On Sat, 03 Mar 2012 09:13:45 +0100, Helmut Wabnig [email protected] ---
-.dotat wrote:

Youre asking wrong questions.
First define a surface with height ZERO as a reference.
There are about 100 different definitions alone for that.
Distance from Earth center, median sea level at Novosibirsk,
or a San Francisco? Water isn't level, it follows gravitation.
And so on.

w.

If in the US, I would assume that the LAT/LONG uses either WGS84,
NAD27, or NAD83 datums. That reduces the number of available options.

Unfortunately, the USGS is still hanging onto NAD27, while most
mapping programs and displays are on WGS84.
http://www.maptools.com/UsingUTM/mapdatum.html
In the People's Republic of Santa Cruz, the error is about 20 meters
east-west, and about 1 meter north-south. I forgot which way. The
problem becomes really bad when trying to locate a mountain top.
20-200 meters of horizontal error can easily move a position from the
peak, to somewhere on the slope, resulting in large altitude errors.

SRTM and SRTM2 are another oddity. They were created from the space
shuttle, using a radar altimeter. Depending on the whether it's
looking at buildings or trees, there's no really good way to determine
of the indicated altitude is the top of a 100ft redwood tree, the top
of a 10 meter high building, or at ground level.

So, my list of rhetorical questions a
1. What is the OP trying to accomplish? If for an FCC license HAAT
calculation, almost any reasonable guess will suffice.
http://transition.fcc.gov/mb/audio/bickel/haat_calculator.html
If for doing Radio-Mobile coverage contours, you'll need to use the
built in mapping tool to find the peak or exact location on the
mountain top. The choice of application depends on what one is
attempting to accomplish.
2. What level of accuracy is really required? The original position
of 37.337408N -121.644073W is specified to 1 millionth of a degree, or
about 0.09 meters.
http://www.csgnetwork.com/degreelenllavcalc.html
It would be interesting to know where this highly accurate number came
from. Better GPS receivers, without DGPS, can do 3 meters accuracy.
3. What datum are you using? I suggest WGS84. If the lookup tool
offers a choice of datums, pick one and stay with it.
4. Are you interested in ground level, building rooftop level, or
tree top level?

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

On Sat, 03 Mar 2012 19:43:47 -0800, Jeff Liebermann wrote:
What is the OP trying to accomplish?

The neighbors and are discussing setting up a neighborhood mesh network
and we need to ascertain, beforehand, where to place masts and which
direction to point them in our mountainous neighborhood (Skyline & Summit
area).

If for an FCC license HAAT calculation, almost any reasonable guess
will suffice.

For us, probably any reasonable answer would suffice - but why not pick
the most accurate for starters is what we're thinking.

What level of accuracy is really required?
The original position of 37.337408N -121.644073W is specified
to 1 millionth of a degree, or about 0.09 meters.

A few feet would probably work just fine for the neighborhood. We each
have acres of land, but the terrain is so rough that only a few spots for
antennas would be useful. That's why we want to choose them ahead of time.

It would be interesting to know where this highly accurate
number came from.

We didn't want to put our actual location on the net, so, we picked an
arbitrary set of numbers from one of the elevation calculators just as an
example. But we're in the roughly 37,-122 range.

What datum are you using? I suggest WGS84.

WGS84.

We have some numbers in NAD83 from the various WISP providers but they
drive us crazy since we have to imperfectly convert them to WGS84 to keep
our numbers consistent.

Are you interested in ground level, building rooftop level,
or tree top level?

All three because we want to site a dozen or more antennas which need to
have clear line of sight over rooftops and trees by at least the first
Fresnel zone.

On Mon, 5 Mar 2012 15:09:40 +0000 (UTC), alpha male
wrote:

On Sat, 03 Mar 2012 19:43:47 -0800, Jeff Liebermann wrote:
What is the OP trying to accomplish?

The neighbors and are discussing setting up a neighborhood mesh network
and we need to ascertain, beforehand, where to place masts and which
direction to point them in our mountainous neighborhood (Skyline & Summit
area).

