[MLB-WIRELESS] Melbwireless Digest, Vol 37, Issue 12
Mike Everest (KBN)
mw at freenet.net.au
Fri Oct 31 21:58:33 EST 2008
Hello 'King' ;-)
That's 61.63Km from here. What do you have there that is transmitting, and
what ssid? I'll be fossicking around for a high gain antenna this weekend
and see if I can hear anything from your direction....
Regards, Mike.
> -----Original Message-----
> From: melbwireless-bounces at wireless.org.au
> [mailto:melbwireless-bounces at wireless.org.au] On Behalf Of
> The King of Foxes
> Sent: Friday, 31 October 2008 5:17 PM
> To: melbwireless at wireless.org.au
> Subject: Re: [MLB-WIRELESS] Melbwireless Digest, Vol 37, Issue 12
>
> my node, JTQ, has a good LOS to point cook and a possible LOS
> to JEE with a 3m mast. im situated on the bay down in beaumaris.
>
> On Fri, Oct 31, 2008 at 12:00 PM,
> <melbwireless-request at wireless.org.au> wrote:
> > Send Melbwireless mailing list submissions to
> > melbwireless at wireless.org.au
> >
> > To subscribe or unsubscribe via the World Wide Web, visit
> > http://wireless.org.au/mailman/listinfo/melbwireless
> > or, via email, send a message with subject or body 'help' to
> > melbwireless-request at wireless.org.au
> >
> > You can reach the person managing the list at
> > melbwireless-owner at wireless.org.au
> >
> > When replying, please edit your Subject line so it is more specific
> > than "Re: Contents of Melbwireless digest..."
> >
> >
> > Today's Topics:
> >
> > 1. Long distance links (mw at freenet.net.au)
> > 2. Re: Long distance links (mw at freenet.net.au)
> > 3. Re: Long distance links (Ben Balbo)
> >
> >
> >
> ----------------------------------------------------------------------
> >
> > Message: 1
> > Date: Thu, 30 Oct 2008 22:26:32 +1100
> > From: <mw at freenet.net.au>
> > Subject: [MLB-WIRELESS] Long distance links
> > To: <melbwireless at wireless.org.au>
> > Message-ID: <0CE5BA63CBF543608C4920F3BA1EE90A at viewbankrise.net.au>
> > Content-Type: text/plain; charset="us-ascii"
> >
> > Hi Folks,
> >
> > I have been thinking about how to set up a second
> Geelong<->Melbourne
> > link, and have considered a few options.
> >
> > One idea is to set up a half-way point somewhere, and I found a
> > prospective spot in portarlington that looked very good. I
> have this
> > kit (like I brought to the last meeting) made up of Mikrotik
> > Crossroads
> > (http://shop.duxtel.com.au/product_info.php?products_id=45) and
> > commTenna
> > (http://shop.duxtel.com.au/product_info.php?products_id=46)
> which from
> > my loungeroom window, I could connect to the hotspot service at the
> > caravan park at Portarlington foreshore. I have a friend
> whi lives a
> > few blocks away, and the lay of the land looked perfect to
> get a bead
> > on my place back the other way.
> >
> > Unfortunately I was defeated by trees (!) and my buddy there isn't
> > willing to set up a pole on his roof, so I'm back to square 1.
> >
> > So I'm still on the lookout for some intermediary location - if
> > there's anyone with a look over the bay to geelong (check
> out node KBN
> > http://www.melbournewireless.org.au/maps/view?id=KBN) I'd
> like to hear
> > from you.
> >
> > For distances greater than about 25Km, I have a plan that
> should work
> > well and still keep us insidethe legal transmission limits too.
> >
> > As you all know, I'm sure, we can't go over 36dB EIRP (4W)
> so with a
> > 600mW radio, and maybe a cable loss of 2, we can only use a
> antenna:
> > 28dBm radio
> > - 2dBi cable loss + 10dBi antenna = 36 (and a 400mW radio will need
> > 12dBi antenna, right?)
> >
> > Now according to my calculations, if we have a receive
> sensitivity of
> > -93 at the other end of a transmitter running at max
> output, then we
> > can only get about 25Km before we run out of signal. If we
> wanted to
> > go 50Km, then we need a receiver with an antenna gain of up
> around the
> > 24dBi mark, which, of course, ends up producing 46dB EIRP on the
> > transmit cycle - oops, over limit!
> >
> > Ok, so I'm telling you what you already know I s'pose, so
> I'll get to
> > the point! ;-)
> >
> > These Mikrotik devices that I use are able to use the two antenna
> > connections to transmit on one and receive on the other.
