can it be? Whenever I'm in meetings the clock always seems to run at half speed. That's 500 millihertz right there.

Re:300 mhz and up? (1)

jamesh (87723) | about a year and a half ago | (#42776213)

How hard can it be? Whenever I'm in meetings the clock always seems to run at half speed. That's 500 millihertz right there.

I bet it's not stable though. You watch the clock more closely next time - I bet two ticks are never quite the same.

Re:300 mhz and up? (0)

Anonymous Coward | about a year and a half ago | (#42774835)

Can't you just make a faster oscillator and use a clock, every 10 ticks is a tick.

Re:300 mhz and up? (1)

volvox_voxel (2752469) | about a year and a half ago | (#42775149)

You can get cheep VCTCXO's (voltage & temperature controlled oscillators) that have a temperature stability of better than 1ppm/C. You can study the root-allan- variance curve from your oscillator data-sheet to see how well it will work.

You can get some very very good VCTCXO's and rubidium atomic clocks second hand if you're a radio amateur guy. They used to be combined in cel towers with crystal oscillators. If you look at the root-allan-variance plot, quarts oscillators have poor long-term stability and excellent short term stability. A rubidium atomic clock has poor short term stability, and excellent long term stability. They need to combine them to get the best of both worlds.

Be sure to phase-lock all your test equipment to the same 10MHz source so that all your instruments will agree.

Re:300 mhz and up? -- narrow-band comments (1)

volvox_voxel (2752469) | about a year and a half ago | (#42775187)

the radio amateur comment was mainly reference to people that can buy expensive equipment used on the cheap, vs those that want to sell a product. FYI: It's possible to create a radio that can transmit a signal all over the world with very little power. The trick is to use a very narrow band source. This makes you sensitive to drift in your oscillator, and is mainly due to temperature. If you had a portable narrow band transceiver, you can use the human body as the thermal regulation source to stabilize your oscillator.

Re:300 mhz and up? (0)

Anonymous Coward | about a year and a half ago | (#42775695)

400 millihertz is 0.4 oscillations per second. Its not that hard actually. Just get a motor that turns an ac generator, slowly (actually 24 revolutions per minute). It can be quite stable actually. Doing it mechanically is much easier than doing it with anything like a crystal. That *would* be crazy. You are correct in describing 400mHz as 400 milliHertz. I get quite annoyed when people randomly substitute the big M with the little m. 1 mm (1 millimeter) is the thickness of a dime. 1 Mm (1 megameter) is about 620 miles. Those who can't tell the difference have no business trying to tell anyone anything. I won't call them stupid though. No I won't.

Re:300 mhz and up? (1)

TwineLogic (1679802) | about a year and a half ago | (#42774873)

You mean "up-converter," but obviously you are correct that there is an easy way to bring signals up to this device, whereas there would be no easy way to bring 3.8GHz down to a lesser device, such as an RTL-based dongle.

Re:300 mhz and up? (1)

cruff (171569) | about a year and a half ago | (#42774511)

You can do a direct conversion SDR with a suitable speedy DSP, or even a fast CPU at HF.

Re:300 mhz and up? (1)

solidraven (1633185) | about a year and a half ago | (#42774563)

Yeah, but the fun is making the microstrip and cavity filters. Nothing quite beats the fun of building your own spectrum analyser. Not to mention the challenge of building a stable multi octave VCO on your own.

Re:300 mhz and up? (1)

msk (6205) | about a year and a half ago | (#42774601)

Meh; I've become an appliance operator as far as ham goes. I turn on my 2m rig only when the weather's nasty. I might like to do HF again, though, if I had the equipment.

Re:300 mhz and up? (1)

solidraven (1633185) | about a year and a half ago | (#42774623)

Well, simulation is key really. Additionally it's amazing how you can get some pretty accurate measurements with crude instruments in the HF range.

Re:300 mhz and up? (1)

Cornwallis (1188489) | about a year and a half ago | (#42774679)

The newest issue of QST has a pretty nifty article on SDR using the DVB-T dongles. Included are details on building a HF convertor which works nicely.

Re:300 mhz and up? (2)

fyngyrz (762201) | about a year and a half ago | (#42774761)

The thing you need to know about those sticks is that they are *really* prone to overload and various nasty IM-like failure modes. Fun, you bet, but you kinda get what you pay for there. If you want them to work well, you'll spend ten times the effort on filters in between the antenna system and the unit in most install situations. In a really rural area you could get away with it, as everything is (relatively) weak then.

Best one out there right now is about $200 US, it's the FUNcube pro+ dongle. That's near-0 through about 2 GHZ, so you get LF through L band, IIRC. Still has some overload issues (not awful, but not what you'd really want, either), but for two hundred bucks, ya can't beat it.

-- Not associated with the FUNcube folks either, other than my (free) SdrDx software [flickr.com] supports it.

30 mhz and down (2)

fyngyrz (762201) | about a year and a half ago | (#42774731)

For HF:

SDR-IQ (about $500 from RFSPACE or a store) and my SdrDx software [flickr.com] (free) -- Windows and Mac versions. 14 bit decoding, USB connection to the computer, ethernet server software (free) available so you can remote the head unit.

192 kHz bw coverage from a few Hz to 30 Mhz: AM, SAM, FM, USB, LSB, CW... output to (free) decoding for SSTV, WEFAX, RTTY, Olivia, Contestia, Domino, Heil, DREAM (digital SW broadcasts), MFSK, MT63, PSK, QPSK, PSKR, THOR, THROB, NAVTEX/SITORB... pretty much you name it.

RF waterfall with palette control, RF spectrum (signal) display, independent analysis scope (RTTY, audio, spectrum, vector, 3D, Smeter/Squelch, carrier, audio waterfall)

Band markings, channel and freq ID database, auto SW station ID, point and click brick wall envelope control, multiple notch filters, TDM filtering, multioctave 50/60 hz filters, memories and memory markers, DSP noise and impulse processing, wideband recording (192 khz at a time) and playback, LPF, HPF, compatible (on the mac) with Audio Hijack Pro and Soundflower for even more audio processing goodness...

External tuning knob support, midi control surface support (to remap real knobs and buttons to other controls like volume, RF gain, squelch, blanker settings, passband edges, tuning by steps, etc.), remote antenna tuning support, remote radio control support (TCP/IP, includes example Python clients.)

SDR makes analog radio look like some very un-serious stuff. I'm listening to some hams on 3870 kHz now.

-- not associated with RFSPACE. I just write code. :)

Re:30 mhz and down (0)

TwineLogic (1679802) | about a year and a half ago | (#42774899)

Your involvement with this might be the reason you didn't do enough research on whether bladeRF is HF-capable.

Re:30 mhz and down (2)

fyngyrz (762201) | about a year and a half ago | (#42775021)

No, the reason is that TFS says "The frequency range to be covered is planned as 300MHz-3.6Ghz.", and "12-bit samples" and this is slashdot, pal. You're bloody lucky I read TFS. lol.

