What's the most accurate elevation tool on the net (freebie)
What's the most accurate elevation tool on the net (freebie). Discuss What's the most accurate elevation tool on the net (freebie), on Wireless Forums.
What's the most accurate elevation tool on the net (freebie)
What elevation tool do you use and how does it compare in accuracy?
I'm trying to do some antenna siting calculations ... and ... for
that ... I need elevation information.
However ... given any set of coordinates ... e.g., Mt Hamilton,
California at coordinates 37.337408,-121.644073 ... I find the following
elevation tools all give DIFFERENT elevations (some are off by more than
a hundred feet!)
Re: What's the most accurate elevation tool on the net (freebie)
Unless you are dealing with a surveyed peak, I would assume all the
elevation data is derived from USGS NEDs (national elevation dataset).
For the most part, they are only 1/3 arc second. I'm speculating that
some of these programs are reporting data from the NEDs as if they are
section of flat areas on the 1/3 arc second grid, while others are
interpreting the elevation using a weighting scheme.
> http://seamless.usgs.gov/
Have you considered running SPLAT! ? It uses 1/3 arc second data. It can
predict line of sight. Generally I find I do better than the SPLAT!
prediction, so if SPLAT! says no, the answer is maybe, but if SPLAT!
says yes, you have line of sight. The program has hooks for predicting
signal strength, models knife edge diffraction, etc.
> http://www.qsl.net/kd2bd/splat.html
For pure line of sight, there is GRASS. However GRASS has a very steep
learning curve.
> http://grass.osgeo.org/
What takes maybe 5 minutes on SPAT can take 2 days on GRASS. I don't
know if the results are that much better.
For the bay area, I suspect SPLAT! is fine. I think it's shortcomings
are in areas where there is really rugged terrain that probably isn't
modeled well.
Re: What's the most accurate elevation tool on the net (freebie)
On Sat, 3 Mar 2012 04:02:49 +0000 (UTC), alpha male
<alphamale@nowherenohow.com> wrote:
>What elevation tool do you use and how does it compare in accuracy?
>
>I'm trying to do some antenna siting calculations ... and ... for
>that ... I need elevation information.
>
>However ... given any set of coordinates ... e.g., Mt Hamilton,
>California at coordinates 37.337408,-121.644073 ... I find the following
>elevation tools all give DIFFERENT elevations (some are off by more than
>a hundred feet!)
>
>1. Google Map API yields 1217.061889648438 meters (3992.985 feet)
>http://maps.googleapis.com/maps/api/elevation/json?
>locations=37.337408,-121.644073&sensor=false
>
>2. Geoplaner yields 1217.1 meters (3993 feet)
>http://www.geoplaner.com
>
>2. Daftlogic yields 1230.988 meters (4038.676 feet)
>http://www.daftlogic.com/sandbox-goo...d-altitude.htm
>
>4. Earthtools yields 1210 meters (3969.8 feet)
>http://www.earthtools.org
>
>5. Heywhatsthat (SRTM db) yields 1213 meters (3980 feet)
>http://www.heywhatsthat.com/profiler-0904.html
>
>Q: Which elevation tool do you use ... & what's the accuracy?
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.
Re: What's the most accurate elevation tool on the net (freebie)
On Sat, 03 Mar 2012 04:02:49 +0000, alpha male wrote:
> What elevation tool do you use and how does it compare in accuracy?
>
> I'm trying to do some antenna siting calculations ... and ... for that
> ... I need elevation information.
>
> However ... given any set of coordinates ... e.g., Mt Hamilton,
> California at coordinates 37.337408,-121.644073 ... I find the following
> elevation tools all give DIFFERENT elevations (some are off by more than
> a hundred feet!)
>
> 1. Google Map API yields 1217.061889648438 meters (3992.985 feet)
> http://maps.googleapis.com/maps/api/elevation/json?
