[HOT] Smartphones using wifi in the field If you ain't in the field or techie ignore this post.
jwhelan0112 at gmail.com
Wed Feb 3 16:54:53 UTC 2016
Oh one last thing, there is a difference between a very small network and
one that gets a bit bigger.
talks about some of the design considerations and note that more hops mean
slight delays which isn't so good for voice.
On 3 February 2016 at 11:16, john whelan <jwhelan0112 at gmail.com> 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
> 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 <mhairi.ohara at hotosm.org>
>> 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
>> On Wed, Feb 3, 2016 at 3:00 PM, Katja Ulbert <mail at katja-ulbert.de>
>>> 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! ;)
>>> On 31 Jan 2016 20:35, "john whelan" < <jwhelan0112 at gmail.com>
>>> jwhelan0112 at gmail.com> 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
>>>> HOT at openstreetmap.org
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