And given that TFS puts the F range at "why would I be interested in that?", and the sample depth at "yawn", why would I *then* go researching more about the unit?

As for my involvement, if any SDR manufacturer wants support, I've been willing to write it free of charge. Just FYI. I've probably put as many hours into the whole SDR thing as anyone you're likely to ever meet; but the fact is, there's an entire range of capabilities out there. This one, according to TFS, falls somewhat short. If TFS is wrong... well, then, perhaps you should be pestering the person who wrote TFS, eh?

Re:30 mhz and down (0)

TwineLogic (1679802) | about a year and a half ago | (#42775079)

Ok, I am looking for an 858 MHz software defined receiver with at least 19 MHz spectrum bandwidth, and 8-bit samples work just fine for me at present. What's the most cost-effective solution for me at present? I only run Linux, so exclusively Windows support will be unacceptable.

I couldn't care less about Ham bands, but 450 MHz and 120 MHz would be "nice to have," as well as 1090 MHz. But I only need 850Mhz - 869MHz.

This bladeRF looks perfect for me.

By the way, I live a few blocks from a commercial FM station and use the RTL-based dongles at present. I don't have any problems with overload, even when tuning 120 MHz (same band in the e4000 LNA). I don't think the dongles really have the problems you stated. They do have a lot of problems (particularly birdies, and a high noise figure), but the concern about overload is urban legend.

Re:30 mhz and down (1)

fyngyrz (762201) | about a year and a half ago | (#42775237)

Probably should grab a copy of "cuteSDR" and get the linux version working (it's a QT project.) From there, build yourself an ethernet server for your chosen SDR (there are linux examples out there), and you're up.

So what's at 850-869 mhz of $400 worth of interest to you?

By the way, I live a few blocks from a commercial FM station and use the RTL-based dongles at present. I don't have any problems with overload, even when tuning 120 MHz (same band in the e4000 LNA). I don't think the dongles really have the problems you stated. They do have a lot of problems (particularly birdies, and a high noise figure), but the concern about overload is urban legend.

Not a legend at all. I use an outdoors discone for above 30 mhz; I'm about 5 blocks from the sheriff's department, and listening to 154.785 or 154.920, I get a huge desense when 155.385 (ambulance) is active. Probably the reverse too, though as I don't monitor the ambulance, I can't say. Even listening around 136 Mhz (WX satellites), I get de-sense when the railroad or sheriff's department fires up locally. That's with an RTL dongle and with the FUNcube, and FUNcube Pro+, all three. I can see the noise floor pump right in time with the signal. When I trap the (huge) ambulance signal out, the effect goes away.

Re your success with FM, your dongle may have an FM broadcast band trap. Or your antenna system might be doing it for you. Heck, your antenna cable might be doing it. RF is somewhat tricky unless you're pretty knowledgable. Another possibility is that you are seeing the de-sense as a constant thing; in that case, you wouldn't know until/unless they take the station off the air.

Also, just FYI, overload is a concern with any radio. Dynamic range is one of the key specs we look at. At some point, once the RF is too hot, radios get in (deep) trouble. Prior to that, they start to de-sense, etc. Depends on the design. An SDR, which depends on digitizing a wideband signal, will get in trouble if the signal exceeds the A/d's highest sample; at that point, all the detail goes out of the signal and the entire bandwidth being sampled is effectively poisoned. That's aside from what happens if there's an RF front end in there, filter(s), a mixer, etc., which quite often, there is.

Re:30 mhz and down (0)

TwineLogic (1679802) | about a year and a half ago | (#42775409)

I can't help but notice that you weren't able to come up with an example of a better SDR for my application. "cuteSDR" doesn't seem relevant because I write all my own code to control the radio, demodulate (FSK/NFM) the signals, correct the parity-checked bits so the CRC matches, decode the content, etc. It's really irrelevant, because I asked you to name a piece of SDR receiver hardware which fits my bill and is cheaper than $400. I am all ears on that subject, but I don't need any pointers to software. I was asking you to substantiate your pooping on this project by providing an example of an SDR device that would be better for the fun I am having, not the fun you are having. You seemed to gloss over that for some reason.

So what's at 850-869 mhz of $400 worth of interest to you?

Public agencies trunked radio, with whom I am cooperating on a proprietary application. Sorry I can't say more than that, but the signal of interest is Motorola SmartNet in my case. The application sprang from having fun monitoring it, and observing the potential for an improvement to their system.

Re your success with FM, your dongle may have an FM broadcast band trap. Or your antenna system might be doing it for you.

No, none of the dongles have FM broadcast band traps, and the antennas are directly connected 800Mhz 1/4 wavelength dipoles. These are both purchased and home-built antennas, I have several of these dongles. I think you missed the part where I can easily pick up very weak and distant 120MHz signals (yes, using the 800Mhz antennas) which use the same front-end filter as broadcast FM, when we are talking about e4000-based dongles. The FM station nearby is so powerful that I owned several devices (telephones, computer speakers) which I've had to replace because the station was audible on their output. And yet, I can hear airplanes that are 50 miles out in the 120 MHz... I realize the 800MHz antenna is slightly antenuating the 95MHz FM signal, but it's also attenuating the 120MHz air band.

RF is somewhat tricky unless you're pretty knowledgable.

At this point, don't trip over your ego. I'm knowledgable enough to be sure there is no front-end filter of any sort reducing the FM broadcast stations. I understand there is a culture around talking up the trickiness of RF, but let's get past that for the sake of reality.

Dynamic range is one of the key specs we look at.

So, surely an expert amateur radio operator such as yourself will realize that 8 bits gives 50dB dynamic range? Which of course is awful. Yet this overload problem doesn't seem to be real.

That's aside from what happens if there's an RF front end in there, filter(s), a mixer, etc., which quite often, there is.

Are you aware the e4000 data sheet is "out there" on the web? Between the antenna and the A/D, I've got: an ESD diode with 6pF capacitance, the e4000 front-end filter and LNA, the e4000 mixer, 5 more amp stages, decoupling caps, then the A/D, then, the single worst part, a "mystery" (undocumented without NDA) FIR with 20 taps. Why you would imagine that a $20 dongle could arrive with an FM broadcast tap is beyond me. The dongles aren't even shielded, and I can easily pick up the FM broadcast with a shielded 50-ohm resistor connected across the antenna input...

I'll give you that it is likely that the FM station is always contributing to my noise floor, but, realistically, the noise floor of the e4000-based devices is already horrible, with an 8-11dB noise figure, lots of birdies around the multiples of 28MHz and 5/3 of that. If any signal were going to swamp the dongles, I would expect that to be 480MHz USB emanations -- in particular because there is no way to attenuate them via adjusting the front-end LNA gain -- the signal appears to intrude after that stage. Yet I can receive at 450MHz just fine, and that is in the same front-end filter band as 480MHz.

