kelabar
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Post by kelabar on Sept 4, 2020 20:45:53 GMT 10
Now I know how Alice felt when she went down the rabbit hole! Thank you, illuminati. So a femtocell would be a standalone replacement for an existing tower? Load a phone comms OS and it could actually use the cellular frequencies, not just wifi? That would give better coverage in a town or neighbourhood. Phones could use their actual transmission power, not the lower wifi power. Power usage may be excessive although firing the system up a few times a day instead of constantly running could reduce this. Or run at lower power most of the time so text is always possible but not voice. I can't find any info on transmission power for femtocells. Would it be more than an amplified router, 4-8W? Can directional antennas be used? Specifically looking at signal range to allow towns to be linked somehow. Apparently a microcell has a range of about 2km. Femtocells about 10m. But the info and naming is confusing. What are cellular signal boosters? Could they be used as repeaters? How common are they? Possibly use a femtocell to give phone comms in one town and use linked directional (amplified) wifi routers to transfer signals over long distances if the cellular signal won't reach or can't be boosted.
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shinester
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Post by shinester on Sept 5, 2020 14:30:20 GMT 10
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kelabar
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Post by kelabar on Sept 5, 2020 19:35:53 GMT 10
Huh? Even the beginners guide didn't help me. I did see '11km range LOS' and disaster.radio as an alternative right at the bottom though. I have absolutely no clue what this is! Please explain in really small words!
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shinester
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Post by shinester on Sept 6, 2020 17:06:31 GMT 10
Ok, so you add on a radio [think CB] to your phone and instead of the cellular [also a type of radio btw] network it uses the frequencies you choose. All of your friends need the same add on. Probably illegal in this fined land. Twice the price of an actual cheap CB radio, no audio. ---- Since your target market is farms/farmers, some more remote places still have people with radios in their vehicles. Not like it was 20 years ago when many people had CB, though what's the situation like? Do you see people's 4WDs in the area with large antenna?
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kelabar
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Post by kelabar on Sept 6, 2020 19:03:03 GMT 10
So buy two of these radio thingys. Put them 11km apart. Bluetooth-connect to them with a phone to send texts between phones at either end? Repeat until coverage area is achieved?
The radio thingy transmits, I assume. Output power? Range is the 11km I saw? Brazilian use has comms over 40km. Better than an amplified router it would seem.
What about repeaters? Don't need them because the radio passes messages to all other radios?
If GPS satellites are working these look to have a direction finding capability. Is that true? Could help to set up directional antennas.
Tl,dr. How would you use these to set up a comms network?
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Post by illuminati on Sept 7, 2020 4:48:13 GMT 10
Maybe explain the use case a bit more and then can find a technology that is best fit.
Like if you just want to chat with Robbo the down the next farm over?
Or do you want to send a message to the whole town’s prepper community? Perhaps it could be sent to Bettsy’s property who lives on the hill and she then relays it to everyone else when they get LOS and ask for an update on the town gossip.
Want to communicate with communities/people up and down the coast to inland and the other coast, other countries?
How many users would there be?
What distances are we talking per leg? Is there line of sight and are there obstructions? The further you are sending the higher it has to be up because the ground interferes more and more.
How much data would you need to send/receive? Simple text messages, just a few, or pictures or high definition video and audio? Does it need to be real-time (like a phone call) or can it be store and receive (like email or a forum post)?
Does it need to be portable or mobile? Mobile in a car or on a person?
Survive an electromagnetic pulse (EMP)?
I think in theory from a pure technology POV running your own 3G/4G network (think like Mexican drug cartel) is going to give most use comparable to normal life. But it would cost a lot, need expertise, and be illegal and likely get detected immediately, and also interfere with the legit networks and their customers.
All the mobile spectrums are licensed, the phones everyone already has don’t support (for mobile) and frequencies that are legally allowed to use for your own stuff.
This leaves the ISM frequencies (e.g. what WiFi and BT etc use), and CB, walkie-talkies, and Ham. The radios (CB etc) you’re only allowed to use for their intended purpose. If you start transmitting some random data protocol on it you’d likely get in trouble. Ham has some data packet protocols but from what I understand it has to be cleartext for everyone to read, can’t be kept secret.