> locations=37.337408,-121.644073&sensor=false
>
> 2. Geoplaner yields 1217.1 meters (3993 feet) http://www.geoplaner.com
>
> 2. Daftlogic yields 1230.988 meters (4038.676 feet)
> http://www.daftlogic.com/sandbox-goo...d-altitude.htm
>
> 4. Earthtools yields 1210 meters (3969.8 feet) http://www.earthtools.org
>
> 5. Heywhatsthat (SRTM db) yields 1213 meters (3980 feet)
> http://www.heywhatsthat.com/profiler-0904.html
>
> Q: Which elevation tool do you use ... & what's the accuracy?
I'd use the info from another licensee's application, (on the same
tower). With the FCC you also must specify which survey you are using.
All towers over 200'(AIR) have their own entry in a tower database.
Re: What's the most accurate elevation tool on the net (freebie)
On Sat, 03 Mar 2012 00:10:32 -0800, miso wrote:
> Have you considered running SPLAT!
I just installed the Splat (Surface Path Length And Terrain) RF analysis
application (version 1.3.0-1) from the default Ubuntu Software Center.
- http://joysofprogramming.com/install-splat-ubuntu/
- $ sudo apt-get install splat (dpkg -s splat)
It's apparently a command-line tool which needs me to download the
database so it may take a while to figure out.
Googling for a "splat!" tutorial, I find it's also a photoshop hack so
it's actually hard to figure out how to use it on the fly.
Q: Do you have a working example or two for how to use it from the
command line?
Quote:
$ splat --help
*** ERROR: No transmitter site(s) specified!
$ splat
--==[ SPLAT! v1.3.0 Available Options... ]==--
-t txsite(s).qth (max of 4 with -c, max of 30 with -L)
-r rxsite.qth
-c plot coverage of TX(s) with an RX antenna at X feet/meters AGL
-L plot path loss map of TX based on an RX at X feet/meters AGL
-s filename(s) of city/site file(s) to import (5 max)
-b filename(s) of cartographic boundary file(s) to import (5 max)
-p filename of terrain profile graph to plot
-e filename of terrain elevation graph to plot
-h filename of terrain height graph to plot
-H filename of normalized terrain height graph to plot
-l filename of path loss graph to plot
-o filename of topographic map to generate (.ppm)
-u filename of user-defined terrain file to import
-d sdf file directory path (overrides path in ~/.splat_path file)
-m earth radius multiplier
-n do not plot LOS paths in .ppm maps
-N do not produce unnecessary site or obstruction reports
-f frequency for Fresnel zone calculation (MHz)
-R modify default range for -c or -L (miles/kilometers)
-db threshold beyond which contours will not be displayed
-nf do not plot Fresnel zones in height plots
-fz Fresnel zone clearance percentage (default = 60)
-gc ground clutter height (feet/meters)
-ngs display greyscale topography as white in .ppm files
-erp override ERP in .lrp file (Watts)
-ano name of alphanumeric output file
-ani name of alphanumeric input file
-udt name of user defined terrain input file
-kml generate Google Earth (.kml) compatible output
-geo generate an Xastir .geo georeference file (with .ppm output)
-dbm plot signal power level contours rather than field strength
-gpsav preserve gnuplot temporary working files after SPLAT! execution
-metric employ metric rather than imperial units for all user I/O
If that flew by too fast, consider piping the output through 'less':
splat | less
Type 'man splat', or see the documentation for more details.
This compilation of SPLAT! supports analysis over a region of
8 square degrees of terrain.
Re: What's the most accurate elevation tool on the net (freebie)
In rec.radio.amateur.antenna alpha male <alphamale@nowherenohow.com> wrote:
> What elevation tool do you use and how does it compare in accuracy?
>
> I'm trying to do some antenna siting calculations ... and ... for
> that ... I need elevation information.
>
> However ... given any set of coordinates ... e.g., Mt Hamilton,
> California at coordinates 37.337408,-121.644073 ... I find the following
> elevation tools all give DIFFERENT elevations (some are off by more than
> a hundred feet!)
>
> 1. Google Map API yields 1217.061889648438 meters (3992.985 feet)
> http://maps.googleapis.com/maps/api/elevation/json?
