Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

Dopler wave o scope use

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Old 10-27-2008, 12:18 PM
  #1  
mk1spitfire
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Default Dopler wave o scope use

I can load in a file and postion the green and red line but don't know what I'm doing. Not very good at german.
Where am I ment to put these two lines? It seems if they are further apart the speed is increased or not acurate.

Any advise please
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Old 10-27-2008, 06:14 PM
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Mike Connor
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Default RE: Dopler wave o scope use

Find one line that is well defined on the left and right side and place your lines like on the picture below.
If you have Google tool bar just right click on the page and go to page info. You then can translate the page to English. If not try the site below.
http://babelfish.yahoo.com/translate_txt
Attached Thumbnails Click image for larger version

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Old 10-27-2008, 06:34 PM
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Default RE: Dopler wave o scope use

Ok thanks Mike,

Other than a well defined line, how do you know which line to choose. The lines are wider along the graph??

The additional instructions are in a pdf file so unsure how to convert that to english translation.
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Old 10-27-2008, 06:56 PM
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Default RE: Dopler wave o scope use

Don't know if it's the latest version, but waveOscope has been translated into english.
Look here: [link=http://happykillmore.com/main_downloads.asp]Happy Killmore's translation[/link]
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Old 10-27-2008, 07:10 PM
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Default RE: Dopler wave o scope use

Hey Mike !! that graphic seems to me familiar .
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Old 10-27-2008, 07:28 PM
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Default RE: Dopler wave o scope use

Ok I think I got the hang of it. It appears that it doesn't matter which line you choose as long as its a good one. Even if you choose a line that is wider apart up the scale, as frequency increases so does same speed even if you had chosen a narrow line back down the scale.



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Old 10-27-2008, 07:37 PM
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Default RE: Dopler wave o scope use

ok thanks lee hop, i cant get the pdf file to open though.


I've just tried doing a jet and a 4 stroke without much luck. Are these two not possible to do?
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Old 10-27-2008, 08:07 PM
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Default RE: Dopler wave o scope use

Any plane that makes a constant noise can be dopplered. Electrics, glow, gas, 2st, 4st, even jets. The motor's noise is used almost like a clock pulse, giving a constant pitch noise that is shifted as the plane goes by.

You'll see several lines, all doing a big swooping dive as the plane goes by. The lines higher up the display seem to swoop more deeply. They all change by the same percentage, though, so they will all give the same speed. They are different octaves of the same motor noise. If you're also calculating for RPM, you then need to know which octave you're measuring from.

I don't use wave-o-scope, I use Spectrogram16 and an XL spreadsheet I found on the OTHER forum, that also returns RPM's. I didn't feel like messing with german translation on my speedy dial-up....

Just choose a single octave line, one that's clear and seems well defined. Measure the frequency just before and just after the plane passes (the top and bottom of the curve). Plug 'em into the spreadsheet, and out pops the speed.

Audio Doppler is very sensitive to how the pass is flown, too. If RPM's are falling thruought the pass, as in agressivly diving, pulling level and doing the pass, the speed output will be inflated, as the falling engine note on top of the doppler will exaggerate the effect. An engine that suffers a lean-stumble mid-pass will show the same effect. Passes flown closer to the microphone are easier to doppler, as the "slew" happens faster.

Google "model aircraft doppler speed analysis" First hit, jfinch's post, #8.

J
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Old 10-27-2008, 08:17 PM
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Default RE: Dopler wave o scope use


ORIGINAL: SpeedBoy

Hey Mike !! that graphic seems to me familiar .
You caught me.
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Old 10-27-2008, 08:26 PM
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Default RE: Dopler wave o scope use


ORIGINAL: mk1spitfire

It appears that it doesn't matter which line you choose as long as its a good one. Even if you choose a line that is wider apart up the scale, as frequency increases so does same speed even if you had chosen a narrow line back down the scale.
You will notice that the further to the right you go, the smaller the +/- speed is. I would use the furthest good line to the right.
This program and my hardware works well with two stroke engines. Some people don't but I have trouble with 4 stroke, DF and Jets.
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Old 10-28-2008, 05:34 AM
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Default RE: Dopler wave o scope use

Ok, cheers
Is there a way of saving the graph to file on wavescope?


Running a video an panning the plane might not give you a true speed???
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Old 10-28-2008, 07:42 AM
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Default RE: Dopler wave o scope use


ORIGINAL: Jburry

Any plane that makes a constant noise can be dopplered. Electrics, glow, gas, 2st, 4st, even jets. The motor's noise is used almost like a clock pulse, giving a constant pitch noise that is shifted as the plane goes by.

You'll see several lines, all doing a big swooping dive as the plane goes by. The lines higher up the display seem to swoop more deeply. They all change by the same percentage, though, so they will all give the same speed. They are different octaves of the same motor noise. If you're also calculating for RPM, you then need to know which octave you're measuring from.

I don't use wave-o-scope, I use Spectrogram16 and an XL spreadsheet I found on the OTHER forum, that also returns RPM's. I didn't feel like messing with german translation on my speedy dial-up....

Just choose a single octave line, one that's clear and seems well defined. Measure the frequency just before and just after the plane passes (the top and bottom of the curve). Plug 'em into the spreadsheet, and out pops the speed.

