Today I struck gold in my university's electronic waste bin, a TDS 2014B! Other than channel 2 being defect it is working perfectly, even the clock was still correct. I already have a 20 MHz analog scope that is great for most of my everyday low/medium frequency applications, but especially for debugging digital systems a digital scope is very handy. Happy to see you have it as well and have some videos using it.
This video answers the question "why mere mortals can not even dream of getting hired by tek". Simply teaching talent on loan from God, as someone I recently lost used to say
This was awesome. I got my EE degree back in 1984 (UT Austin). I remember doing the math for the FFT but never really understood them. This was an excellent tutorial. Thanks!!!
I'm not going to pretend I totally understood this video, but half way through I looked up what RMS is now I know. All ways interesting and well presented videos, again add to watch later when I'm more informed. thank you.
Oh cool! I just used my iPad 'Audio Tool' app to generate white noise. I ran that into my Behringer Mixer. And from the mixer into my TDS2014B. Now I can see what the Low, Mid, and High EQ controls REALLY do. I used a BNC to RCA adapter for the scope CH1 connector. Works great. Thanks for the video.
I only just caught up with this video. I half know what the FFT function was for, but this video really helped to make things clear. BTW the link to the note pages doesn't work anymore. Thanks for this.
Very good Alan, I am not a lucky owner of those nice scopes having all the nice Gismo's But it was interesting to know what it is and the meaning of when I listen to other groups having those features.Like always very interesting and reason to listen to very well explained Tks for the Efforts 73's Alan
Alan thanks for this video also thanks to share those helpful informations. Aloud to suggest to prepare a tutorial for baluns,in past you teach us how we can wind a triffilar choke now if you find time teach us the way to apply them on transmission line.. Best regards Kostas. .
Alan, Excellent video, good in depth tutorial on using the scope controls. May I suggest you do a part 2 video and talk about the limitations of using the scope FFT as compared with a spectrum analyzer. Show some more complex signals that would have more components. Possibly some real world signals like a HF or VHF ham TX signal, audio waveform, etc. What can a low end spectrum analyzer do that this FFT will not do. Thanks dwight, N7KBC
Hello w2aew, first of all thank you for all the information that you are sharing here. This is very useful. I was wondering if you have any video regarding the basics of delta-sigma modulators (steps like calculating filter coefficients, R and C values, plotting ffts in scope, etc). Thanks.
Would this tds2000 have enough resolution to check the harmonics on a 220Vac (60Hz) signal? I mean... The harmonics would be on 120hz... 180hz... 240hz... Would it be able to present a lower frequency in the horizontal scale to use the cursor to check the magnitude of each low frequency harmonics?
Tony T. Sure, just use an RF Sampler (see my videos on that). Beware though, the scope FFT will be limited to about 45dB of spur free dynamic range or so - making it difficult to resolve some distortion components from the transceiver.
Hi Alan, a short while ago I asked you about a problem I was having with my THS720A (old) DSO at work. I said it was traversing the screen in bursts. When in roll mode or a slow time base the trace would leap frog across the screen. You said you didn't know why this would happen but would ask around at work to see if anyone had any ideas. I found the answer yesterday. The scope was producing a trace and I had 4 measurements displayed on the right of the screen (max) 2 for each channel. It was the displaying of these measurements that was the cause. I deleted them and the trace moved normally. I thought you might be interested to know this. Thanks for great videos by the way.
+Michael Hawthorne Oh, very interesting. I guess the processing delay in the creating the measurements paused the waveform scrolling or something like that. Weird.
Hey Alan, could FFT be used as an audio analyzer (20hz-40khz) or THD? I believe it's possible as I've been playing around with my scope and it seems to work pretty darn good, I use it for crossover points; boost @certain fhz; adding odd harmonic components "THD"?... I enjoy your tutorials, thanks for sharing.
***** It's not for accuracy, its more just as a reference. I measure the xover filter points with sine waves and same for the fhz boost. As for the THD measurements I do have an old HP 333A, just haven't powered it up in a while. Any experience on those measuring units?
in fft mode you are scanning DC to max. supporting Frequency, do you have any antenna or the incoming waves come to BNC connector without antenna? (the red graphs am talking about)
very goodt it seens it us not one signal! it is range of signals, with different power strength! some graph are high some low, you mean your Function generator will make range of frequency? if yes it is Sweep or other modulation let US. know. thanking you in advanced.
