27km link

coolmhz · #1 (**permalink**) 07-27-2005, 11:25 PM

I have been playing around with a 27km link over the last week it seem to work ok but the data transfer is a bit slow 12-18KB/s max <_<
What were are using is

Site one Edimax EW-7207APg runing in Ap Mode with 3 meters of RG58 Cable and a 24dBi Grid Antennas

Site two Edimax EW-7206APb runing in Client Mode with 2 feet of LMR100 Cable and a 24dBi Grid Antennas

Packets: Sent = 1000, Received = 1000, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 3ms, Maximum = 68ms, Average = 4ms

What to do next
Shorten the Cable to around 2 feet on the first unit

Noodles · #2 (**permalink**) 07-28-2005, 01:00 PM

Looks like a very noisy signal, but I guess you'd get that on a link that long

Try replacing the coax you're using with LMR400 or some other low loss cable, I don't think RG58 is very good

But congrats on actually getting a signal

Mad-Mendez · #3 (**permalink**) 07-29-2005, 04:04 AM

Quote:

Originally posted by Noodles@Jul 28 2005, 11:00 PM
Looks like a very noisy signal, but I guess you'd get that on a link that long

Try replacing the coax you're using with LMR400 or some other low loss cable, I don't think RG58 is very good

But congrats on actually getting a signal

[snapback]4819[/snapback]

I concur with noodles, every bit will help i suppose, hmmm would slapping on an amplifer make it better or not? Though that would then start getting into dicey territory with going way over EIRP wouldnt it?

Quite impressed though, and suprised that the green signal value is almost constant (very few peaks etc). The graphs of snr ive seen frm netstumbler have always been all over the place (like the noise in red).

coolmhz · #4 (**permalink**) 07-29-2005, 07:23 AM

Is it worth going out and buying 3 meters of LMR400 and two Categories and loss 0.65 dB for 3 meters or put the AP in a box on the pole and shorten the RG58 to around 2 feet and loss 0.5dB

I was thinking about putting a booster on it but with the EIRP limits it is holding me back

Does any one know if the are going do be doing the some way the USA EIRP works
here is how it works over there with Point to point links

Point to point links are also permitted with directional antenna. The maximum transmitter input to the antenna reduces by 1dB for every 3dB increase in antenna gain above 6dBi. The maximum e.i.r.p. for point to point links is summarised in the following table:
Table 3 - Summary of e.i.r.p. Allowed in USA at 2.4GHz
Transmitter output Max. Antenna gain Max. e.i.r.p.
1W 6dBi 4W
0.5W 15dBi 16W
0.25W 24dBi 63W

When I did the scan it was starting to rain

that’s way I was getting a noisy signal

Noodles · #5 (**permalink**) 07-29-2005, 02:28 PM

I wouldn't amplify if I were you, adding an amp in the mix will amplify the noise as well.

I would try using a short length of lmr400 if you can. Stay away from RG58 if possible

Check the attenuation charts: http://www.universal-radio.com/catalog/cab...perf.html#atten (lower is better)

Then try the test again when it isn't raining and see if you get a better signal/throughput.

Mad-Mendez · #6 (**permalink**) 07-30-2005, 01:34 AM

Quote:

Originally posted by Noodles@Jul 30 2005, 12:28 AM
I wouldn't amplify if I were you, adding an amp in the mix will amplify the noise as well.

I would try using a short length of lmr400 if you can.
Then try the test again when it isn't raining and see if you get a better signal/throughput.

[snapback]4822[/snapback]

Yes there is the amplifying of the noise as well as noodles has mentioned, mostly the eirp holding you back though. Damn limits...

POE should help you cut down the length of cable as much as possible, which is what youve said pretty much. In the end it does come down to money, just probably reuse the cable...
Hmm is it possible to reuse the 2 feet of lmr 100 cable? 1 foot for the first site? and the other 1 foot for the other? See that way you can save money and minimise loss in the cable.

Well, rain... over a shortish distance its bad enough, its got to be vicious over a 27 Km distance!

try it again when its not raining, id say it would make a HUGE difference.

Also im curious as to what the longest link is in New Zealand.
If you need some help maybe these guys could help? But looking at their links, youve got the longest one so far

http://www.crc.net.nz/topology.php

Congrats.

Finally, where DID you get pretty pictures like that from?? i want! i want! What software and maps did you use?

warlord · #7 (**permalink**) 07-30-2005, 06:59 AM

Quote:

Originally posted by Mad-Mendez@Jul 30 2005, 02:34 PM
Finally, where DID you get pretty pictures like that from?? i want! i want! What software and maps did you use?

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Hey there guys, Yes we have managed to up our throughput to about 30Kb/s, (Im at Site 1), The program you want for the cool mapping is called "Google Earth" download it free from Google.

Mad-Mendez · #8 (**permalink**) 07-30-2005, 09:12 AM

"google Earth" you say? Id heard about that but hadnt bothered to install it due to the lack of detailed maps like the ones for New York City and so on. Though after seeing that ill play around with it. Cheers.