UmTRX Digest, Vol 4, Issue 35

Alexander Chemeris alexander.chemeris at gmail.com
Sun Oct 28 21:20:04 UTC 2012


On Sun, Oct 28, 2012 at 11:31 PM, Darby <darbysgoodies at gmail.com> wrote:
> On Sun, Oct 28, 2012 at 12:26 PM, Alexander Chemeris
> <alexander.chemeris at gmail.com> wrote:
>> On Sun, Oct 28, 2012 at 10:08 PM, Darby <darbysgoodies at gmail.com> wrote:
>>> On a side note, for power -Something that could come in useful since
>>> its got ethernet, PoE?
>>
>> PoE is an option, but UmTRX require too much power for the standard
>> PoE and we think that for lab usage PoE is an overkill.
>>
> Whats the total power budget? 802.3AF should be kosher with 13w at the
> device, 802.3AT (PoE+) should be good up to a little over 20w
>
> Im with you on the lab piece, Im just thinking of a seemingly
> ubiquitous power source in a industrial environment -I bring this up
> since so many industrial Wifi AP's (Gateworks, JJPlus, etc.) are PoE
> powered

According to our latest measurements, UmTRX alone requires ~15W:
https://code.google.com/p/umtrx/wiki/UmTRXv2_Power

If you add UmSEL, it will add few Watts as well, but it should be
below 20W I think. So PoE+ may be an option for a UmTRX without an
external PA.

When we discussed internally, we discarded embedded PoE for a couple of reasons:
 1. We focused on medium-range cells which would need an external PA.
And in this case we're out of PoE power range. In case of a pico-cell
output power (50-200mW) we could do with PoE.
 2. We decided that for the first iteration we'd better focus on more
important issues and use an external PoE adapter if needed.
 3. PoE by default has 58VDC output. We replaced all capacitors to
tantalum ones and IIRC there was a concern that increasing input
voltage range to 48VDC may considerably add to the BOM cost. This is
according to my memories - I hope Andrey Sviyazov could correct me if
I'm wrong.

Taking all this into account, I think we might consider adding PoE
option in some later version, but it's not a focus for us now. If
someone wants to help us in adding this feature - please go ahead.
It's an open-source project after all.

>>>> 2. Enclosure. We'd love to have a nice table-top enclosure for UmTRX,
>>>> but it requires a significant effort to source, design and assemble.
>>>
>>> If anyone has some preexisting case designs, there's always protocase
>>> (protocase.com) or Rapid sheet metal
>>> (http://www.rapidsheetmetal.com/parts/enclosures.aspx) -Im sure theres
>>> plenty of other sheetmetal fabshops that will do custom work though,
>>> If youre wanting to use something a bit more generic -Theres
>>> enclosurehub.com
>>
>> Interesting. Do you know similar ones in Europe? We manufacture in
>> France and shipping enclosures from US doesn't look like a good idea.
>>
>
> Not that Im aware of, I know of protocase since they did the backblaze
> storage pods & you can order anything from them in individual piece
> quantities -But thats not to say that there arent plenty of others
> that offer the same services, I would imagine there would be a fair
> amount of places in europe that will do sheet metal enclosures -If you
> want something extruded though, they might have a MoQ to make the cost
> of the die fabrication feasible...?

With 15W-20W power consumption Andrey Sviyazov is worried that a sheet
metal enclosure might not be enough. I'm still inclined to give it a
try for a lab enclosure, though.

That said, we don't have manpower to do this right now. I estimate
this as at least a week of work and thus as I mentioned - if someone
is willing to make a design, we're ready to assist by all means.

-- 
Regards,
Alexander Chemeris.
CEO, Fairwaves LLC / ООО УмРадио
http://fairwaves.ru




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