> locations=37.337408,-121.644073&sensor=false
>
> 2. Geoplaner yields 1217.1 meters (3993 feet)
> http://www.geoplaner.com
>
> 2. Daftlogic yields 1230.988 meters (4038.676 feet)
> http://www.daftlogic.com/sandbox-goo...d-altitude.htm
>
> 4. Earthtools yields 1210 meters (3969.8 feet)
> http://www.earthtools.org
>
> 5. Heywhatsthat (SRTM db) yields 1213 meters (3980 feet)
> http://www.heywhatsthat.com/profiler-0904.html
>
> Q: Which elevation tool do you use ... & what's the accuracy?
Re: What's the most accurate elevation tool on the net (freebie)
On 3/3/2012 7:59 AM, alpha male wrote:
> On Sat, 03 Mar 2012 00:10:32 -0800, miso wrote:
>> Have you considered running SPLAT!
>
> I just installed the Splat (Surface Path Length And Terrain) RF analysis
> application (version 1.3.0-1) from the default Ubuntu Software Center.
> - http://joysofprogramming.com/install-splat-ubuntu/
> - $ sudo apt-get install splat (dpkg -s splat)
>
> It's apparently a command-line tool which needs me to download the
> database so it may take a while to figure out.
>
> Googling for a "splat!" tutorial, I find it's also a photoshop hack so
> it's actually hard to figure out how to use it on the fly.
>
> Q: Do you have a working example or two for how to use it from the
> command line?
>
>
Quote:
> $ splat --help
>
> *** ERROR: No transmitter site(s) specified!
>
> $ splat
>
> --==[ SPLAT! v1.3.0 Available Options... ]==--
>
> -t txsite(s).qth (max of 4 with -c, max of 30 with -L)
> -r rxsite.qth
> -c plot coverage of TX(s) with an RX antenna at X feet/meters AGL
> -L plot path loss map of TX based on an RX at X feet/meters AGL
> -s filename(s) of city/site file(s) to import (5 max)
> -b filename(s) of cartographic boundary file(s) to import (5 max)
> -p filename of terrain profile graph to plot
> -e filename of terrain elevation graph to plot
> -h filename of terrain height graph to plot
> -H filename of normalized terrain height graph to plot
> -l filename of path loss graph to plot
> -o filename of topographic map to generate (.ppm)
> -u filename of user-defined terrain file to import
> -d sdf file directory path (overrides path in ~/.splat_path file)
> -m earth radius multiplier
> -n do not plot LOS paths in .ppm maps
> -N do not produce unnecessary site or obstruction reports
> -f frequency for Fresnel zone calculation (MHz)
> -R modify default range for -c or -L (miles/kilometers)
> -db threshold beyond which contours will not be displayed
> -nf do not plot Fresnel zones in height plots
> -fz Fresnel zone clearance percentage (default = 60)
> -gc ground clutter height (feet/meters)
> -ngs display greyscale topography as white in .ppm files
> -erp override ERP in .lrp file (Watts)
> -ano name of alphanumeric output file
> -ani name of alphanumeric input file
> -udt name of user defined terrain input file
> -kml generate Google Earth (.kml) compatible output
> -geo generate an Xastir .geo georeference file (with .ppm output)
> -dbm plot signal power level contours rather than field strength
> -gpsav preserve gnuplot temporary working files after SPLAT! execution
> -metric employ metric rather than imperial units for all user I/O
>
> If that flew by too fast, consider piping the output through 'less':
>
> splat | less
>
> Type 'man splat', or see the documentation for more details.
>
> This compilation of SPLAT! supports analysis over a region of
> 8 square degrees of terrain.
>
SPLAT! isn't a photoshop hack, but you can use gimp (or I suppose
photoshop) to hack with the png files it creates. I take the png files
and chop them up so they are acceptable to google earth, then make an
overlay out of them. Splat can do it, but unless things have changed, it
makes a kml file that can be too large for GE to accept. GE wants tiled
imagery. I haven't run it in maybe 18 months, so I can't really say much
without setting it up again.