> That means
> > that if the receive antenna is connected to a 24dBi grid
> antenna and
> > the transmit antenna has just a 12dBi panel or something, then we
> > should be able to get a nice solid long distance link
> happening, and
> > keep within the legal limits no probs!
> >
> > Now, there's also the other issue that affects stability of a
> > Melb-Geelong link, and that's the bay. Most of you
> probably also know
> > that when shooting over water, relfections from the surface
> can end up
> > causing interference on the direct transmissions,
> especially when the
> > path between the two antennas is exactly a half wavelength
> longer (or
> > 1.5, 2.5, ... etc) than the reflected path - thus
> cancelling out the signal waveforms.
> >
> > So you probably also know that two antennas set up the
> right distance
> > apart will help overcome this effect using the default diversity
> > switch mode, but if we use the above technique to have two antennas
> > with different gains, then we run into EIRP limit troubles again.
> >
> > There *is* a solution! ;-)
> >
> > Once again, the Mikrotik systems come to the rescue with a special
> > 'Nstreme Dual' mode. In this mode, a router with two
> radios installed
> > can be set up to transmit on one radio and receive on the
> other. The
> > usual benefit of this technique is to get a full duplex radio link,
> > but the other cool benefit is that we can also use dual high gain
> > antennas on the receive circuit for diversity, and one (or
> two) lower gain antennas on the transmit.
> >
> > Sound cool? I sure think so :-)
> >
> > So anyone interested in some experimentation? I'm quite
> keen to give
> > it a go, and I'll even help you out by offering some of
> this gear at
> > or below cost. If you're game, let me know - on or off
> list is fine
> > by me :)
> >
> > Cheers!
> >
> >
> >
> > ------------------------------
> >
> > Message: 2
> > Date: Thu, 30 Oct 2008 22:50:31 +1100
> > From: <mw at freenet.net.au>
> > Subject: Re: [MLB-WIRELESS] Long distance links
> > To: <melbwireless at wireless.org.au>
> > Message-ID: <D1DD05101D0E4E42BE1B4A882A3F87E7 at viewbankrise.net.au>
> > Content-Type: text/plain; charset="us-ascii"
> >
> > Just wanted to clarify a couple of points after reading that over
> > again :-}
> >
> > It's not ME that has the 'other' melb-geelog link, of
> course, but it
> > kinda looks like I'm suggesting that in the first sentence
> ;-) That's
> > Peter's link, and how it is set up: I have no idea (but I'd like to
> > talk about
> > it!:-)
> >
> > Secondly, that's 100Km in my discussion about the 24dBi
> antenna, not 50Km!
> >
> > Cheers!
> >
> >> -----Original Message-----
> >> From: melbwireless-bounces at wireless.org.au
> >> [mailto:melbwireless-bounces at wireless.org.au] On Behalf Of
> >> mw at freenet.net.au
> >> Sent: Thursday, 30 October 2008 10:27 PM
> >> To: melbwireless at wireless.org.au
> >> Subject: [MLB-WIRELESS] Long distance links
> >>
> >> Hi Folks,
> >>
> >> I have been thinking about how to set up a second
> Geelong<->Melbourne
> >> link, and have considered a few options.
> >>
> >> One idea is to set up a half-way point somewhere, and I found a
> >> prospective spot in portarlington that looked very good.
> I have this
> >> kit (like I brought to the last meeting) made up of Mikrotik
> >> Crossroads
> >> (http://shop.duxtel.com.au/product_info.php?products_id=45)
> >> and commTenna
> >> (http://shop.duxtel.com.au/product_info.php?products_id=46)
> >> which from my loungeroom window, I could connect to the hotspot
> >> service at the caravan park at Portarlington foreshore. I have a
> >> friend whi lives a few blocks away, and the lay of the land looked
> >> perfect to get a bead on my place back the other way.
> >>
> >> Unfortunately I was defeated by trees (!) and my buddy there isn't
> >> willing to set up a pole on his roof, so I'm back to square 1.
> >>
> >> So I'm still on the lookout for some intermediary location - if
> >> there's anyone with a look over the bay to geelong (check out node
> >> KBN
> >> http://www.melbournewireless.org.au/maps/view?id=KBN) I'd like to
> >> hear from you.
> >>
> >> For distances greater than about 25Km, I have a plan that
> should work
> >> well and still keep us insidethe legal transmission limits too.
> >>
> >> As you all know, I'm sure, we can't go over 36dB EIRP (4W)
> so with a
> >> 600mW radio, and maybe a cable loss of 2, we can only use
> a antenna:
> >> 28dBm radio
> >> - 2dBi cable loss + 10dBi antenna = 36 (and a 400mW radio
> will need
> >> 12dBi antenna, right?)