For mobile spectrum in theory, you could buy some spectrum or licence some off one of the big telcos that own it. But you’d need a lot of clout and money.
In the future there will be Starlink that Space X has been launching and there’s some competitors. Maybe that is something to use if the scenario you’re envisioning still has enough functioning satellites left in the constellation. If fixed line and mobile Internet is down but satellite Internet is still working. Maybe strategic cruise missiles, nukes, and hacking would take out our telcos, NBN, gov, and all the satellites that were above us during windows of the detonations, but the satellites on other side of planet might survive, and after interference has dissipated will resume functioning even if it’s reduced coverage (constellation has holes in it where instead of 24/7 coverage of 99% globe it now cuts in and out because a bunch of satellites are missing and now you need to wait for the hole to pass and the next satellite to fly over.
I think you may need to go old school like the donkey express and phone trees. You use a Ham radio or travel or send someone to Robbo’s and tell him a message for Davo, and he tells Davo when he gets drops in etc. Or have p2p long distance wireless (WiFi or proprietary), same thing relating messages (but could be tech based rather than manual/human) hook up several strategic properties and even towers etc, and have some hub and spoke, maybe decentralised if there’s the budget. Distributed is the most resilient, and most expensive (more gear).
If you have line of sight you can use lasers, which doesn’t need the height to avoid the interference. Would work for fixed positions, not mobile. Maybe an earthquake or something would wreck alignment/aiming. Mega volcano would occlude it. Nuclear Winter ash occlude it.
Food for thought.
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kelabar
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Post by kelabar on Sept 7, 2020 8:58:26 GMT 10
Maybe explain the use case a bit more and then can find a technology that is best fit. Nope. Can't. Not what I am looking at. The exact opposite. What technology is available after a disaster and how can it be used for comms. I have no idea what will happen. But, regardless of the actual situation, if I can say to some tech-dudes "Oi, here's the software, set up a system" and leave them to it, then 'bingo', comms of some sort. Sounds good to me. If it is only connecting 2 places over short range, so be it. If it can be expanded to cover a larger area, great. If it can connect separate towns, even better. If it can be expanded to join cities this would be the best outcome. International would be awesome but unlikely for a system improvised from whatever is around. It may not be possible at all but we will be very lonely if existing comms go down. How are your family and friends doing in the next neighbourhood, the next town, the next state? How will you know if hostiles are headed for your location; cyclone and bad weather warnings; medical emergencies? All things we take for granted today which would really help if things go to crap. Not fussed if it is only a text warning sent out to everyone in a small area, this is much quicker and has more info than the town bell or siren. PTT voice would be great. Standard phone comms even better. The more area the system can work over the better. With burning cities or occupation or any scenario, anything will be better than nothing. What happens when your comms plan doesn't work? If you don't have a plan B you may not have any comms at all even though equipment is just sitting there waiting to be used. It may have to be 'shank's pony', or a heap of paper messages given to a truckie, or carrier pigeons. But the reason we don't do this now is every electronic method however simple is quicker and easier. I like easy. Don't worry if you don't get what this thread is about. If this sort of thing is needed, things will be really bad. Not a lot of people like to think about that. And thanks, great info in your post.
