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Disaster.radio: a disaster-resilient communications network powered by the sun (disaster.radio)
318 points by tlrobinson on Dec 11, 2019 | hide | past | favorite | 130 comments

Ham radio (or amateur radio) operators have historically filled this role - providing essential communications in the event of a disaster.

I wonder whether this project (if it's successful) would indicate that their numbers have declined past an inflection point, where their presence and availability is no longer assumed.

This won't replace HAM radio in a disaster scenario. This might provide a long-distance digital comms capability post-disaster. Even then, LoRa throughput is so low that I don't see how it would be useful unless an entire region goes full zombie apocalypse and this network replaces... I don't know, messenger pigeons?

In a long range configuration, LoRa has a theoretical max throughput of about 140bps (bits) and that's assuming only one device is transmitting and no packet loss.

LoRa is built for low power, long range, low throughput sensor networks. It's not really suitable for a chatty mesh network. To get an idea of the intended use for it, take a look at LoRaWAN limits:

* An average of 30 seconds uplink time on air, per day, per device.

* At most 10 downlink messages per day, including the ACKs for confirmed uplinks.

* A good goal is to keep the application payload under 12 bytes, and the interval between messages at least several minutes.

A messenger pigeon could at least cary 1TB of micro sd card data. LoRa is like less than the symbol rate of honey bees.

“Never underestimate the bandwidth of a station wagon full of tapes going down the highway.” -Andrew Tanenbaum

... or a carrier pidgeon with an SD card, it would seem :-)

But if you lose that carrier pigeon to zombie crows, you lose the SD cards. No factory to make new ones. The risk/reward ratio would be intolerable.

What is the symbol rate of an sd laden carrier pigeon?

African or European?

Well, you have to know these things when you're a king, you know.

SD cards are tiny. Probably 20 or 30TB.

This seems to check out. Given 1TB micro SD cards, a card weight of 2.55 grams each, a carrier pigeon being able to hold 75 grams, and the unrealistic but good enough assumption of no further weight being carried (e.g. tape or something else to keep everything from falling off the pigeon), we get 75 / 2.55 = 29.4117647059 (or 29 even taking the floor, since it doesn't make much sense for a pigeon to carry a partial card).

All these numbers are from google summaries, without further source checking.

Yeah but during zombie apocalypse you don't know what else that pigeon might be carrying.

Also your TB sized packet might get lost, or eaten.

Couriers are more reliable, though still not perfect.

In a long range configuration, LoRa has a theoretical max throughput of about 140bps (bits) and that's assuming only one device is transmitting and no packet loss.

Human speech has an average rate of 39bps.

Lowest bitrate speech codecs have rates like 450bps, 700bps (Codec2) and 1600bps (LPCNet)

https://github.com/mozilla/LPCNet https://github.com/drowe67/codec2

Conceivably one could reach 39 bps with near-realtime speech, tone, inflection and tempo recognition. Put the result into a zstd compressed SSML stream and perhaps even reach 16 bps. https://stackoverflow.com/questions/46108940/is-there-a-way-...

If you already carry 39 bps of information efficiently by 39 bps actual bitstream, it's not losslesly compressible. That's by definition. Not even by zstd :)

You might want to let Motorola know since DMR needs needs multiple orders of magnitude(2-4 kbps) for their voice codec.

That's the bitrate of a codec to transmit speech that humans can hear and understand... but the actual rate of data communicated by speech is about 39 bps -- and that's pretty universal, regardless of language:


how is this number useful or comparable to digital codecs that are being discussed here? It's an interesting piece of research sure, but I don't see the relevance

Because voice comms are typically used by hams in disaster response -- you pointed out that LoRa tops out at 140 bits, so I responded that that's still 3X faster than voice.

As explained above, the most efficient voice codecs still need orders of magnitude more than that.

This magical 39 bit codec doesn't exist and probably won't ever exist. Even if it did exist, it loses information like timing, identity of the speaker (how they sound), and their tone. By the time you encode all of that, you'll be right back around the range of dmr. And if you're willing to discard all that, then just use digital text in the first place.

Exactly, don't use the codec and send voice, just send the text directly.

That's not speech then.

If you're talking about compression, Q-codes[1] were invented long before most of us were born.

[1] https://en.wikipedia.org/wiki/Q_code

I didn't say it was speech, I was comparing the 140bps data rate mentioned by the parent poster with the 39bps data rate from human speech, and pointing out that even 140bps is well above the data rate possible with plain speech.

Any increase in effective data rate of speech afforded by Q codes can also be used to increase the data rate of data transmission.

And as people keep pointing out, the 39bps figure does not refer to speech. It only refers to a single component of speech, which is the syllables being spoken.

When people are talking, they're exchanging far more information than that at a far higher information density rate. Which is why everyone keeps telling you that what you're talking about is not really speech.

The study you linked is focused on linguistics and the effective 'symbol rate' of various spoken languages, by taking syllables spoken per minute and dividing that by the total number of possible syllables in each language.