Re:30 mhz and down (2)

fyngyrz (762201) | about a year and a half ago | (#42775521)

I can't help but notice that you weren't able to come up with an example of a better SDR for my application.

I can't help but notice that I didn't claim there was one. :) You do know what a "straw man" is, right?

"cuteSDR" doesn't seem relevant because I write all my own code to control the radio, demodulate (FSK/NFM) the signals, correct the parity-checked bits so the CRC matches, decode the content, etc. It's really irrelevant

CuteSDR is a great starter app that can be tweaked to work with anything. You didn't mention that you wrote your own code, just that you wanted "linux support", and inasmuch as that would mean, get ready, "software", I pointed you at the software that would support whatever hardware you wanted to run, which I had already assumed you had identified, because, get ready, you had said so. If, as you say, you write your own software, then "linux support" is pretty irrelevant, because you'll be doing the writing. I just figured you were looking for software because I'm unaware of any SDR with a "linux connector" or a "linux spectrum", ya dig? Consequently, I pointed you at something that had already done most of the difficult stuff. You're welcome, even if you're maybe kinda working a bit too hard at missing the point.

Public agencies trunked radio

I see. Something commercial, then, from the secrecy, etc. Good luck with the project.

Why you would imagine that a $20 dongle could arrive with an FM broadcast tap

"trap" -- typo, dunno if it was yours or mine, too lazy to look. A trap can be as simple as a coil and a cap, especially in this kind of setup. Small, too, at 100 MHz or so. Nothing expensive.

Are you having a bad day? My sympathies, if so. You seem to be grasping at the idea I'm your adversary. I'm not. I'm just some guy on the Interwebz.

Re:30 mhz and down (0)

TwineLogic (1679802) | about a year and a half ago | (#42775627)

If, as you say, you write your own software, then "linux support" is pretty irrelevant

By "linux support," what I mean is either a working USB driver for it, or a data sheet if there's no USB driver. The bladeRF is open hardware, with even the schematic available and all chips having public data sheets. A device that does not support linux would be a device with no programming information and no driver. I imagine they exist, but maybe I am wrong and there is no such device in the existing market of devices made by hams.

I can't help but notice that I didn't claim there was one. :) You do know what a "straw man" is, right?

You claimed this device wasn't as good as the devices which already exist. That is why my argument is not a "straw man" but a "prove that." I actually have an application for this device, but you claimed that the device was not as good as others already available but intended for the Ham market. As it turns out, the device is a better deal for my application than anything out there.

Are you having a bad day? My sympathies, if so. You seem to be grasping at the idea I'm your adversary. I'm not. I'm just some guy on the Interwebz.

The only negativity I've read toward this project has uniformly been from Hams. From that group, there has been a generally dismissive tone of, "sniff, it doesn't go down to kilohertz..." As a group, you seem to be anti-anything that isn't for Ham applications.

The negative comment you posted is your fault. Yes, it was modded up by dummies, but you posted it. Why do people need to see your negative opinion as the first post? That was pretty lame, in my book. You're not just some guy on the Interwebz when you top-post a fund-raising article with a disparaging comment, you're a negative nancy with some say in the outcome.

BTW, of course "tap" for "trap" was a typo, as you can read in my post there are several other occurences of the word "trap" spelled correctly. Your suggestion that I might have been regurgitating your typo, as if I wouldn't know a "tap" from a "trap", is again an occassion where you are tripping over ego.

Re:30 mhz and down (1)

fyngyrz (762201) | about a year and a half ago | (#42775937)

My comment was spot on accurate, near as I can tell. So I'm perfectly happy to take it as "my fault".

If the thing starts at 300 mhz, as TFS says it does, then there's the basis for the comment.

As for the rest, ok, whatever. You have a nice day.

Re:30 mhz and down (0)

TwineLogic (1679802) | about a year and a half ago | (#42776079)

Mmmpf. HF is where all the fun is. :)

Savoring the "accuracy" now... Mmmmpf. Somewhat tasteless in that regard.

Re:300 mhz and up? (1, Interesting)

TwineLogic (1679802) | about a year and a half ago | (#42774833)

Actually, the bladeRF has baseband input with 20MHz bandwidth, and same with output. The ADC and DAC pins are available at the baseband signal. So perhaps your nay-saying is motivated by ignorance or jealousy.

Re:300 mhz and up? (1)

fyngyrz (762201) | about a year and a half ago | (#42774889)

Nah, even knowing that, it's motivated by the fact that connecting the DAC to anything would be a royal PITA. There are SDRs out there that plug an play almost DC to L band; slap 'em into the USB port and get on with it.

Sorry, there are just too many good SDRs out there already that are basically plug and play USB or ethernet. 14 bit, 16 bit and more. A 12 bit SDR that doesn't get below 300 Mhz? Nah. Not really in the running unless you want to deal with the (very, very few) interesting signals above 2 GHz or so.

The little tuner sticks are cute. but RF wise, they stink. The best one is about $200, and it's just ok, though the bandwidth is amazing. You want a *good* SDR, go visit RFSPACE, that's bottom of the price stack, and they go up from there. There are *many* vendors.

For hams who want to transmit, check out Flexradio. A decent range of SDRs. All plug and play.

Re:300 mhz and up? (-1, Redundant)

TwineLogic (1679802) | about a year and a half ago | (#42775041)

So, I went to visit RFSPACE... With regard to the SDR-IQ:

The hardware samples the whole 0.0001-30 MHz band using a high performance

LOL. What is the use of that for a non-Ham?

Re:300 mhz and up? (4, Informative)

fyngyrz (762201) | about a year and a half ago | (#42775091)

LOL. What is the use of that for a non-Ham?

LOL. Well, let's see. International shortwave broadcasts, both analog and digital. You know, news about other than the Kardashians. AM radio broadcasts (US and elsewhere, depending on your antenna systems.) Longwave broadcasts. Aero beacons. Military and utility monitoring. Solar flare monitoring. Monitoring ultrasonics, such as bats and insects. Submarine communications. Time stations. Citizens band. R/c device monitoring. Coast guard. Commercial marine communications. Weather reports (teletype, naxtex, FAX WX maps, greyscale satellite images.) All kinds of analysis of all of these. And yes, all kinds of ham radio monitoring too... you don't have to be a ham to listen and/or decode. There are eleven ham bands in the range 0-30 Mhz.

Just a brief overview, of course. HF is where the fun is, I assure you. I can monitor from almost DC to several GHz here, and HF is definitely where it's at as far as I'm concerned.

Propagation (1)

fyngyrz (762201) | about a year and a half ago | (#42775253)

I should also have mentioned that LF, MF and HF signal propagation is endlessly entertaining. If you roll that way. I do. :)

Re:300 mhz and up? (3, Interesting)

TwineLogic (1679802) | about a year and a half ago | (#42775289)

International shortwave broadcasts, both analog and digital. You know, news about other than the Kardashians. AM radio broadcasts (US and elsewhere, depending on your antenna systems.) Longwave broadcasts.