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kelabar
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Post by kelabar on Sept 7, 2020 13:09:22 GMT 10
So it looks like a wifi system would most likely be able to be set up from existing hardware. Install the OpenWrt software in a router. Need a computer. Hopefully this can be done from saved software, not requiring a download at the same time. This changes the OS the router is using but doesn't affect the router software. (Is it possible to either partition or run at the same time as the existing OS?) Packages like 'asterisk16' and 'baresip' support telephony. Run an antenna on an extension cable to a high point. Range should be in the 100s of metres but very patchy as distance increases. Text would be possible for long distances even if voice is not. The 15mW transmission power of phones will give fair range, fixed mounting of phones near windows may give better range. (Are external wifi antennas possible for smartphones without modification?) Enhancements could include: amplifying routers. setting up more routers at suitable distances within the local area to improve signal strength. use of wifi extenders connected by ethernet cables (maybe). For longer range: directional antennas sending signals to repeater routers, still not sure if these repeaters would need a phone or computer attached to rebroadcast the signals. The local limitation is the transmission power of the phones but they can still receive stronger router signals from much longer distances. And apparently a lot of security systems use wifi as well so they could provide more equipment. This link was really helpful to me. www.choice.com.au/electronics-and-technology/internet/connecting-to-the-internet/buying-guides/wireless-routersAnd au.pcmag.com has some great info for tech dinosaurs like me! For info, apparently Windows 8,1 and 10 don't support ad hoc networks. May be relevant to someone. IIUC, ethernet cables can also be used to connect routers. Anyone know the maximum length of an ethernet cable run to still give useful function? It must be in the 10s of metres as they are used inside large houses. And what are a couple of common routers in Aus? Generally a cheap one is included when people buy stuff, I think, so some will be much more common than others. Features or power isn't as important as commonness (if that is actually a word!).
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Post by illuminati on Sept 9, 2020 2:55:06 GMT 10
From memory the standard is about 200m over cat5 etc. But it can work longer. There’s many standards, it wouldn’t surprise me to find there’s some long range standard when using the right cables.
If you can plug a switch or router or similar along the way that will regenerate the signal, then you can create a long daisy chain. This would have many Single Point of Failure (SPOF), so wont be very reliable. But I suppose you can just fix it when it breaks.
This isn’t the best way to solve the “I want a long cable” problem. But it’s one of the easiest low tech ways to do it I suppose, with commonly available hardware.
Better would be fibre optic, which can go 80km or more, depending on the cable and the transceivers (lasers/receptors).
Connecting an antenna via an extension cord often won’t work well because there will be a lot of noise and power loss etc. better to put the router as close to the antenna and then run an Ethernet cable down.
I don’t know if any phones that you can plug an external wifi antenna into. I suppose you could mod one if you knew what you were doing. Probably easier to use a personal/pocket wifi router that had been modded to have a more powerful antenna and then connecting the phone to it. The router would be easier to mod.
There’s many many wifi routers. Many brands. Anyone model doesn’t last on the market long, they are constantly coming out with a newer model, which often has less storage, less ram, weaker CPU etc, but is cheaper to produce, and it still functions. There focus is on cheaper, and people are just focus on shiny and marketing. A lot of people have spares from when they change providers and get a new one, or move home and the setup is slightly different. Like you switch from ADSL to NBN and need a new modem because it’s VDSL rather than ADSL. If you just want basic wifi and wired use whatever you have and can get free or cheap etc.
If you want to run OpenWRT or one of the other open source firmwares then you’ll need models that are compatible. If you want to run asterisk and lots of software on the router itself it’s handy to have a decent amount of RAM and storage and CPU. Nowadays they aren’t as bad as they were in the past where they were quite limited in capacity. But some new models are still very lean.
There’s also RaspberyPi’s, and all the Single Board Computers (SBCs) like Gumstix and things like that, which can run HostAPd and effectively be a WiFi router.
If you deploy many WiFi routers you can look into making a mesh using things like BATMAN. There’s probably better options now but I haven’t researched it.
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kelabar
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Post by kelabar on Sept 9, 2020 9:53:56 GMT 10
...it’s one of the easiest low tech ways to do it I suppose, with commonly available hardware. Thanks, exactly what I am looking for. Much appreciated. Looks like it would be fairly simple to set up some sort of comms with existing hardware. Either a mesh network or a system based around one server/computer and expanded out into the area. Cabling to other routers spaced up to 200 m away would increase coverage so the low wifi power of phones wouldn't be so limiting. Or have other routers closer if reception is bad and use wifi instead of cable. So put the server in the centre of town and have 4 or 6 other routers spread around it. This would give a much larger area covered with higher reception. Then use directional antennas to reach other systems either in the same town/neighbourhood or 'repeater'ed to towns 10s of kilometres away. Good basic info here too: www.lifewire.com/Thanks, everyone. You guys are great!
