Flutter: $20 Wireless Arduino with 1 km range | Hacker News Reader

Flutter: $20 Wireless Arduino with 1 km range

kickstarter.com

363 pointstrafnar139 comments

Lots of misinformation in these comments. For those dreaming of building a mesh Internet alternative, consider that these devices are not being designed for TCP/IP. From the looks of the KS page, they are going to speak a mesh protocol but likely something proprietary, perhaps similar to ZigBee, that is designed as a wire-replacement protocol for Arduino-to-Arduino comms. That's a long way from Internet routing.

They are offering a WiFi shield but it's backed by the Arduino. Not really something that you want to mesh-route TCP/IP, in my opinion. There are more suitable choices.

I'm also a little concerned about selling a device that is so high-powered by default. I'm assuming that they're using 900 MHz here. Is it really necessary for everybody to transmit with enough power to reach 1 km? In the US, there's a FCC rule that says that amateur radio operators use the minimum power necessary when transmitting. I'm not sure if it applies to a device like the Flutter but it probably should.

From the datasheet of the TI radio they're using[0], the maximum programmable output power is +12 dBm, which is about 16 milliwatts.

There's no way you're going to see the advertised range with the antenna pictured. For comparison, the wifi hardware in your laptop typically outputs around 100-200 milliwatts.

Edit: TI appears to have a "range extender" part (i.e. a power amp) that can kick the output power up to +27 dBm (500 mW) at the band that they're using. I don't see any mention of this part on the kickstarter page, but this is the only plausible way I can see for them to get anywhere near the range advertised.

Half a watt seems pretty high to me too, but apparently it's comfortably within FCC limits [1][2], and since ISM devices are designed for consumer use (as opposed to licensed use by a competent radio operator), I don't think the same rules about being clever with output power would still apply here.

[0]: http://www.ti.com/lit/ds/symlink/cc1101.pdf

[1]: http://www.afar.net/tutorials/fcc-rules/

[2]: http://www.beagle-ears.com/lars/engineer/wireless/fccrules.h...

Hah, thanks for the edit. Yeah we've already gotten the range. I've even checked the output of our boards with a radio expert (google Earl McCune, he's an advisor), and using his many expensive Agilent scopes we've experimentally verified that performance of my design is pretty much exactly on par with the reference designs, taking into account that we are using a custom designed RF balun [1] instead of the discretes they use on the reference design. Our RF Expert confirmed I had made a good choice with that, as the losses are tiny compared to ease of manufacturing it provides.

[1] (I think it's this one, I'd have to check the part number, they have a couple similar ones). http://www.johansontechnology.com/datasheets/chipset-specifi...

Are you sure you're able to legally transmit at 1km. Had thought antenna gain + transmit power had to be around 0 dBm, at least for 434MHz.

Hadn't seen the rules for 900MHz though.

First thing that crossed my mind too. It's definitely forbidden in Europe.

Yup, but we can 868MHz in Europe, and with all the support from international backers I think we may end up doing that as a stretch goal! Just have to talk it our with our RF expert, which we're doing!

The Xbee Pro 900 is 50mW, for reference.

This is what I initially thought as well, having built an ISM band transceiver around the 350/400 MHz bands a few years ago. I recalled much lower power limits.

(I had posted something along the lines of "there's no way in hell the FCC would let you transmit at half a watt" but have since edited).

Apparently the 900 MHz bands are different, and the FCC has rules governing output power going into the antenna (1 watt), as well as an effective radiated power (which essentially places limits on your antenna gain) (4 watts).

[1]: http://www.afar.net/tutorials/fcc-rules/

Wow that is very much radiated power!

I remember range testing a 434MHz product and being hundreds of meters away (line-of-site). The product passed FCC testing.

So a watt going into a 6dBi antenna... Flutter's measurements make sense now!

I'm pretty sure that to get 1 Watt you have to use direct sequence or frequency-hopping spread spectrum under FCC part 15.247... Just sitting on a frequency as a 15.249 device or general ISM device you aren't allowed to use much power at all.

See FCC part 15.247: http://www.gpo.gov/fdsys/pkg/CFR-2001-title47-vol1/pdf/CFR-2...

I work with UHF Gen2 RFID readers all day which do 1 Watt/30 dBm into 6 dBi = 4 Watts EIRP, but they are definitely required to do hopping.

EDIT: and after looking at the 50 mW 900 MHz XBee units, they are doing hopping as well according to their datasheet.

So it looks like if you want to keep the range, you may want to start looking at hopping algorithms...

From my reading of the rules, you are limited to broadcasting +36 dBm EIRP (30 dBm [1W] into a 6 dBi antenna -> 4W EIRP). This can be a single frequency. In the 900 MHz band, your bandwidth is limited to 902-928 MHz (US limitations, different in other global regions).

You can happily beam out a 915 MHz single-tone CW carrier at +36dBm EIRP all day and that is fine.

The reason your gen2 reader is frequency hopping is not FCC mandated but protocol mandated. The UHF RFID gen2 tags have a high manufacturing variation and the RF frequency response varies greatly between tags. Some tags may be resonant closer to 902 MHz and some tags may be resonant closer to 928 MHz. Hopping over various frequencies allows the reader to address all tags in its view.

The only reason the readers are "required" to do hopping is to conform to the gen 2 protocol. In fact, from what I remember you can use the LLRP (low-level reader protocol) to stuff the frequency hopping table with a single frequency so that it will stop frequency hopping.

(My PhD was on high-data rate (up to 100 Mbps) rfid/backscatter communication.)

Wifi operates at a higher frequency and data rate, which both reduce range.

exactly this ^

Sigh

I was wondering whether I'd get called out for omitting this. You're right, of course. :-)

Well, you're partially right (and it's a bit of a mess, which is why I left it out in the first place). Yes, increasing the data rate reduces range when all else is equal. The carrier frequency doesn't actually matter. The bandwidth does matter, but not in the way that you'd expect. Increasing your channel bandwidth actually increases your range when your receiver is noise limited (which is necessarily the case when you're making the range/bitrate trade-off). But the "power" term in the standard formulas assumes you're measuring the total power in your band (not carrier power). So you can't reap the benefit of doubling your bandwidth without also doubling your transmit power (unless you're using a true spread spectrum transceiver, which is a different beast).

There are plenty of other factors, but when you're thinking about these things, you ultimately want to form an intuition for "what is the minimum energy per bit needed to make my receiver happy?" and "how much transmit power do I need to deliver that energy, given a specific antenna and desired range?" [1]. This analysis lets you ignore the specifics (modulation technique, multiple carriers, multiple antennas, spread spectrum, etc) that make it difficult to compare this TI radio and your 802.11n card, but still gives you a very accurate result.

