[Battlemesh] FCC Contacts about Wifi Regulations

Paul Gardner-Stephen paul at servalproject.org
Fri Aug 5 13:44:32 CEST 2016


On Fri, Aug 5, 2016 at 8:59 PM, Juliusz Chroboczek <
jch at pps.univ-paris-diderot.fr> wrote:

> > In other words, the only hardware restriction is you need the serial
> port,
> > which is the case on various other routers anyway, but we make the
> serial port
> > accessible on the outside of the unit.
> Okay, that makes sense.
> > We are using DA-15 and DB-15 connectors for the power and utility (i.e.
> for
> > GPIO, and also to make USB charging ports if required) connectors, so
> that
> > people can chop up old PC joystick and VGA cables if they need to.
> That doesn't make any sense.  I have dozens of 12V power adaptors with
> a 5.5mm barrel jack, I can find one in every electronics store, in every
> toy store, and if everything else fails, I can go buy a cheap landline
> phone at my local supermarket and cannibalise the power adapter.

This is quite true.  My question then is whether it is better to require
two connectors (since we need one for this annoying regulatory issue for
getting humanitarian gear quickly through borders), or have it in one.  I
can see your point, and see advantages to it.

> On the other hand, I have no idea where my soldering iron is (I haven't
> used it in years), and I probably don't have any DA-15 connectors lying
> around.  I do have a few VGA cables with DB-15, but only at work, not at
> home, and I need them.

Understood. I agree DA-15s are harder to find these days, but that is the
cable we will be providing with the unit, with either USB tail, or solar +
battery tail, depending on model.

> > Since the intention is that Mesh Extenders will often be running from
> > solar(+ optional battery), there is already no "standard" connector that
> > we could be using.
> LiPo batteries with JST-PH connectors are available in every toy store,
> but I have no idea about LiFePO4.  I suggest you go to your local toy
> store (pick one with expensive model planes), and check what's readily
> available (as opposed to what needs to be ordered).

Yes, LiPo can work, in which case a regular USB LiPo battery pack is the
simplest solution we would aim for there I think.

The LiFePO4 specification came from some further requirements that have not
been discussed yet, in particular, around safety and longevity of the
batteries. The nuisance is we can have the easily available LiPo, or the
harder to get but perhaps better LiFePO4.  The current trade-off is to
allow any battery technology with a USB output, but give more integrated
support for the safest chemistry, for use with a solar panel.

> > We could, in theory, add a micro USB port as well [...] increase [...]
> > the size of the unit
> You're putting both a DA-15 and a DB-15 there, and you worry about the
> size of a micro-USB connector?

It is size and cost, given that it would need to be IP66 rated (it turns
out that IP66 rated DA and DB connectors are cheap and easy to get for
various strange reasons).

> > Anyway, please keep up with the feedback, as it is extremely helpful.
> With all due respect, Paul, you sound like you've already made your mind
> and are not actually willing to take our feedback into account.  Three
> people are telling you the same thing, please think about it.

It might not look like I am taking the feedback into account, but this is
not the case. I am having to juggle quite a number of conflicting
requirements, and am genuinely looking for the best solutions that still
meet the requirements as best as possible.  Even if I can't change the
specifications enough this time around, I am taking all these points on
board for future design cycles.  In particular, thinking about the best way
to manage the power side of things.

It has also been good to work through the way that we are managing the
blasted spectrum regulatory/political problems, and while I think we all
agree that the ideal world would be different, that our current plan of
approach is not going to cause big problems for third-party firmware.
Also, the realisation that we can supply non-firmware-locking cables for
those markets that don't require it (probably most other than the USA), is
a refinement that I had not previously thought of, and is a tangible change
that I am implementing.


> -- Juliusz
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> Battlemesh at ml.ninux.org
> http://ml.ninux.org/mailman/listinfo/battlemesh
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