Equations to calculate range?

Hi,

I actually found a use for a clear LOS shot, so started giving it some
consideration. I am unclear as to what equation that can be used to
predict (to an extent) range? From googling, I've found many of them --
which all yields different results.

I'm trying to "baseline" what is possible, starting with the upper range
antennas that are approachable (cost-wise). Two 32 dBi parabolics would run
me just over $500, which is about high as I'd be wanting to invest.

Its unclear to me how to calculate and predict (to an extent, of course),
what "real world" expectations could be.

The shot would 802.11a (5Ghz) and for simplicity lets assume that it is a
completetly clear LOS shot with absolutetly no obstacles and in clear
weather with no (or very little) RFI.

Is it possible to calculate a ball park figure for range, given:

Transmit power before hitting the antennenas: 18 dBm (63 mW, 802.11a, 5Ghz)

Antennas: parabolic on both ends, giving 32 dBi gain each

Receive sensitivity: -73 dBm to -84 dBm (It could lower, but this range,
based on specs, should yield acceptable data rates)

Thanks!

(Or, should I say, thanks in advance, Jeff!) :^)

"Eric" <(E-Mail Removed)> wrote in message
newsj%Vf.60493$(E-Mail Removed). ..
> Hi,
>
> I actually found a use for a clear LOS shot, so started giving it some
> consideration. I am unclear as to what equation that can be used to
> predict (to an extent) range? From googling, I've found many of them --
> which all yields different results.
>
> I'm trying to "baseline" what is possible, starting with the upper range
> antennas that are approachable (cost-wise). Two 32 dBi parabolics would
run
> me just over $500, which is about high as I'd be wanting to invest.
>
> Its unclear to me how to calculate and predict (to an extent, of course),
> what "real world" expectations could be.
>
> The shot would 802.11a (5Ghz) and for simplicity lets assume that it is a
> completetly clear LOS shot with absolutetly no obstacles and in clear
> weather with no (or very little) RFI.
>
> Is it possible to calculate a ball park figure for range, given:
>
> Transmit power before hitting the antennenas: 18 dBm (63 mW, 802.11a,
5Ghz)
>
> Antennas: parabolic on both ends, giving 32 dBi gain each
>
> Receive sensitivity: -73 dBm to -84 dBm (It could lower, but this range,
> based on specs, should yield acceptable data rates)
>
> Thanks!
>
> (Or, should I say, thanks in advance, Jeff!) :^)

Oh, these this was the antenna I was eyeballing:

http://www.fab-corp.com/product.php?...cat=268&page=1

(I'd get two, of course.)

In article <pj%Vf.60493$(E-Mail Removed)>,
Eric <(E-Mail Removed)> wrote:
>Hi,
>
>I actually found a use for a clear LOS shot, so started giving it some
>consideration. I am unclear as to what equation that can be used to
>predict (to an extent) range? From googling, I've found many of them --
>which all yields different results.
>
>I'm trying to "baseline" what is possible, starting with the upper range
>antennas that are approachable (cost-wise). Two 32 dBi parabolics would run
>me just over $500, which is about high as I'd be wanting to invest.
>
>Its unclear to me how to calculate and predict (to an extent, of course),
>what "real world" expectations could be.
>
>The shot would 802.11a (5Ghz) and for simplicity lets assume that it is a
>completetly clear LOS shot with absolutetly no obstacles and in clear
>weather with no (or very little) RFI.
>
>Is it possible to calculate a ball park figure for range, given:
>
>Transmit power before hitting the antennenas: 18 dBm (63 mW, 802.11a, 5Ghz)
>
>Antennas: parabolic on both ends, giving 32 dBi gain each
>
>Receive sensitivity: -73 dBm to -84 dBm (It could lower, but this range,
>based on specs, should yield acceptable data rates)
>
>Thanks!
>
>(Or, should I say, thanks in advance, Jeff!) :^)
>
>
>
>
>


The Ham Radio folks know how to do this and there are charts in one of
the handbooks. If youir numbers are sccurate you get genuine results.


Google for "pass loss calculation". There are all sorts of
solutions. SOme may work for you.


--
a d y k e s @ p a n i x . c o m

Don't blame me. I voted for Gore.

