Oh one last thing, there is a difference between a very small network and one that gets a bit bigger.
https://commotionwireless.net/docs/cck/networking/guidelines-for-mesh/ talks about some of the design considerations and note that more hops mean slight delays which isn't so good for voice. Cheerio John On 3 February 2016 at 11:16, john whelan <[email protected]> wrote: > With fifty users sharing files you probaly want to use a couple of linked > hubs, that's where the TP-LINK MR3020 starts to shine. I have one here and > one waiting to be picked up at the computer store to test but its freezing > rain here in Ottawa at the moment so there is a layer of ice on the > sidewalk, not so good for walking on. However you can use two laptops > independantly and collate the files later on. > > If you are texting only then one hub should be enough for fifty users, for > voice calls depending on the traffic it should just work since not everyone > will be using it at the same time. For file transfer, depending on the > size of the files you might want to split the load over more than one hub. > > For voice over more than one hub you need to link them so you need two or > more TP-Link devices with the special firmware. Linked in this way you can > send a text to a device that is not available and in theory it will be > delivered when it comes in range next. > > From a practical point of view Paul's mesh extender combines a hub with a > small radio so you can link over longer distances. It uses the same > frequency as a car garage opener to build the mesh. It also comes in a > plastic box to keep the weather out. Unfortunately it's not quite in > product yet but bug New Zealand's Red Cross and they should have some idea > of time frames. > > If you're using a TP-LINK MR3020 it does require a power source, but > battery powered USB boxes are around to extend the battery life of a > smartphone. > > http://developer.servalproject.org/dokuwiki/doku.php > > https://en.wikipedia.org/wiki/Serval_project > > It appears you can use any wifi hub that supports peers. Note this isn't > quite the approach that the Serval team has been using up until now and I'd > need to play with the specific router to get the configuration sorted out > so stay with the specific Tp-link device or the win 10 hot spot and test it > before you go out in the field. > > The portable wifi hub the TP-link is cheaper than a laptop, around $40 > locally. If you want to link them up then you need to flash them with a > different firmware. I haven't done this yet but it is on the to do list > and it should be possible with a laptop but does require running some form > of unix on the laptop but that can be done under windows. Once it is set > up then it takes a couple of minutes to update the firmware on the hub. > Want me to write up the process on how to configure one for stand alone > use? Where would you like this written up? Note different coutries have > slightly different rules for wifi etc. and a standard TP-Link hub > understands these so which country it will be used in is part of the setup > process. Hopefully the linking firmware takes this into account. > > Note there are other solutions than serval for sharing files, especially > using a hot spot from a laptop. Essentially you can use the laptop as a > web server, in theory you just need the appropiate .html file(s) on the > laptop. So you can link windows laptops together using this technique you > don't need serval for this. > > If you use html5 code and have the downloads as .zips then you should be > able to click on the link and the file will download automatically. I have > some simple sample html5 code floating around if anyone wants some. I > think most smartphones can handle .zip files. > > The other thing to note is that wifi devices such as Nexus 7 tablets can > use voice to smartphones running Serval. In general wifi tablets are > cheaper than smartphones. > > and you thought the HOT mailing list was just about mapping. > > Cheerio John > > On 3 February 2016 at 09:02, Mhairi O'Hara <[email protected]> > wrote: > >> Cheers John! We're collecting data on financial services, education and >> health facilities in Eastern Uganda and are looking for sharing solutions >> that don't involve the internet. With up to 50 students at times, sharing >> files via usb sticks and external hard drives is not ideal as it can be >> time consuming. Will look into the setup to see if it could work for us >> here. >> >> Mhairi >> >> >> On Wed, Feb 3, 2016 at 3:00 PM, Katja Ulbert <[email protected]> >> wrote: >> >>> Thanks for this valuable information, John! >>> >>> >>> On 31/01/16 22:34, Pete Masters wrote: >>> >>> Really interesting, John.... Thanks for the post. Just conducted >>> training in DRC on data collection and base mapping. We tried to focus as >>> much as possible on offline solutions. Wish I'd read this before we'd been, >>> not just after! ;) >>> >>> Pete >>> On 31 Jan 2016 20:35, "john whelan" < <[email protected]> >>> [email protected]> wrote: >>> >>>> I've been playing around with Serval software on Android. Ideally it >>>> needs a wifi mesh set up using multiple firmware modified TP-Link MR3020 >>>> portable routers with custom software connected to a small radio device >>>> which turns it into a mesh extender. >>>> >>>> The original concept was to turn the smartphone into a router but the >>>> latest Android software well anything above 2.2 denies access to do this. >>>> Besides which rooting the phone in this manner is not good from the >>>> security point of view. >>>> >>>> However if you are running Windows 10 and your Laptop supports it, most >>>> should, you can turn your laptop into a wifi hot spot that other devices >>>> can connect to. Note you should not need to be connected to the Internet >>>> for this to work. >>>> >>>> Translation Android smartphones running Serval within say 100 meters of >>>> the laptop can now talk to each other. I haven't tried a phone call, I >>>> don't have two Smartphones to hand, but messaging certainly works. >>>> >>>> You should also be able to transfer files certainly from one smartphone >>>> to another and if Serval doesn't support file transfer to the host laptop >>>> there are other apps around that do. So things like the latest maps for >>>> Osmand etc can be brought down once to the laptop then propagated out to >>>> smartphones or a smartphone sent by mail, mule etc to the wifi hub can then >>>> connect and distribute files etc. >>>> >>>> I haven't looked at the implications of interconnecting laptops perhaps >>>> with cat 5 cables and although phone calls should be fine across one wifi >>>> hub theoretically each hub used in the hops adds a small delay so voice >>>> quality over multiple hops may not be ideal. >>>> >>>> Cheerio John >>>> >>>> _______________________________________________ >>>> HOT mailing list >>>> [email protected] >>>> https://lists.openstreetmap.org/listinfo/hot >>>> >>>> >>> >>> _______________________________________________ >>> HOT mailing >>> [email protected]https://lists.openstreetmap.org/listinfo/hot >>> >>> >>> >>> _______________________________________________ >>> HOT mailing list >>> [email protected] >>> https://lists.openstreetmap.org/listinfo/hot >>> >>> >> >> >> -- >> Mhairi O'Hara >> Mobile: +62 822 4701 1475 >> Email: [email protected] >> twitter <https://twitter.com/mataharimhairi> | linkedin >> <http://uk.linkedin.com/in/mhairiohara> | facebook >> <https://www.facebook.com/hotosm> | website <http://hotosm.org/> >> >> *Humanitarian OpenStreetMap Team * >> *Using OpenStreetMap for Humanitarian Response & Economic Development* >> > >
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