Perfectflight Datacap - Export Velocity Data?

BackSeatBryce

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Hey everyone,
The latest copy of the Perfectflight Datacap program plots altitude, velocity, temperature, and battery voltage vs time natively in the Datacap program. It also allows you to export raw data for use in Excel or some other program. However, it only lets you export altitude, air temp, and battery voltage as a function of time; it doesn't let you export velocity as far as I can tell. Does anyone know if this is possible?

upload_2019-6-2_10-18-3.png

upload_2019-6-2_10-18-21.png

Thanks,
Bryce
 

mikec

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The PF2 file is just a text file and has the velocity in it, you could easily import that into Excel or whatever.
 

manixFan

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The PF2 file is just a text file and has the velocity in it, you could easily import that into Excel or whatever.
Exactly. On the Mac I can just copy the file, change the extension to .txt and it will import directly into Excel (or Numbers.) In Excel, just set the column delimiter to 'comma' and it will import correctly. (With Numbers it figures it out automatically.) On Windows you can do the same thing - just copy the file and change the extension to .txt.

Just be aware though that you can't really get true velocity with just barometric data, you can only get a change in barometric altitude over time. If your rocket weather-cocked or you have noisy baro data, the results will be less than ideal. Also, if you break Mach during the flight, you'll have to filter the data around the transition. Finally, notice the first few samples are just before launch detect so it's best to remove those from the graph. And once you deploy the main you really need to heavily average the data to get anything meaningful.

Tony

Sample of imported .pf2 file in excel:

excel.png
 

mpitfield

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I think you're going to the "Data" > "Inspect" to grab your data. If you want everything goto "File" > "Save" or "Save As" and save it as a ".csv" file. On a Mac, it does not add the extension, so you have to specify. Then you can open it up with Excel and save as an Excel Workbook if you like. I just did this for my flights from NYPOWER last weekend. Attached is one example of the data, plus the formatting I added.
 

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manixFan

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I think you're going to the "Data" > "Inspect" to grab your data. If you want everything goto "File" > "Save" or "Save As" and save it as a ".csv" file. On a Mac, it does not add the extension, so you have to specify. Then you can open it up with Excel and save as an Excel Workbook if you like. I just did this for my flights from NYPOWER last weekend. Attached is one example of the data, plus the formatting I added.
Just FYI, doing a 'save as' gives you the exact same file as just renaming the original .pf2 file. When I tried the 'save as' on my Mac just now, it would not let me add the .csv extension, it renamed it ###.csv.pf2. I had to remove the .pf2 extension in the finder. So to me it seems easier to just duplicate the file and rename it with a .txt extension right at the finder. I haven't tried it on Windows but I suspect it will let you add the .csv extension directly.

Now, to rant about Excel for a moment. What I don't understand is that even when you choose 'CSV' (Comma Separated Values) in the import screen, the delimiter is not set automatically to a comma, you have to manually choose it. Why does Microsoft even offer CSV (as opposed to TXT) if it doesn't do the obvious and automatically choose comma as a delimiter? Seems like such a basic oversight.


Tony
 

mpitfield

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My "save" and "save as", functions differently. If I save without adding an extension, it saves without an extension. If I add one it takes .csv and the file is happy. It has never saved as a .pf2 file. I wonder why there is a difference in how it behaves. I am running Mac, but this is my second Mac and both behaved the same. I think I also have it installed on my office workstation. I am curious so I will have to check and test it this week.
 

SpaceManMat

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Now, to rant about Excel for a moment. What I don't understand is that even when you choose 'CSV' (Comma Separated Values) in the import screen, the delimiter is not set automatically to a comma, you have to manually choose it. Why does Microsoft even offer CSV (as opposed to TXT) if it doesn't do the obvious and automatically choose comma as a delimiter? Seems like such a basic oversight.

Import function is for importing text for a variety of formats. CSV is a supported file type, you just need to open it normally.
 

manixFan

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Import function is for importing text for a variety of formats. CSV is a supported file type, you just need to open it normally.
Yes, that does work. But many times I want to add a CSV file to an open spreadsheet - for example if I am comparing 2 altimeters to each other. I open the first file and then I just want to use import to add the data from the second file. Even though I choose 'CSV' from the import type, it does not automatically set a comma as the delimiter. (Of course I could open the 2nd file, select all, copy, close the file, switch back to the original file, and paste - but that's a lot of extra steps.)

This is the 21st century - setting the right delimiter isn't exactly rocket science from a programming standpoint. It's a minor nit, but still, it's also Microsoft. You'd think they could do better.