On Tue, 28 Mar 2006 00:20:37 GMT, "Eric" <(E-Mail Removed)> wrote:

>(Or, should I say, thanks in advance, Jeff!) :^)

No way today. Billing, taxes, one crisis, and a evening antenna
project in the rain.

Start here:
| http://en.wikibooks.org/wiki/FAQ_for...k_Calculations
There are at least a dozen posting in the last few months where I've
walked someone through the link calculations. Any one of these can be
used as an example:
| http://groups.google.com/groups?q=fa...2006&safe=off&
Give it a try, post your calcs, and I'll check your work (later).


--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558 (E-Mail Removed)
# http://802.11junk.com (E-Mail Removed)
# http://www.LearnByDestroying.com AE6KS

"Jeff Liebermann" <(E-Mail Removed)> wrote in message
news(E-Mail Removed)...
> On Tue, 28 Mar 2006 00:20:37 GMT, "Eric" <(E-Mail Removed)> wrote:
>
> >(Or, should I say, thanks in advance, Jeff!) :^)
>
> No way today. Billing, taxes, one crisis, and a evening antenna
> project in the rain.
>
> Start here:
> |
http://en.wikibooks.org/wiki/FAQ_for...k_Calculations
> There are at least a dozen posting in the last few months where I've
> walked someone through the link calculations. Any one of these can be
> used as an example:
> |
http://groups.google.com/groups?q=fa...2006&safe=off&
> Give it a try, post your calcs, and I'll check your work (later).
>
>
> --
> # Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
> # 831-336-2558 (E-Mail Removed)
> # http://802.11junk.com (E-Mail Removed)
> # http://www.LearnByDestroying.com AE6KS

Thanks. <Kicking myself for overlooking Wiki. Duh!>

You got me pointed in the right direction.

I definetly will read everything, starting off there. I'm planning on
weather-proofing and mounting the AP's as close to the antennas as possible,
hopefully right on right on their "support structures", to minimize
cable-loss as much as possible.

Wow, don't know if I'm doing the numbers completetly correct yet (I will be
familiarizing myself), but some playing around is showing that 32 dBi gain
gives much more range than I thought. I would guessing like maybe a mile
and a half. LOL

"Al Dykes" <(E-Mail Removed)> wrote in message
news:e0a06o$8uk$(E-Mail Removed)...
> In article <pj%Vf.60493$(E-Mail Removed)>,
> Eric <(E-Mail Removed)> wrote:
> >Hi,
> >
> >I actually found a use for a clear LOS shot, so started giving it some
> >consideration. I am unclear as to what equation that can be used to
> >predict (to an extent) range? From googling, I've found many of them --
> >which all yields different results.
> >
> >I'm trying to "baseline" what is possible, starting with the upper range
> >antennas that are approachable (cost-wise). Two 32 dBi parabolics would
run
> >me just over $500, which is about high as I'd be wanting to invest.
> >
> >Its unclear to me how to calculate and predict (to an extent, of course),
> >what "real world" expectations could be.
> >
> >The shot would 802.11a (5Ghz) and for simplicity lets assume that it is a
> >completetly clear LOS shot with absolutetly no obstacles and in clear
> >weather with no (or very little) RFI.
> >
> >Is it possible to calculate a ball park figure for range, given:
> >
> >Transmit power before hitting the antennenas: 18 dBm (63 mW, 802.11a,
5Ghz)
> >
> >Antennas: parabolic on both ends, giving 32 dBi gain each
> >
> >Receive sensitivity: -73 dBm to -84 dBm (It could lower, but this range,
> >based on specs, should yield acceptable data rates)
> >
> >Thanks!
> >
> >(Or, should I say, thanks in advance, Jeff!) :^)
> >
> >
> >
> >
> >
>
>
> The Ham Radio folks know how to do this and there are charts in one of
> the handbooks. If youir numbers are sccurate you get genuine results.
>
>
> Google for "pass loss calculation". There are all sorts of
> solutions. SOme may work for you.
>
>
> --
> a d y k e s @ p a n i x . c o m
>
> Don't blame me. I voted for Gore.

Thanks, I'll google that and lurk around Ham radio sites as well!

