[AusNOG] Bandwidth in Phillip Island

Fri May 4 12:19:30 EST 2012

That 193km link truly blows my mind.

My only experience with links over water is one we have near our office from
a transmission site at a high point to a property low near the water.

We have only ever been able to get this to work using 2.4GHz however this
still suffers a lot of change in its signal depending on the tide and
reflections it gets.

Thank you for sharing your thoughts Scott. Not being an RF engineer but
having to manage IP networks with wireless links I am always interested in
learning more.

Regards,

Alex Maclaren
Network Operations Analyst
Cirrus Communications Pty Ltd 

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1300 552 698

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1300 556 790

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alex.maclaren at cirruscomms.com.au

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New Signiture

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From: Scott Rowlandson [mailto:srowlandson at vertel.com.au] 
Sent: Friday, 4 May 2012 11:27 AM
To: Mike Everest; Alex Maclaren; ausnog at lists.ausnog.net
Subject: RE: [AusNOG] Bandwidth in Phillip Island

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-microwave
-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

E: srowlandson at vertel.com.au | W:  <http://www.vertel.com.au/>
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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

f|: 

1300 556 790

e|: 

alex.maclaren at cirruscomms.com.au

w|: 

http://www.cirruscomms.com.au/

New Signiture

This is an e-mail from Cirrus Communications Pty Ltd. It is confidential to
the named addressee and may contain copyright and/or legally privileged
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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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