> >>
> >> Now according to my calculations, if we have a receive
> sensitivity of
> >> -93 at the other end of a transmitter running at max
> output, then we
> >> can only get about 25Km before we run out of signal. If
> we wanted to
> >> go 50Km, then we need a receiver with an antenna gain of up around
> >> the 24dBi mark, which, of course, ends up producing 46dB
> EIRP on the
> >> transmit cycle - oops, over limit!
> >>
> >> Ok, so I'm telling you what you already know I s'pose, so
> I'll get to
> >> the point! ;-)
> >>
> >> These Mikrotik devices that I use are able to use the two antenna
> >> connections to transmit on one and receive on the other.
> That means
> >> that if the receive antenna is connected to a 24dBi grid
> antenna and
> >> the transmit antenna has just a 12dBi panel or something, then we
> >> should be able to get a nice solid long distance link
> happening, and
> >> keep within the legal limits no probs!
> >>
> >> Now, there's also the other issue that affects stability of a
> >> Melb-Geelong link, and that's the bay. Most of you probably also
> >> know that when shooting over water, relfections from the
> surface can
> >> end up causing interference on the direct transmissions,
> especially
> >> when the path between the two antennas is exactly a half
> wavelength
> >> longer (or 1.5, 2.5, ... etc) than the reflected path - thus
> >> cancelling out the signal waveforms.
> >>
> >> So you probably also know that two antennas set up the
> right distance
> >> apart will help overcome this effect using the default diversity
> >> switch mode, but if we use the above technique to have two
> antennas
> >> with different gains, then we run into EIRP limit troubles again.
> >>
> >> There *is* a solution! ;-)
> >>
> >> Once again, the Mikrotik systems come to the rescue with a special
> >> 'Nstreme Dual' mode. In this mode, a router with two radios
> >> installed can be set up to transmit on one radio and
> receive on the
> >> other. The usual benefit of this technique is to get a
> full duplex
> >> radio link, but the other cool benefit is that we can also
> use dual
> >> high gain antennas on the receive circuit for diversity,
> and one (or
> >> two) lower gain antennas on the transmit.
> >>
> >> Sound cool? I sure think so :-)
> >>
> >> So anyone interested in some experimentation? I'm quite
> keen to give
> >> it a go, and I'll even help you out by offering some of
> this gear at
> >> or below cost. If you're game, let me know - on or off
> list is fine
> >> by me :)
> >>
> >> Cheers!
> >>
> >> _______________________________________________
> >> Melbwireless mailing list
> >> Melbwireless at wireless.org.au
> >> http://wireless.org.au/mailman/listinfo/melbwireless
> >>
> >
> >
> >
> > ------------------------------
> >
> > Message: 3
> > Date: Fri, 31 Oct 2008 01:25:01 +1100
> > From: Ben Balbo <ben at benbalbo.com>
> > Subject: Re: [MLB-WIRELESS] Long distance links
> > To: mike at viewbankrise.net.au
> > Cc: melbwireless at wireless.org.au
> > Message-ID: <4909C3BD.8040702 at benbalbo.com>
> > Content-Type: text/plain; charset="iso-8859-1"
> >
> > Hi!
> >
> >> Unfortunately I was defeated by trees (!) and my buddy there isn't
> >> willing to set up a pole on his roof, so I'm back to square 1.
> >
> > Whereabouts in Portarlington? I have a place there and am hoping to
> > get a friend on Langdon St, between Fisher and Brown,
> involved as he's
> > higher up than I am. Alternatively, I'd be happy to whack a pole on
> > our place (subject to council blah blah) on the corner of
> Batman and Willis.
> >
> > BB
> >
> > -------------- next part -------------- A non-text attachment was
> > scrubbed...
> > Name: signature.asc
> > Type: application/pgp-signature
> > Size: 260 bytes
> > Desc: OpenPGP digital signature
> > Url :
> >
> http://wireless.org.au/pipermail/melbwireless/attachments/20081031/fef
> > 09ff4/attachment-0001.bin
> >
> > ------------------------------
> >
> > _______________________________________________
> > Melbwireless mailing list
> > Melbwireless at wireless.org.au
> > http://wireless.org.au/mailman/listinfo/melbwireless
> >
> >
> > End of Melbwireless Digest, Vol 37, Issue 12
> > ********************************************
> >
> _______________________________________________
> Melbwireless mailing list
> Melbwireless at wireless.org.au
> http://wireless.org.au/mailman/listinfo/melbwireless
>
More information about the Melbwireless
mailing list