It says nothing about how much information is actually exchanged between individuals doing the speaking. It doesn't factor tone, accent, pronunciation, mood, pacing, etc all of which are critical components of spoken communication and add up to a lot more than 39bps.

So when you say 'speech is 39bps and this thing does more (it mostly doesn't), therefore this thing is better than speech'. People keep telling that no speech is not actually 39bps and what you're talking about is identical to just written text in this context.

I think the parent means human speech in (compressed) text form.

Only of you downsample to text. The inflection, tone and manner of speaking convey huge amounts of data, reguardless of how much is used for framing. This is to ignore facial expression, gesticulation, and posture, which are also part amd parcel of human speech, phones be damned.

Sure (well, I'm not sure I'd say it's "huge" amounts of data, but there's definitely some non-verbal information embedded in speech) but this is disaster communications, not a newscast, I don't want to try to read subtle emotions from tone of voice, I want information -- if the sender is feeling anxious about something, I want him to tell me, I don't want to try to guess how bad conditions are because his voice was a little shaky.

That's the supposed maximum cognitive throughput, not the (currently) practical encoding rate.

That's the rate that's important. Human speech is sent and received by humans, if you're going to send computer generated speech faster than that (faster than a human can comprehend) and decode on the other end by computer, why use speech at all?

The SX1276 will do 9380 bps at its lowest sensitivity, so it could be boosted, depending on range. FSK mode will go much faster. I wonder if these disaster radios will auto negotiate rates.

I would probably prefer a DSSS with a DSSS-compatible CSPRNG similar to AES/CFB.

Does anyone know such a cryptographic system?

All it takes is a couple of lowly hams with mobile radios to cover a huge area...in practice during recent emergencies here in rural norcal, ham radio was really useful, for updates on general news, determining the status of communities around the county, passing messages, and fire spotting. Some of those guys driving up to hilltops were putting their lives at risk so the rest of us could benefit.

We practice every week, so everybody who is an active ham knows the local frequency and they know that there will be updates every hour on the hour.

On top of that, the local WIN System repeater (Western Intertie Network, check their website) was up on backup power, meaning I could have used my walkie-talkie-type radio to get help from distant places like Ireland or Hawaii, if it would have been useful. To say nothing of the amateur radio satellites and HF operation.

One of our local nets during the emergency was a tech-talk net, with about 41 check-ins, all but one on emergency power, when the usual is about 7-12 people. The time was used to discuss lessons learned and one ham is an expert with generators and warned everybody: Change the oil every few days if you are running 24/7. A lot of people were surprised to hear that. And many of them only had one generator to burn through.

To give another example of the usefulness: Imagine, your power goes out, and a day passes without anything exciting happening, so you take a nap, forgetting that the reason the power is out is actually high fire risk.

In a few minutes you wake to a phone call. Your ham radio friend tells you he just heard on the radio a wildfire started a few miles north of your community. This is not on Facebook, it's not anything your neighbors know about.

So you have no idea what to do but fortunately they keep calling with updates from the radio. Eventually they call and give you the all clear and let you know your evacuation warning was lifted, so you don't have to take whatever you can and leave town with your family, spending money and using every last nerve you have just to figure out the next 24 hours.

This is just one specific example that happened here. Everybody else would have warning via text if they were lucky (had battery, tower connection, and proper system configuration), and final warning via a sheriff's vehicle siren if that didn't get through to them. In this case the person receiving calls never got a single text message.

...you have no idea what to do...

This highlights a critical element of emergency notifications and response: you have to have a plan for how to deal with warnings and alerts. If you don't, then the alert is worthless.

It may even be worse than useless by throwing an otherwise orderly and predictable population into a panic.

How you respond to an emergency, in general, is to reduce risks and consequences. This may mean moving out of the area, but more generally, it means moving out of immediate harm's way. In the event of an earthquake, that can simply be to more out of range of falling debris, or into a solidly-constructed building. For a tsunami, gaining elevation on a secure base (terrain, a very solidly-constructed building). And, of course, responding to changing circumstances and conditions as appropriate.

For widespread disasters -- hurricane and wildfires -- exiting the region or moving to a location that's unlikely to be overwhelmed by the forces at play, is helpful.

For high wind, rain, cold, heat, etc., the challenges often play out over a longer period of time.

Disaster response as with security risks should revolve around threat models. What are the foreseeable threats, what are their specific mechanisms of action (e.g., fire, smoke, heat, wind, flood, ground movement), what's the effected range, and how can the hazards be reduced, mitigated, or countered?

Then there are the long-term survival needs: water, food, shelter, transport, injury and health treatment. Ultimately, rebuilding or relocation.

In one of the biggest disasters of all time, the Bianqao hydroelectric dam collapse following the intersection of a tropical storm and a cold-weather front, about 30,000 deaths were the immediate result of flooding. Another 150,000 or more resulted over the ensuing days and weeks from disease and starvation given both the disruption to ordinary life and the inability to move rescue, recovery, and relief personnel and supplies into the affected area.

None of which has an immediate relation to the ham vs. mesh-network radio debate, but calls into consideration that each are only a small part of an overall disaster response plan.