I saw a GPS mentioned. I never found GPS elevation to be too accurate. I
have a barometer in my GPS. I never used it, so I can't vouch for it's
accuracy. But you can enter in the pressure from the airport, or
calibrate it to a known reference (known altitude for a position).
Note that sometimes these markers are on private property. Other times
they are in the middle of the street! it pays to look at the reference
on google earth before trying to use it. My Garmin gps60cs was good to
4ft, basically one lsb.
You could get a nearby reference, call the barometer, then quickly move
to your spot before the pressure changes. Or you might get lucky and
find there is a marker there already.
Topo maps have lines of constant altitude, usually on 20ft contours. You
could interpolate from the map.
If you really need accurate data, just pay for a survey. I would guess
something that simple is under a grand. I've paid for land surveys and
they are a few grand, but the altitude at one point is pretty simple.
Potentially the civil engineering firm might have topo data on file that
is not available to the general public. For instance, I paid for a
satellite topo to be done on some property. The civil engineering firm
has it on file and I'm sure it gets peeked at by other people.
Re: What's the most accurate elevation tool on the net (freebie)
On Sat, 03 Mar 2012 09:13:45 +0100, Helmut Wabnig <hwabnig@.- ---
-.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 are:
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?
Re: What's the most accurate elevation tool on the net (freebie)
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.
Interesting quotes from that helpful reference (with my comments in
parenthesis).
"In the Continental United States the difference between WGS 84 and NAD
27 can be as much as 200 meters." (I wonder how they handle the constant
creep which occurs out here near the San Andreas fault line).
"Every map that shows a geographic coordinate system such as UTM or
Latitude and Longitude with any precision will also list the datum used
on the map." (I'd change "will" to 'should' based on my experience the
past two weeks on the web)
"The Global Positioning System uses an earth centered datum called the
World Geodetic System 1984 or WGS 84." (That's what I prefer.)
"For all practical purposes there is no difference between WGS 84 and NAD
83." (Good to know.)
"On a USGS topographic map ... The datum will always be NAD 27... A
dashed cross in the SW and NE corners of the map gives a visual
indication of the difference between the two datums." (This is good to
know.)
"If you are engaged in a mission that requires more [than several hundred
meters] precision, then your datums should match." (Since we're siting
antennas on private hilly land, we probably want two or three meters
accuracy in position and a half-meter to a meter in elevation accuracy so
our datums must match.)
Re: What's the most accurate elevation tool on the net (freebie)
On Mon, 05 Mar 2012 15:30:57 +0000, alpha male wrote:
> On Sat, 03 Mar 2012 19:43:47 -0800, Jeff Liebermann wrote:
> (I wonder how they handle the constant
> creep which occurs out here near the San Andreas fault line).
What I mean by that is that it's a right-slip fault, and it moves by
centimeters to inches each year (sometimes in feet to yards, both in
elevation and in position) ... but ... how do they know if the west side
moved north or if the east side moved south?
I wonder what they use for their frame of reference since it depends on
which side of the fault you're on if you want to say the west moved north
or that the east moved south.
Re: What's the most accurate elevation tool on the net (freebie)
On Mon, 5 Mar 2012 15:09:40 +0000 (UTC), alpha male
<alphamale@nowherenohow.com> 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?
This is an interesting antenna HAAT (Height Above Average Terrain)
program ... but I'm not quite sure what use it is because it gives a 360
degree average height ... but most 2.4Ghz antennas I'm dealing with are
directional.
You enter the latitude, longitude, & height of the antenna, and then it
tells you, for example, for 360 degrees, the average antenna height above
ground for 2 to 10 miles along each radial, the result of which can go
negative.
The output is a text file. It's interesting, but, without graphics, I'm
not sure how to use the results properly when just going point to point.