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shinester
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Post by shinester on Sept 12, 2020 13:18:34 GMT 10
Doable, not easy, lots of potential problems you would want to have practiced solutions for or at least the right resources. - Range quite limited, would have to be close to router to have phone [10mw] pickup wifi [100mw] - phone stays near router to work
- Range of router to router has to be increased with the right antenna/location - do you know how to make them/can you put them up high/can you beam them to the next guy? Most routers have 1 antenna, newer ones have multiple [channels] which could be used to have different antennas for different purposes. You could put them outside up on a roof with a zip lock bag or just inside the roof would help do if not made of metal. The higher the antenna the better. Unless you have the right leads I wouldn't try to take the antenna off the unit.
- Setting up the mesh network would require knowledge of specific routers and/or firmware to upgrade the routers to be able to do that. Manuals of many routers and software [as well as a laptop with all of the info on it] would needed so that as many routers could be turned to this where possible. That alone to me is a big undertaking and would be essential.
- Comms limited - right software, potentially voice, text easy.
- Less secure - always transmitting on the same channel, anyone with a phone or laptop could see many wifi's when near. Even if network is hidden, plenty of tools to find hidden networks. Find hidden networks Same deal as above, if things were crap, then it's not that likely people would have software to find networks. Could be found with people doing fox hunts for radio, though you'd have to have equipment to do so. In the rural situation you have supplied, if farmers were supporting one another then it might not matter too much.
- Power supply - can you supply electricity to charge the car battery to keep it working? 150Wh/day+ approx would need a panel of about 75W+ to supply just it. 7-10 more watts for the phone. Car batteries have a useful about 650Wh of useful charge, so would work with the right charger. You could save some fuel and charge car batteries [think jumper leads] enough with a little fuel every 3 days. We've talked on this, power supply regulation for solar, and it's quite tricky unless you've got some knowledge on the topic. I've got decent knowledge in electronics and how circuits work and untested idea on how to make some rudimentary regulators from the regulators electronic equipment and I would need at least a decent soldering iron, solder and a multimeter. I would prefer to have a bunch of cheap electronic components like 14V zenner diodes [10c ea] and high current transistors [or derivatives] and a bunch of solar regulator diagrams as well. Do you have a means and/or knowledge of providing the right power to the router itself from 12V? It's pretty easy using plain diodes found in every power supply for electronic gear each drops the voltage by 0.6V. So if it needs 5V DC, you could use 12. Can you identify them and solder them? Normally they're not surface mount, though they may be in an IC, but they'll be there as you need to make what's called a bridge to take AC power to DC. This is a key area and only someone with the right knowledge could make this happen. Not saying someone has to be an electrical engineer or be a hobbyist since 10 like myself but knowing what bits do what in a circuit, what to pull out to charge the battery is important to make something happen.
Pretty straight forward for me, for most that's not easy.
----------------- I would start working on the knowledge. See below, this is a power/rectifier diode. It allows electrons [energy/electricity] to move in only one direction, it's importance for you is more about it's voltage drop of 0.6V. [there are many other ways, but this is simplest to do]. This will take 12-14V from the car battery to whatever lower voltage your router needs. If you look at your router the panel on the back should tell you the input voltage, if not the transformer you plug in the wall will. This is the voltage you need to get to from a car battery. Doesn't have to be 'perfect' but close to it is what you're aiming for. Work that out, how many diodes do you need for your own router?
Now if you unscrew the cover plate on some electronic device that takes '240V from wall' you can find the diodes. They usually look like above.
I can see 6 diodes. They all work much the same, bigger ones are typically good for higher current [amps], the silver end is the negative, point it to towards the negative of the battery.
This board has surface mount diodes, they look similar to the round ones above but they're square. They work much the same but are harder to solder/easier to kill with heat. Once you see one you'll see how the little letters give away where the rest of the diodes are. There's at least 4 diodes [probably 5, but I would have to see from another angle] there and 1 zenner diode. Can you find them? Learning how to solder isn't hard, though getting some tips from youtube would be a good idea.
With that small piece of information you ought to be able to get a car battery voltage to what you need for the router with some wire, soldier, soldiering iron and a multimeter [to check your voltage].