A signal from a function generator can have many different frequency components simultaneously. Distortion in a sinewave will show up as harmonic frequency content. Other signal types have different frequency content - for example, a squarewave has frequency content at the fundamental and odd harmonic frequencies.
I do not understand the amplitude. If i watch on your scope it shows approx 65dBV. You said that your input is 2v pk-pk, so that means 0.707 Vrms. How to interpret those 65dbV?
+dancdt I don't know where you see 65dBV. The vertical scale is relative for the FFT on this scope, so you have to use cursors to get the actual value. 0.707Vrms is -3dBVrms, and this is shown at about the 10 minute mark in the video.
+w2aew thank you for answering. I was thinking that the bottom was 0 dB, so I watched wrong, when in reality 0 dB is between the 7 and 8 division of the vertical axis. Thank you very much for the reply
+dancdt You can use the vertical position control to move the FFT math trace up or down, so there really isn't an absolute reference on the screen (thus, you need to use the cursors)
Hi Alan, is it possible to use external function generator to sweep and using FFT of an oscillscope to see the response of a low or high pass filter and get that nice corner frequency like your video #106 at 2:21 . Thanks
+Daniel Ditko Not unless your scope includes a feature to give you a "Max Hold" function on the FFT result. Not many scopes do that. In order to do this with a scope FFT, you'll likely need to use a broadband noise source as an input signal. I do this technique in video #128 where I use a scope FFT to measure the frequency response of different filters in an HF receiver. The measurement starts at about the 7:12 mark in this video: th-cam.com/video/_z2pglvBWg4/w-d-xo.html
Now the real trouble is: noise measurement I did \ tried noise measurements and failed to understand: whether it is possible (must be), how to convert dBm to nV/squrt(Hz), where to put the cursor. I did consider: limiting BW, discrepancy between actual to displayed parameters, 8\10 bit resolution I know that there are many other things to consider but I do not need exact results. Could you put that DSO aside a spectrum analyzer and measure the same signal ?
0MoTheG I'm thinking about doing a video on the comparison and trade-offs of a scope FFT vs. a spectrum analyzer... Food for thought for a future video.
Your "copy of the notes pages" link takes me to www.qsl.net/w2aew/#link which seem to have your notes. What is an updated URL? Never mind. Found it here: www.qsl.net/w/w2aew//youtube/FFTonTDS2000.pdf
Today I struck gold in my university's electronic waste bin, a TDS 2014B! Other than channel 2 being defect it is working perfectly, even the clock was still correct. I already have a 20 MHz analog scope that is great for most of my everyday low/medium frequency applications, but especially for debugging digital systems a digital scope is very handy. Happy to see you have it as well and have some videos using it.
Stellar job explaining FFT and the points involved. Fantastic
Very well explained, sharp and clear, as usual.
Thank you very much for the video.
Yepp
This video answers the question "why mere mortals can not even dream of getting hired by tek". Simply teaching talent on loan from God, as someone I recently lost used to say
Thanks for this! Well done, clear and concise. It is obvious that you put a lot of thought and work into these.
This was awesome. I got my EE degree back in 1984 (UT Austin). I remember doing the math for the FFT but never really understood them. This was an excellent tutorial. Thanks!!!
Glad you enjoyed it. We're about the same age - got my EE in '85.
I'm not going to pretend I totally understood this video, but half way through I looked up what RMS is now I know. All ways interesting and well presented videos, again add to watch later when I'm more informed. thank you.
Alan, Thanks for the video. This is exactly what I was looking for.
Excellent addition to a fantastic series of very educational videos. Thank you.
Thanks for the great explanation.
Oh cool! I just used my iPad 'Audio Tool' app to generate white noise. I ran that into my Behringer Mixer. And from the mixer into my TDS2014B. Now I can see what the Low, Mid, and High EQ controls REALLY do. I used a BNC to RCA adapter for the scope CH1 connector. Works great. Thanks for the video.
Great application!
Excellent! I have been looking for this video
I have this very scope at home. Even though I've used the FFT functions, I still picked up a very tips. Thanks! Brett/KA7CGB
Great, informative, clear video.