My original point (which still stands) is that you can't feasibly build a 1 kbps transceiver with 16 mW transmit power and a two inch monopole antenna and expect to get anywhere near half a km of range with the TI radio. It simply isn't sensitive enough.

[1] http://en.wikipedia.org/wiki/Eb/N0

(As an aside, Eb/N0 was one of those things that I found incredibly confusing when I first learned about it in a communication theory class - I recall several homework assignments where we had to solve for Eb/N0 symbolically for various theoretical transceivers. I only realized how useful it was after building real radios and plugging in actual numbers. Once you get the hang of it, it becomes a very good bullshit detector for "overly optimistic" range, bitrate, and power trade-offs that doesn't require spending hours in front of a simulator.)

It doesn't sound like you're familiar with the Friis equation [1], which shows how carrier frequency is inversely related to transmission distance.

The receivers are probably around -90 dBm sensitivity, which would place the system's range around a kilometer and would improve depending on their PA and LNA characteristics.

[1] http://en.m.wikipedia.org/wiki/Friis_transmission_equation

Please. This is actually a common misconception about the Friis equation. It assumes an isotropic antenna with an effective area that is dependent on lambda. But physical antennas have an effective area that varies with lambda squared (obvious on something like a horn or a dish with a real 2-D aperture, but even simpler antennas behave this way). It turns out that this perfectly cancels out the frequency dependent term in the equation when the transmitter and receiver use the same antenna, leaving you with only the reduction in power density as you move away from the transmitter.

I had a professor give an epic lecture about this several years ago, but this is the best I could find on short notice [1].

As it turns out, there is a real source of frequency dependence in your path loss, which is the atmosphere. Your link budget calculation is really just an annoying geometry problem. Conservation of energy still holds, so you should be immediately suspicious when the naively applied Friis equation (which does not take atmospheric effects into account) makes received energy vanish just because you cranked up the frequency. Just as you should be suspicious when you receive more energy than you transmit when you're in the antenna's near field. Always know what your approximations imply.

The receivers are actually a bit more sensitive than that (the TI chip is ~-120 dBm at the target frequency; the whole package could be close to -114 dBm if designed well).

The claim I made was that you can't get half a km on 16 milliwatts. I cited 16 milliwatts because it's the max transmit power of the TI chip alone. You cannot make this go half a km with the antennas shown on the kickstarter page. You'd either need more power, or one of the antennas would need to be a dish. Even in an unreasonably quiet environment, you'd run out of energy at the receiver way before running into frequency or bitrate dependent effects.

But it turns out that 16 milliwatts is not the output power used. TI makes an amplifier that increases the output power to half a watt. In this case you'll easily get the half-km range.

[1]: http://www.dslreports.com/forum/r24210307-Reconciling-the-Fr...

You're right we're speaking a bit tangentially. Hadn't heard of the Friis argument that frequency doesn't matter as long as antennas on RX and TX are the same. I'm not sure I understand it yet.

Nevertheless, let's get some numbers on the page to see if I'm misunderstanding the subject.

Here's a rough link budget with some estimates

TX/RX antenna gain is around 0dBi (seems reasonable [1]) TX power = 16mW = 12dBm [2] RX sensitivity = -90dBm (personally, better than -100dBm seems aggressive)

Roughly, our link budget formula can be... Path loss = TX power + TX gain + RX gain - Rx power [3] Path loss = 102dB

Ideal free space loss over 1km at 900MHz is around 91dB [4]. Therefore, we have about 10dB margin in our link budget to transmit 1km. We also have a few dB margin in the antenna and receive sensitivity estimate.

[1] http://store.rfdesign.com.au/antenna-900mhz-2dbi-monopole-rp... [2] http://www.cpcstech.com/dbm-to-watt-conversion-information.h... [3] http://skypilot.trilliantinc.com/pdf/link_budget.pdf [4] http://en.wikipedia.org/wiki/Path_loss

They cancel perfectly when the antennas are the same. There's a scale factor when they're different, but the frequency dependence still goes away.

So I'm adding about 10dB for noise, and getting a path loss that's about 15 dB higher, giving me an expected range closer to 100 m. What are you using for the antenna's effective area?

Do you agree with lpmay's explanation of Friis? Path loss increases as frequency increases. However, if aperture is constant while frequency decreases, which increases path loss, gain increases, which offsets the increase in path loss, and there is no change in link budget.

My receive sensitivity has noise included. It's why I think -100dBm seems for a 900MHz TI chip (could be wrong? didn't design this system...). Factor in noise/packet loss/PER or however you want to quantify, and I'd guess you'll get to a measured RX sensitivity of ~-90dBm.

Mentally, I equated RX sensitivity at data rate with RX power, which shouldn't be done for explanation purposes, but my original formula should still hold.

What are you using for path loss [1]?

[1]: http://en.wikipedia.org/wiki/Path_loss

Take this as the kind of half-cooked thought it is at this point (long day, about to go to bed and don't want to crack open the textbook), but the fact that your path loss leaves 10dBm of power above your Rx sensitivity doesn't mean you have 10dBm of link margin. I'm not completely sure, but I'd guess it means you have 10dB of SNR (theres a units from dBm to dB thing I haven't completely resolved in my head). Whether that makes your link work or not depends on the bitrate, modulation you choose and BER you can accept (and etc). If your modulation scheme needs 9dB of SNR (proportional to Eb/N0) to operate at an acceptable BER, your system may only have 1dB of actual link margin.

We're circling around some good stuff. Night though, thanks for the information to think about.

Can you explain more what you mean? I think you're getting at something I agree with, but you're also saying some things I don't think are quite right...

Firstly I don't know what you mean by the Friis equation "assumes an isotropic antenna". It explicitly accounts for the gain of each antenna, in the direction of the link, relative to an isotropic radiator. The fact that it's relative to an isotropic radiator is just how all gains are measured. In fact, the antenna pattern doesn't matter at all to the link, only the gain in the direction of the link (Friis assumes no multipath). Whether the receive and transmit antenna are "the same" or "different" really doesn't make a difference.

This is the distinction I think you're trying to make, and which I agree with:

If gain is held constant, link margin improves as frequency decreases because of reduced path loss at lower frequencies. If instead antenna aperture is held constant as frequency is lowered, antenna gain will decrease at the same rate as path loss improves and there is no net effect to the link.

Both answers are technically correct, in a fixed gain scenario where your antenna can grow as large as necessary to hold gain constant, (or the scenario doesn't allow for high gain, narrow beamwidth antennas) lower frequencies will make longer links. In systems where aperture is constant (which is the case for many practical systems) antenna gain will improve as quickly as path loss degrades when you go to higher frequencies, and there is no net advantage at any frequency.

