I am trying to use the HFTA program in the latest Antenna manual. I printed
the instructions from the CD and attempted to download NED data from the
seamless.usgs.gov site. It appears that the usgs people have "improved"
their web site since the instructions were written. I played with the site
but was unable to download anything that would work.

My PC screen resolution is 1280x1024 with 16-bit color. (I think this is
relevant.)

I receive the first page of the usgs site and select the map of the United
States. The next page has a large rectangle in the middle where a map
should appear (I assume) but it remains blank. I cannot find a place to
select RASTER=NED, as specified in the HFTA instructions. I could input a
coordinate box and then download a zip file, but MicroDEM rejected the file
as not containing valid data.

Are there any updated instructions for obtaining the NED data?

Bill
W2WO

Bill Ogden wrote:
I am trying to use the HFTA program in the latest Antenna manual. I printed
the instructions from the CD and attempted to download NED data from the
seamless.usgs.gov site. It appears that the usgs people have "improved"
their web site since the instructions were written. I played with the site
but was unable to download anything that would work.

My PC screen resolution is 1280x1024 with 16-bit color. (I think this is
relevant.)

I receive the first page of the usgs site and select the map of the United
States. The next page has a large rectangle in the middle where a map
should appear (I assume) but it remains blank. I cannot find a place to
select RASTER=NED, as specified in the HFTA instructions. I could input a
coordinate box and then download a zip file, but MicroDEM rejected the file
as not containing valid data.

Are there any updated instructions for obtaining the NED data?

Yes, there is a revised manual to replace the one on the CD. Go to
www.arrl.org and search for HFTA.

--
73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

Hi Bill

I have also found seamless to be a little less intuitive than it all use
to be. I was only just trying to get a hold of some raw SRTM data and
find that they dont. (There is an FTP site still avail tho) However I
found a nice easy way to drive the website. I apologise if I am
repeating what you have already tried.

- From the main page click on the US. When the viewer comes up click on
the second button under "Downloads" (control bar mid LHS). This is
"Define area by Co-ordinates"

- In the popup window that arrives (make sure you have allowed popups
for this site on your web browse - if such a limitations exist) enter
the co-ordinate limits of your requirement. Change to Decimal degrees as
needed. Then click on the Add Area button.

By default it tries to give you NED in ArcGrid format as a zip file. If
you click on "Modify data Request" you can change the kind of data you
are downloading. I suggest you check what kind of format the HFTA pgm needs.

Whatever you select it then packs up (can take maybe 30 secs) and
downloads to your PC. Obviously you have to unpack it to use it.

My PC also has a large blank rectangle when I go to the viewer. I had
assumed it was my setup and was going to get aorund to fixing it.. Only
I wont now! All other USGS map etc sites seem to be fine so I suspect
there is a server problem. (I use Firefox 1.01 SuSE Linux 9.1 Prof)

Cheers Bob VK2YQA



Bill Ogden wrote:
--snip--

Are there any updated instructions for obtaining the NED data?

Bill
W2WO

Bob - what is the best source of detailed topographical data for VK?

(Tried to e-mail you off-list, but it was bounced. I'm asking on behalf
of a mate in VK4 who wants to run HFTA.)


--
73 from Ian GM3SEK

Hi Ian

Yep sorry about that. Its a spam reduction exercise. Use bcnuup instead
of bcnntp and you'll get me.

At work we use a mix of Auslig/Geoscience Australia 9 arcsecond and the
SRTM 3 arcsecond data for our RF coverage stuff. The 9 arcsecond stuff
costs $$ from http://www.ga.gov.au but the SRTM stuff is free -
ftp://e0mss21u.ecs.nasa.gov. It does however need void removal. There
are a few other ASCII datasets of higher resolution available from GA
but they tend to be restricted to populated areas. If your VK4 mate
wants void removed SRTM data get back to me and I'll send them a CD.

Geoscience has free downloads of 1:250K topo maps but anything of a
higher resolution also costs.

If you are after only NSW data there is a nifty map portal
http://maps.nsw.gov.au that allows you to look at very high res topo
information.

I dont know if NED data is available for Australia. There may be some
conversion utility to use SRTM data but I havent checked... There are
quite a few apps out there that do conversions. Have a look at Blackart
(http://www.terrainmap.com) and LandSerf.

Sorry I cant give an exact answer. I havent looked at HFTA at all.

Cheers Bob Vk2YQA

Ian White GM3SEK wrote:

Bob - what is the best source of detailed topographical data for VK?

(Tried to e-mail you off-list, but it was bounced. I'm asking on behalf
of a mate in VK4 who wants to run HFTA.)

Had a quick look at HFTA

You need some kind of profile of the path you want to examine. I'd
suggest you download 3dem and use its profile output function (draw a
line and it graphs the result and makes an ASCII text file of the
results) You can use SRTM data for input. This will give you 90m odd
horiz resolution.

You'll be able to create an ASCII text file as outlined in the HFTA PDF
manual page 2 - and use that for input.

I cant for the life of me remember the URL for 3dem but I remember you
have to register an email address agaanst it. I dont think any spam was
generated from it. If you get lost gimee a shout and I'll see if I can
legally upload it to you - or I'll find the URL!

Go for it!

Cheers Bob

Bob Bob wrote:
Hi Ian

Yep sorry about that. Its a spam reduction exercise. Use bcnuup instead
of bcnntp and you'll get me.