Thank you for the math explanation at the end
Hi Alan, thanks a lot . That is great and very useful technique !
Thank you so much for this video. You are a legend
awesome video! Thank you!
I only just caught up with this video. I half know what the FFT function was for, but this video really helped to make things clear. BTW the link to the note pages doesn't work anymore. Thanks for this.
I fixed the link for the notes pages: www.qsl.net/w2aew/youtube/FFTonTDS2000.pdf
Thanks, great class.
Thanks Alan. Great informative video.
This is very useful. very clear. Loved it
Very good Alan, I am not a lucky owner of those nice scopes having all the nice Gismo's But it was interesting to know what it is and the meaning of when I listen to other groups having those features.Like always very interesting and reason to listen to very well explained Tks for the Efforts 73's Alan
Thanks again Alan for another great video, you always make it look so simple! 73 - Dino KL0S
Great Video, I learned a lot!
Thanks!
Great video. Thanks Alan.
Very good Alan, thanks a lot. this is great
Thanks a lot I learned a lot
Thanks for the great tutorial. 👍✊
Great, great, great! Thanks
Alan thanks for this video also thanks to share those helpful informations.
Aloud to suggest to prepare a tutorial for baluns,in past you teach us how we can wind a triffilar choke now if you find time teach us the way to apply them on transmission line..
Best regards Kostas. .
Alan,
Excellent video, good in depth tutorial on using the scope controls. May I suggest you do a part 2 video and talk about the limitations of using the scope FFT as compared with a spectrum analyzer. Show some more complex signals that would have more components. Possibly some real world signals like a HF or VHF ham TX signal, audio waveform, etc. What can a low end spectrum analyzer do that this FFT will not do.
Thanks
dwight, N7KBC
Dwight Merkley All good topics - fuel for future videos.
@@w2aew very good suggestion, I never found a video about this comparison. FFT vs SA
Hello w2aew, first of all thank you for all the information that you are sharing here. This is very useful. I was wondering if you have any video regarding the basics of delta-sigma modulators (steps like calculating filter coefficients, R and C values, plotting ffts in scope, etc). Thanks.
Would love to have one of those scopes.
Great video thanks.
EXCELLENT
Can the Tektronix TDS2000 oscilloscope analyze frequencies from 10Hz - 2MHz?
Would this tds2000 have enough resolution to check the harmonics on a 220Vac (60Hz) signal? I mean... The harmonics would be on 120hz... 180hz... 240hz... Would it be able to present a lower frequency in the horizontal scale to use the cursor to check the magnitude of each low frequency harmonics?
Hello sir need to learn fully use of ociliscop .how to use in mobile phone PCBA repair
Thank you for this informative video!
Can FFT someway be safely coupled to check signal quality from a transceiver?
Tony T. Sure, just use an RF Sampler (see my videos on that). Beware though, the scope FFT will be limited to about 45dB of spur free dynamic range or so - making it difficult to resolve some distortion components from the transceiver.
***** Thank's!
Thanks sir
In FFT magnitude scale, Red arrow mark - on Y axis does not indicate 0dB. What does it indicate? Why is so?
The red arrow on the Y axis is the vertical scale expansion reference point. If you adjust the vertical scale, it expands/contracts around this point.
Hi Alan, a short while ago I asked you about a problem I was having with my THS720A (old) DSO at work. I said it was traversing the screen in bursts. When in roll mode or a slow time base the trace would leap frog across the screen. You said you didn't know why this would happen but would ask around at work to see if anyone had any ideas.
I found the answer yesterday. The scope was producing a trace and I had 4 measurements displayed on the right of the screen (max) 2 for each channel.
It was the displaying of these measurements that was the cause. I deleted them and the trace moved normally.
I thought you might be interested to know this.
Thanks for great videos by the way.
+Michael Hawthorne Oh, very interesting. I guess the processing delay in the creating the measurements paused the waveform scrolling or something like that. Weird.
can you please explain how can we calculate THD from this FFT analysis ??
Sure, here's a video on that: th-cam.com/video/s_cVP5gu4SY/w-d-xo.html
Great
Hello, why Fmax is 1/2 of the sample_rate?
