I would like to simulate the strength of a signal emitted from an antenna and received by a receiver.
As a first approach r.los gives a good start. Anyway, more accurate results could be obtained by taking obstruction in the first Fresnel Zone into account. Finally, having a way to calculate the impact on indirect paths/reflections, should lead to a reasonably accurate signal strength map.
Did anybody work on some of these issues, possibly in combination with GRASS? Is there a good starting point for the calculation of the obstruction within the first Fresnel Zone. And the reflections?
I would like to simulate the strength of a signal emitted from an antenna and received by a receiver.
As a first approach r.los gives a good start. Anyway, more accurate results could be obtained by taking obstruction in the first Fresnel Zone into account. Finally, having a way to calculate the impact on indirect paths/reflections, should lead to a reasonably accurate signal strength map.
Did anybody work on some of these issues, possibly in combination with GRASS? Is there a good starting point for the calculation of the obstruction within the first Fresnel Zone.
I don't really understand what you are speaking about (i.e. am completely incompetent in this field), but would v.net.visibility be something for you ?
On Thu, Apr 17, 2008 at 12:05 PM, Peter Hopfgartner
<peter.hopfgartner@r3-gis.com> wrote:
Dear GRASS community,
I would like to simulate the strength of a signal emitted from an antenna
and received by a receiver.
As a first approach r.los gives a good start. Anyway, more accurate results
could be obtained by taking obstruction in the first Fresnel Zone into
account. Finally, having a way to calculate the impact on indirect
paths/reflections, should lead to a reasonably accurate signal strength map.
Did anybody work on some of these issues, possibly in combination with
GRASS? Is there a good starting point for the calculation of the obstruction
within the first Fresnel Zone. And the reflections?
On Thu, Apr 17, 2008 at 7:58 AM, Markus Neteler <neteler@osgeo.org> wrote:
On Thu, Apr 17, 2008 at 12:05 PM, Peter Hopfgartner
<peter.hopfgartner@r3-gis.com> wrote:
> Dear GRASS community,
>
> I would like to simulate the strength of a signal emitted from an antenna
> and received by a receiver.
>
> As a first approach r.los gives a good start. Anyway, more accurate results
> could be obtained by taking obstruction in the first Fresnel Zone into
> account. Finally, having a way to calculate the impact on indirect
> paths/reflections, should lead to a reasonably accurate signal strength map.
>
> Did anybody work on some of these issues, possibly in combination with
> GRASS? Is there a good starting point for the calculation of the obstruction
> within the first Fresnel Zone. And the reflections?
Maybe only as an idea of how complicated radio propagation can be. The
referenced page on Wifi / GRASS doesn't really do any important math
or modeling-- rather it was more a test case on interpolating signal
strength measurements.
I am sure that Brad Douglas has some good insight into radio wave
propagation modeling.
On Thu, Apr 17, 2008 at 7:58 AM, Markus Neteler <neteler@osgeo.org> wrote:
On Thu, Apr 17, 2008 at 12:05 PM, Peter Hopfgartner
<peter.hopfgartner@r3-gis.com> wrote:
> Dear GRASS community,
>
> I would like to simulate the strength of a signal emitted from an antenna
> and received by a receiver.
>
> As a first approach r.los gives a good start. Anyway, more accurate results
> could be obtained by taking obstruction in the first Fresnel Zone into
> account. Finally, having a way to calculate the impact on indirect
> paths/reflections, should lead to a reasonably accurate signal strength map.
>
> Did anybody work on some of these issues, possibly in combination with
> GRASS? Is there a good starting point for the calculation of the obstruction
> within the first Fresnel Zone. And the reflections?
Maybe only as an idea of how complicated radio propagation can be. The
referenced page on Wifi / GRASS doesn't really do any important math
or modeling-- rather it was more a test case on interpolating signal
strength measurements.
I am sure that Brad Douglas has some good insight into radio wave
propagation modeling.
I do not know if splat can account for near-surface conditions (i.e.
Fresnel Zone) or higher elevation atmospheric parameters (ionosphere).
It would be nice to have a couple of more robust LOS-like modules in
GRASS for this type of work.
from the description on the web page it seems that Fresnel Zones are in
SPLAT, at least in recent versions.
I will have a look at it, tomorrow.
SPLAT is pretty cool, and if all you want is to compute some RF coverage
maps it works well as a standalone application. It would make an interesting
project for GRASS integration.