It's true those are all present, but "interesting" is in the ear of the listener. None of those qualify as "interesting" in my book.

Aero beacons.

You mean like VOR? Those are up in the low 100MHz, of course...

Military and utility monitoring

Army ground is 40.5 MHz, again 40.5 > 30. Are there other military signals (we'll get to ELF in a minute)? What utility signals are below 30 MHz? I see them in the 400s around here.

Solar flare monitoring.

Ok this is a little interesting, I'll give you this one.

Monitoring ultrasonics, such as bats and insects.

Ummmmm. Those little buggers use radios?

Submarine communications.

These are on ELF, I'll give you that. But they are encrypted, of course, and they are also immune to traffic analysis. What is fun about monitoring them? Plesae don't tell me these are in the clear...

Time stations.

What is interesting or useful about this, especially given the GPS timebase being globally available?

Citizens band.

One person's interesting is another person's ridiculous, I suppose.

R/c device monitoring.

You mean 27MHz R/C? The servo signal seems particularly boring, unless you are operating the R/C device, in which case you can look at it.

Coast guard. Commercial marine communications. Weather reports (teletype, naxtex, FAX WX maps, greyscale satellite images.)

All of these are somewhat interesting, I'll give you that.

HF is where the fun is, I assure you.

I'm having more fun at higher frequencies, I assure you. I think 1090 MHz is more interesting than anything you mentioned. 121.5 is worthy of note. The 450s and 850s (public safety and government) are pretty interesting to most people. Other people enjoy trying to figure out SCADA traffic in the 400's.

My complaint with your Score-5 first post is that you are pooping on a great project because your personal interests don't align. You're a ham. You think that is interesting. Good for you. As a ham, you also have a certain "authority" with some people. That authority is misused or misplaced when you dismiss a good project on the basis of having made an engineering decision that fits the interests of others, but not yours. I am very interested in getting access to the 2.4GHz wi-fi spectrum at the level of the signal. But my interests are more in software, software security, and things like that. So this particular SDR example from RFSPACE is of pretty much zero interest to me.

This (1)

ridgecritter (934252) | about a year and a half ago | (#42775355)

Mod up, please. Informative for me, would mod you as such if I could. Thank you.

Re:300 mhz and up? (0)

Anonymous Coward | about a year and a half ago | (#42775359)

Ummmmm. Those little buggers use radios?

If only there were some sort of device that could convert acoustical pressure waves to low-level electrical signals at the same frequency.

Someone should really get on that.

Re:300 mhz and up? (5, Interesting)

fyngyrz (762201) | about a year and a half ago | (#42775489)

You mean like VOR? Those are up in the low 100MHz, of course...

No. I'm talking about CW format beacons. They're all below 540 kHz. Very useful to see what LW prop is going on.

It's true those are all present, but "interesting" is in the ear of the listener. None of those qualify as "interesting" in my book.

Well, sure. That's the way everything is, isn't it? I'm answering you from my perspective, because you asked me.

Are there other military signals

Yes, tons of 'em. Not just out of the US, either. You can also see spectrum probes sliding across the various portions of HF; hear mystery "coded" signals (numbers stations), even see some weird stuff that's (thus far) eluded any explanation, like slow carriers that transit the 49 meter SW band, right through the commercial stations and a very sedate and extremely stable pace. No idea what that is. Just find it interesting.

Ok this [flares] is a little interesting, I'll give you this one.

LOL, thanks.

Ummmmm. Those little buggers [bats, insects] use radios?

All you do is for your "antenna", you hook up a tweeter or a supertweeter, and hang it out by your eaves, attic entrance, etc. Feed that to the SDR-IQ. All manner of hilarity ensues. Including the lady of the house going "what, bats? We have BATS?!?!?"

What is interesting or useful about this, especially given the GPS timebase being globally available?

Well, they're also typically frequency references. You can do a number of things with them. First, they tell you about propagation (because they're always on, so you know what's on bounce by what you can hear.) You can do some cool experiments like these [radiohobbyist.org] . They give you deep sea weather reports, too. WWVH (Hawaii) and WWV (Colorado) give you an instant tip because one uses a womans voice, the other a mans. You can tell how prop is going by what you hear. There is also BCD coded time on there. And many nations have time signals, if you know where they are (and my software does.)

[CB] One person's interesting is another person's ridiculous, I suppose.

Well, yes, exactly. CB is bloody hilarious to listen to. At least to me. And it also, because it's so busy, serves as another type of prop indicator. Even if the ham bands are dead, for instance, you can tell they are open, just not in use, when the CB bands are open.

You mean 27MHz R/C? The servo signal seems particularly boring, unless you are operating the R/C device, in which case you can look at it.

What it tells me is that it's time to go outside and check the skies for our local air club, so I find it quite useful. Think of it as a "beacon for fun." I can also tell the guys if they're making a mess - too broad, etc. Listening is not everything; analysis and reaction is interesting as well.

I think 1090 MHz is more interesting than anything you mentioned. 121.5 is worthy of note. The 450s and 850s (public safety and government) are pretty interesting to most people. Other people enjoy trying to figure out SCADA traffic in the 400's.

Ok, great. More power to you.

My complaint with your Score-5 first post

Dude, seriously, don't blame ME for slashdot moderation. It's totally broken and I've said so for years, but in any case, I didn't mod the darned post myself so I don't see how I should accept any blame for it whatsoever. Seriously. The mods here are only on crack when they aren't on meth. It's something in the perl code. Nasty stuff. As for the first post, I saw the story (twitter feed), read TFS, hit post, wrote what I had to say, and posted it. Not my fault I got there first. Where the heck were you? lol

As a ham, you also have a certain "authority" with some people.

LOL. Oy. They probably think I'm 80 years old, hiding in the back room polishing my guns while listening to Rush Limpballs, as I spend my time asking people all over the world what my signal strength is. Because that's mostly what *I* think when I listen to other hams, Noodles bless their imaginary souls. Even though, due to circumstances beyond my control, I ended up in the blinking ARRL handbook, not even hams think I'm an authority on much of anything. Really funny remark, though, kudos.

That authority is misused or misplaced when you dismiss a good project on the basis of having made an engineering decision that fits the interests of others, but not yours.

Naw, see, what you're saying here is that because I'm involved or informed or whatever, I can't have an opinion. But see, the reason I'm involved is because I'm enthusiastically involved, and I *do* have opinions, and I have just as much right to express them as you or anyone else. And you have just as much right to express yours, etc., ad infinitum. Feel free to disagree, to pummel me about the head and shoulders with facts and counter opinions, and I'll not complain a bit. Telling me I can't *have* an opinion will go right by me because I think it's a nutzo position. You dig?

So this particular SDR example from RFSPACE is of pretty much zero interest to me.

