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Best nodes for 'portable infrastructure' deployment

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Best nodes for 'portable infrastructure' deployment

For the last several years our local ARES group has supported a 100km race in the mountains south of our town.  We have dabbled with 2GHz AREDN but haven't really done anything serious with it yet.  For this year's race, we'd like to establish an AREDN net from town to the races operations center 9 miles away.  This would involve one 5 MHz path between a mountain close to town where we have an existing 2GHz node (pointed the wrong way), to a TEMPORARY battery operated mountain top node.  And from that latter site, a 2 GHz link down to the operations center a few thousand feet away.

We haven't used 5 GHz before, but from what I gather, that is important when you are going to have more than one node at a site.  So, the question is what is the most suitable nodes to use for this 5 GHz link.  Since we have to hike into the one site, minimizing the size and weight of what we are carrying is helpful (mind you we already have to carry the 35AH battery). 

I was thinking a pair of XW nanostations (one 2GHz and one 5 GHz) would work well at that site (and another 5GHz nano at the other end of the path).  If my calculations are correct, it should have the gain to make the 9 miles. The beam width is wide enough that we should be able to point it pretty easily.  And it is pretty light and small.  And if I'm understanding how the DtD part works on these, that would mean we'd simply power both nanostations off of their respective primary NICs, and we tie the two secondary NICs to each other for the DtD.  So no need for carrying up an Ethernet switch or other hardware (or powering it).  So... basically we just need the two nanostations, the battery, appropriate cables, and a mast to support them that won't blow over in the wind.

Does that sound right?  Any argument for alternatives such as the nanobeam (even lighter and smaller)... or the higher gain (but harder to point?) and heavier nanobridge or powerbeam?  Any significant differences between these in regards to battery consumption?  I presume they'll all work off of 12VDC?




This all seems like it would work. The only thing I would probably do is get a PowerBeam M5-300 for the non-mountain side to better guarantee a strong link. Same price, a tilting mount to point up to the mountain, just as portable as a nanostation, plus you'd have more options for the next event. A nanostation on the mountain would be good and allow for more than one node to connect from various angles if needed. They are basically 55 degree sectors. Give em some downtilt if possible.

It will all run from 12V at the node. How many hours is the event? No significant differences in current draw.

Thanks.  I thought about the

Thanks.  I thought about the PowerBeam M5-300 for the reasons you described.  My only concern was that in my group, I'm the only one with experience pointing microwave dishes (40 years in broadcast TV).  I was wondering how much trouble novices would have pointing a narrow beam width antenna.  Perhaps I'm overthinking it.  A few dB extra margin certainly isn't going to hurt though.

The event goes from Noon Friday until @10pm Saturday... so about 34 hours.  But we'd set up the mountain top site earlier on Friday, so that is over 36 hours of run time for two nodes.  If my math is right, we're talking about something like 18Ah, but offhand I don't remember what the lowest battery voltage is when they say a battery is rated for 35Ah. Do you think a 35Ah battery will see us through?



As long as you have a laptop nearby, the dish can be peaked with the realtime SNR chart page very easily. The beam isn't that tight. It should only take 5 minutes, including a couple minutes of letting it "settle", where it usually improves on its own.

The last measurements I did saw 3-4W from each of those models at idle. It does jump around. 2x 4W at 12V for 36hours is 24Ah (67% discharge of 35Ah). That's 11V or so and unpredictable under load. Supposedly the nodes will run down to 10V but that's putting a real hurt on the battery and assumes it will provide what it says. If you're moving voice or video or anything continous the load will probably go up. It's a slow enough draw where it "might" work, but I would be far more comfortable with a 2nd battery. You don't want it crashing on the last kilometer. Alternatively, a 10W 12V solar panel could boost it just enough for the event duration. No controller needed with this load, just parallel it.


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