Sure, sorry.

So you're right that the two antennas being the same doesn't really matter. What I meant was that if the two antennas are the same, the entire part of the Friis equation that deals with frequency dependence goes away (the lambda / (4piR) part). If the antennas are different, the frequency dependence still goes away, but there's some new scale factor.

There are two interesting things that you want to know about your antenna. The gain, which measures directivity, and the effective area, which roughly corresponds to the cross section of sky that the antenna can listen to. Going from the transmitter to the receiver, you have some transmit power going into the antenna. You now want to figure out what the power density is in the vicinity of the receiver. You get this by spreading the power over a sphere and multiplying by the antenna gain of the transmitter.

Now you need to know how much of that power density is seen by the receiver. This is slightly more complicated than the transmit case, because you now have to take into account the antenna gain of the receiver (i.e. where it's pointing), which the Friis equation considers, as well as how big a chunk of sky it's listening to (i.e. effective area), which the Friis equation does not consider.

It turns out that the effective area is a function of lambda^2 (an antenna of some size and ideal frequency will have an easier time collecting higher frequency signals, and a harder time collecting lower frequency signals). So the lambda^2 from the effective area cancels the 1/(lambda^2) from the Friis equation.

"you can't feasibly build a 1 kbps transceiver with 16 mW transmit power and a two inch monopole antenna and expect to get anywhere near half a km of range with the TI radio"

I mean... you say that, but we did, and we're not doing anything special, I just set two android phones to volley their GPS position over USB to the board, send it over radio, and calculate the distance on the other end. I then verified the calculations manually using google earth and landmarks.

Here's what texas instruments has to say [1] about the radio: "You can achieve a range of several km with the CC1101 without any problems (line of sight). The output power can be programmed up to 12dBm and the sensitivity level on the receiver is dependent on the programmed baud rate. With a sensitivity of -112dBm and an output power of 12dBm, 915MHz ; the expected range with Friis equation adapted to take into account the height from the ground would be approx 3km."

We're being advised by Earl McCune, a serious Silicon Valley Radio expert (google him, he's awesome), and he donated some of his time to help test the board with his nice Agilent RF stuff. He was impressed with the performance of this little chip, and was also impressed that my layout nearly perfectly matches the TI reference design.

[1] http://e2e.ti.com/support/low_power_rf/f/155/t/15984.aspx

Wait, so you're not using the additional TI power amp?

Well shit... Now you have my attention. I obviously missed something if I was off by two orders of magnitude. I'll take a closer look when I have some more time.

In the meantime, I would strongly suggest adding as many technical details to the kickstarter page as you can (output power, for starters. A (rough) schematic would be fantastic).

Edit: Actually, do you have any specs on the antennas you've tested?

Back of the envelope, and assuming their design is the same like their board pictures posted on the kickstarter page (i.e. no PA, all RF done inside the chip):

The CC1200 puts out 14 dBm [1]. Receive Sensitivity from the datasheet at 915 MHz is -122 dBm @ 1200 baud, -110 dBm @ 50 kbps, and -97 dBm @ 500 kbps. Very good overall. (all these values are from the datasheet.)

Free space ideal path loss at 915 MHz and 1 km is -91.7 dB [2]. This gives an ideal budget of 44 dB. Toss in some antenna gain and you should have plenty to play around with for losses in the passives, connectors, antenna alignment, etc. 3 km is pushing it, with another 10 dB of path loss. So I would think 1 kilometer is easily attainable at 1200 baud with this chip.

However, things start to change with FCC compliance... 15.249 devices (a lot less limitations, including fixed frequency) can transmit at max -1 dBm. [3] So the compliant device at 50 kbps, -1 dBm, 1 km has 15 dB ideal budget, right on the edge of working. 500 kbps is probably not going to happen at 1 km except in perfect conditions.

So now you want to use hopping as a 15.247 device to get the limit up to 30 dBm/1 Watt. This chip doesn't support DSSS, so we are frequency hopping. This limits us to a channel bandwidth of 500 kHz, so you can't run at high speeds - maybe 200 kbps or so? Downside is you are spending some time hopping and waiting for PLLs to stabilize, there is a chance for interference on certain frequencies resulting in periodic dropouts until you hop to the next frequency, and the software side/hopping coordination is tons more complex. But you would be able to communicate pretty far!

Also, note that RF is very unfriendly and link budgets can easily be used up with obstacles in the way, walls, trees, not to mention pesky humans etc.

Hopefully this clarifies some things? Please let me know as well if I am off anywhere, I know a little about this but it is also late...

[1] http://www.ti.com/product/cc1200 (see datasheet) [2] http://www.qsl.net/pa2ohh/jsffield.htm [3] http://rfcalculator.mobi/convert-dbuv-3m.html, 15.249 allows 50 mV/m @ 3m = 93.89 dbuV/m @ 3m = -1.34 dBm EIRP. [4] FCC 15.247 & 15.249

We are definitely designing these to support mesh networks, and though I haven't written it down anywhere yet, we're not going to default the radios to full on, that will either be automatically configured (probably too difficult, but I'll look into it) or just manually specified. I would really love to make it automatic though, and for anything under constant comms they could easily communicate their signal strength in the ack if needed to coordinate that. The mesh protocols are still under development (that's what we need Kickstarter for!).

Our wifi + ethernet shield makes it easy to have an always on device that routes traffic for home Flutter networks, but you can also just plug the board into your PC over USB and feed it traffic that way, you can run arbitrary data of any size over the link and all communications are guaranteed (or explicitly timeout), so I think piping TCP/IP over it will be easy.

You can also use a raspberry pi and one of our boards to accomplish what the network shield does (for roughly the same price) but the network shield is designed for exactly this purpose, and many people will find value in that.

It's tough to pitch an Arduino with lots of highly technical capabilities - Arduino users just want to know "but can i make a wireless beer brew setup?" That's the kind of information we try to speak to on the KS page. We're also still learning what questions people have!

Thanks for the reply, Taylor. Perhaps you can explain this to me:

What niche are you guys trying to fill with this? I guess I'm just not seeing it yet. You talk about "piping TCP/IP" over the data link but how is this superior that using any of of the dozens of other powerful, low-cost, mesh solutions purposely designed for TCP/IP routing?

Maybe you're trying to fill the "talk to my kegerator" niche. OK, but how is this superior to the Xbee shield [0]? That shield interfaces with a number of different Xbee products that offer a wide variety of power outputs and ranges. These Xbees do mesh networking out of the box. How does Flutter do it better? Help me understand. :)

[0] https://www.sparkfun.com/products/10854

I don't think XBee is anywhere near that range. Plus, a Flutter is cheaper than an XBee shield + an Arduino.