Audio Doppler is very sensitive to how the pass is flown, too. If RPM's are falling thruought the pass, as in agressivly diving, pulling level and doing the pass, the speed output will be inflated, as the falling engine note on top of the doppler will exaggerate the effect. An engine that suffers a lean-stumble mid-pass will show the same effect. Passes flown closer to the microphone are easier to doppler, as the "slew" happens faster.

Google "model aircraft doppler speed analysis" First hit, jfinch's post, #8.

J
Hi J,

Can you tell me where I can find the spread sheet? I had it saved but now can't find it. I also use a different spectrum player because it reads 4 strokes better that Wave o scope. It is a little more work to have to use a separate spread sheet but at least it can read the 4 strokes. I couldn't get wave o scope to do it.

Thanks, Terry
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Old 10-28-2008, 07:56 AM
  #13  
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Default RE: Dopler wave o scope use

Here is spreadsheet, i think

http://www.rcgroups.com/forums/showa...hmentid=944234
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Old 10-28-2008, 09:40 AM
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Default RE: Dopler wave o scope use

ORIGINAL: mk1spitfire

Ok, cheers
Is there a way of saving the graph to file on wavescope?


Running a video an panning the plane might not give you a true speed???
I use Paint Shop Pro to capture the screen and save as a jpg file. While the program is open and active you can also use alt/print screen to copy it to the clip board and then paste to Microsoft Word ctrl/v or other graphic word processor.

Panning with the camera is not a problem. The microphone is one place and the plane should fly in a straight line in front of the camera. Two to four seconds is all you need.

Edit - Change Print Shop Pro to Paint Shop Pro.
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Old 10-28-2008, 10:10 AM
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Default RE: Dopler wave o scope use

cool, didn't know that about print screen.
i ve tried spectrogram 16 too now but just get a fuzz off graphics and no lines when trying to caputure 4 stroke sound passing.

Should the cursor be on the line or next to line?
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Old 10-28-2008, 10:20 AM
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Default RE: Dopler wave o scope use

Hmmm... It's possible that there's alot of background noise hiding the plane's sound.... I've never had a problem, so no help here...

I centre the cursor in the line, both coming and going. What's important is that you are consistant.

J
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Old 10-28-2008, 10:40 AM
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Default RE: Dopler wave o scope use

umm, the sound is good. Just goblede gook on screen for this particular 4 stroke pass.


Also, working out rpm on spectrogram 16 spreadsheet. Is no 6 box allways the rpm?
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Old 10-28-2008, 09:00 PM
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Default RE: Dopler wave o scope use

Any chance you can email a sound file to me? I'd like to see....
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Old 10-29-2008, 04:00 PM
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Default RE: Dopler wave o scope use

Can you attach the wave file here so I could try my Spectrum player and see if I can get a good reading?

I use this freeware

[link=http://www.visualizationsoftware.com/gram.html]Spectrogram Version 16[/link]
By Visualization Software LLC

It will play MP3 or Wave and I can see 4stroke files well enough to get the frequencies.

If you can attach the wave file I will see if I can dopler it for you.

Blessings, Terry
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Old 10-30-2008, 07:10 AM
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Default RE: Dopler wave o scope use

I have tried the file with spectrogram 16 and that doesn't produce a readable wave.
Rc universe won't let me attatch a wav file. Seems jpegs,gif,txt only.
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Old 10-30-2008, 09:52 AM
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Default RE: Dopler wave o scope use

ok, with help of jburry i have dismissed the higher frequencies using spectrogram 16 and succeeded in achieving this 4 stroke wave files speed.
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Old 10-30-2008, 02:54 PM
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Default RE: Dopler wave o scope use

Fun it was, too.

Looks to me like a 4st doubles the number of octaves shown, likely from the every-second-revolution exhaust note. The display was more cluttered and busy than I'm used to with 4 strokes, but clear lines were there when the frequencies were restricted on the vertical scale.

The model has a 14x8 prop and is said to tack in the 9K range on the ground. No accurate ground tach available, but it's a clue...

We were able to plug the resulting Spectrogram frequencies into the speed calc xls sheet, which gave us something on the order of 98mph and 11,500 RPM. These numbers jive fairly well with either a slippery ship (she is exceeding geometric pitch speed by somewhere near 10%, which we know can and does happen), or the speed could be somewhat inflated by an improperly flown pass.

I dislike automated software, prefer to measure and plug in values myself. That's why I choose spectrogram/spreadsheet over wave-o-scope. Ask software to make a decision for you, and 7 times outta 10, it'll choose what you didn't want....

It was fun dopplerin' that, Spitz.

J
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Old 10-30-2008, 03:09 PM
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Default RE: Dopler wave o scope use

So when you type in your values the RPM is given at octave 6? Or better yet could you give a summery of how to get your values with the spreadsheet....Gofastz
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Old 10-30-2008, 04:27 PM
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Default RE: Dopler wave o scope use

yer dude.cheers
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Old 10-31-2008, 09:59 PM
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Default RE: Dopler wave o scope use

In Mk1spitfire's post above, #13, there's a link to the spreadsheet file. The thread on that forum that links to the spreadsheet (link's at the upper left of the page) gives a complete explanation, by the guy that made the spreadsheet. I can't do better!

J
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