I would try to get between .6 and 1. If you expose the second zone then the
phase canceling starts and reduces your signal level.



Thank You,
Brian Webster

-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Mike Hammett
Sent: Tuesday, January 08, 2008 9:24 AM
To: WISPA General List
Subject: Re: [WISPA] Radio Mobile


So then should I be engineering my customer links to .6 Fresnel instead of
the > 1 that I've been trying to achieve?


-----
Mike Hammett
Intelligent Computing Solutions
http://www.ics-il.com


----- Original Message -----
From: "Brian Webster" <[EMAIL PROTECTED]>
To: "WISPA General List" <wireless@wispa.org>
Sent: Wednesday, January 02, 2008 8:26 AM
Subject: RE: [WISPA] Radio Mobile


> 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" <wireless@wispa.org>
> 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: wireless@wispa.org
>>
>> 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: wireless@wispa.org
>>
>> 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: wireless@wispa.org
>
> 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: wireless@wispa.org
>
> 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: wireless@wispa.org

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: wireless@wispa.org

Subscribe/Unsubscribe:
http://lists.wispa.org/mailman/listinfo/wireless

Archives: http://lists.wispa.org/pipermail/wireless/

Reply via email to