Anyone bulding remote controlled "stuff" will be delighted.

Yeah, exactly this. Used to be, you buy an Arduino Fio and an xbee module[1], and for $50 you get max 100m range? Two nodes then cost $100, which is enough for one project and one device to route traffic to mobile, lets say.

With Flutter, for $100 you can have 5 nodes, so you can have the beer brew monitoring, control some lights, measure the humidity of your greenhouse, and build a robotic car you can drive with your phone.

We're trying to hit commodity pricing for consumer mesh hardware so people can just toss it in whatever they want to make and easily handle the communications they need.

And not relying on another radio module manufacturer means we can design the product to be everything we need and nothing we don't, and only pay for board manufacture once, instead of paying for a module (which is a manufactured board) that you then put on your own manufactured board.

The radio and cpu should be on the same board and should be very useful (hence open and arduino). Then we can really build a network of things.

You seem proud of the fact that with your $20 pricing you are turning your module into a commodity.

Although I'm sure consumers will cheer you on, I think the typical entrepreneurial thought is that having your product turn into a commodity is a bad thing because there is no money in it.

Do you have a different viewpoint on this?

TCP/IP is a fun idea and I think people will get some use out of it for mesh and darknet purposes, but the target is Arduino users (aka "regular people"). That said, I'm designing the protocol so professionals can use it too. We may end up forking it, and doing what Raspberry Pi did, giving people Rasbian for regular folk and other distros (featured in the same place) for hardcore users.

And you asked why not the shield you linked to?

This is why: https://dlnmh9ip6v2uc.cloudfront.net//images/products/1/0/8/...

That is a $25 shield, $23 radio, and a $29 arduino all stacked on top of eachother, and you get 100m range max. Wouldn't you rather have a single board for $20 or $30 that meets those needs and lets you reach out up to a kilometer or more?

I can't speak for the creators of Flutter, but I can definitely attest to that TCP/IP with full mesh routing should be doable with the Flutter hardware. We (Thingsquare) have the CC1101 as one of our supported hardware platforms and use it to run full TCP/IPv6 networking over a self-forming mesh. The system is used in a number of commercial products and systems. The chip-level firmware is open source so I guess the creators or backers of the Flutter system might even be able use it pretty much out of the box: http://thingsquare.com/tech/

One of the things needed to get full IP routing working is to do channel switching over the sub-GHz connection. Both the FCC and ETSI regulations let you transmit at a higher power and with longer bursts if you switch channels with a regular interval and if you back off if you find other transmissions in your channel.

That said, TCP/IP routing over a sub-GHz CC1101 link isn't going to be very fast. It is suitable for automated devices but not a general purpose replacement for WiFi connectivity. For IEEE 802.15.4g-compliance, the raw bit rate is 50 kbit/s which isn't a lot. The CC1101 can be run in faster, non-802.15.4g compliant, modes though.

Agreed. This isn't going to form the 'alternate Internet' that some people are clamoring for. But there are tons of applications (machine->machine) where a basic serial/ssh is all that's required.

We've had similar hardware in the field for 3+ years now, covering ~50 square kilometers in a mesh configuration.

Absolutely! There's lots of hardware around, but being able to turn an Arduino project into an emergency beacon or IP link has some benefits too, and $20 is likely cheaper than what's been around. At $20 these are commodity prices, which I don't think we've had for high quality general purpose computing + wireless platforms.

It's always good to see cheaper hardware - our early 'proof of concept' hardware were based on an 'Arduino FIO' + 'XBee Pro' which came out to ~$60. Then quickly migrated to a TI MSP430 + CC2500(CC1100) which slashed the price to <$20 all told. We're now on the ARM M3/M4 SoC bandwagon as well. So I understand that angle.

I'm sorta curious as to what you plan on using the $80k for. Are you going to farm out PCB fabrication to OSHpark/China/whatever - or get a pick and place machine, CNC mill, and try to do everything inhouse?

Anyways, best of luck with the project.

We have a lot of resources for manufacturing in China. I've personally ordered a few thousand assembled boards from Gold Phoenix through the course of my old job, which was... fun.

We've got a lot of connections in Silicon Valley to tap too for finding hardware partners. I'm not particularly interested in becoming a fab house, unless it's cheaper (including headaches).

Thanks for the well wishes!

ARM, IO pins, on board antenna.

$30 adds an external antenna and battery charging circuitry.

ISM bands, mesh networking. The chip they are using do 1200bps and 2400bps at low power, but the data sheets talk about 600kbps capabilities of the modem. I'd plan on the 1200 or 2400 if you are thinking 1km. Look to IEEE 802.15.4-2003 (Low Rate WPAN) for more information. (TI CC1200, or currently TI CC1101).

They are aiming for strong cryptography. Keys are kept in a dedicated crypto IC. (Atmel ATSHA204)

Shields planned for RC servers, LAN, and bluetooth.

This could be my new favorite Arduino class board.

I thought Arduino = ATMega, is any ARM coming close in terms of power usage?

Arduino due is an ARM cortex m3 (microcontroller ARM). ATmega's aren't particularly known for their power consumption, you have always been able to get lower power ARMs.

The plan is for it to be my favorite, and I'm designing it, so I hope so!

I'm trying to design the system I've needed for years, because the problems I've had building robots generalize to nearly all the problems that Arduino users have.

We are aiming to nail this.

I'm encouraged to see that projects like these are at least becoming aware that they will face challenges getting FCC certified as intentional radiators (and are required to in the first place!) but I still think they might be underestimating this difficulty. I've seen projects burn $90k going back to the testing lab over and over tweaking this and that to get within acceptable specs only to find when they went to production that a few key things on their BOM were discontinued by suppliers and they essentially had to start over.

Best of luck to them.

It looks like they are using TI chips for the wireless (CC1101 for prototyping but it looks like they are targeting the CC1200 for release).

The have a little more technical information on their website - http://www.flutterwireless.com/press.html

http://www.ti.com/product/cc1101 http://www.ti.com/product/cc1200

Thats actually a really good choice. Like choosing the LTS version of your distro to develop on. Things have definitely gotten better than the "bad old days" my war stories are from. These new integrated radio-on-a-chip are much easier to deal with and manufactures are taking their reference designs seriously with an eye toward helping smaller projects clear these hurdles. Using TI instead of obscure-asian-manufacturer is also a good choice.

That said, if they're depending on ($80k - kickstarter fees) alone to get off the ground, I think that's a bit sparse. Then again, they seem to have done an above average level of pre-campaign development.

still waiting for chips which do DSSS (http://en.m.wikipedia.org/wiki/Direct-sequence_spread_spectr... ).