But... of course. I wasn't speaking for you. I was speaking for me. You are aware that this is the intertubez, right? Where every assneck has a pants-poopingly annoying opinion? And wants to "share" it with you to the point where you want to dial 911 and cry assault? Worse, this is slashdot, where not only is the preceding true, but we're all slightly bonkers as well? I mean, really. Read some comment threads. I guarantee you, you will find opinions you didn't ask for, lol.

Re:300 mhz and up? (1)

hawguy (1600213) | about a year and a half ago | (#42775795)

Coast guard. Commercial marine communications. Weather reports (teletype, naxtex, FAX WX maps, greyscale satellite images.)

All of these are somewhat interesting, I'll give you that.

Aren't marine communication transmitted in VHF (~156MHz), and weather satellite images at 137Mhz? Well outside the 30Mhz upper limit of the RFSPACE device?

Re:300 mhz and up? (1)

AmiMoJo (196126) | about a year and a half ago | (#42776569)

The big one that nobody has mentioned is Wireless M-Bus on 168MHz. It is used for all kinds of metering applications - electricity, water, gas and so forth. There are a vast number of devices already using it.

How does this compare with the Ettus USRP B100? (1)

Anonymous Coward | about a year and a half ago | (#42774507)

The foremost question on my mind is how this compares with the devices from Ettus, like the USRP B100 The $400 minimum price (which the summary helpfully fails to mention) is not bad but there's not exactly a lot of history backing bladeRF up.

Yes, this is my first question too (1)

Su27K (652607) | about a year and a half ago | (#42776579)

Why do we need this project when USRP is already doing it for years?

Wy not cover the whole band at once? (2)

NixieBunny (859050) | about a year and a half ago | (#42774529)

I'm currently working on a research-grade gizmo that will digitize that entire 4 GHz wide band as one entity. It's to be used for an astronomical spectrometer. It's darn near doable today, the only problem being how to get the oscilloscope companies to shake loose a few 10 Gigasample/sec A/D chips.

Re:Wy not cover the whole band at once? (0)

Anonymous Coward | about a year and a half ago | (#42774565)

and that's why these telescopes have a supercomputer at 10,000 feet.

Re:Wy not cover the whole band at once? (1)

solidraven (1633185) | about a year and a half ago | (#42774579)

I'm wondering, have you tried interleaving 1 GSa/s units? They're more likely to cough those up considering how long they've been around. Though the clock distribution might become problematic.

Re:Wy not cover the whole band at once? (1)

NixieBunny (859050) | about a year and a half ago | (#42774765)

RF bandwidth is the issue. The 1 GSPS digitizers only have one or two GHz of RF bandwidth, so we'd have to make a big messy RF processor to capture the entire band. Besides, the goal of the project is to advance the state of the art!

Re:Wy not cover the whole band at once? (1)

solidraven (1633185) | about a year and a half ago | (#42776535)

Mhhh, you sure? I've seen a few that were pretty high up in bandwidth, they use the same method to make some of their high end scopes. Then again, you are trying to make a Fourier analyser so you will need a pretty sharp filter at 4 GHz. Good luck with it!

Re:Wy not cover the whole band at once? (0)

Anonymous Coward | about a year and a half ago | (#42774767)

you'll need amplification before the ADC and without some band limiting before it you'll be amplifying the full 4GHz noise bandwidth so your needed dynamic range goes through the roof

Re:Wy not cover the whole band at once? (1)

TwineLogic (1679802) | about a year and a half ago | (#42774867)

Well that's a brilliant question. Let's suppose we obtained 10 Gsps. How would we send those samples to the computer? Two E-SATA cables, maybe? It just doesn't seem very doable.

Re:Wy not cover the whole band at once? (1)

NixieBunny (859050) | about a year and a half ago | (#42775471)

Yup, I'm looking at eight 10gig Ethernet cables. But they are working on 40gig Ethernet, so life will get better.

It's inevitable that we'll eventually digitize the air that we breathe.

Re:Wy not cover the whole band at once? (1)

TwineLogic (1679802) | about a year and a half ago | (#42775583)

Yup, I'm looking at eight 10gig Ethernet cables.

WUT? Have you considered, oh, I dunno, PCI Express x16? They do make extension cables for that, to get outside the chassis.

Re:Wy not cover the whole band at once? (2)

volvox_voxel (2752469) | about a year and a half ago | (#42775083)

I have a radio astronomer friend that works on the CARMA sub-millimeter array doing signal processing/FPGA work. They use a (2) 26GSPS 3bit ADC (made by Hittite) for each orthogonal polarization for each antenna. They actually get >15 effective bits because they do averaging over 10 seconds (the SNR drops by the square-root of the number of samples). I am amazed that they can recognize hundreds of molecules, and subtitles of radio spectra with a 3bit ADC. There is a lot of interesting signal processing at CARMA. You can read about all kinds of interesting tricks to get high sideband rejection for your spectrometer bins, etc. One trick employed by oscilloscope companies [at least in the past] is to simply have a bank of ADC's, and use precision delays on the clock inputs. One ADC would see the clock pulse, the second one would see the clock that was staggered by 100ps, the next stage after that would be staggered another 100ps, and so on. You can get passive LC delay lines that are quite precise.

Re:Wy not cover the whole band at once? (0)

Anonymous Coward | about a year and a half ago | (#42775979)

Consider that a sigma-delta converter is (or can be) a 1-bit ADC. :) 3 bits is a luxury!

Bewolf Cluster (1)

Anonymous Coward | about a year and a half ago | (#42776333)

Run a Bewolf cluster of 100Mhz bandwidth SDRs that cover the whole specturm you're interested in.

Can they change the way my Smart Phone GPS works? (1)

bogaboga (793279) | about a year and a half ago | (#42774545)

SDR hobbyists have been using the inexpensive receivers to decode airplane data transmission giving locations and mechanical condition, GPS signals, and many other digital signals traveling through the air around us.

I mean, I would like to use my smartphone as a GPS without requiring a data connection (strictly speaking);

Just like how those GPS units from Garmin, TomTom et al work.

Possible?

Re:Can they change the way my Smart Phone GPS work (1)

Gordonjcp (186804) | about a year and a half ago | (#42774559)

That's just a case of finding (or writing) an app for your phone that uses the normal GPS receiver and a suitable pile of maps. The difficulty is not the data connection, it's storing and rendering all the map data.

Re:Can they change the way my Smart Phone GPS work (0)

Anonymous Coward | about a year and a half ago | (#42774711)

Sygic has one such 'offline' app for Android. Works well. And as you mention, the map data is huge, and needs to be downloaded one time before being able to use the app.

Re:Can they change the way my Smart Phone GPS work (1)

QuasiSteve (2042606) | about a year and a half ago | (#42774741)

Which, in turn, really isn't that much of a difficulty. The guy even compares it to a TomTom, and those generally have less than 2GB of storage as it is and will still let you store even the smallest of streets + a bunch of other data (e.g. approximate location of a house number along a street, zip codes, etc.) for the better part of a continent.