As distributed, SPLAT only works when you give it digital elevation models
in a very specific file format, and it produces PPM output (not
georeferenced) to display its results.
I've often thought that it would be cool to adapt it to a GRASS module that
can work with any GRASS elevation data and produce a GRASS raster of RF
loss and radio coverage instead of an ungeoreferenced image file. SPLAT
itself is a fairly simple program once you get digging in it (the math is
not simple, but the code structure is), but the integration project has always
been too daunting for me.
--
Tom Russo KM5VY SAR502 DM64ux http://www.swcp.com/~russo/
Tijeras, NM QRPL#1592 K2#398 SOC#236 AHTB#1 http://kevan.org/brain.cgi?DDTNM
"And, isn't sanity really just a one-trick pony anyway? I mean all you get is
one trick, rational thinking, but when you're good and crazy, oooh, oooh,
oooh, the sky is the limit!" --- The Tick
On Thu, Apr 17, 2008 at 05:36:18PM +0200, we recorded a bogon-computron
collision of the <peter.hopfgartner@r3-gis.com> flavor, containing:
> Dylan Beaudette wrote:
>> There is also an open source application called 'splat' :
>> http://www.qsl.net/kd2bd/splat.html
>>
>> I do not know if splat can account for near-surface conditions (i.e.
>> Fresnel Zone) or higher elevation atmospheric parameters (ionosphere).
>>
>> It would be nice to have a couple of more robust LOS-like modules in
>> GRASS for this type of work.
>
> from the description on the web page it seems that Fresnel Zones are in
> SPLAT, at least in recent versions.
>
> I will have a look at it, tomorrow.
SPLAT is pretty cool, and if all you want is to compute some RF coverage
maps it works well as a standalone application. It would make an
interesting project for GRASS integration.
As distributed, SPLAT only works when you give it digital elevation models
in a very specific file format, and it produces PPM output (not
georeferenced) to display its results.
I've often thought that it would be cool to adapt it to a GRASS module that
can work with any GRASS elevation data and produce a GRASS raster of RF
loss and radio coverage instead of an ungeoreferenced image file. SPLAT
itself is a fairly simple program once you get digging in it (the math is
not simple, but the code structure is), but the integration project has
always been too daunting for me.
I wonder if the core code used in SPLAT would scale better than the current
r.los algorithm. If that is the case, it might be a nice candidate for an
r.los replacement for GRASS 7...
Funny you folks brought up SPLAT! A slightly more user friendly version of the program (free but not open source): http://www.cplus.org/rmw/english1.html
SPLAT has the drawback that it can only use the 3 arc second DEMS. Radio Mobile can use (in theory) DEMs down to 1/3 are second. The drawback to both programs is the fixed array size. For splat, the size is fixed at 3600x3600. Radio Mobile can vary the size, but no larger than 2000x2000. These programs are old, dating back to the days when computers were very limited in RAM and speed.
One nice thing about both programs is they read back the height at the transmitter location. Since the DEM doesn't show the peak altitude but I suppose an average over the region, the altitude used by the program is often less than real life. I find a get more accurate results by finding the altitude used by the software, then adding enough to it to reach the known altitude of the peak.
When I get the chance, I'll do some comparisons between the programs.
Incidentally, one real annoyance with r.los is that it can't accept lat/lon.
Here is an example of using GRASS for a similar study:
I do not know if splat can account for near-surface conditions (i.e.
Fresnel Zone) or higher elevation atmospheric parameters (ionosphere).
It would be nice to have a couple of more robust LOS-like modules in
GRASS for this type of work.
from the description on the web page it seems that Fresnel Zones are in
SPLAT, at least in recent versions.
I will have a look at it, tomorrow.
SPLAT is pretty cool, and if all you want is to compute some RF coverage
maps it works well as a standalone application. It would make an
interesting project for GRASS integration.
As distributed, SPLAT only works when you give it digital elevation models
in a very specific file format, and it produces PPM output (not
georeferenced) to display its results.
I've often thought that it would be cool to adapt it to a GRASS module that
can work with any GRASS elevation data and produce a GRASS raster of RF
loss and radio coverage instead of an ungeoreferenced image file. SPLAT
itself is a fairly simple program once you get digging in it (the math is
not simple, but the code structure is), but the integration project has
always been too daunting for me.
I wonder if the core code used in SPLAT would scale better than the current r.los algorithm. If that is the case, it might be a nice candidate for an r.los replacement for GRASS 7...