We can do DSSS, but our radio engineer (google Earl McCune) advised us that FHSS, while in some ways more complex (actually he just said it's tricker to design "right", which I'm fine with), will be vastly better for rejecting interference and intentional blocking.

interesting. does he mean frequency hopping ? if yes then i would not immediately agree however...

edit: i'm not a radio engineer just saying based on practical experience.

edit2: just googled . congrats on having this guy on your team.

Thanks! He's a serious silicon valley radio expert. He actually was a member of the homebrew computer club and brushed shoulders with Woz and Jobs before spending the rest of his career advancing radio in silicon valley. He helped lab test my designs, and he's really been an asset in verifying that what I think I did right, I actually did (Texas Instruments has some really great reference material). We experimentally verified on his equipment that my design basically exactly matches the performance characteristics of TI's reference design, and one of our RF component suppliers offers a $600 service where they put your device in their RF chamber to test emissions, which the engineer told me is a much better deal than you'd normally get at that price, but they only do it to help customers get off the ground. Before launch we spent a lot of time speaking to a lot of other professionals and kickstarter folk who have gone through the certification process, and it sounds like it's going to be manageable, especially with Earl McCune's help! I've done all the work on my own, but having a reliable expert is extremely critical in making sure the hardware will not be a problem!

I believe this is the reason Wifi USB dongles are so ubiquitous, even in other electronic devices.

In general, the more modularized you can make your "politically inconvenient" technology parts the better. The trouble with "but with a radio integrated!" projects is that when you change any other parts on the board, you are required to re-certify the entire thing, even if the radio portion hasn't changed. This spells trouble for fast-moving "versioned" parts like ARM cpus, especially when you're small scaled and the version you're on might get discontinued next month.

The chips broadcast right in the 70cm ham band (440 MHz). If you're a licensed ham, then you don't need FCC certification and can just build one yourself :-).

Of course, then you can only sell to hams...

All the embedded projects I ever did with radiomodems on them (quite a few, including a laser game and associated hardware) had the radiomodems on them as daughter boards for that exact reason.

Atmel has been really good about supporting CPU footprints over many generations (their customers don't like redesigns either), and the FCC rules seem to give you a pass as long as you haven't changed things electrically. There's actually a reasonable amount of wiggle room - basically if there is no reason a board should perform differently, they say it doesn't need to be recertified. (at least, that's what they say)

That said, our goal is to brave the waters of the FCC to provide quality radio products to the open source community. If we succeed in getting funded, we should be able to handle the occasional new testing needed for any product changes.

We have some higher volume plans which will help pay for that. Arduino is only part of what we're doing. :)

This all started because there weren't any open source module designs for the CC1100 radio, so I made one and put it on github (actually I was using the 2.4ghz CC2500 at first). Eventually I slapped an arduino on, and boom, useful thing!

If someone who'd designed a radio board wanted to understand more about getting FCC certified, where would you point them?

I'm imagining quadcopters carrying these out to far flung geographical locations and creating a 'drone net' anywhere (hazardous terrain, repressed nations, etc.).

You should google for 'wireless sensor networks'. There are some really cool research projects in this field.

This is the first time I've tried to back something on ks but sadly I've hit a wall, "us shipping only" on every level of funding.

Can you add a tier for euro/intl backers? I'd love to see this product.

For a KS with a goal this low, they likely aren't targeting anything but US-approved radios.

Have you read the FAQ? http://www.kickstarter.com/projects/2021474419/flutter-20-wi...:

"Currently, Flutter only operates in the 915MHz radio band, which is US only for consumer electronics. Our boards support the few other bands used throughout the rest of the world, so we can design versions for Europe and other regions, but unless our campaign is well over-funded, we're not able to commit to international versions. Spread the word and maybe we can!"

Thanks, in my hurry to back I had not, I was going to say that there could at least be a t-shirt tier which didn't appear backable from the 'checkout' screen but actually it looks like it is, so I'll go for that.

edit: Kickstarter is preventing me from getting the $25 t-shirt tier, asking me to say I'm in the US and otherwise looping back to the same page.

Eeek, good catch! Now that the level has backers I can't change it, but we are working on a better plan for international backers, and I will contact Kickstarter and see if they can open up the shipping option on that reward! I'll post an update for international backers soon!

If you want something similar but simpler, take a look at the JeeNode: http://jeelabs.org/ (Arduino+RFM12B)

Other advantages: already exists and costs 22.50 USD. (http://moderndevice.com/product/jeenode-v6-kit/)

and comes with an excellent set of libraries.

Interesting. Does our product not seem simple? We're working on some fancy mesh protocol stuff for making DIY projects easy, but those features don't have to be enabled at all. You definitely could use this just like an arduino with a radio attached, we'll have full libraries for sending data to any device directly, and our code will have copyleft licences (thinking GPL, haven't decided yet) and we will encourage forks.

You can look at them as basically just compute and radio modules - they can be used however you'd like!

With simpler I meant: something if you just want to do some RF within your home using Arduino. But Flutter looks very exciting if you want to do something more fancy :)

I'm not clear, what type of bandwidth can we expect from this? I can see this being useful even if it's very low bandwidth, but I'd like to know what I'm getting into.

How does it handle interference? I'm assuming 1 kilometer is optimal. How does the encryption affect transfer speed? There's a lot of important questions that need to be answered before I'd consider putting down money on this.

The Kickstarter doesn't directly say this, but it uses the ISM band (900mhz in the US). The chip they're using has a maximum throughput rate of 500kbps. They're combining the features of wifi and bluetooth for fast speeds over short distances and supplementing it with an ISM radio for slower speeds over longer distances.

Since it has 256-bit AES encryption, I would guess they are basing it off something like an XBee/ZigBee/RFBee.

Seeing this made me think of the exact same question. Also, what bandwidth do you get at 1km distance?

By the way, for lower ranges, there are allready solutions out there, like the TI CC3000[1] and the electric imp[2]. They use wifi though.

On a related note, don't put weird antenna spouting rat nets projects into central park if you're not looking for some fun with homeland security.

[1]http://www.ti.com/product/cc3000 [2]http://electricimp.com/developers/

They're saying max 1.2Mbps on the press page

http://www.flutterwireless.com/press.html

It's been a hectic few days organizing all that information, but here's the lowdown:

Currently we are using the CC1101 Radio, which maxes out at 600kbps. It's an excellent radio, but has been basically unchanged since 2006, when TI bought chipcon (who made the CC1101).

