Nuts & Volts - May 2004

Near Space

Example 2

KD4STH- 11>APT310,WIDE3-3:/143130h4313.72N/11721.12W>272/029/A=111840 KD4STH- 11>LIME,WIDE3-2:/143130h4313.72N/11721.12W>272/029/A=111840

Example 3

143130h4313.72N/11721.12W>272/029/A=111840

F o r

E l e c t r o n i c s

you got home? Either you or one of your crew members will have saved a TNC log of the flight. It is a copy of all the APRS traffic during the mission. This is a text file, so it’s readable with a text editor, like Wordpad (it may be too large for Notepad).

Open the TNC log with the text editor of your choice. The first thing you’ll notice is that there is a great deal of traffic from chase crews and local hams. In fact, most of the text you see has nothing to do with the posits from your NS craft. Make yourself a cup of tea because you’re going to be editing the TNC log for some time.

The first step is to delete lines of text that did not originate from your Tiny Trak 3. Delete every sentence that does not begin with your callsign. Save your file frequently.

If a digi-peater was within range, you’ll see some posits that were repeated before getting to your APRS station. In those cases, you’ll see something that looks like the data in Example 2.

NUTS & VOLTS E v e r y t h i n g

Notice that, except for the destination field, the second posit is identical to the first one. Realizing this, our next step is to delete all of the repeated posits. I prefer to do this manually to ensure accuracy. Before making deletions, look carefully at the posits. There may be times when you only see the repeated posit, not the original one. Be sure that you don’t delete the repeated posit if your TNC log does not contain the original posit. Save your work again.

Next, get rid of the callsign and routing information. In

Example 2, this means:

W>

/A=

/

KD4STH- 11>APT310,WIDE3-3:/

Here’s where the Find/Replace feature comes in handy. In WordPad, select “Edit,” then “Replace.” In the “Find What” field, type the callsign and route text. Leave the “Replace With” field blank. Now click “Replace All.”

Sit back and watch your PC make editing changes at warp factor six. You may notice that there were some damaged or repeated posits that didn’t contain the information in the “Find What” field. You’ll have to clean these up manually, unless you have lots of repeated posits. Save your work again.

Now you are left with sentences that look like that in Example 3.

Use the “Replace All” option to replace the following characters with a comma:

h N/

Be sure to do the last two in the order indicated and to save your work after every replacement.

Now you have posits that look like that in Example 4.

The last step is to add commas between the hours, minutes, seconds, and minutes of latitude and longitude. Again, I have found that it is more accurate to do this manually. Don’t forget to save the changes frequently.

Your final result will be a text file that looks like Example 5.

Congratulations — the hard work is over and the fun stuff begins.

You’re now ready to import the text file into a spreadsheet. I’ll explain how I do this in Excel. Even if you use another spreadsheet, you should find the procedure to be similar.

When you open the text file in Excel, it will ask how the text file is formatted. Tell the Text Import

Wizard that the file is delimited and, in the second screen, specify that only commas delimit the file. On the third screen, click the Finish button. Look over the spreadsheet and verify that there were no errors in formatting the TNC log.

If you find an error, back out of the file without saving it, make the necessary changes to the modified text file, and then repeat the process of importing the file back into Excel. If you’re happy with the results, save the file. Now let’s produce some science.