Somebody already mentioned Osmand, I myself tend to use Navfree. Works just fine as long as you ignore some of the routing they provide (right turn + U-turn + right turn = going straight.. admittedly, at some lights, this really is the faster route.. but then there's the 'exit highway, cross minor road, get back onto highway' quirks).

That, to me, is really the superficial difficulty - and why most people enjoy google's directions (which are almost on par with TomTom's).

I say superficial, because even more difficult - apparently - is making the app work intuitively and offering features people commonly need.

Just again as an example, and here Google's directions could really shine if they bothered...
There's a road that seems to connect with another road and allows you to get from A to B in less than half the time compared to when that connection isn't there. Unfortunately, that connection is not there - it's 250 yards or so of private land with private 'road' and the owner is flipping off the government until they offer enough to take away the 12 feet strip of non-arable, barren, littered-with-junk land from him.

On my TomTom, I would have to tell it that a road isn't accessible, find me an alternative. Unfortunately, since that section is not a separate section, I can only tell it that I can't enter the road that's leading up to that section, at all. It makes me go around even longer.

On Navfree, I can't even point to a road. I can only say that for whatever reason, I can't go down the next N miles (or yards). Since the turn-off to the way around is a few miles out, I have to tell it, at that point on the map, that I can't go down the next few miles. The result is that it, too, decides that the turn-off is not an option since I just told it I can't go down the next N miles. I have to drive up to the section, tell it I can't go down the next 100 yards or whatever, and then it'll suggest the usual way around.

On Google's Navigation.. I don't even know how I would do this. Possibly go to the 'alternate routes' screen, but I think I'd have to start a new navigation.

On web-based Google Maps? Click the trajectory, drag over to what to me looks like an alternate route, and have Google tell me 'yup, you can go through here... it's N miles long and will take you M minutes'.
That's a major positive usability factor of web-based Google Maps.

Add to that list things like lack of support for multiple destinations, lack of routing options (offering only 'fastest' is just sad, 'fastest' and 'shortest' is substantially better, but what happened to 'easiest' (more relaxed version of 'fewest turns'), ease of getting directions from A to B where A is not your current position, etc. etc. and the navigation apps really still have a long way to go. Storing the maps is definitely not the difficult part.

Re:Can they change the way my Smart Phone GPS work (1)

DMUTPeregrine (612791) | about a year and a half ago | (#42774749)

Google Maps has this, you can save areas to the phone. They take quite a bit of space though.

Re:Can they change the way my Smart Phone GPS work (1)

bogaboga (793279) | about a year and a half ago | (#42774811)

I have downloaded more than 400MB of map data but in order to even get directions to some place (on the map I have downloaded), my smartphone says it needs a data connection for this! Trouble! I will try those other solutions and report accordingly.

Re:Can they change the way my Smart Phone GPS work (1)

csnydermvpsoft (596111) | about a year and a half ago | (#42775193)

Many phone map apps don't do the route-finding on the device, even if they have the map data - they request the route from a remote server. The maps are for display only.

Re:Can they change the way my Smart Phone GPS work (0)

Anonymous Coward | about a year and a half ago | (#42775211)

Sadly you need a data connection in order to use it even with cached maps. If you have a wifi-only music player with GPS like the Galaxy Player 5, you're out of luck.

Re:Can they change the way my Smart Phone GPS work (1)

dido (9125) | about a year and a half ago | (#42774569)

I've been using Osmand to do that on my Android phone for years. You just need to download maps for the area around you beforehand.

Re:Can they change the way my Smart Phone GPS work (1)

ericloewe (2129490) | about a year and a half ago | (#42774677)

The data connction is used for two things:

Almanac - not strictly needed, as it's transmitted with the GPS signlas, but at sub-dialup speeds.

Maps - needed, but nobody said they have to be streamed. Google just pretty much decided they should and dragged everyone along. Nokia maps has long had the option of downloading local copies of the maps. There are also apps, like TomTom's, which provide essentially everything present on a standalone GPS device, usually with a subscription payment model.

Re:Can they change the way my Smart Phone GPS work (1)

safetyinnumbers (1770570) | about a year and a half ago | (#42775389)

This is one reason I chose to buy a Nokia C6-01 - I can download whatever worldwide maps I want and it does route-planning (including recalculating if I miss a turn) without needing any data connection. Useful as I have pay-as-you go with T-Mobile.

The map scrolling and zooming is faster than my Garmin and TomTom dedicated units, too.

You can do it today (1)

tanveer1979 (530624) | about a year and a half ago | (#42776769)

I could not get your question. Even today, you can use your phones GPS without data connection. Many offline navigation apps exist which do not require data(only one time to download the app and the map for your country) on your phone.

No mention of FCC certification? (0)

Anonymous Coward | about a year and a half ago | (#42774575)

This thing is an intentional radiator. The FCC requires certification for ALL intentional radiators, verifying that they comply with the requirements for each and every band they are capable of being operated in.

I saw no mention on the Kickstarter site about FCC (or companion CE) approval.

Re:No mention of FCC certification? (1)

solidraven (1633185) | about a year and a half ago | (#42774589)

Most countries have an exception in their laws for experimental low power devices...

Re:No mention of FCC certification? (1)

msk (6205) | about a year and a half ago | (#42774619)

and accommodation for hams

Re:No mention of FCC certification? (1)

EmagGeek (574360) | about a year and a half ago | (#42774817)

That is correct. US Law requires anyone marketing an intentional radiator obtain FCC equipment authorization under Part 15, Subpart J of "the Rules," _before_ the device is marketed for sale.

There is an exception in 15.23 for home-built devices, but this project does not quality, as the exception in 15.23 only applies to home-built devices, and not those that are purchased in kit form.

Re:No mention of FCC certification? (0)

Anonymous Coward | about a year and a half ago | (#42775249)

what is the definition of an "intentional radiator"? it doesn't say how much power it can actually put out but wouldn't something like this be more a like a very advanced signal generator? does your standard sine/square/etc. signal generator require the same?

Expansion Boards Interfaces (5, Informative)

Nuand (2831497) | about a year and a half ago | (#42774597)

Hey guys, I'm John (the guy from the video). We are very excited to have made it here on Slashdot! We just wanted to post up a comment that we also left on the Kickstarter page addressing the concerns of those interested in frequencies under 300mhz. The usable frequency range of the bladeRF does indeed start at 300MHz but goes up to 3.8GHz. Having one (or even two) front-ends spanning this many octaves is a challenge, however the bladeRF performs exceptionally well over the entire range. That however may not have been the case had we included the circuitry needed to reach those lower frequencies. As a solution, we added an expansion board interface to the bladeRF. One of our first expansion boards will be a block up/down converter. We wanted to wait a little bit to get some feedback from people to see what frequency ranges people were interested in seeing. As of now it seems very likely that we will look at going from as close to DC as possible up to a minimum of 11GHz. So as soon as we do our engineering homework and see what's possible we will make an official announcement about this on the Kickstarter page.