Ok. Go thee unto:
http://www.cplus.org/rmw/english1.html
Follow the destructions at:
http://www.cplus.org/rmw/download/download.php?S=1
For maps, download the SRTM3 maps for your area from:
http://rmw.recordist.com
Do not bother with DEM, SRTM1, or other maps. Do NOT unzip the maps.
My directory shows about 600MBytes of SRTM3 data for everything for
the SF Bay and Monterey Bay areas. You can set Radio-Mobile to
automatically download a map if needed, but it's easier to just
download the maps ahead of time.

Follow a simple example such as:
http://www.cplus.org/rmw/afirst.html
to get started. There are also numerous tutorials on the web.
Note that the program uses the concept of "networks" which will be key
to modeling a mesh. Locate your nodes, use realistic values, and
build a model. This part is a PITA and requires considerable time and
effort. Draw the (optical) coverage areas for each node, and the line
of sight:
http://joelgranados.wordpress.com/2011/11/05/wireless-link-calculations-radio-mobile/

You're going to have a big problem in the Santa Cruz Mountains call
trees. These are cellulose and water obstructions that may or may not
appear at the correct altitude on the elevation profiles. 2.4GHz will
NOT penetrate foliage, especially when wet. You'll need to manually
adjust your path profiles for the tree line. If the trees are inside
the Fresnel zone, you'll have losses.

If you have problems, ask here, or preferably the Yahoo Radio-Mobile
group at:
http://groups.yahoo.com/group/Radio_Mobile_Deluxe/

I have a really bad attitude about mesh networks. Bug me if you want
to hear the full rant. For a sample, see the dismal performance of an
early mesh network (MIT Roofnet - Meraki).
http://pdos.csail.mit.edu/roofnet/doku.php?id=interesting
"Surprisingly, the performance over a two hop route is
less than 1/2 that of one hop routes, implying routes
tend to interfere with themselves."
Also:
http://sha.ddih.org/2011/11/26/why-wireless-mesh-networks-wont-save-us-from-censorship/
covers the main problems. Do you really want a phone call at 2AM from
a neighbor asking if the network is down?

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 3/5/2012 8:26 AM, Jeff Liebermann wrote:
On Mon, 5 Mar 2012 15:09:40 +0000 (UTC), alpha male
wrote:

On Sat, 03 Mar 2012 19:43:47 -0800, Jeff Liebermann wrote:
What is the OP trying to accomplish?

The neighbors and are discussing setting up a neighborhood mesh network
and we need to ascertain, beforehand, where to place masts and which
direction to point them in our mountainous neighborhood (Skyline& Summit
area).

Ok. Go thee unto:
http://www.cplus.org/rmw/english1.html
Follow the destructions at:
http://www.cplus.org/rmw/download/download.php?S=1
For maps, download the SRTM3 maps for your area from:
http://rmw.recordist.com
Do not bother with DEM, SRTM1, or other maps. Do NOT unzip the maps.
My directory shows about 600MBytes of SRTM3 data for everything for
the SF Bay and Monterey Bay areas. You can set Radio-Mobile to
automatically download a map if needed, but it's easier to just
download the maps ahead of time.

Follow a simple example such as:
http://www.cplus.org/rmw/afirst.html
to get started. There are also numerous tutorials on the web.
Note that the program uses the concept of "networks" which will be key
to modeling a mesh. Locate your nodes, use realistic values, and
build a model. This part is a PITA and requires considerable time and
effort. Draw the (optical) coverage areas for each node, and the line
of sight:
http://joelgranados.wordpress.com/2011/11/05/wireless-link-calculations-radio-mobile/

You're going to have a big problem in the Santa Cruz Mountains call
trees. These are cellulose and water obstructions that may or may not
appear at the correct altitude on the elevation profiles. 2.4GHz will
NOT penetrate foliage, especially when wet. You'll need to manually
adjust your path profiles for the tree line. If the trees are inside
the Fresnel zone, you'll have losses.

