15 year old High School sophomore noob here. We (crazily) are attempting to put up a CubeSat (shameless plug www.seakingspace.com). Using the Lora SX1268 433Mhz we tested the Semtech transceiver across the Catalina channel. 25+ Miles SF factors 7,9,11 at 125 BW. Worked great. We did a link budget and should work over 500KM line of sight no prob. The SX126X is the new improved version of the Lora chip. Im sure a verion with it will come out shortly.
We're making an open-source $30 GPS/mesh radio, would like advice
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Re: We're making an open-source $30 GPS/mesh radio, would like advice
#62Maybe resubmit this post so the link works. I would love this for music festivals. They have some solutions but they are hundreds of dollars. If people in the group could put this on a backpack it would be a game-changer. Music festivals also have a big problem with internet access. If they could put host a few powerful repeaters in the middle with electrical and have 5% of attendees (staff) with these they could pro…
Solutions of hundreds of dollars? For what exactly? Reminds me of the movie Hackers where they used buzzers. And why not? The only thing you gotta do is use pre-planned keywords/acronyms. I went to several (music) festivals, big ones between 2002 till 2004 with a few smaller gigs later until 2009 or so. Back then we just used SMS or phone call. I didn't even always have a plan during the mentioned years. Especially o…
You have to look at the issue from the organizer PoV and not as the event goer. You need to have some kind of reliable communication channels for the staff. The result of 10 years of experience of trying to cause that is for me that analog UHF radios work, wired VoIP phones work and just using whatever smartphones the staff works and combination of these three technologies gives you the SLA level you need. DECT is meaningful solution of the same problem, but the handsets are expensive and even more so if you want some broadcast/PTT capability and ideas like “well, we have bunch of Nokia S60 handsets that should in theory support wifi as LTE/CAE radio layer” is pure nerding-out that does not solve any kind of real issue and instead creates new ones
Re: We're making an open-source $30 GPS/mesh radio, would like advice
#63Please get a newsletter up - would purchase this in a heartbeat.
Re: We're making an open-source $30 GPS/mesh radio, would like advice
#64XBee it's already at an $30 and $15 price point, I think to 'disrupt' you would need to be profitable at a -10x price point. This is my opinion. I'm usually wrong. But you asked.
> I'm usually wrong. That's either insightful, or sad... and I can relate.
Haha not sad. It's hard to have an informed opinion, better to acknowledge it.
I am impressed with the XBee series 3 modules that I've bought. Digi is 100% behind the product. The documentation is great. The engineering is of the 'we're go to the Moon' era not 'move fast and break things' crap the perforates startups. I'm very impressed so they're a tough entrenched to beat.
Re: We're making an open-source $30 GPS/mesh radio, would like advice
#65Note that there are limits to how large a mesh network can scale, it's likely to start running into problems with several hundred users. You can scale larger by limiting data to short text messages, but you'll probably never be able to handle more than 10,000 users, unless you can find a way to create high bandwidth backbone links between clusters of users. There has been a lot of research on this in the wireless sen…
That's true in practice with current radios, but it was a beautiful discovery in 2006 that it's not true in theory! In a world where radios are perfect and nodes cooperate to do decentralized beamforming, the capacity-per-node of a random mesh network scales as the number of nodes increases. See Ozgur, Leveque, and Tse, "Hierarchical Cooperation Achieves Optimal Capacity Scaling in Ad Hoc Networks," IEEE Trans. Info. Theory (2007) (https://arxiv.org/abs/cs/0611070).
(Also worth reading: Tim Shepard's Ph.D. dissertation from 1995 (http://groups.csail.mit.edu/ana/Publications/PubPDFs/Timothy...), which predates a lot of the "information theory" interest in this subject.)
Re: We're making an open-source $30 GPS/mesh radio, would like advice
#66I guess my only advice is make sure the software keeps to the duty cycle limits of the license free band. And note that different countries may have different regulations on what is allowed on the frequency LoRa uses, if using it is even allowed.
Also which of the ISM bands are valid in which country. (We sold off the bottom half the 915 band here to telcos, so only the upper half of it is available in .au)
And in EU the whole 915MHz ISM band simply does not exist and is “the original GSM band” with the added caveat that there are some safety critical services inside the GSM's uplink/downlink guard band.
Re: We're making an open-source $30 GPS/mesh radio, would like advice
#67Note that there are limits to how large a mesh network can scale, it's likely to start running into problems with several hundred users. You can scale larger by limiting data to short text messages, but you'll probably never be able to handle more than 10,000 users, unless you can find a way to create high bandwidth backbone links between clusters of users. There has been a lot of research on this in the wireless sen…
That's true in practice with current radios, but it was a beautiful discovery in 2006 that it's not true in theory! In a world where radios are perfect and nodes cooperate to do decentralized beamforming, the capacity-per-node of a random mesh network scales as the number of nodes increases. See Ozgur, Leveque, and Tse, "Hierarchical Cooperation Achieves Optimal Capacity Scaling in Ad Hoc Networks," IEEE Trans. Info.…
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Re: We're making an open-source $30 GPS/mesh radio, would like advice
#68This looks neat.
How does this differ from disaster.radio? More portable?
I ask because I really think these are important projects and I'm not sure which to contribute my time towards.
Re: We're making an open-source $30 GPS/mesh radio, would like advice
#69Hi ya'll, so we've spent a few weeks making device software and an android app to convert a $30 chinese gps/radio into a long range mesh radio for hikers. It is working fairly well now (though still an alpha) and we'd love more people to try it and/or have fun coding on it. We got about 30 users (and some devs from this hackaday article) but we'd love more users and devs to join this happy-happy project: https://hack…
What frequency band are you using? ISM is the only one that permits store-and-forward / automatic operation, as the gotenna people found. You say a few miles per node - I am having trouble seeing how that's possible without elevating all the nodes
Can you use MURS for this? Or potentially GMRS if the operators are licensed?
Re: We're making an open-source $30 GPS/mesh radio, would like advice
#70Howdy,
as the founder of the Serval Mesh adhoc networking protocols and hardware, what I would look for in a new radio is:
1. True packet radio mode, that doesn't hide the radioness of the link etc, but lets the programmer use it's strengths.
2. UART link, ideally using 3DR/RFD900 compatible connector (then we can include it directly in our existing systems, and so can others).
3. Field-flashable, but with robust protections on the boot loader, as it is not uncommon for a radio to be on the boot serial interface, on hardware that has only one serial port.
4. Support 434, 868 and 905-935MHz ISM bands.
5. Use advanced interference tolerant wave-forms, like Chirped Spread Spectrum or even something better.
6. Fully open chipset/firmware design, so that it can be truted.
Anyway, poke me at paul@servalproject.org if you would like to talk further about it.
Paul.