[MLB-WIRELESS] New Node to be

[Paul James]

Hi,

Are you really getting 1.2M BYTES/s = 9.6M BITS/s or did you mean to say
1.2 M bits/s?

I have a number of links running with the WRT54GS and get about 2M
bits/s over an 8.6km link using 24dBi Grids at each end.

If you are getting 1.2M Bytes over 10Km I would love to know more
details.

Regards,

Paul

-----Original Message-----
From: melbwireless-bounces at wireless.org.au
[mailto:melbwireless-bounces at wireless.org.au] On Behalf Of Ratbaggy
Sent: Thursday, 18 May 2006 6:04 PM
To: melbwireless at wireless.org.au
Subject: Re: [MLB-WIRELESS] New Node to be


Hi David,

The Sparklan radios that we have in the hop between Templestowe Lower
and 
Kangaroo Ground draw 200 mA at 12.5V (2.5 Watts).  A WRT54G draws 250 mA
at 
12.5V (3.1 Watts).  The R100 draws 800 mA at 5V (4 Watts) but also seems
to 
run OK at 4 volts for the same current consumption and a 20% reduction
in 
power to 3.2 Watts.

The power consumption does go up a bit when you load them up with
traffic.

The Sparklans are basically a WRT54G minus the 5 port switch with half
the 
flash memory but happily run the Freifunk flavour of OpenWRT.  We have
these 
sorted out pretty well now and they run 1.2 Megabytes/Second real
throughput 
on our 10 km link.

I feel fairly confident that we can take our pick of the above units.
We 
may get away with another radio and that would be a bonus.

For example, with a Sparklan and a WRT54G we are at 0.45 Amp for a total
of 
10.8 A/H per day, definitely worth a try.   ...and with a fully charged 
battery, 18 days of backup from the 200 A/H batteries!

With a Maximum Power Point switchmode regulator (expensive) you can get 
almost all of the available energy from a solar panel because it matches
the 
impedance of the panel to that of the battery in effect converting the
18 V 
at 4.4 A to 13 V at 6 A although on a small installation for the cost of
one 
of these babies it is probably cheaper to buy a second panel.

Dave.

----- Original Message ----- 
From: "David Ashburner" <d_ashburner at hotmail.com>
To: <melbwireless at wireless.org.au>
Sent: Thursday, May 18, 2006 12:52 PM
Subject: Re: [MLB-WIRELESS] New Node to be


> >
>> * Mark (IKD ILW etc.) has offered to purchase an 80 watt solar panel 
>> and
>> construct the power system.
>> We'll monitor the performance over the first weeks to see exactly how

>> much more solar capacity is required.
>> * A pair of 12V 100A/H battery have been purchased.
>>
>
> how much power is an interesting issue.  I look forward to see how 
> much
> you can get out of the panel.
>
> I'm assuming you are going to run the routers/radios from the 
> batteries,
> they will be up 24 x 7
> they probably draw less then the 1 amp the plug pack is rated at but
it 
> makes a good first pass estimating figure.
>
> 2 units x 1 amp x 24 hours = 48 Ah per day so your batteries could run

> the
> system for 4 days without sun. But it's the problem of not recovering
full 
> charge over a period of time that is going to be the hard one.
>
> 80 watt panel at say 18 volts gives you  4.4 amps for something like a

> max
> of 6 hours in VIC so you have a max of 2.4 amps charging for 6 hours =
14 
> Ah
> The battery will have to provide  48 - 12 = 36 Ah
> I'm thinking you are going to go into deficit . Of course the AP's
will 
> probably draw a lot less than 1 amp each so it might do it.
>
> One other thought is if the site is only for relaying data ( no AP
> access ) you could run one radio in WDS mode and configure a WDS link
at 
> either end. It would halve the available throughput but use half the 
> power.
>
>
>
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