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kelabar
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Post by kelabar on Sept 15, 2020 10:13:52 GMT 10
Great info. I doubt if I could find that anywhere without studying electronics for months. Good one. As for my soldering skills?... well, I'm better with a hammer! Apparently software can be loaded onto routers without internet access. SSH is used in Linux and PUTTY in Windows. So save the relevant software and load it after comms go down. The software seems to be specific to every router. A generic program capable of running on all of one brand or type would be nice. There is already existing software to make routers act as repeaters. 'relayd' is mentioned in the OpenWRT website. Interestingly, ethernet cables may be able to be used over much longer distances. From limited research it appears the amount of traffic going through the line generates most of the noise or disruption, so restricting usage at any one time may increase the length of run possible. No doubt there is a physical limit as well.
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shinester
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Post by shinester on Sept 15, 2020 13:54:37 GMT 10
You could most likely narrow down the software for routers by having a look at what the providers give customers in the area. If it's rural you might not have too many choices and you could then narrow down what hardware is likely to be in the area. Yeah you can run the Ethernet cables for 100m via spec and probably longer in the real world with a drop in speed.
Soldering's not hard, essentially heat up metal area and put soldier on the tip and watch it pour/melt and attach to the metal. You could just open the router and twist wires around the connections and add tape.
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kelabar
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Post by kelabar on Sept 17, 2020 18:33:34 GMT 10
Was looking at this webpage and could even understand some of it! wiki.teltonika-networks.com/view/RelaydI had an idea. Is it possible to connect a smartphone to a router with an ethernet cable? Then the router could be on a tin roof and the phone in the house. Connected by the cable. This would get around the limited wifi power of the phone and interference from the metal roof. The only transmissions would be from the router then with much greater wattage and, being much higher, much better LOS range. At the cost of powering a router as well. Feasible? EDIT: Routers are on gumtree for free or less than $10. Just need to check compatibility and output power. I can actually try this without spending hundreds of dollars. Win! 2ND EDIT: What about ethernet switches? Could they be used to increase the length of ethernet cable runs by acting as repeaters?
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shinester
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Post by shinester on Sept 19, 2020 16:37:13 GMT 10
Money way - You don't need to put the router on the roof, you only need to put the antenna on the roof, run an antenna with a lead to the router. These start at about $10 and go up.
Non - money way - If you put the router on say an old chimney inside a couple of plastic bags, that router will be on one side of the house. The phone will probably work near a window on that side even with a tin roof.
Yes routers are dim a dozen, people usually just get them with their internet company and when they switch they get the new router. You could make up a few that work with car batteries for nothing but time. Don't need an Ethernet switch unless you're running cat 5 cable and need lots of nodes or over 100m, aka you won't need it.
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shinester
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Post by shinester on Sept 20, 2020 13:56:19 GMT 10
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kelabar
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Post by kelabar on Sept 20, 2020 20:04:50 GMT 10
Link not showing for me.
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shinester
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Post by shinester on Sept 21, 2020 1:41:52 GMT 10
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malewithatail
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Post by malewithatail on Dec 13, 2020 14:01:16 GMT 10
Just having the radio isnt enough, as well as knowing how to operate it and the appropriate protocols, you need some knowledge as to how it works and how to fix it when it breaks down.
The ideal would be to have someone in your group that is a electronics wizz to repair electrical gear that is going to break down and cant be replaced as the shops are closed. I suggest you get a recent copy of the Amateur Radio Handbook, published by the ARRL, and also the one published by the RSGB in Great Britain. Any of the versions of the above books have useful information, even pre war ones. The theory doesn't change between valve and solid state gear. Also, at the very least you need the service manual for each of your radios, including the full circuit diagram, parts list, voltages expected etc, so at least, if you find a wizz they can have some info and a chance to fix it.
It would be a good idea to have enough knowledge to be able to construct your own simple receivers and transmitters from junked TV sets etc. The Amateur service is privileged in that we are the only organization that can legally build and operate on air homemade transmitters for any of our bands.
Times coming when we will be on our own, not only with food, water etc, but all the other things we take for granted. Being prepared is not just food etc, but having to survive with little or no input from modern society.
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