Be assured that the Amateur Radio community is quite active; especially regarding emergency communication and disaster preparedness.

Personally, I am active with the Connecticut Amateur Radio Emergency Services(CT-ARES), which is a local organization part of the larger national ARES organization(http://www.arrl.org/ares). Both of these offer training and procedures for facilitating communication during emergencies. CT-ARES works with the state of CT, in particular the Red Cross and many local town governments.

My activities include participating in regular 'nets' (http://www.ctares.org/networks.php) which are station tests which serve to prove that my radios work in various failure scenarios. Other members are even more active and practice their communication skills by offering supplemental communication for various events like marathons, fairs, etc.

It comes down to this; you don't know something works unless you regularly use it.

de K2CHA

PS: One should also test their backups by actually restoring from them...

Thanks for the assurance! My grandfather was a lifelong ham (KJ6NK) and I have many fond memories of sitting with him in his radio room while he participated in various nets or picked up QSOs.

I think that depends a lot on the area and local clubs, some are better than others.

While this looks interesting I'm curious if they've done the numbers for Lora throughput. It's very, very low(which is also what makes it able to punch through everything).

Honestly I'm surprised they're not going for a p2p directional wifi. You've got a lot more hardware to choose from(pretty much all WISP hardware) and it has much better throughput with the benefit of dedicated links. Anything that's omnidirectional is going to have to deal with collisions which is not an easy thing to do.

Using LoRa and going omni-directional lets you get away with less upfront setup and a sparser node coverage. Point to point requires some knowledge of node locations for bringing more areas online.

Numbers have dropped a substantial amount in recent years but there are new people getting certified all the time. The cost of hardware keeps going down too. As a HAM its bad for me to get down in these guys for making an effort to produce a product for disaster readiness but...I think the common place FRS radio sets available in every big box store for less than 30 dollars are a more practical tool that everyone should own. CQ CQ CQ VE7 xray mike lima!!!

VE7XLM de KM6NHH. Good point on the FRS. I'm helping coordinate a local neighborhood FRS net here and we are looking at setting up a wider-area GMRS repeater as well; we just had the hilltop location offered by another ham and ran some tests.

BTW my recent emergency experience is documented here:


I happy to see you got a chance to put your tools/experience to good use helping people. It's horrible what is going on down there with the fires and power situation. I decided to get my license as something to do with my Father, a local club(Delta Amateur Radio Society) was offering a ten week course. I was very surprised at how technical the course and subsequent exam was, I have since moved out to a farm and have not set up my station yet but am currently on a LTE internet connection with a solar backup.

After reading your blog on the fires I think that may have been just the nudge I needed to get back into it.

VE7XML qsl KM6NHH(I messed up my cs in my earlier post!)

Ps just looked up your call sign, its interesting that in the US your licenses expire after 10 years, here in Canada its a lifetime license.

> in the US your licenses expire after 10 years

Yeah, but we don't have to re-test, and it can all be renewed online for free.

There really is not a decline in numbers, though. This seems more an attempt to make a single widget to replace needing hams. Communications in disasters is not so much a function of having the best power toys but rather the best operational doctrine.

Hams have the operational doctrine and also the flexibility in terms of tools to use. If the message doesn’t get through on one frequency band, change bands. If your transmitter modulation isn’t working, switch modes all the way downward to continuous wave Morse Code if you have to. The sun has been on a multi-week streak without sunspots so High Frequency communication will take operator skill to get messages through.

I don’t think numbers are declining.

In related news, see https://www.rrmediagroup.com/News/NewsDetails/NewsID/18899

I think it’s more of a result of the recent availability of inexpensive low power (relatively) long range radios that operate on the ISM bands, i.e. LoRa.

APRS is probably the closest thing to this in ham radio, but it typically requires multi-watt VHF radios.

We don't have anything to do with disaster.radio (maybe that should change), but we do have an existing single board computer that runs Linux, has a LoRa radio, and wifi. A somewhat similar product, but we use this for reception of a satellite data broadcast.


It has the 2.4 GHz LoRa radio, the SX1281. It also has a wideband mixer and synthesizer, which allows transmission across 85 - 6000 MHz. You should be a ham in order to play with the tx-side. The SX1281 is not compatible with sub-GHz LoRa.

Super interesting, how does it work in terms of pricing? Is the satellite data broadcast free? It's really neat how most of the US is convered. This might be a stupid question but do you need a license to use this and/or LoRa radio?

Yes, the broadcast is free to receive.

To use the transmit outside of ISM bands, you definitely need to be a ham (and stay within ham bands).

Neat little board and nice price point. This seems like it would be generally used as a client/relay for satellite transmissions? Any common applications to help me understand how it's used?

The primary use is for receiving our data broadcast in places that have limite/no/costly connectivity. We want to provide a basic information service that's available everywhere. Right now there is an audio stream coming down (Voice of America; it's free content), news feeds, weather updates, and the day's popular Wikipedia articles. It's a 10kbs datacast.

We also act as a relay for ham packet radio (APRS). Hams can send messages that eventually get picked up by internet-connected gateways. We take APRS messages tagged with OTHER and broadcast then over the two satellite beams.

