[OLSR-users] OLSRd configuration with multiple channels

[Jose Ildefonso Camargo Tolosa]

John Gorkos wrote:

>>Cool.  One more question on this: I plan to implement that like this:
>>
>>Card1--"out1"--+                     +--"out1"--Antenna1
>>               +-single LMR400 cable-+
>>Card2--"out2"--+                     +--"out2"--Antenna2
>>
>>Sorry about the poor ascii art :( .  In that graph there are two
>>splitters, one acting as a mixer, and the other splitting.  Will that
>>work? (I have never done anything like that).  Each of the antennas will
>>be about 120º apart (they are 14º panels).  There may be a third antenna
>>for "local" coverage.  well, I'll not redact all of that again, here is
>>the question I asked in another group (still no answer from them, and I
>>want to double check this).
>>    
>>
>You will wind up with two dead radios within seconds of applying power.
>  
>

:-S

>The signal will follow the path of least resistance, which will basically come 
>out of one radio, bypass the splitter, and fire straight into your other 
>  
>

Well, I know that.

>radio.  Replace LMR-cable with steel tubing and Card1 and Card2 with Gun1 and 
>Gun2, and pull the trigger.  The bullet will not go where you want it to.  On 
>the other side, you don't want to use a splitter like that for your antennas, 
>either.  The antenna's are designed to provide a 50 ohm impedance to the 
>transmitter.  the splitter will monkey up that impedance and cause your SWR 
>to rise at your transmitter.  There are ways to do impedance matching with a 
>splitter, but they are beyond the scope of this discussion.. :)
>  
>

Well, I'm not planning to use a tube preciselly (ie, a T connector, at 
least that's what I think :-S ).  I plan to use these:

http://www.hyperlinktech.com/web/signal_splitters_2400_2way.php

Wich I think that do impedance matching, but I'm not sure on 
that........ If only I had high frequency impedance checking equipment I 
could do the test, but I have not that equipment. :(

I could also build a impedance transformer..... wait.... no, I can't, I 
don't have the tools nor the materials, nor the skills to do such a 
thing :( .

>>Also, what would happend If I have, say, one panel and one omni
>>antenna (the omni in the "back" and over the omni, at least one feet
>>above (30cm)), I assume that they will see each other, but.... will
>>there be any "bizzare" interference like a feedback, something like a
>>"reflection". The panel and the omni will be horizontally polarized
>>
>>Well, the omni will be there only if I can build those slotted
>>waveguide omnis :-S (I want to build the 8 slots per side version,
>>wich I think that will have enough vertical beam width (can anybody
>>confirm this?)), does anybody knows another horizontal or circular
>>polarized omni?, with at least 7dBi gain and a beamwith of at least
>>15º (adding the up and down, ie, 7.5º up, 7.5º down, something like that).
>>
>>    
>>
>ok, I give up.  you are trying to do some bizarre stuff here with your radios.  
>Slotted waveguide antennas are simple to design and mercilessly tricky to 
>build.  your best bet is to use a CNC milling machine.  a dremel tool and a 
>yardstick will yield nothing but frustration.
>  
>

I'll describe it quite simple: I have to build a wireless network that 
covers a whole city (in order to have "movile" nodes), and I didn't 
wanted to put A LOT of radios all over the place, but I would also to 
have some sort of "redundancy", and wanted to use OLSR.

Anyway, that's how all of this started:  I just disigned to have two 
repeaters, one at one moutain (at NW), and the other at other moutain 
(at SE) in order to get redundacy; I wanted to use OLSR because I had 
not to worry that much about routes, and the protocol would "act" in 
case that one of the repeaters died.  There are three nodes wich doesn't 
see both of the repeaters, and I can connect them to other node wich 
have visual to both, and then I have redundacy.

Now, the other part: I though about using two or more directional 
antennas, but then sombody suggested: "It would be nice if we just put 
more nodes in the city, and we have the other repeaters for redundacy on 
the more important ones".  I personally think it is a waste of money 
(well, it will be fun), but they got a point: there will be more than 
two "movile" stations, in fact, they would like to have LapTop/PDAs 
connected anywhere in the city.  That's why I need the omnis, and I want 
them to have horizontal polarization, because I read that they have 
better performance in urban areas (and are better matched for laptop 
computers).  But this far the only horizontal polarized omni is the 
slotted wave guide, wich is rather hard to build (no, I don't have a 
CNC, but I have a friend who is building one, maybe I can ask him to do 
the try), but I don't want to go though all the work if I don't know 
whether the 16 slots omni waveguide (8 per side) will give me the 
necessary vertical beamwidth (about 15º).  I'm also considereing 
circular polarization, because have good match for horizontal an 
vertical polarized

Once again, thanks for your help, all this info have been very usefull.

Sincerely,

Ildefonso Camargo