If you have problems, ask here, or preferably the Yahoo Radio-Mobile
group at:
http://groups.yahoo.com/group/Radio_Mobile_Deluxe/

I have a really bad attitude about mesh networks. Bug me if you want
to hear the full rant. For a sample, see the dismal performance of an
early mesh network (MIT Roofnet - Meraki).
http://pdos.csail.mit.edu/roofnet/doku.php?id=interesting
"Surprisingly, the performance over a two hop route is
less than 1/2 that of one hop routes, implying routes
tend to interfere with themselves."
Also:
http://sha.ddih.org/2011/11/26/why-wireless-mesh-networks-wont-save-us-from-censorship/
covers the main problems. Do you really want a phone call at 2AM from
a neighbor asking if the network is down?


I've used Radio Mobile and SPLAT!. I never got a warm and fuzzy with
Radio Mobile. Of course, it is a bit more complicated to use SPLAT!.

One obvious advantage to SPLAT! is it can analyze very large areas. Not
all that useful in the case of this wifi setup, but very useful in sigint.

On Tue, 06 Mar 2012 01:24:06 -0800, miso wrote:

On 3/5/2012 8:26 AM, Jeff Liebermann wrote:

Ok. Go thee unto:
http://www.cplus.org/rmw/english1.html
Follow the destructions at:
http://www.cplus.org/rmw/download/download.php?S=1
For maps, download the SRTM3 maps for your area from:
http://rmw.recordist.com

Oops. I meant the SRTM1 maps.
http://dds.cr.usgs.gov/srtm/version2_1/SRTM1/

I've used Radio Mobile and SPLAT!. I never got a warm and fuzzy with
Radio Mobile. Of course, it is a bit more complicated to use SPLAT!.

I've used both. Radio-Mobile has a very steep learning curve.
Important functions are buried deep into obscure menus, useless trivia
is scattered all over the menus, there's no logical sequence of
operation, and many of the terms require expertise in cartography.
Debugging errors is tricky as important items, such as the performance
characteristics of the radios, are scattered over a half dozen menu
pages. I find myself constantly referring to my cheat sheet in order
to get anything done. However, I haven't found anything else that
even comes close to what it does.

One obvious advantage to SPLAT! is it can analyze very large areas. Not
all that useful in the case of this wifi setup, but very useful in sigint.

http://www.qsl.net/kd2bd/splat.html
Splat is somewhat easier to use, but as you note, is designed to
display repeater coverage. It's less useful for close in coverage, or
showing coverage details, as in mountainous or urban jungle terrain.

Both programs put considerable effort into implementing complex
terrain models. For 2.4 and 5.7Ghz, optical line of sight is close
enough.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Oops. I meant the SRTM1 maps.
http://dds.cr.usgs.gov/srtm/version2_1/SRTM1/

I've used Radio Mobile and SPLAT!. I never got a warm and fuzzy with
Radio Mobile. Of course, it is a bit more complicated to use SPLAT!.

I've used both. Radio-Mobile has a very steep learning curve.
Important functions are buried deep into obscure menus, useless trivia
is scattered all over the menus, there's no logical sequence of
operation, and many of the terms require expertise in cartography.
Debugging errors is tricky as important items, such as the performance
characteristics of the radios, are scattered over a half dozen menu
pages. I find myself constantly referring to my cheat sheet in order
to get anything done. However, I haven't found anything else that
even comes close to what it does.

One obvious advantage to SPLAT! is it can analyze very large areas. Not
all that useful in the case of this wifi setup, but very useful in sigint.

http://www.qsl.net/kd2bd/splat.html
Splat is somewhat easier to use, but as you note, is designed to
display repeater coverage. It's less useful for close in coverage, or
showing coverage details, as in mountainous or urban jungle terrain.

Both programs put considerable effort into implementing complex
terrain models. For 2.4 and 5.7Ghz, optical line of sight is close
enough.


My recollection of Radio Mobile is you need to crank down the minimum
angle that it sweeps to get any accuracy. Like I said, I prefer SPLAT!
for the accuracy. Even so, it is only as good as the NED. However, if
SPLAT! says you can see it, then you can see it. I thought Radio Mobile
was simple to run, at least for one transmitter at a time. Far easier
than SPLAT, which requires compilation parameters to set the array size.
Radio Mobile, at least when I read it, was stuck at 3600x3600. If you
exceed that array, and note it uses a 1/3 arc second grid, the program
interpolates.