Ah! Ok, that helped tremendously, thank you. Very cool technology and application!

Hey there! I am the current maintainer of the disaster radio firmware https://github.com/sudomesh/disaster-radio/ and the LoRaLayer2 routing protocol https://github.com/sudomesh/LoRaLayer2/ that is intended to mesh disaster radio nodes. The website doesn't include many of our latest developments, if you would like to stay in the loop, it's best to join our mailing list https://sudoroom.org/lists/listinfo/disasterradio or follow our wiki where I am posting development updates https://github.com/sudomesh/disaster-radio/wiki

Happy to answer questions as I am capable.

It's cool to see this up on the front page, thanks for all the interest!

I have also been thinking about a P2P radio mesh: http://radiomesh.org

I'm a bit stuck at trying to manually change frequency of the LoRa radios. It seems the standard does not allow it but the HopeRF chip I use have methods for selecting frequency and bandwidth around that frequency.

If so, that would allow for a multi-frequency protocol over LoRa that could scale!

I was working on something vaguely similar to this and to LoRaHaM: https://github.com/elvis-epx/sdr/tree/master/LoRaMaDoR

but most hams around are stuck in 2M analog, some even find configuring a subtone too complicated, so it is difficult to work on something no one will bother to use.

I'd be really interested to see what impact this will have on the site they link to http://disasteradio.org/ some tiny little band.

It would be neat to see what sort of traffic spike they get after being linked from a story that made it to the front page of HN.

in answer to your question: 1000 hits in ten minutes baby! that's showbiz! (someone PMed me about it already haha)

Yay! I'm one of the devs on disaster.radio and we're big fans. We're actually having our weekly meeting at our hackerspace sudo room https://sudoroom.org/ in Oakland, CA right now and listening to your track Drop The Bomb https://www.youtube.com/watch?v=s0S-HOOp_VY which has been something of an unofficial theme song for us!

omg <3 <3!! I gotta play in Oakland one day, I've never been but I have met way too many hilarious wonderful kooks living out there.. PS new disasteradio album is less about post-apocalypse and more an equal mix of solarpunk and SYNTHESIZER TRANSMISSIONS FROM THE TEMPORAL VOID

I'm glad I came back and followed that link. I'm programming an Atari 2600 ROM right now, this is perfect background music for it!

yay good luck! PS I did a tune for atari 2600 cart! https://www.youtube.com/watch?v=Y80BzcS5bKw

That was rad as hell.

They’re a fun artist! I’ve seen him live a few times around Wellington.

Open source radio tech is great!

This is the radio chip used in their hardware: https://www.semtech.com/products/wireless-rf/lora-transceive...

Very similar to the CC1200 I used in a radio I designed in 2013: https://www.ti.com/product/CC1200

Low data rate networks are super interesting. The long range let’s you do things you wouldn’t do with WiFi. But what i would really like is a high bandwidth long range mesh. The issue you run in to is who owns the spectrum. In the US it’s private communications companies that buy large chunks of spectrum. I’d like to see more valuable spectrum allotted for public use. This would pave the way for free or very low cost municipal cell phone service. Unfortunately there is big money interested in making sure that doesn’t happen. And with “business friendly” people in the FCC, the idea of free communications doesn’t have much traction.

This radio project looks cool. Ideally we’d have a generic 915mhz radio in our cell phones. I guess since this device also has WiFi, you could connect a phone pretty easily. Let’s beg the Librem folks to add a sub-Gigabertz radio (915/868/433MHz) to their next phone. :-D

Maybe they should integrate it with disaster mapping software like Ushahidi (https://www.ushahidi.com) instead of programming yet another chat silo.

Never heard of ushahidi. It looks expensive. We developed a free, open source mapping app that uses MapBox vector tiles on to which you can drop pins that are then shared with neighboring nodes over the LoRa radio. Check out development here, https://github.com/sudomesh/disaster-radio-map it hasn't been tested on latest dev hardware and might need some work to improve the loading of map tiles.

AFAIR Ushahidi is open source

To clarify: not meant to diss secure scuttlebutt. Integration with disaster relief software would be nice, I meant.

This is nice :)

Two parts can be replaced I guess with better alternatives though:

1. Risc-v chips for esp8266. Why? Because they are built on open source standard, are cheaply available, and are generally very powerful.

2. 802.11ah for LoRa. Why? Well, lora is highly optimized towards power optimization at the expense of data transfer rate. Data rates offered by LoRa might not be suitable for anything much demanding other that IoT. 802.11ah on other hand is also optimized for power, but still can operate up to at multiple 100mbps of data rates, with range in many KM's and supporting thousands of connections per installment.

This might help: https://www.electronicdesign.com/industrial-automation/what-...

ESP8266 is cheaper than RISC-V and powerful enough. It's not open source but that doesn't seem to be a deal breaker for this project.

802.11ah has only 1km range which is not enough for this purpose. LoRa is rated at more than 10km range at 292bit/s up to 50kbit/s. Also the chip used in this project costs only around $6.

