[OZAPRS] SEQ coverage plot - first pass

Ray Wells vk2tv at exemail.com.au
Sat Sep 29 16:18:39 EST 2007


Hi All,

Just to add a little more to what Peter has said, the program used to 
produce the coverage plot is SPLAT! by John Magliacane, KD2BD.

SPLAT! is a Linux program available for download via here 
http://www.qsl.net/kd2bd/

The program has a large variety of options including line of site paths, 
pathloss in dB, field strength in dBuv/m (only in the latest unreleased 
version that I've been trialling). As well as producing colour plots the 
program will produce a large variety of graphs normally associated with 
path predictions. A locations file can also be added to title sites and 
geographic points of interest. When the Google Earth option is chosen 
this file is not used (because Google Earth supplies the information, 
and more).

Output is normally in ppm format but this can be converted to png format 
with Imagemagick, etc. A 34MB ppm file will shrink to about 5MB in png 
format. Additional output options include a geo file for working with 
xastir and a kml file to permit the resulting plot to be viewed in 
google Earth - this is brilliant! However, Google Earth baulked at the 
png file so I converted back to ppm with Irfanview (another free Windows 
program).

Maps used by SPLAT! are those obtained by the STS99 Space Shuttle 
mapping mission which radar mapped all of the world's land masses. The 
maps for Australia can be downloaded here 
ftp://e0srp01u.ecs.nasa.gov/srtm/version2/SRTM3/

Accuracy of the maps is 3 arc seconds or about 90m.

The maps do have a few voids and I use a Windows program called FSDEM 
(free download) to fill the voids. One day I'll try to make it work in
Wine.

If you would like a coverage plot of your repeater/digi site (Australia 
only), just give me a yell. While you are yelling include the following;
Latitude in either dd.dddddd, dd mm ss or ddd mm.m
Longitude in the same formats
Tx ERP
Tx antenna height

Traditionally, field strength readings are taken with a receiver antenna 
height of 30'. For mobile APRS a value of 5' is probably more realistic. 
Please specify a value is you don't want 30' used.

I don't need site elevation, this is obtained from the map automatically.

Ray vk2tv

Peter Schrader - VK4TGV wrote:

>Hi All,
>Thanks to Ray (VK2TV), who took the data I gleaned from UI-View32 and
turned
>them into a coverage plot of all of the digis in SEQ VK4.
>
>I made a few guesses for some of the digi heights above sea level, as
most
>of the digi operators seem to have an aversion to answering my emails
and/or
>joining the vk4aprs Yahoo group.  
>
>I have uploaded the file to the Yahoo group, for those who are have been
>reluctant to join the group you can download the 5MB file here
>http://rumpleteazer.net/SEQ2.png
>
>If the Vk4 APRS webmaster is listening, your website would be a great
place
>for this file.
>
>Cheers,
>Peter
>VK4TGV 
>
>_______________________________________________
>Ozaprs mailing list
>Ozaprs at aprs.net.au
>http://aprs.net.au/mailman/listinfo/ozaprs
>
>  
>

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