Tony
 

manixFan

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My "save" and "save as", functions differently. If I save without adding an extension, it saves without an extension. If I add one it takes .csv and the file is happy. It has never saved as a .pf2 file. I wonder why there is a difference in how it behaves. I am running Mac, but this is my second Mac and both behaved the same. I think I also have it installed on my office workstation. I am curious so I will have to check and test it this week.
Hmm, that is interesting. I am running Mojave on my laptop and El Capitan on one of my older iMacs. My 'Save' is grayed out if I am working with an existing file, I can only choose 'Save As'. My guess is you are doing the Save on a newly downloaded file? On both Macs using 'Save As' I get the dialog shown below. It would be interesting to know if it's a system setting somewhere. Would make life a bit easier.

Since copying the file and changing the extension takes less time than opening the app and doing a save as, I'm not sure it's really worth messing with. Just one of those software things.

Tony

Screen Shot 2019-06-03 at 12.19.50 PM.png
 
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mpitfield

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Hmm, that is interesting. I am running Mojave on my laptop and El Capitan on one of my older iMacs. My 'Save' is grayed out if I am working with an existing file, I can only choose 'Save As'. My guess is you are doing the Save on a newly downloaded file? On both Macs using 'Save As' I get the dialogue shown below. It would be interesting to know if it's a system setting somewhere. Would make life a bit easier.

Since copying the file and changing the extension takes less time than opening the app and doing a save as, I'm not sure it's really worth messing with. Just one of those software things.

Tony

View attachment 384887

I am running Mojave 10.14.5, and I cannot recall what I was running on the previous MacBook Air but it was a 2011 model. It would have been the latest version back then, or likely 2013 to 2015 when I was uding it for rocketry.

I just checked by connecting to an altimeter on my 3" Darkstar that I launched last weekend and I downloaded the file again, this time paying close attention.

Screen Shot 2019-06-03 at 6.12.25 PM.jpg

Screen Shot 2019-06-03 at 6.12.40 PM.jpg

My "save" is also greyed out.

Screen Shot 2019-06-03 at 6.12.47 PM.jpg

However, I can save and either provide an extension or no extension, but nothing is masked or limited when it comes to the extension.

Screen Shot 2019-06-03 at 6.13.03 PM.jpg

Screen Shot 2019-06-03 at 6.13.27 PM.jpg

To be sure that it does not have a hidden ".pf2" extension, I looked at the properties and sure enough, it is just a .csv file.

Screen Shot 2019-06-03 at 6.13.36 PM.jpg

Obviously, there is a difference, and it makes more sense than mine is behaving incorrectly, but I would rather have it work like this than the alternative.

BTW my version of DataCap does not have a version number, but it was installed on July 13th, 2016.
 

manixFan

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...<snipped>Obviously, there is a difference, and it makes more sense than mine is behaving incorrectly, but I would rather have it work like this than the alternative...<snipped>...
So the difference must be that since I am opening an existing file that started with a .pf2 extension, the app requires it even when doing a save as. But if you are starting with a new file just downloaded from the altimeter, such as you did, you can rename it as you'd like since it does not already have an extension.

Just for the heck of it, I did a save as in Excel and tried to change the extension, and it would not let me, I got the same message as I posted above. But Photoshop let me rename a .psd file with .txt using save as, so it's not strictly an OS thing.

Hmm, learn something new everyday!


Tony
 

mpitfield

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So the difference must be that since I am opening an existing file that started with a .pf2 extension, the app requires it even when doing a save as. But if you are starting with a new file just downloaded from the altimeter, such as you did, you can rename it as you'd like since it does not already have an extension.

Just for the heck of it, I did a save as in Excel and tried to change the extension, and it would not let me, I got the same message as I posted above. But Photoshop let me rename a .psd file with .txt using save as, so it's not strictly an OS thing.

Hmm, learn something new everyday!


Tony

I have never tried to open up a file once exported. I strictly do all my data analyses in Excel; which is far more powerful.
 

manixFan

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I have never tried to open up a file once exported. I strictly do all my data analyses in Excel; which is far more powerful.
That's exactly what I am doing, using Excel to analyze my data. But a lot of the time I am working with files that are sent to me in .pf2 format, which is really what started this whole process. I also am going back and looking at old flights where the only file I have is the original .pf2 file. Those are the cases where the situation I describe occurs.

You would run into exactly the same issue if you tried to export a .pf2 file someone sent you to analyze.


Tony
 
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