Are there any RISC-V cores with WiFi and good software / toolchain support available for about $1 today? I wasn't aware of any, but I guess chips like those GD32Vs have been getting popular quickly...

Very cool. Reminds me of goTenna Mesh, which is already deployed globally (albeit closed-source and without a power source): https://gotennamesh.com/products/mesh

Without meaning to hijack this thread: does anyone know of any volunteering opportunities deploying / maintaining communication networks for disaster relief? Ericsson Response (https://www.ericsson.com/en/about-us/sustainability-and-corp...) is a group doing exactly what I'm after, but seems to be internal-only.

We have a good number of local hams working on mesh networking projects here in rural norcal, including exploring options for emergency use. I know of 5-7 locally and at least another 4-5 one small city over. There have been some recent test runs locally for distance and coverage.

One of the goals is to set up a pan tilt camera to remotely watch for wildfires, and we are seeking Ubiquiti gear for use on the project. We'd like to link it from inland to the coast which will take some doing but is probably possible. There's a really impressive mesh network project in Washington state, one I recall in Texas, etc...we are talking hilltops and mountaintops connecting whole communities.

Ham radio has served us well here during recent emergencies. After the recent 4-5 day power outage & wildfires, one of the county-coverage repeaters that didn't have backup power was set up with backup power.. Other than that even my non-ham friends were saying that listening to the ham radio frequencies was more helpful than listening to first responders via radio. Also, broadcast FM radio was really nice and there were hourly updates, calls with county officials, etc. Facebook was ridiculous because it has no idea that you are suddenly needing updates from your sheriff first, and everything else later. Cell data speeds were about ISDN level or maybe a tad faster. I accidentally made duplicate purchases on Amazon because I couldn't tell if my first purchase went through due to slow load times.

On ham frequencies we had people on hilltops directly watching and monitoring the fires, calling out what they were seeing long before the fires hit the news.

Anyway if you want to get into this, definitely get your ham license. Give yourself 2 weeks of study and dive in. Working with hams you'll find it much easier to get access to know-how, gear, people, etc. Even if you work independently somehow, the free education is worth it.

In ham radio in the US there’s ARES, RACES, etc, but you’ll typically need a ham radio license (not that hard to get, though)

Throwaway account here.

I actually had an interesting experience relating to this. A small handful of remote disaster coordination groups have self-organized over Zello (a PTT walkie talkie app for phones that uses data.) Their primary purpose seems to be to organize broadcasts of relevant information to groups of people who would "listen in" during dangerous conditions. The groups volunteers consist primarily of people that have internet connections and can broadcast from a safe location during the storm. These are similar to this idea [0].

I participated in one of these groups during a major hurricane in the US a year ago. My experience was mixed. It was interesting and fun to monitor social media, news sites, and NWS for alerts, hazards, and announcements. On the other hand, I was struck with how disorganized the groups were.

It was like there was a "vigilante" group of disaster responders who were giving guidance and advice that was of questionable quality. I encountered more than one member of the group that actively used the channels to spread fear and uncertainty, (like claiming that the hurricane would cause a risk of "meltdown" at a nearby nuclear power plant.) After I tried to bring up the fact that this was potentially harmful, I was verbally abused by the group leader and banned from the channel.

While these "bad eggs" are not the only part of these groups, other more well-meaning members might still not be well trained to handle very real crises.

I'm not sure the best way to handle this sort of problem, but I felt like sharing my story might provide value to anyone else who might consider getting involved with this sort of thing.

[0]: https://fortune.com/2016/08/20/cajun-navy-tech-louisiana-flo...

Cisco TacOps comes to mind... is this what you’re thinking?


Thanks for the suggestion. Yes, that's the kind of thing, but understandably it also looks limited to Cisco employees.

I get what your seeking now - I wish I knew of an org to suggest. I’ve long felt that there should be some sort of comms focused volunteer org like this. I guess you could say all of the major network operators already have things like mobile lte towers so there may not be a need — but then you see things like Irma and think how well did they do during that event and could ordinary people have coordinated more quickly and effectively? I guess another possibility might be the Red Cross? But again using the examples highlighted in this thread where folks were literally scanning for new fire outbreaks and sending alerts via ham... I don’t see that within red cross’s mandate... seems like there there should be an existing org, I just don’t know what it is called unfortunately.

That's a cool use of LoRa. I think it makes a lot of sense to have asynchronous super low-bandwidth text messages in such a scenario. You won't have time to man the radio 24/7, instead you just check if there are new messages of interest every now and then. For this use case, low power usage is essential, you want to be able to receive messages 24/7 even if there is a cloud cover for several days in a row.

For even longer range it would be nice to have a certain percentage of nodes that can also communicate with HAM radio amateur satellites.

If the people who created this are here in the thread, some questions on the power system...

1. What is your baseline calculation for Wh per day produced by the PV panel?

2. More precise specifications on the PV panel?

3. What is the calculated load in Wh per day? How much of this is dependent on data traffic level? (eg. Does it go into a sleep mode?)