The CC1200 was recently announced as a successor, and it looks pretty amazing. The max data rate of that chip is 1.2Mbps, and it has increased transmit power and sensitivity. The chip is priced roughly the same as the CC1101 and is based off of the same code, so we should be able to port everything to it quickly and pick up development with it. There is a possibility that the chip will have some flaw that makes it a show stopper, but it's intended by Texas Instruments to be a nearly drop in replacement, and if it does what the datasheet says it should handily work for us.

There is a possibility that we will end up not being able to use the CC1200 though, giving us a max data rate of 600kbps in that case, and I realize I need to make that clear, so I will go write up that copy on our Kickstarter page now. I definitely don't want there to be any confusion about what we're selling, so I apologize for not making that clear to any backers, I'll mention the change in our coming backer update, which will largely be directed at international backers, who we are working to accommodate!

I wonder what the power consumption is like, and if it would be practical to run one off of solar power.

Exactly my question. I `dream` about an autonomous wireless mesh.

yes you absolutely can do this! We will have ultra low power sleep modes, and the radio can turn on briefly to send status, or listen in low power mode for remote communications.

I see encryption everywhere in the pitch, but nothing about authentication. Doing a little research, the datasheet indicates their crypto module [1] does support HMACs. That said, I'm a little leery of a pitch that (a) doesn't appear to understand the distinction between encryption and authentication and (b) doesn't state they plan on providing both.

Just my 2c.

[1] http://www.atmel.com/Images/Atmel-8740-CryptoAuth-ATSHA204-D...

Hey there! I'm the designer of the product (and co-founder). Totally understand, we've been working as hard as we can to provide clear information, and I had a lot more written about encryption and cryptoauthentication before I realized it may be too focused (we want to get regular people excited about building projects). Cryptography is incredibly important to me, and my ultimate plan is for these boards to be useful in creating dark mesh nets so people can communicate freely even when others try to cut them off. The protocol will be lightweight and we support sending arbitrary data, so it shouldn't be hard to patch it into a network. I still remember the cryptocat articles from a couple months back, and the snooping from the NSA has turned me into a crypto evangelist, so I absolutely intend to provide real strong cryptography. I also understand how skeptical people are (and should be) about crypto systems, so as I'm still learning about this stuff I've been careful not to boast too much before I've got the exact system sorted.

Currently the plan is full support for multiple master keys for different purposes (one for firmware updates, one for data, perhaps one for trusted guests, out of 16 total possible keys), per-packet session keys using AES-256, and I'm very curious about ECC, which it appears our system might support, since the encrypt/decrypt are software (though the new radio has an AES-128 hardware engine too).

We'll give a LOT of detailed information on the development of this system as it happens (after the kickstarter). My plan is to design a system that any HN reader would be proud of. We're not going to "let open source do it", we're writing it ourselves and I've loaded my tablet full of crypto e-books so I can genuinely learn from the ground up how to do that. Even if ultimately I don't write the software, I absolutely will not sell a system as cryptographically secure unless I personally understand how it is built and why it is secure.

Your enthusiasm is encouraging, just keep in mind the standard warning that crypto is very easy to do wrong (and wrong in a way that's hard to detect until your platform is blown wide open, see e.g. the PS3 root key disaster). In particular, a ton of academics argue that encryption (e.g. vanilla AES) by itself isn't very useful, and authenticated encryption [1] should be the default offered to standard users. There are multiple ways to achieve this, your hardware may support AE modes like GCM or others.

Keep in mind that crypto's only half the battle, and even "perfectly valid" crypto can still leave your platform vulnerable to things like replay attacks [2]. e.g. lets say someone uses your board as a doorbell: a crafty attacker can sniff the doorbell packet and replay it constantly if you don't use something like a request counter.

Point is: you shouldn't make your users cobble those steps together, they'll get them wrong. You're in fact very likely to get them wrong yourself, if (as you say) you're still learning the ins and outs of crypto. I wish you the best of luck, but keep in mind that you have a long journey ahead of you. I'd particularly recommend you complete the Matasono crypto challenge [3] before you even think of trying your hands on raw crypto primitives.

1. http://en.wikipedia.org/wiki/Authenticated_encryption 2. http://en.wikipedia.org/wiki/Replay_attack 3. http://www.matasano.com/articles/crypto-challenges/

Did you consider using the ATAES instead of the ATSHA? It has onboard authenticated AES (AES-CCM).

Long distance is tempting, but it isn't necessarily a good idea. All kinds of wireless interference/collision will make available bandwidth really low.

For example, on 2.4 GHz 802.11 protocols, there are 11 channels from 1 to 11. All wireless routers operating in US have to be on one of the 11 channels. When there are other wireless APs within the range, you and others share the channel. There's a limitation on how much bandwidth a channel can give in total. That's the hard limitation, given that CSMA/CA works well. That's why channel 3 and channel 8 often work great (most wireless routers have default channel choice 1, 6, or 11) - they are far away from defaults that others are using.

Same thing applies to 5 GHz 802.11 networks.

Now back to this project. 1 km is really long distance. You get communication range as large as a circle with radius being 1 km. There are a lot of wireless devices that fall in this range. You might not get affected by them since they don't have that powerful antennas, but your signals will effectively lower the bandwidth of all routers in the area.

For 2.4Ghz only channels 1, 6 or 11 should be used as those are the only interdependent non-overlapping channels.

http://www.cisco.com/en/US/docs/wireless/technology/channel/...

http://blog.saddey.net/2007/07/08/wifi-insights-why-you-shou...

That's interesting to know! Thanks for the link.

Hey HN! I'm the creator and co-founder of this project. I've been designing robots since I was 15 and hacking on electronics since I could hold a screwdriver. What I think you'll like most about this project is the open source long range encrypted wireless link our mesh provides. I discovered Hacker News about a year ago and have been a regular reader since, so I remember Cryptocat, the NSA, and all the other things that reminded us why cryptography is important, and why implementing it is critical.

So, a few answers:

Yes, you can do encrypted mesh networks over long range. I'm a hardcore robotics guy at heart - the name "Flutter" was chosen exactly because this protocol is designed to be as lightweight as possible, and though the mesh protocol itself is still being developed (basically, that's why we need kickstarter, aside from the fact that I'm tired of ramen), I really intend for the protocol to stay out of the way. You'll also have full control over what happens, so you can always turn meshing off and use hard addressing. It's still really simple to use that way and cheaper than everything else I've seen that compares.