"Eric" <(E-Mail Removed)> wrote in message
news:UK1Wf.60569$(E-Mail Removed). ..
>
> "Jeff Liebermann" <(E-Mail Removed)> wrote in message
> news(E-Mail Removed)...
> > On Tue, 28 Mar 2006 00:20:37 GMT, "Eric" <(E-Mail Removed)> wrote:
> >
> > >(Or, should I say, thanks in advance, Jeff!) :^)
> >
> > No way today. Billing, taxes, one crisis, and a evening antenna
> > project in the rain.
> >
> > Start here:
> > |
>
http://en.wikibooks.org/wiki/FAQ_for...k_Calculations
> > There are at least a dozen posting in the last few months where I've
> > walked someone through the link calculations. Any one of these can be
> > used as an example:
> > |
>
http://groups.google.com/groups?q=fa...2006&safe=off&
> > Give it a try, post your calcs, and I'll check your work (later).
> >
> >
> > --
> > # Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
> > # 831-336-2558 (E-Mail Removed)
> > # http://802.11junk.com (E-Mail Removed)
> > # http://www.LearnByDestroying.com AE6KS
>
> Thanks. <Kicking myself for overlooking Wiki. Duh!>
>
> You got me pointed in the right direction.
>
> I definetly will read everything, starting off there. I'm planning on
> weather-proofing and mounting the AP's as close to the antennas as
possible,
> hopefully right on right on their "support structures", to minimize
> cable-loss as much as possible.
>
> Wow, don't know if I'm doing the numbers completetly correct yet (I will
be
> familiarizing myself), but some playing around is showing that 32 dBi gain
> gives much more range than I thought. I was guessing like maybe a mile
> and a half. LOL

Oh, pretty cool too, springboard'd from there to a site that calculates
azimuth/elevations based on two Lat/Longs. Didn't even think about that.
That'll give me an excuse to finally do something worthwhile with my GPS.
:^)

On Tue, 28 Mar 2006 03:14:41 GMT, "Eric" <(E-Mail Removed)> wrote:

>Oh, pretty cool too, springboard'd from there to a site that calculates
>azimuth/elevations based on two Lat/Longs. Didn't even think about that.
>That'll give me an excuse to finally do something worthwhile with my GPS.

I use a map, SA Topo! program, Delorme Street Atlas, Topozone, Google
Earth, or anything else that gives Lat-Long. There are lots of web
sites that will calculate distance:
http://www.wcrl.ars.usda.gov/cec/java/lat-long.htm
http://www2.nau.edu/~cvm/latlongdist.html
http://www.movable-type.co.uk/scripts/LatLong.html
That's the easy part.

Next, you get to calculate the Fresnel Zone clearance to make sure
there's nothing in the way. Minimum is 0.8 times the Fresnel Zone
clearance. I suggest downloading and doing battle with Radio Mobile:
http://www.cplus.org/rmw/english1.html
To do the point to point freznel zone calcs, see:
http://pizon.org/rmw/ptp.html
Be sure to use the SRTM maps and NOT the DEM/DTEM maps. This is a bit
of a learning curve, but methinks well worth it. The nice part is
that it's free.

Incidentally, I don't think you're going to like the 32dBi 5.7GHz dish
antennas. The solid dish is about 3 ft across and weighs about 25lbs.
The fiberglass radome doubles the weight. Add another 5-10 lbs in
brackets. It took two of us on the tower to muscle it into place.
Alignment was successfully accomplished after removing the feed and
shooting a green laser through the feed mount.
http://www.pacwireless.com/products/...ish_5ghz.shtml
The antenna is not counterbalanced and will require a rather
substantial mounting pipe.



--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558 (E-Mail Removed)
# http://802.11junk.com (E-Mail Removed)
# http://www.LearnByDestroying.com AE6KS

Eric wrote:

> Wow, don't know if I'm doing the numbers completetly correct yet (I will
> be familiarizing myself), but some playing around is showing that 32 dBi
> gain
> gives much more range than I thought. I would guessing like maybe a mile
> and a half. LOL

I don't know the numbers, but based on my own experience and Jeff's "6dBi
doubles the range" I'd have to guess that's achievable. Remember though
that the Fresnel zone is quite wide at that range. You need not just line
of site, but no obstacles in the Fresnel zone.
--
derek