Re: What's the most accurate elevation tool on the net (freebie)
On Mon, 5 Mar 2012 19:46:16 +0000 (UTC), alpha male
<alphamale@nowherenohow.com> wrote:
>On Sat, 03 Mar 2012 19:43:47 -0800, Jeff Liebermann wrote:
>
>> <http://transition.fcc.gov/mb/audio/bickel/haat_calculator.html>
>
>This is an interesting antenna HAAT (Height Above Average Terrain)
>program ... but I'm not quite sure what use it is because it gives a 360
>degree average height ... but most 2.4Ghz antennas I'm dealing with are
>directional.
>
>You enter the latitude, longitude, & height of the antenna, and then it
>tells you, for example, for 360 degrees, the average antenna height above
>ground for 2 to 10 miles along each radial, the result of which can go
>negative.
I wrote that before you disclosed what you were trying to accomplish.
Had your intent to obtain accurate altitude readings been for the
purpose of applying for an FCC station license, you would have needed
the HAAT calculations to estimate coverage area. For building you
mesh network, you don't need HAAT calculations.
<http://en.wikipedia.org/wiki/HAAT>
The first paragraph should explain what HAAT means.
>The output is a text file. It's interesting, but, without graphics, I'm
>not sure how to use the results properly when just going point to point.
Hint: You can always take a table of number and create a graph or
graphic. Going the other direction is not so easy. Most propagation
and antenna design software generates an output table (text file),
from which a graphic is later generated.
Re: What's the most accurate elevation tool on the net (freebie)
On 3/5/2012 8:26 AM, Jeff Liebermann wrote:
> On Mon, 5 Mar 2012 15:09:40 +0000 (UTC), alpha male
> <alphamale@nowherenohow.com> 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.
Re: What's the most accurate elevation tool on the net (freebie)
On Tue, 06 Mar 2012 01:24:06 -0800, miso <miso@sushi.com> 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.
Re: What's the most accurate elevation tool on the net (freebie)
On Tue, 6 Mar 2012 19:13:12 +0000 (UTC), alpha male
<alphamale@nowherenohow.com> 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.
Re: What's the most accurate elevation tool on the net (freebie)
> 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.
Re: What's the most accurate elevation tool on the net (freebie)
> 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.
>
>
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.
Re: What's the most accurate elevation tool on the net (freebie)
On Tue, 06 Mar 2012 19:14:32 -0800, miso <miso@sushi.com> 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.
Re: What's the most accurate elevation tool on the net (freebie)
On Tue, 06 Mar 2012 19:52:36 -0800, Jeff Liebermann <jeffl@cruzio.com>
wrote:
>On Tue, 06 Mar 2012 19:14:32 -0800, miso <miso@sushi.com> wrote:
>>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.
Looks like the balloon trackers have the same problem with Radio
Mobile Deluxe.
<http://showcase.netins.net/web/wallio/RMD.html>
"The 2000x2000 software elevation matrix limits paths to
2000km for 1000m data (30-arc second), 200km for 100m
data (3-arc second) and 130km for 30m data (1-arc second)."
Re: What's the most accurate elevation tool on the net (freebie)
>
> It is a simple click to change the step size even down to 0.01 of a
> degree in the polar plot, or just run a Cartesian plot where you can
> specify down to one pixel resolution.
>
> Jeff
Yes. I'm just mentioning cranking down the angle to save someone a few
meaningless runs. It didn't occur to me to do the math as you suggested,
but it makes perfect sense.
I was running the beta version of splat-hd. I could do 6 degree x 6
degrees at 1/3 arc second. Each degree is 3600x3600, so I could do
21600x21600. If you want to do "mountain-topping", you need that kind of
span.
Looking at the overlays I generated, I had to hack the output into 12 to
20 blocks, 3600x3600 at a time, to make it google earth compatible.
Hopefully the new version does this automatically.
I believe this was the program I was trying to get to work to do the
cookie cutting. Looking at the bug report, it still looks like it has
issues.
> http://www.maptiler.org/
I got really good with GIMP to do the cookie cutting. Still a PITA.
What's the most accurate elevation tool on the net (freebie) 
Linear Mode