I absolutely will not sell a product as "cryptographically secure" unless I believe it is, and I understand that the "smallest" flaw in a cryptographic system can render the entire system worthless. I am learning everything I can about cryptography, starting with some amazing e-books I have found on the subject, and just like wireless

Our data rate is proportional to our range (this is generally true for any radio system), so we get 1km range at low data rates (1200baud tested, but we physically ran out of test room and had a strong signal). Theoretically this radio can do 3km at 1200 baud and it looks like we should be able to do 1km at 30kbps at least. Also I think the new radio chip doubles all the data rates in these cases (I would have to confirm), and I do know the new chip has higher transmit power and higher sensitivity, so range should be even better.

There is a cheap radio amplifier (PA and LNA) called the CC1190, and texas instruments has all kinds of datasheets on using either of the two radios we are working with to give us 10km range, or much better data rates at 1km, etc. We're going to design the protocol with expansion in that direction in mind, if people really dig the range thing (it's a bit much for a beer brew setup, but if you want dark meshnets, lets do it!)

I'm a hacker at heart. I first learned lockpicking at the old Noisebridge location (the original one). I love 3D printers and open source, did a rant/thread about open hardware on the Ultimaker mailing list a year back (I was one of the first in the bay area to get an Ultimaker too, and designed a new mount for it that I have on thingiverse). I got on hackaday for some 3d printed helicopter blades, and have been building robots since I was 15. There's a longer bio about me on our site, at flutterwireless.com

See also me ten years ago talking about robots (and I feel silly for the "few people do" comment, but I was 15 and trying to keep it simple). http://www.youtube.com/watch?v=8FJu1eL_dYs

Please ask me anything!

I noticed you say that the radio band is US only but does it exclude Canadians from using Flutter as well? I only ask because you seem to mention Europe and Asia as 'international'.

Honestly I completely didn't expect the outpouring of support from international backers. We're two hackers in silicon valley building a product out of my apartment, and honestly canada, mexico, europe - I'm not surprised you guys want it (that's the point!) but I was completely blown away at how serious the international support is! I'm thrilled, excited, and happy to figure it out though!

I think we probably can sell in all of North America without changes, I'm checking on it. Europe is also pretty easy design wise, I just need to consult with our radio expert about certification, it was something I just did not look into, with all the things it takes to make this happen! But I should update the FAQ to say "we're" looking into it, since we absolutely now are!

Consider this post a vote from Australia. I'd gladly buy a half dozen of the Pro's if they were available to us.

Hey Taylor, Greetings from Belfast, Northern Ireland (Well, not currently, I travel a bit... anyway).

Disappointed that this appears to be US only. would love to use a few of these for monitoring our Hackerspace!

Actually I'm also involved in mobile ad hoc security research so might try and 'acquire' a few of these for testing out some collaborative network theories on our quadcopters... but can't do that as current delivery status stands!

Good luck with certification.

Will it be possible to change the radio firmware without losing FCC certification?

Does the message go straight from one end of the mesh network to the other, or can it store things for later forwarding?

Can it really support a mesh network with thousands of clients? In a mesh network with thousands of clients, how much bandwidth does each client get?

How do you divide time between different clients - is it contended like wifi so you have to keep the network uncongested?

How does roaming work? What triggers provoke roaming events?

If I want to communicate with one device 10cm away and another 10km away at the same time, is that possible? How do you avoid near-far problems?

I'm glad you stayed away from other ARM Cortex chips with TrustZone and SecureOS installed. I see the propriety chip you use for radio is pretty simple. Are there other proprietary systems on here?

Also, I don't feel comfortable donating before a finalized hardware design is reached. I feel the potential for bait-and-switch is too high and no words will convince me otherwise due to the nature of crowd-sourcing EULA, sorry.

TrustZone is exclusive to Cortex-A ARM chips. These are the big, beefy chips that run mobile phones and tablets.

This (Flutter) is using a Cortex-M ARM chip, which is entirely different. These are used in small, embedded devices. Like wireless headphones, or robotics. Cortex-M chips don't have TrustZone.

I understand your reservations, crowd funding can be a crap shoot. I've already got the BOM sorted out for the final hardware, we're just hitting kickstarter to verify that all the work required to finish this will be worth our while.

The more backers we get, the easier delivering this hardware will be. I won't try to convince you of anything you can't be convinced of, but I will tell you that if you are interested I would really appreciate your support, and as per the kickstarter terms of service I can at least promise that if what we are delivering does not meet your needs, you can cancel your order and we will refund the full amount.

The EULA does require me to either deliver or refund you, and I absolutely will comply with that.

I'd also suggest waiting to see? You could back us at $25 so you get the updates, and then cancel before it finishes if you would prefer not to spend any money at all.

And yeah, the radio chip is pretty simple. It's basically a cheap general purpose radio. The other proprietary chip is the Atmel ATSHA204, which you don't even need to use, but provides some excellent cryptographic functions.

Either way, I look forward to winning you over at some point, even if that's not till the products ship and the reviews are in! :)

I'm glad that it's going to be open-source, but are there also any plans to have the crypto professionally audited?

I want to buy a bunch and build an alternate internet mesh network a la https://twitter.com/Stammy/status/372450697742008322

It probably doesn't have good enough range, especially through obstacles. Most of the nodes in our mesh use 15dbi antennas for that reason.

So this is really great, with the range, but I'm still looking for a decent wifi range, low powered wireless tag network. The closest I can find is http://www.mytaglist.com/ , but I think the price is too high for the tags (used to be lower and then they jacked it up, on the hub as well), and they're creepily restrictive with their source code. The short lived GreenGoose looked like an option but is dead now. Anyone have any ideas of other solutions?

There's an Italian company called ForiniCom that built its own devices; they are around 40-50$ to produce, but they truly provide a Mesh network.

Unfortunately it's only in Italian: http://com-com.it/

I know they are managing more than 4,000 nodes now, and it works great.

I also know that offering a service like this is hard. A kickstarter campaign sometimes makes things look too easy.

Don't worry, I know this isn't easy, but I don't like easy things, they're boring. My last project involved hand-winding motor coils for a linear motor I built from scratch, along with a 24v 10A per channel driver board & ARM CPU mainboard I designed and built. It was a pretty neat system, but robots are complicated, so I'm going to sell circuit boards for a while and dive into software development some more.

Simone you can't compare the two things: they are an ISP and according to their tech pages it looks like they're using linux-powered devices in order to create an Hiperlan mesh network for internet access. It's like comparing.. a Raspberry PI with Telecom Italia/T-Mobile/Verizon deploying their own home routers for Internet access... You're also saying "offering a service is hard", Flutter is not offering a mesh service, they're trying to provide an Arduino compatible electronic board with long range wireless communication and with mesh and crypto features.

Very cool. The type of thing that could be used to set up a nice little mesh network, although I'm guessing it would have to be restricted bandwidth-wise, which is kind of what I always envisioned anyway. Nice that it has that on-chip crypto.