Re:Expansion Boards Interfaces (1)

BigDish (636009) | about a year and a half ago | (#42774643)

I went to college with Robert, and ordered one of these on day 1 of the kickstarter. Tell Robert to get his ass in gear and make the downconverter - I need it to use for my intended purpose (tune 75MHz) :-)

Re:Expansion Boards Interfaces (2)

EmagGeek (574360) | about a year and a half ago | (#42774825)

Have you obtained FCC type acceptance pursuant to Part 15, Subpart J of the Rules?

Re:Expansion Boards Interfaces (1)

cdwiegand (2267) | about a year and a half ago | (#42775739)

If it doesn't transmit, then strictly speaking it's not necessary. Just sayin'.

Re:Expansion Boards Interfaces (0)

Anonymous Coward | about a year and a half ago | (#42776713)

It does transmit. I think you mean Part 2, Subpart J.

Re:Expansion Boards Interfaces (0)

Anonymous Coward | about a year and a half ago | (#42775391)

Will you be able to seperately tune the RX and TX bands?

Re:Expansion Boards Interfaces (0)

Anonymous Coward | about a year and a half ago | (#42776691)

John, does what you are doing comply with Part 15 of the FCC's rules?

Lame (1)

ArchieBunker (132337) | about a year and a half ago | (#42774695)

This is gonna cost like $300-$400. Nobody is going to buy that except maybe a few researchers or dedicated RF hobbyists.

Re:Lame (1)

thoriumbr (1152281) | about a year and a half ago | (#42774847)

First, define "a few"...

And it's not lame. They are doing an amazing piece of hardware, and even if it's pricey today, it is a start. I am pretty sure the price will go down in the following years, and more and more people will be able to use it.
As the time of writing, they have already passed $34k, and I am sure they will hit the $100k mark soon. I don't have that much money to invest on them, otherwise I would already been waiting for my unit to come.
And I am not a researcher nor a dedicated hobbist...

Re:Lame (1)

TwineLogic (1679802) | about a year and a half ago | (#42774851)

It covers 20x the bandwidth of an RTLSDR dongle, for 20x the price, and it also transmits and has an on-board FPGA and Arm9. So you are probably wrong.

Re:Lame (3, Interesting)

fyngyrz (762201) | about a year and a half ago | (#42774935)

...of which there seem to be a very large number.

Heck, there are a *lot* of brands of SDRs out there for sale. It's quite surprising, perhaps, but there it is. I own several.

The thing is, you can get far better performance out of a decent SDR than you can out of any analog radio ever made. For a fraction of the cost, and with features you could never have had.

Just think of the many radios that have sold in the past, then imagine all those people waking up to the idea that they can have tons more performance. Everything from AM radio and SW radio to ham radio and police monitoring... all for relatively cheap and *amazing* performance.

How different? You could have bought yourself an ICOM R-8000 for over ten thousand dollars... yet today, slap a little box down on your desk and *wildly* outperform the thing. For a few hundred bucks.

Every radio person I've been the first to show my SDR systems to has done the gape/jaw-drop thing. Every one. And well they should. My friend Bob told me "It seems like you're cheating" :)

Re:Lame (1)

wramsdel (463149) | about a year and a half ago | (#42775763)

Can you define what you mean by "performance" above? Nothing I've read about amateur SDRs has shown them to "wildly" outperform analog radios in:
MDS
Noise figure
Blocking dynamic range
Intermod
Desense
Third-order intercept
Power consumption
In fact, certain SDR architectures may include things like spurious-free dynamic range impairments that are significantly *inferior* to analog radios. I don't deny that there are many things an SDR can do that an analog radio simply can't, chief among them being accommodate new modulation schemes without hardware modification, but I think they're far from a complete replacement for analog.

Re:Lame (2)

fyngyrz (762201) | about a year and a half ago | (#42775925)

SDR performance advantages: ability to dig signal out of noise. Ability to remove noise. Ability to control the bandpass. Sharpness of filtering. Ability to see what's going on around the signal, and spot signals, in unbelievably low-signal or high noise conditions -- or both. Time division multiplex filters that pull out many carriers at one time and leave excellent audio behind. Ability to ID digital signals visually in just moments... every type of digital signal has a different spectral "signature", and so I know I'm looking at Olivia, or RTTY, or SSTV, or whatever. Ability to record, and play back, entire bands. High resolution realtime carrier analysis. Ability to remote the receiver head. Precision metering. Completely reconfigurable in seconds. Direct integration with all manner of analog signal processing (eg soundflower, Audio Hijack Pro, and just about every audio plugin you ever heard of.)

Ability to get right in there and code whatever feature you want.

I had a Yaesu FT-2000, with the DMU and speaker and all the goodies. My $500 SDR-IQ wiped that thing out. On the same antenna, it could pull signals out of the noise that simply were impossible to hear at all on the FT-2000. It eliminated noise the Yaesu couldn't do a thing about, not with DSP modes and not with the blanker. The bandpass control (shift, width) wasn't even remotely comparable to the ability to drag a razor edged upper or lower bound. I sold the FT-2000 and its accessories. It was pointless, just a ton of knobs and buttons that couldn't even come close to keeping up.

I also have an FT-980, an old school analog ham radio; also can't keep up, just hears noise, mostly.

Here, the FT-2000's (presumably) greater sensitivity was useless; the noise level was too high, and it couldn't get rid of it. The SDR-IQ, plus software, eliminates the noise, so I heard much more. Then, having heard it, I can isolate it better because of the bandpass.

It doesn't do you any good to have certain types of specs unless you have a pristine signal environment. And where can most of us find that? Unless... unless you have RF signal processing that's so good as to obviate the noise. And that's what sits on my desk.

The SDR-IQ is not a top of the line SDR; RFSPACE (and others) make much higher performance ones. Yet it just kills in operation. I'd like to try the higher end ones someday. But I know from using this that an analog radio just can't get there.

I have lots of other SW radios, receive-only, also. The FT-2000 was the best receiver, but I've been collecting them for years. None of them can touch the SDR-IQ.

And finally, all this at about the cost of the high-end microphone for the FT-2000, the MD-200.

I'm not really talking about "stick" type SDRs here. You need a decent front end, and you need stable, high resolution sampling to avoid various artifacts. But if you can meet that fairly low standard, it can be an eye-opener.

Also -- like any radio -- you need to know your way around the tools you have. Given that I wrote my own, it's fair to say that I'm an expert user. But I also spent a lot of time with that FT-2000, I can tell you, and it's limits were surpassed the very first day I put the SDR-IQ on the same antenna.

Re:Lame (1)

wramsdel (463149) | about a year and a half ago | (#42776049)

Okay, so most significantly what I'm hearing is superior weak-signal performance by virtue of good DSP. I'll buy that. Your point about front-ends and the "stick" SDRs is well taken. I've never taken these things seriously because I take a look at most of the front-ends and there's...nothing. No filtering, no shielding, no preselection. And to think that some of them are 8-10 bits and depend heavily on pre-converter gain management, with nothing more than a silicon VGA with a few hundred microamps at best of bias...wow. It's damn scary. I can't imagine taking any of them to a mountaintop somewhere that has 25 transmitters going full-bore on a dozen bands and having a good experience with it. Maybe I'm just an RF design bigot. Anyway, I'll look into the SDR-IQ, sounds like an interesting piece of gear.