4. Have you calculated this for sunlight levels in mid winter, off grid, at latitudes 48 and above? The Wh produced in a day, week or month by that size panel somewhere like North Vancouver, BC, will be really low from November to February due to short day lengths and winter weather.

The hardware section mentions:

> disaster.radio nodes are capable of functioning in most moderately sunny locations

I live in Northern Europe (54N) and wanted to use an old phone as a time lapse camera in a remote location without power or internet (hence the phone rather than something like a Raspberry Pi). The battery when fully charged would last ~3 days, so I just needed a solar panel big enough to keep it topped up.

I figured a 20W solar panel would be sufficient, as most phones use way less than that when charging. In my initial testing in direct sunlight this panel was barely able to keep the battery % the same, let alone charge it. I'm not sure whether I just needed or a bigger panel, or it was just the 20W solar panel I got from eBay not really being 20W. If anyone has any experience with this I'd still like to do the project :-)

That will almost certainly need a much bigger panel. If a phone is a 3W constant load, that's 2232Wh in a month, except in summer there is no way a nominally 20W cheap PV panel will keep up with that from October to March at latitude 54. Combination of short daylight hours and overcast weather so rarely any direct sunlight.

The 20W rating is at what is called standard test conditions, basically equivalent to direct sunlight in the Arizona desert.

You'd probably want at least a nominal 180W panel and a basic 25 Euro PWM PV charge controller.

The rating for a panel is the absolute best case where it has full direct sunlight and the panel is cold. Most of the time you will be getting less than the rated power.

In Germany, the solar panels in commercial installations produce about 10% of their peak wattage averaged over a year. I guess these are installed in locations with good insolation. So at best you could assume some 2W on average from your 20W panel. But if it didn't even work in direct sunlight, the panel was probably broken.

In theory, couldn't you boost the input light by using a couple of mirrors (one capturing light below the panel, one above the solar-incident light shining down at a Summertime angle?) or some carefully position Fresnel-style lensing?

Is polarisation of the reflected light an issue?

I am the current maintain of the firmware for this project. Recently, I've been doing development for it using the LILYGO TTGO ESP32 dev board (V2.1_1.6) https://www.aliexpress.com/item/32915894264.html?spm=a2g0o.p... Therefore, power consumption specs should be similar to this board.

We are working on a new board design with an integrated solar panel and two LoRa radios, but I am less involved in that part of the project, so I can't answer all your questions on the power system. Perhaps this link will help, though it has not been updated for the ESP32, https://github.com/sudomesh/disaster-radio/wiki/Power

Currently, it does not have a sleep mode, I recall there being some concerns with waking up from sleep mode back when I was dev'ing with the ESP8266, not sure if that has changed on ESP32, have not re-approached the idea it since switching to ESP32.

We did have some do some tests with an off-the-shelf 15W solar panel and a super-cap, it seemed to work well. Check out their report, https://sudoroom.org/pipermail/disasterradio/2019-December/0...

Love this. I was just without internet for a few days last week, and as a bit of a "prepper" I couldn't help but think if long term disaster situations and what I would want to do for internet and communication in such an event.

I'm actually getting a ham radio for christmas (don't tell my wife I know) and while that will fill almost every NEED for communication, it certainly leaves room for improvements. Text chat is very convenient, maps are very convenient, so I think this project is a great start.

If you love ham radio, text messages, and maps, boy are you going to get your money's worth out of APRS and digital modes. Haha. We have a digi-net here locally and whenever I'm able to participate I often end up just holding my phone (AndFlMsg) to my HT. Works great.

This is awesome! Super smart set of basic apps, and having it just be a normal WiFi hotspot is great. I could see it actually being quite usable in a disaster scenario.

Kickstarter the hardware for like $100 and I bet it would do really well. I'd buy one right now. Or let me donate!

Looks like there's an "app store". Curious how that works. I assume that would be a major bandwidth/tragedy of the commons issue, but perhaps there's some way to have a higher QoS channel for the critical apps.

First thing I thought? If I can survive long enough we can still communicate in a zombie apocalypse! (Yes, I'm still persevering with The Walking Dead after 10 seasons)

I am often curious what mental itch people are scratching with "zombie apocalypse" fantasies. It's clear at any rate that "zombies" are really "people it's okay to kill". It's as if people are hungering for a simpler, more brutal time where your problems are largely constrained to kill or be killed - a kind of civilization wanderlust. I do not think it is healthy.

I'm petrified of such an event. It's why I fantasise how I may survive, because I know I wouldn't!

Disaster Radio. Does one need an FCC ham license to own/operate an endpoint? What are the frequencies? After some light poking on the website I don't see any info on that. Love the idea though.

there is also this: https://www.nycmesh.net/ , somewhat related and can be used as a back up information/communication source

The ESP8266 is a wifi chip, so almost certainly OK to operate without a license unless you're doing something really bizarre with antenna gain to get above the 36 dBm EIRP threshold.

LoRa can run in any band you want, but it's almost universally deployed in ISM bands as well, 315/433 or 868/915 MHz. I don't think I've ever seen a LoRa chipset that would push enough power to exceed part-15 regs.

