Re: Map Prefetch & Saving

Bradley Haney <kc9gqr@...>

In a car. I normally have my igate running but been having some internet trouble. Should have it a running full time by the end of the weekend. How do I save maps. So I don't have to have a data connection all the time. Brad
Sent from my BlackBerry®

-----Original Message-----
From: "Lynn W. Deffenbaugh" <>
Date: Fri, 19 Feb 2010 09:00:28
To: <>
Subject: [aprsisce] Map Prefetch & Saving

Bradley Haney wrote:
Lynn, your software is awesome. Been using in my. Old hp travel
companion and kenwood d700. Works wonders. I have a bluetooth. Serial
adapter plugged into the radio. So its all wireless.
Thanks for the kind words. I've seen your snowmobile running around and
tried to send a message to you the other morning, but apparently there's
no bi-directional IGates in your area because I didn't receive any
acks. I was wondering if you were really on a snowmobile or in a car
that was wishing it was a snowmobile!

One question. How do I save maps so I do not have to have a data
connection going all the time. I would only really need about 3
counties of maps
There's a menu option under View / Maps / Prefetch that will handle the
prefetching of the maps. Then you need to edit the XML file to make
sure the map tile purger doesn't do away with them. Here's the procedure:

Only do the following when you have an Internet connection and time to
wait for the prefetcher to pull in the map tiles! We're talking
thousands of them!

1) Zoom and pan the map so that an area of interest is all that is
visible. On Win32 you can even size the window to help focus on the
interested area.

2) Select View / Maps / Prefetch. The client will tell you how many
tiles cover the area including several zoom levels closer. Don't panic,
this will be a large number!

3) Once you click Yes, the client will queue all of the missing map
tiles. This can take a while (even just to queue them) so be patient.
Once all have been queued, the actual count will be displayed. This may
be less than the original count because some of the tiles have probably
already been cached.

4) The yellow circle will begin expanding as the tiles are fetched, but
you don't need to wait for it. Double-clicking an empty spot on the map
will provide you some visibility into the queue length and the states of
the threads doing the retrieval.

5) You can now repeat steps 1 through 4 at various zoom levels to make
sure you have all of the tiles you want. If you miss some, the client
will simply stretch the next higher zoom level to cover the hole if/when
you get into one.

OK, about 5 minutes after the yellow circle has expanded and
disappeared, double-clicking an empty spot on the map will tell you the
current state of your cache. For example, my Windows Mobile has 8,386
tiles over 38.77MB while my desktop has 55,349 tiles over 323.41MB (yes,
I zoom all over the world from my desktop). So, how do I make sure they
don't get purged. You edit a hidden parameter in the XML file!

1) Close the client. If you don't do this, any changes you make to the
XML file will be lost when you DO close the client as it is completely
rewritted by the client on close.

2) Locate and edit APRSISCE.xml (or APRSIS32.xml). On Windows Mobile,
it will be in your My Documents folder and probably synched to you
desktop. Make sure you wait for the sync to finish after closing the
client. On Win32, it will be in the default directory where you run the

3) Edit this file with a plain text editor. You're looking for a tag
called <OSM.RetainDays> which is probably set to something like 7.
Change that value to 0 and it will disable the Tile purger and keep
everything you've ever fetched.

4) Save the file and wait for it to re-sync back over to your Windows
Mobile device before restarting the client.

You can still pre-fetch additional tiles whenever you have a
connection. However, when you're going to be connectionless, I would
recommend unchecking the Enables / OSM Fetch Enabled. This will prevent
the client from even attempting a connection to the OSM server for any
missing tiles in the event it needs one while you know you'll be out of

Oh, and if you think about it, please send me the string of numbers from
the OSM Map Tiles popup that starts with Sec: and has 5 numbers after
it. These are internal timing numbers that gauge the various phases of
the Tile fetcher. You have to do this after the prefetch queue has
completed and BEFORE you close the client. Knowing these numbers might
help me do some performance tuning on the tile fetcher in a future version.

And finally, if any of you actually do this procedure, let me know how
it works out when you go Internet-less. My son, KJ4DXK, is planning to
run in this mode with his home-brew tracker, but he still needs to do
some code on his end before he'll have it in operation. I'm anxious to
know if it actually works!

Lynn (D) - KJ4ERJ - Author of ARPSISCE for Windows Mobile and Win32

Bradley. Kc9gqr


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