Re:Lame (1)

wramsdel (463149) | about a year and a half ago | (#42776193)

And speaking of front-ends, there's some funky stuff going on in the bladeRF's:
http://nuand.com/bladerf.pdf [nuand.com]
C331, the receive switch blocking cap, is 6.8pF. At 300 MHz, it has a capacitive reactance of 78 ohms. Unless there's a good reason for that (e.g. RF tuning), that's pretty irregular. Typically switch blocking caps are chosen to have very low reactance at the frequency of interest, so as to minimally perturb the 50 ohm environment of the switch port. The reference curves in the switch datasheet were taken with 47pF caps.

Another oddity: the switch control lines are bypassed at the switches with 8.2pF. The bypassing itself is good practice, but again, I question the value. At 300 MHz that's not a very effective bypass. Bumping up the cap values and adding a series element, a ferrite bead or even a resistor, would provide better rejection of environmental RF. My guess is that those traces are run on the surface layer, unshielded, as well.

Re:Lame (1)

Simulant (528590) | about a year and a half ago | (#42776947)

Can you recommend any sub-$200 USB SDRs?

Power does not matter (0)

Anonymous Coward | about a year and a half ago | (#42774729)

If you're sending outside the ISM Band, you're technically breaking the law, no matter if you are broadcasting 1uW or 1MW. If you're sending in licensed mobile band, you can expect the Blue-White striped helicopters...

Re:Power does not matter (1)

fyngyrz (762201) | about a year and a half ago | (#42774955)

Nope. There are still experimenters bands, ham bands, etc. There's even "the lost band" down in LF where we can fool with transmit capabilities without concerning ourselves with the FCC.

In the US, you can also broadcast at low power in the AM and FM broadcast bands, though there are some restrictions on antennas and so forth.

The FCC is basically the enemy of the people here; it spends its time making sure the RF spectrum is kept from the people and given wholesale to corporations. But they've not quite managed to kill off hams and experimenters. Yet.

good start (1)

drwho (4190) | about a year and a half ago | (#42774845)

over 1/3 of the way there, just a few days after it was announced. Of course, the posting here on slashdot has helped a lot. I hope the momentum continues.

Correction: 28MHz and, yes, it does cover HF band (1)

TwineLogic (1679802) | about a year and a half ago | (#42774859)

I wanted to correct my own submission.

First, the bandwidth, or amount of spectrum that is instantaneously analyzed, is 28MHz, not 20 as I wrote.

Secondly, some troll^H^H^H^H^H nay-sayer posted that this device cannot be used for HF. In the first place, the device can receive and transmit 0-20MHz because the baseband signal pins of the ADC and DAC are available on a header. In the second place, up-converters easily solve this "problem," whereas hitting 3.8GHz is a great advantage to this device.

Re:Correction: 28MHz and, yes, it does cover HF ba (0)

Anonymous Coward | about a year and a half ago | (#42775063)

whereas hitting 3.8GHz is a great advantage to this device.

Which is? Seriously, I can't think of one offhand.

Up to 2.5GHz I can see, but 3.6?

When do I get my magic radio? (1)

Above (100351) | about a year and a half ago | (#42775247)

I am not a Ham. I'm not interested in being one. That said, I have chased listening to some interesting things from time to time. I went to the effort of installing a long line antenna to listen to some shortwave from around the world. I have a scanner I've used to listen in on trains and planes.

What I want is a "magic radio". I want the interface to look something like a google search box, and take a wide range of inputs. I want to be able to enter a radio station call sign, a frequency, a call sign and get back a list of things that might match. Clicking on one would tune it in on one of these SDR radio thingies, and perhaps pop up some info that says what sort of antenna(s) should work so I can connect the right one to the computer.

I am not interested in transmitting, or at least, when I am I can use more traditional gear.

Re:When do I get my magic radio? (0)

Anonymous Coward | about a year and a half ago | (#42776747)

I also want a "magic radio".

I'm thinking of cellphones and tablets and laptops that can work on all cell phone broadcast frequencies and networks, can receive updates to unlock access to new frequencies that these cell phone companies keep buying, can get GPS, digital AM and FM, and OTA digital TV, from a single chip.

Wireless routers and network adapters that just need a firmware update to unlock access to new wifi frequencies and standards.

If they want to push cell phones, they need to include additional functionality. Speed only gets you so far.

No HF? Not that interesting. (1)

CrAlt (3208) | about a year and a half ago | (#42775267)

They are knocking out a big market by not having HF. Alot of interesting weird stuff on HF to analyze with a SDR. Thats where most of the ham activity is also.

I have one of the cheap 70mhz+ USB ones. Other then playing around with it some on 144mhz there isn't much going on in my local area on UHF and above.

Restrictions? (0)

Anonymous Coward | about a year and a half ago | (#42775433)

I like this project, and I've signed up on Kickstarter. However, I'm wondering if because this will allow access to frequencies that the Feds prefer nobody in the civilian world tune in, their frequency range will be windowed - some freqs not available by law. Any communications law practitioners care to opine?

Re:Restrictions? (0)

Anonymous Coward | about a year and a half ago | (#42776779)

IANAL, but unless they plan to market the SDR as a consumer-grade radio scanner in the USA, they shouldn't have to block out the 824. - 849.Mhz Tx & 869. - 894.Mhz Rx ranges used by analog cell-phones. Even if they did try to block out certain frequencies, most purchasers would be able to easily bypass any such restrictions.

becoming the norm (1)

speedlaw (878924) | about a year and a half ago | (#42775569)

as a ham who learned back in the day, i just bought a baofeng radio. it is sdr. why not ?

For us not in the know about SDR... (1)

mbourgon (186257) | about a year and a half ago | (#42775917)

Where's a good primer on what it is, where to buy a good $20 SDR (and which to buy), and what it can be used for?

Re:For us not in the know about SDR... (1)

Anonymous Coward | about a year and a half ago | (#42775967)

Here you go

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

Re:For us not in the know about SDR... (1)

fossilstar (716525) | about a year and a half ago | (#42776121)

I suspect there's a zero missing from that price.

$25 or $600? (1)

dohzer (867770) | about a year and a half ago | (#42776083)

I'm wondering how much I should donate. I'd like to have hardware, but I'm a bit poor right now.
Am I better off just investing $25 and then purchasing a module once it's released (and I have some more loose change)? Will it be more expensive once it's released?

Board hardware is closed/proprietary! (1)

Anonymous Coward | about a year and a half ago | (#42776875)

See kickstarter FAQ. Too bad. Neeeexxt!

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