71–80 of 176 posts
XBee 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.
This 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.
The difference is: disaster.radio is targeted as a "just in case emergency radio build on custom hardware, that joins a mesh with other folks who bought the same emergency radio."
This is a $30 radio (with built in GPS+radio+CPU+battery+OLED screen) already available from a chinese mfg. Then you put our app on it and have a group navigator you can use with your friends while skiing or hiking, instead of buying a $100 closed source kickstarter (and it will run eight days on a charge)"
Please get a newsletter up - would purchase this in a heartbeat.
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 verio…
Earlier quoted context omitted.
This stack overflow question has some nice pictures of the LoRa "chirps". They use rising/falling frequency modulation to allow operation at startlingly low signal to noise ratios. (Also, the hardware they're using is fairly generic, and pretty much all the vendors selling them offer them in 915/920MHz and also 868MHz and 433MHz variants. I've seen claims of over 10km range with 433MHz LoRa gear without special anten…
LoRa has very peculiar modulation scheme that in the end is not CDMA-ish spread spectrum but an interesting way how to extend straight FSK into spread spectrum modulation with respectable processing gain and interference rejection.
If someone else's ISM radio is using a specific frequency (perhaps with CDMA or TDMA), a "chirp" that's spears over about a hundred kHz and -20db or so down in the noise is unlikely to bother them, but is quite useable/reliable for the LORA gear to detect.
Earlier quoted context omitted.
LoRa has very peculiar modulation scheme that in the end is not CDMA-ish spread spectrum but an interesting way how to extend straight FSK into spread spectrum modulation with respectable processing gain and interference rejection.
I recall reading that part of the design was so that not only was it good at rejecting interference, but that it also caused little interference to other users of the spectrum. If someone else's ISM radio is using a specific frequency (perhaps with CDMA or TDMA), a "chirp" that's spears over about a hundred kHz and -20db or so down in the noise is unlikely to bother them, but is quite useable/reliable for the LORA ge…
Earlier quoted context omitted.
You're wrong. It's a mistake to treat terrain and foliage as the same thing. I have extensive experience with 3 completely different, narrowband and wideband, 902-928 MHz radio data systems as well as just playing around in the range with my software defined radios (hackrf, rtlsdr, etc). 902-928 has almost no advantage over 2.4 GHz when it comes to line of sight issues with terrain. In fact, it's more problematic due…
This stack overflow question has some nice pictures of the LoRa "chirps". They use rising/falling frequency modulation to allow operation at startlingly low signal to noise ratios. (Also, the hardware they're using is fairly generic, and pretty much all the vendors selling them offer them in 915/920MHz and also 868MHz and 433MHz variants. I've seen claims of over 10km range with 433MHz LoRa gear without special anten…
https://electronics.stackexchange.com/questions/278192/under...
Howdy, 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 pro…
btw: Back when I was writing Andropilot I also wrote a fair portion of the code that is in those RFD900 radios (or at least was, I haven't checked in a while). I'm super glad you are using them!
Note 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.…
Howdy, 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 pro…
Thanks for the feedback. I think this project is a little bit different, we are focusing for now on making a nice end-user friendly consumer product using hardware that is already shipping from various aliexpress vendors. our tag line is "An opensource hiking, pilot, skiing, Signal-App-extending GPS mesh communicator for $30" We are currently using RadioHead mesh library, but we might shift to a common implementation…