[AusNOG] Bandwidth in Phillip Island

Fri May 4 11:26:41 EST 2012

Morning all, I have a bit to add on this topic as general education but
everyone has been pretty accurate so far.

What is said below is correct, 5.4/5.8 will stretch 10's of kilometres
with the proper dishes, we have one going 40-50Kms in 5.4. Mike just
spoke on that while I was typing.

5.4/5.8Ghz is hardly effected by rain fading. 15/18/20/32/80Ghz are all
very much effected by rain but this can be designed out with the proper
fade margin. So is a laser link (laser is pretty much the same frequency
as light so if you can see through a rain storm you can't get a laser
through it). 

Ref: http://happy.emu.id.au/lab/rep/rep/9510/picspace/fig24.gif

Reflections off the water surface can be accommodated for and designed
out, most programs like pathloss allow you to do ray tracing based on
different tidal heights, fog layers etc. You can then do things like
moving the dish out of the worst point of reflection (by blocking the
path to the water) or using spatial/frequency diversity. 

If you are interested Aviat networks recently deployed the worlds
longest over water microwave link. 

http://blog.aviatnetworks.com/2011/05/04/the-worlds-longest-all-ip-micro
wave-link/

For a serious 70Kms over water link would require a 7.5/8Ghz link with
big dishes very high towers/mountains and spatial diversity but the
license with the ACMA for that alone is $9000 a year. 

So you can try with the ubiquiti's, I would suggest getting a microwave
engineer to design the link or at least learn to use something like
radio mobile http://www.cplus.org/rmw/english1.html and design it
yourself but again you will need big towers to get around the earth
curvature at that distance. 

Regards,

Scott Rowlandson

Senior Network Engineer

T: 02 8399 7718 | M: 0434 317 153 | F: 02 9699 0077

A: 15-17 William Street, Alexandria NSW 2015

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From: ausnog-bounces at lists.ausnog.net
[mailto:ausnog-bounces at lists.ausnog.net] On Behalf Of Mike Everest
Sent: Friday, 4 May 2012 11:05 AM
To: 'Alex Maclaren'; ausnog at lists.ausnog.net
Subject: Re: [AusNOG] Bandwidth in Phillip Island

Good morning Alex, all,

Actually, my comments about exceeding limits was in response to the
mention of nanostation product in the original post :-}  I have seen way
too many examples of people installing gear that has fixed antenna and
then turning up the tx power to max to get 'better speeds' on the
resulting links. The same goes for other vendor models, e.g. MikroTik,
that it is easy to configure them to operate beyond the regulatory
limits.  

I'm sorry if my comments were interpreted as meaning that 5GHz links
can't be used for longer distances - to the contrary: 5GHz is a great
way to achieve good speeds over distance so long as it is used with
care! :-)

When transmitters with tx capability of 30dBm connected to 30dBi
antennas, it is sometimes far too tempting to just 'turn it up a bit'
;-) 

The article linked in that same post documented a 50Km link using 5.8GHz
has EIRP at about 58 dB - that's, what, about 250x our regulatory limit
:-D

I think that a discussion about power output limits is always relevant
when talking about microwave data links :)

Cheers!

Mike Everest.

Shop.duxtel.com.au

From: ausnog-bounces at lists.ausnog.net [
mailto:ausnog-bounces at lists.ausnog.net] On Behalf Of Alex Maclaren
Sent: Friday, 4 May 2012 9:46 AM
To: 'Craig Askings'; ausnog at lists.ausnog.net
Subject: Re: [AusNOG] Bandwidth in Phillip Island

I beg to differ of all this discussion about the EIRP limits in
Australia meaning wireless link distances can only be 2-3km.

We have many links of over 15km operating at legal limits.

It is just a matter of having enough gain on your dishes.

For instance, if you have two BulletM5 radios and 27dbi grid dishes,
over 10km operating in the 5.4GHz range, your theoretical signal is
-72dBm.

This would be more than enough signal to achieve full modulation on the
link.

Regards,

Alex Maclaren
Network Operations Analyst
Cirrus Communications Pty Ltd 

t|: 

1300 552 698

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1300 556 790

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alex.maclaren at cirruscomms.com.au

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From: ausnog-bounces at lists.ausnog.net [
mailto:ausnog-bounces at lists.ausnog.net] On Behalf Of Craig Askings
Sent: Thursday, 3 May 2012 9:07 PM
To: ausnog at lists.ausnog.net
Subject: Re: [AusNOG] Bandwidth in Phillip Island

Don't expect more than a couple of kms at the class licence EIRP limits
that have been set for Australia.

On 3/05/2012 9:03 PM, Martin Hepworth wrote: 

Uniquiti's AirFiber http://www.ubnt.com/airfiber could be an option.

-- 
Martin Hepworth
Oxford, UK

On 3 May 2012 09:31, Mike Everest <ausnog at duxtel.com> wrote:

> Ubiquiti Nanostation/Bullets can easily get upto 15Kms without issues.
TCO
> is in the hundreds.

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