Would be good to see how it performs as a mesh in an urban area, though. Would these need to be mounted atop buildings? On eaves? On light poles?

Definitely needs a weather-proof enclosure, too!

Why are they able to be able to get so much more range out of this product than regular Wi-Fi is able to get?

Much higher radio power level.

actually not at all, we have less TX power than most wifi devices. The data rate is inversely proportional to range, as is the frequency. We operate at a lower frequency than wifi (915 MHz), and a much lower data rate (your Arduino probably does not need a 100Mbps connection). This gets us range without blasting people with radio or having trouble with the FCC.

> actually not at all, we have less TX power than most wifi devices.

Another post in this thread says 16 mw, compared to about 50 mw for an 802.11 class device, so that's rather low and I'm somewhat surprised by the range claims. I suspect the chosen antennas play an important part.

> The data rate is inversely proportional to range, as is the frequency.

Unless I have misunderstood the above sentence, it implies that the range increase as the frequency drops. In a word, no, because among other things, thermal noise increases as frequency drops. A low data rate will buy you more range, but range doesn't increase as frequency drops.

> This gets us range without blasting people with radio or having trouble with the FCC.

Maybe. It turns out that 915 MHz is a pretty busy area of the spectrum in many places -- successful communication might be harder in practice than the ideal case.

Lower bandwidth... and from one other comment they could be using lower frequencies as well.

wifi can do 1km easily just use more tx power and a suitable antennas.

I want a UK one! Damn those poorly distributed airwaves.

The EU allows the 136Khz band for amateurs I believe. It would be like communicating via semaphore in the fog and would probably need pretty large antenna, but we could be talking some serious arduino <--> arduino range... 50km+ I'd expect.

Awesome project. Reminds of SparkCore which was on KickStarter earlier this year:

https://www.sparkdevices.com/

I wonder if it would be possible to wire an antenna to the Spark and match the 1km range of the Flutter....

SparkCore uses TI's CC3000 unit (http://www.ti.com/product/cc3000) which is a 2.4GHz wi-fi module.

Flutter is using CC1001/CC1200, which are 900MHz radios. 900MHz (as a longer wave) will travel much farther to begin with, plus the module is designed for longer-range use :)

(Also if you put a 900MHz antenna on a 2.4GHz radio you're gonna have a bad time)

Yeah, they're in the same space as us. We hope that our range, low price, and extreme flexibility will really win people over. Wifi is not really a good protocol for Arduino. If you just want to send a few bytes (like "On", "Off", or sensor data like "215"), then wifi is across the board many levels more complex than is needed.

Flutter isn't the minimum needed, but it's essentially the minimum needed to build a secure mesh solution.

And unlike wifi modules, we have bare metal control over our radio chip, which gives us a lot more room for doing interesting things, like indoor 3D positioning (which we haven't tested yet, so I have no statistics on the accuracy... yet).

The cool thing is, we will research indoor positioning, and every other use of this board we can. I think an open radio and computing module with encryption, long range comms, and ultra low power usage (sleep modes should allow for a year on a coin cell, though again, that has not been verified yet).

This looks promising but two questions:

1. How do new nodes authenticate into the network? 2. Is it possible to get a USB version that could hook into a higher powered device, say a Raspberry Pi, that would act as the gateway to the internet for this mesh network.

1 half mile = 0.804672 kilometres

Tested to 1 kilometer, mentioned in the Features section at the link.

Which in the end is the range you can get from Wifi line of sight with the right antenna but with much higher bandwith.

And you are allowed to pump more power through 2.4GHZ as opposed to 900MZ and 2.4 antennas have better gain properties.

About high range antennas, I'm more excited by the sigfox technology (25 miles/40 km range) : https://news.ycombinator.com/item?id=6285796

How come it says $20 in the title, then doesn't let you buy anything for $20?

If the KS is successful they will sell boards starting at $20.

From the KS page: "Flutter Basic ($20)

Still under development, the Flutter basic is tiny and simple. You get all the features of Flutter in a circuit board with an low-profile integrated antenna, rather than the large antenna shown in the video. Featuring micro USB for power and programming, components on both sides to reduce size, an LED, and a button, as well as plenty of digital and analog I/O."

"$5 shipping to anywhere in the US included."

What happened to the claims of open source? Their github page ( https://github.com/flutterwireless ) is empty!

Such a shame the first device is US only (although I understand why, regulation, etc...)

I guess I'll have to wait until they hit a stretch goal for an EU design!

Anyone knows what band is going to be used for wireless communication? And are there any plans for the certification in EU?

Does anyone see what are the range differences between the two models? (basic and pro)

We rated both as 1km max, but the basic will have an integrated antenna, with reduced performance. The current radio chipset theoretically maxes out at 3km though, and we haven't actually maxed out range ever, before maxing out distance (we have to use google earth just to find places!).

Pro will have better range due to the antenna, but the basic will get a pretty high-performing antenna too.

That pretty ambiguous. If they don't have the same range, then you shouldn't just ballpark them as both "1km max" because that doesn't really tell me anything.

The first app that comes to my mind is using those for a secured messaging protocol.

Seems great for meshnets, and I think this is only the beginning of such technology.

Deff.

I'm actually seriously considering starting a meshnet in my neighborhood.

I'm considering it for my university-it doesn't have a mesh net yet. Like someone said in here, autonomous, self sufficient quadrocopters that power mesh servers is also my dream. What stack and chips / devices are you going to use?

I'd give $100 to the kickstarter that has a meshnet node in a box that's basically plug and play.

look at project byzantium - depends on a regular computer to use or a raspberry pi but the whole goal of the project is "plug and play" software that will allow you to at the push of a few buttons get an ad-hoc wifi mesh set up.

http://project-byzantium.org/

Do it! As soon as we have the new hardware up and running we're going to play with mesh nets ourselves!

Can someone explain how this is any different from electric imp or Zigbee.

I'll try! (I made it)

Electric imp is Wifi and does not function without an internet connection (at least, thats what they told us at the first hackathon). It also doesn't function without a router.

We're a lot closer to Zigbee - basically the same idea. We send data directly from board to board, unlike wifi which always runs through your router. We basically use every board as a router.

The advantage over zigbee is price, Arduino, openness, and range. We have 10 times the range of $22 zigbee modules, and 5 times the range of their $50 modules, all in an easy arduino package.

Does that answer your questions?

Perfect. Exactly what I've needed for a lot of project ideas.

I wouldn't be putting too much money up for this until it's clear what frequency they'll be using and what (if any) FCC certification is finished.

What band is it using?

915 MHz ISM. We're working on international support.

I made it, so ask away if you have any other questions!

Half a mile is not a kilometer...

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