The grid is 10 meters on a size for 1/3 arc second. That means you can't
"see" more than 36km. Plenty for wifi, not so good for repeaters or even
photography.

I generally do two runs with SPLAT. First I check the altitude when the
radio is to be located. If it doesn't match the topo map, I add the
difference in altitude to the transmitter height. Then run it again.

I have a 90 mile path to analyze, so I guess I'll see what these
programs can do lately. But if Radio Mobile is stuck at 3600 pixels,
that is a show stopper.

On Tue, 06 Mar 2012 19:14:32 -0800, miso wrote:

My recollection of Radio Mobile is you need to crank down the minimum
angle that it sweeps to get any accuracy.

True. 1 degree resolution at perhaps 20km is:
tan(1deg) * 20km = 350 meters
resolution. Not great resolution, but good enough for wide area
coverage. For wi-fi, the range is much less, so the "squares" shown
on the map will be correspondingly smaller.

Samples of wide coverage area RM calcs.
http://802.11junk.com/jeffl/coverage/k6bj/
We recently moved our tower and antenna, when the building that
previously supported them was demolished. So, I recalculated the
coverage. I believe I used 1 degree resolution.

than SPLAT, which requires compilation parameters to set the array size.
Radio Mobile, at least when I read it, was stuck at 3600x3600. If you
exceed that array, and note it uses a 1/3 arc second grid, the program
interpolates.

I'm too lazy to check the numbers right now. Maybe tomorrow.
Meanwhile, this article claims that Splat is limited to 3600x3600
while Radio-Mobile is limited to 2000x2000. No clue at this time
who's correct.

I have a 90 mile path to analyze, so I guess I'll see what these
programs can do lately. But if Radio Mobile is stuck at 3600 pixels,
that is a show stopper.

A 90 mile PATH (line) is quite different from a 90 mile radius
coverage (area) radius.


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

On Mon, 05 Mar 2012 08:26:29 -0800, Jeff Liebermann wrote:

If you have problems, ask here, or preferably the Yahoo Radio-Mobile
group at:
http://groups.yahoo.com/group/Radio_Mobile_Deluxe/

The first problem I'm having is locating a Linux (Ubuntu) Radio Mobile
download ...

On Tue, 6 Mar 2012 19:13:12 +0000 (UTC), alpha male
wrote:

On Mon, 05 Mar 2012 08:26:29 -0800, Jeff Liebermann wrote:

If you have problems, ask here, or preferably the Yahoo Radio-Mobile
group at:
http://groups.yahoo.com/group/Radio_Mobile_Deluxe/

The first problem I'm having is locating a Linux (Ubuntu) Radio Mobile
download ...

Is that suppose to be some kind of thanks for doing your research?
In the future, if you need assistance, get it from someone else.

RM mostly runs under Wine:
http://radiomobile.pe1mew.nl/?How_to:Wine
The problems listed are not fatal as you can download the SRTM maps
manually, and can simply export the result as a Google Earth overlay
to obtain street map detail.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

RM mostly runs under Wine:
http://radiomobile.pe1mew.nl/?How_to:Wine
The problems listed are not fatal as you can download the SRTM maps
manually, and can simply export the result as a Google Earth overlay
to obtain street map detail.




This guy got it going. ;-)
http://forum.winehq.org/viewtopic.ph...ab4164 902614

If Alpha Male has linux, why even screw with Radio Mobile? Just run
SPLAT!. For a small array, the KML SPLAT generates should be fine for
Google Earth. My issue was the array was too big to feed GE directly.

GE has an "aperture" size that doesn't appear to be consistent between
PCs. GE expects the images to be tiled with no tile larger than the
aperture. On my PC, that is 3600x3600. That is probably why you could
load the Radio Mobile output to GE.

Incidentally, there are programs designed to take a PNG and tile it, but
I never got them to work. But it has been a while since I tried them.