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.
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 , 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.
 (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...
Hadn't seen the rules for 900MHz though.
See FCC part 15.247:
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...
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.)
(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).
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 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?" . 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.
(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.)
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  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.
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?
The CC1200 puts out 14 dBm . 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 . 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.  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...
 http://www.ti.com/product/cc1200 (see datasheet)
 http://rfcalculator.mobi/convert-dbuv-3m.html, 15.249 allows 50 mV/m @ 3m = 93.89 dbuV/m @ 3m = -1.34 dBm EIRP.
 FCC 15.247 & 15.249
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.
I had a professor give an epic lecture about this several years ago, but this is the best I could find on short notice .
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.
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.
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.
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 )
TX power = 16mW = 12dBm 
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 
Path loss = 102dB
Ideal free space loss over 1km at 900MHz is around 91dB . 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.
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?
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 ?
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.
We've had similar hardware in the field for 3+ years now, covering ~50 square kilometers in a mesh configuration.
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'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!
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!
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 ? 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. :)
And you asked why not the shield you linked to?
This is why:
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?
Anyone bulding remote controlled "stuff" will be delighted.
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.
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?
$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'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.
Best of luck to them.
The have a little more technical information on their website - http://www.flutterwireless.com/press.html
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.
edit: i'm not a radio engineer just saying based on practical experience.
edit2: just googled . congrats on having this guy on your team.
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!
Of course, then you can only sell to hams...
Can you add a tier for euro/intl backers? I'd love to see this product.
"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!"
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.
You can look at them as basically just compute and radio modules - they can be used however you'd like!
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.
By the way, for lower ranges, there are allready solutions out there, like the TI CC3000 and the electric imp. 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.
Since it has 256-bit AES encryption, I would guess they are basing it off something like an XBee/ZigBee/RFBee.
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!
Just my 2c.
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.
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 . 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  before you even think of trying your hands on raw crypto primitives.
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.
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).
Please ask me anything!
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 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!
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.
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.
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! :)
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.
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.
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!
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.
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.
I wonder if it would be possible to wire an antenna to the Spark and match the 1km range of the Flutter....
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).
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)
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.
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."
I guess I'll have to wait until they hit a stretch goal for an EU design!
Pro will have better range due to the antenna, but the basic will get a pretty high-performing antenna too.
I'm actually seriously considering starting a meshnet in my neighborhood.
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?
I made it, so ask away if you have any other questions!