Matt,
There are many things to consider with mapping data. SRTM and other
terrain
files all have their native map projection and datum. It takes someone
strong in the GIS and mapping field to make sure these files get overlaid
and used properly without shifting any one of the layers out of alignment
with the other. I use various GIS tools to achieve these tasks. The USGS
does provide good quality clutter data for free but it does require someone
to find it and then get it in a format they can use and/or convert it to the
proper projection and datum to match their existing data. So to answer your
question, I prefer the free data the taxpayers paid for when available. I
have also paid for very high resolution clutter data (1 to 2 meter
resolution) but that gets expensive because that gets tediously created by
hand and someone has to pay for that. Vendor to vendor does not seem to
matter as much as converting it properly once obtained.
Thank You,
Brian Webster
www.wirelessmapping.com <http://www.wirelessmapping.com>
-----Original Message-----
From: Matt Liotta [mailto:[EMAIL PROTECTED]
Sent: Wednesday, January 02, 2008 9:39 AM
To: [EMAIL PROTECTED]; WISPA General List
Subject: Re: [WISPA] Radio Mobile
I have found most people don't purchase clutter data even when using the
commercial tools when used as part of a fixed wireless operation. They
generally just put in an average height to use. This is what we do as
well even though we purchased clutter data. Although, we aren't using
commercial software; our application was written in-house. We weren't
able to use the data because it didn't match up correctly with SRTM. The
data vendor suggested buying ground data to match the clutter data, but
we didn't want to pay for ground data when SRTM is free and good.
In your experience, have you been able to get clutter data to match up
with SRTM? If so, what resolution and what data vendor did you use?
-Matt
Brian Webster wrote:
> Mike,
> As mentioned by another, try adjusting the height of one end or the
> other
> to increase signal level. As Mac will tell you, higher on a site is not
> always better. If you can engineer a path to obstruct as much of even
number
> Fresnel zones as possible it will help your signal level. Even and odd
> number Fresnel zones cancel each other out. Using an obstruction to cover
up
> as many even number zones as possible gives some gain. This is why you
hear
> people say that you want to design a microwave backhaul with a .6 Fresnel
> zone clearance. The danger in doing that with Radio Mobile, is the level
of
> detail in your terrain files. Radio Mobile is capable of using 10 meter
> resolution terrain data from the USGS Seamless data distribution site (the
> default that the program downloads from the internet is 30 meter), or if
you
> want, Roger (the Radio Mobile author) can create the data in SRTM format
to
> use in Radio Mobile http://www.lurodata.com/. While this gives excellent
> terrain data details, it still does not show your clutter (trees,
> buildings). Take a look at this site to see the differences in terrain
data
> http://www.sector14.net/~curt/ned/
>
> You can do some visualization of clutter data in Radio Mobile at 1
> kilometer resolution for free. If you download this file
> http://www.geog.umd.edu/landcover/1km-map/UMD1km_L.zip you will have the
> world clutter data at 1 KM resolution. This file can then be overlaid in
> Radio Mobile as a map layer. It will not let you use it as part of a
> prediction, but you can get an idea of the type of land cover to expect
for
> any given area. You can also use this file in conjunction with the "RM
Path"
> program in Radio Mobile to insert the clutter in your path profile
> inspections. To do this you must first edit the "landheight.dat" file
(using
> notepad) in your Radio Mobile main directory. The numbers in this file
> correspond to the color coded legend on a land cover map layer merge. Each
> value is in meters and would be changed to represent the average clutter
> heights for each clutter class in your area. Once this is complete you
would
> then do a path profile in Radio Mobile. In that window do a file "export
to
> RMPath", chose the custom option and I like to use 1000 points in my
export.
> This will save a file (name it whatever you want or just overwrite the
> default) and open the RM Path program window. In this path profile you
will
> see the terrain cross section with the clutter data layered on top. The
> colors match what you would see as a merged layer on the map. At this
point
> you will NOT have a new signal level calculated based on clutter
absorption,
> but you will know what to expect for path blockages. You can also manually
> edit the test file that was exported to insert any know obstructions in
your
> path. Keep in mind, this data is very general in that it paints a whole
> square kilometer with the same class of clutter. Its not the best in the
> world, but for free it gives you a lot more to look at before you do a
truck
> roll. This used in conjunction with Google Earth is just one more tool a
> WISP can use.
>
> I have been in the wireless industry for 18 years (including Senior RF
> Engineering Manager at EarthLink). I currently have Planet, ICS Telecom by
> ATDI and Radio Mobile as RF prediction tools. While Radio Mobile does not
do
> many of the advanced features I need to design PCS and Cellular networks,
I
> will attest that given the same data to start with, I can do predictions
> that match or beat the expensive commercial tools when it comes to simple
> field strength plots (which is what you want for coverage maps and path
> studies). Where the commercial tools excel, is when I can get high
> resolution clutter and building data. Radio Mobile simply does not have
> these capabilities (although I work with the author on a regular basis to
> improve Radio Mobile). I would highly recommend each WISP get one person
on
> their staff to become somewhat proficient in this software. It can save
you
> a lot of aggravation.