HOWEVER, to be strictly legal, a part-15 device actually needs to be tested and certified thereas. Otherwise the parts can only be sold as a kit and stuff, which is how pretty much all lora stuff is sold right now. And you'd be hard pressed to piss anyone off enough to care.

> Otherwise the parts can only be sold as a kit and stuff

Yeah. Disaster Radio does not look like a "kit" at all. Not for "an average user" at least. I'd be cautious building and operating hardware that can potentially get me in trouble with authorities.

Still great general idea though, to build a solar-powered kit that's easy to setup and operate, a kit that makes sure there is a "plug-and-play" solution in case of a disaster (natural or not), kit that also delegates legal responsibility to the "creator"/manufacturer.

Okay, I should've been clearer about my initial post, that it's breathtakingly unlikely for anyone to get in trouble doing this.

Look at the unmitigated chaos on CB for a sense of how much the FCC feels like enforcing anything on the unlicensed bands. Probably 95% of CBers are running above-legal power, many of them by _several orders of magnitude_, and behold, the field in which the FCC grows its fucks, it is barren.

It uses WiFi for local communications and LoRa for the mesh network, both of which operate on frequencies that don't require licensing.


Interesting, so how is it different from similar projects, e.g nycmesh.net, I mentioned above? Is it a promo for the custom hardware design initiative? hardware that's more modular, cheaper, focused than traditional brands?

NYC Mesh and similar networks use point-to-point relatively high bandwidth links (e.x. Ubiquiti radios commonly used by WISPs)

Disaster.radio uses LoRa which is very low bandwidth and typically omnidirectional antennas. It only uses WiFi to connect users’ “terminal” devices to the node within a short range.

Yes! To expand on this a bit, disaster.radio locally hosts web apps, e.g. a vector tile map of the local area, and serves them up over WiFi to local devices with a reasonable bandwidth, then uses the very low bandwidth of LoRa to share points on the map added by users over long distances (e.g. where you can get water, food, etc).

disaster.radio is not a replacement to a existing internet infrastructure like NYC Mesh. Setting up a high bandwidth mesh network is a lot of work. Each node needs a non-trivial amount of power (enough to make solar hard) and nodes generally need line of sight which requires good mounting locations and planning.

We, the creators of disaster.radio, actually also run a small wifi-based mesh network https://peoplesopen.net/ and the idea for disaster.radio came out of frustration with difficulty of mounting wifi nodes (finding interested people in good locations, then negotiating with landlords for permission to mount on rooftops and running ethernet cable for PoE into building, then finding another location within line of sight and repeating the process). We thought: What if we could make a "mesh throwie" where installation was as easy as throwing it on a roof (and maybe strapping it to something).

No, you do not need a license.

Wifi is 2.4/5ghz.

"LoRa uses license-free sub-gigahertz radio frequency bands like 433 MHz, 868 MHz (Europe) and 915 MHz (Australia and North America)." -Wikipedia

What license? In event of disaster there will be nobody to check or enforce licenses.

To an extent, I feel good that the Secure Scuttlebutt guys are behind this.

A good direction to develop would be to talk to FEMA and its global counterparts. There is literature on what is needed in disaster. Instead of an insular tech-world development of such a platform having disaster response practitioner insights might be useful.

For sure, SSB is a cool community. Cel wrote demo software that allowed a disaster radio node to post messages to SSB. Check out the source on git-ssb, https://git.scuttlebot.io/%25SyAU1pa6g6yYcELjTrBG4JY41vjuP6H...

And agreed, once we have stable hardware and firmware, talking to local disaster response practitioners would be a great way do test deployments and get feedback on the software design and usability. I'm curious about the disaster-related literature you referenced, would love to read it.

This software is available pre-flashed onto cheap LoRa boards now.

$40 for a pair https://www.aliexpress.com/item/4000396836096.html

Using 900 MHz means you only get line of sight which means you need height above terrain. In a disaster maybe you can get this without paying anyone any money so this might be feasible.

Using HF would be better in almost all ways except size though.

900Mhz will punch through some stuff and the spread spectrum chrip Lora uses will do non-LoS[1] under some conditions. The bigger issue is to get that capability Lora is a really low bit-rate(on the order of bits-per-second) and polled instead of ad-hoc.

[1] https://arstechnica.com/gadgets/2019/10/lostik-usb-lora-radi...

Yeah, I heard the same thing. So now I own a bunch of 900 MHz transceivers, telemetry dongles, and equipment. I don't think it deserves the good rep it gets. It may punch to the other side of the house or do okay through some pine trees point-to-point but at the slightest hill or gentle dip it's done. It's best to treat it like a microwave link. And for a microwave link it has a pretty significant fresnel zone.

I always thought it would be cool to make a little portable kit to fly an antenna/relay in case of emergency. The practical solution would probably be a parafoil, but a chemical hydrogen generator and balloon would be way more fun.