Hey Alan, could FFT be used as an audio analyzer (20hz-40khz) or THD? I believe it's possible as I've been playing around with my scope and it seems to work pretty darn good, I use it for crossover points; boost @certain fhz; adding odd harmonic components "THD"?... I enjoy your tutorials, thanks for sharing.
You just have to be careful, since you generally can't expect much more than 45-50dB of spur free dynamic range from a scope preamp/ digitizer.
***** It's not for accuracy, its more just as a reference. I measure the xover filter points with sine waves and same for the fhz boost. As for the THD measurements I do have an old HP 333A, just haven't powered it up in a while. Any experience on those measuring units?
jeanious2009 OK, good, so long as you understand the limitations. I don't have any experience with the 333A.
can this oscilloscope be used to find the resonant frequency of a coil?
Look for my video regarding self-resonance.
Man I just want to ask something i have the same scope that you are using but my firmware is 4.2 how did you updated it do you remember?
If yours is a non-letter suffix model like mine (not a B or a C suffix), then firmware can only be done at a service center, as far as I know.
@@w2aew thanks for the reply man appreciate about your comment.
in fft mode you are scanning DC to max. supporting Frequency, do you have any antenna or the incoming waves come to BNC connector without antenna? (the red graphs am talking about)
I have a signal coming from my function generator.
very goodt it seens it us not one signal! it is range of signals, with different power strength! some graph are high some low, you mean your Function generator will make range of frequency? if yes it is Sweep or other modulation let US. know. thanking you in advanced.
A signal from a function generator can have many different frequency components simultaneously. Distortion in a sinewave will show up as harmonic frequency content. Other signal types have different frequency content - for example, a squarewave has frequency content at the fundamental and odd harmonic frequencies.
I do not understand the amplitude. If i watch on your scope it shows approx 65dBV. You said that your input is 2v pk-pk, so that means 0.707 Vrms. How to interpret those 65dbV?
+dancdt I don't know where you see 65dBV. The vertical scale is relative for the FFT on this scope, so you have to use cursors to get the actual value. 0.707Vrms is -3dBVrms, and this is shown at about the 10 minute mark in the video.
+w2aew thank you for answering. I was thinking that the bottom was 0 dB, so I watched wrong, when in reality 0 dB is between the 7 and 8 division of the vertical axis. Thank you very much for the reply
+dancdt You can use the vertical position control to move the FFT math trace up or down, so there really isn't an absolute reference on the screen (thus, you need to use the cursors)
Hi Alan, is it possible to use external function generator to sweep and using FFT of an oscillscope to see the response of a low or high pass filter and get that nice corner frequency like your video #106 at 2:21 . Thanks
+Daniel Ditko Not unless your scope includes a feature to give you a "Max Hold" function on the FFT result. Not many scopes do that. In order to do this with a scope FFT, you'll likely need to use a broadband noise source as an input signal. I do this technique in video #128 where I use a scope FFT to measure the frequency response of different filters in an HF receiver. The measurement starts at about the 7:12 mark in this video:
th-cam.com/video/_z2pglvBWg4/w-d-xo.html
Now the real trouble is: noise measurement
I did \ tried noise measurements and failed to understand: whether it is possible (must be), how to convert dBm to nV/squrt(Hz), where to put the cursor.
I did consider: limiting BW, discrepancy between actual to displayed parameters, 8\10 bit resolution
I know that there are many other things to consider but I do not need exact results.
Could you put that DSO aside a spectrum analyzer and measure the same signal ?
0MoTheG I'm thinking about doing a video on the comparison and trade-offs of a scope FFT vs. a spectrum analyzer... Food for thought for a future video.
I for one would be highly interested in the topic for one is tempted to misuse a DSO for a SA.
@@w2aew 2x same suggestion, excellent.
The update rate of the Tektronix TDS2000 is pretty fast.. is the processing done in hardware?
***** It is only doing a 2048 point FFT, providing a 1024 point result. I believe it is being done in firmware.
***** Thanks! I own a DS2072A and its very slow (FFT done in software)
Your "copy of the notes pages" link takes me to www.qsl.net/w2aew/#link which seem to have your notes. What is an updated URL? Never mind. Found it here: www.qsl.net/w/w2aew//youtube/FFTonTDS2000.pdf
ane plyn ynna