>
>
>
> Thank You,
> Brian Webster
> www.wirelessmapping.com <http://www.wirelessmapping.com>
>
>
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> Behalf Of Mike Hammett
> Sent: Tuesday, January 01, 2008 5:15 PM
> To: WISPA General List
> Subject: Re: [WISPA] Radio Mobile
>
>
> Right, the AP isn't directly at the client, but it says there's only 0.8
db
> of loss due to that. It says I lose 7.4 dB due to obstruction (when I
have
> a 1.4 Fresnel zone) and 6.6 due to statistics.
>
>
> -----
> Mike Hammett
> Intelligent Computing Solutions
> http://www.ics-il.com
>
>
> ----- Original Message -----
> From: "Brian Webster" <[EMAIL PROTECTED]>
> To: "WISPA General List" <[email protected]>
> Sent: Tuesday, January 01, 2008 3:00 PM
> Subject: RE: [WISPA] Radio Mobile
>
>
>> Radio Mobile is not doing a simple free space loss calculation. There
will
>> be a fade margin factored in based on the numbers you use for mode of
>> variability. If you open the path profile window then do a "view"
>> "details"
>> you will get a text window that shows all the calculation details the
>> program used to derive the numbers. That is the first place to start to
>> look
>> for the difference. The other thing you may be seeing is that if you
don't
>> have the antennas aimed directly at each other, in the calculation you
>> will
>> be getting the gain from something other than the strongest point in the
>> pattern.
>>
>>
>>
>> Thank You,
>> Brian Webster
>> www.wirelessmapping.com <http://www.wirelessmapping.com>
>>
>>
>> -----Original Message-----
>> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
>> Behalf Of Mike Hammett
>> Sent: Tuesday, January 01, 2008 12:03 PM
>> To: WISPA General List
>> Subject: [WISPA] Radio Mobile
>>
>>
>> How do I figure out how Radio Mobile arrives at it's signal level? On a
3
>> km link in 5 GHz, I'm off 15 - 20 db from Eje's power calculator. What
>> the
>> radio link window says is really close to the input numbers for Eje's
>> calculator. Why they're different is that I actually used the right
>> antenna
>> files and hard fixed the AP at N, S, E, and W.
>>
>>
>> -----
>> Mike Hammett
>> Intelligent Computing Solutions
>> http://www.ics-il.com
>>
>>
>>
>> -------------------------------------------------------------------------
-
> --
>> ----
>> WISPA Wants You! Join today!
>> http://signup.wispa.org/
>> -------------------------------------------------------------------------
-
> --
>> ----
>>
>> WISPA Wireless List: [email protected]
>>
>> Subscribe/Unsubscribe:
>> http://lists.wispa.org/mailman/listinfo/wireless
>>
>> Archives: http://lists.wispa.org/pipermail/wireless/
>>
>>
>>
>> -------------------------------------------------------------------------
-
> ------
>> WISPA Wants You! Join today!
>> http://signup.wispa.org/
>> -------------------------------------------------------------------------
-
> ------
>> WISPA Wireless List: [email protected]
>>
>> Subscribe/Unsubscribe:
>> http://lists.wispa.org/mailman/listinfo/wireless
>>
>> Archives: http://lists.wispa.org/pipermail/wireless/
>>
>
>
>
> --------------------------------------------------------------------------
--
> ----
> WISPA Wants You! Join today!
> http://signup.wispa.org/
> --------------------------------------------------------------------------
--
> ----
>
> WISPA Wireless List: [email protected]
>
> Subscribe/Unsubscribe:
> http://lists.wispa.org/mailman/listinfo/wireless
>
> Archives: http://lists.wispa.org/pipermail/wireless/
>
>
>
> --------------------------------------------------------------------------
------
> WISPA Wants You! Join today!
> http://signup.wispa.org/
> --------------------------------------------------------------------------
------
>
> WISPA Wireless List: [email protected]
>
> Subscribe/Unsubscribe:
> http://lists.wispa.org/mailman/listinfo/wireless
>
> Archives: http://lists.wispa.org/pipermail/wireless/
--------------------------------------------------------------------------------
WISPA Wants You! Join today!
http://signup.wispa.org/
--------------------------------------------------------------------------------
WISPA Wireless List: [email protected]
Subscribe/Unsubscribe:
http://lists.wispa.org/mailman/listinfo/wireless
Archives: http://lists.wispa.org/pipermail/wireless/