Some way to get height above terrain is required. One of the more game changing ways I've heard about is using specially shaped TEM mode launchers with thin single wires to transmit RF power up to a hovering quadcopter to be rectified. Glenn Elmore has published some articles about these surface wave transmission lines in the amateur radio magazine QEX (mirrors at: http://www.sonic.net/~n6gn/) and documented some 50w power tests on his youtube channel, https://www.youtube.com/user/n6gnSWTL

I implemented a pair of these launchers designed for my 900 MHz "wifi" setup using a ubiquiti 900 MHz tranceiver running broadband hamnet firmware. It seemed to carry the signal to the antenna as well as a similar length of RG-6 coax. http://erewhon.superkuh.com/swtl_launcher_complete.jpg It was a little fragile and the connection to the SMA connector broke on one. Some day I need to resolder it and put one end up in a tree. Glenn's 2.5d metallized paper designs look much easier to build and more robust.

I was hoping this would use meteor scatter (https://en.wikipedia.org/wiki/Meteor_burst_communications)

Might as well throw in EME as well ;-)

I wonder if SpaceX's StarLink (if it ever gets finished) will continue to function independently in the event of global disaster. Having equipment around that can communicate with that sounds like a good idea.

I don't think they will, at least not in their default configuration. They do have the capability to communicate between the satellites but I'm not sure that they are setup to deliver data going strictly between two Starlink'd users without going through a ground station. There's also the problem of just keeping them up, being low flying satellites they'll need periodic boosts which are planned from the ground iirc.

Both of these could be turned over to an automated system though I suppose.

Hey, nice project. Can you comment or point me what hardware do I need to buy to get my own node?

If there are too many options maybe put a hardware matrix?

Thanks! I am the current maintainer of the firmware, juul is correct. I am actively developing with the LILYGO TTGO ESP32 dev board. If you are interested in development then you can buy one from aliexpress, if you are looking for a finished product, then you should wait for us to finish the next iteration of our custom board. Here's board that is currently supported thttps://www.aliexpress.com/item/32915894264.html?spm=a2g0o.p...

Hi. Thanks! Some of our contributors have added support for some of the off-the-shelf TTGO ESP32 + LoRa boards but I'm not sure we're ready to call it stable. I'll ping them to come here and answer your question. The previous ESP8266-based solution was just a bit under-powered for serving up the vector tile maps and we're not supporting that anymore.

We're also about to finalize some new custom boards with ESP32 and two LoRa modules (meshing on a single channel kinda sucks) and will make an announcement on our site as soon as that's ready to try out.

What is the specific use case of the low bitrate long distance radio? Very basic news dissemination? FidoNet like message relay?

What is the estimated range of the antennas? Several miles with line of sight?

"powered by the sun" buddy everything is powered by the sun

How well would these hold up after a solar storm or EMP?

It depends.

In the case of an EMP it depends on how close you are and how much damage it does. If it is close enough to fry the electronic circuits of the disaster radio, then it's toast. Then again if you're that close everything that could connect to the disaster radio would also be toast. You'd be OK if you kept the setup in a highly shielded bag and only deployed it after the disaster (EMP) struck... however you'd still have the problem that your only device to connect would also have to be stored in the shielded bag.... and it's not much use of a mesh network if everyone else got fried too (because they didn't shield bag storage).

As for Solar storm. I presume you're talking about something like the Carrington Event ( https://en.wikipedia.org/wiki/Solar_storm_of_1859 ). So again, it depends on the scale. Based on the research I've seen, the equipment may keep working - but the radio propagation is a different story. GNSS systems will likely be toast, so that's not going to work at all. Radio propagation, depending on a lot of factors, will likely be affected. If you're in a heavily populated area with lots of notes - it may not make a different at all. If you're out in the fringe areas and only have a few nodes barely within reach - then your mesh might get cut off. However in theory with varying "jamming" by the storm, and retries built into the system, your messages could eventually get through.

EMPs aren't really a plausible weapon. Sure you can detonate a nuke, but by that time, you've already launched an ICBM, so you're screwed because of mutually assured destruction.

If you want disrupt an electrical grid, there's a lot of easier -- and less likely to have an obvious calling card -- than setting off a nuke.

And if you're thinking about some other type of EMP weapon, forget it. They're not practical. While a theoretical weapon, they're not a realistic one. It's fantasy.



Or you have your nuke already in place because you violated that treaty about nuclear weapons in space and can set it off without launching a rocket first.

There are better uses for that nuke.

was my first thought as well, but after watching the video it looks like it's something you can quickly setup AFTER the incident. To deal with the aftermath I guess?..

After the EMP you don't set up mesh network. Instead you start moving perpendicular to wind direction, away from the epicenter, to avoid the fallout.

An EMP pulse weapon would be detonated hundreds of miles about the ground, how do you figure out the wind direction where that device was detonated after the internet, commercial radio stations, etc have all been knocked offline (assuming your personal electronics survived)

EMP's have numerous causes besides nuclear bombs, perhaps "After the blast" is more appropriate here.

It's probably a better idea to shelter in place for a week, with windows closed and a hepa filter installed.

You wouldn’t get much fallout from EMP. It has to be an upper atmosphere detonation to get the EMP.

yeah, but you can't be moving forever. When you stop and setup a base, you will need something more than a basic walkie-talkie, right?

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