Capturing a Frequency Sweep on a Digital Scope

Thread Starter

SamR

Joined Mar 19, 2019
1,293
I'm working on resonant circuits and breadboarding RLC filter circuits. I'm supplying Vs at 5V and sweeping the frequency. Placing one scope channel on the Vs input and 2nd on Vo output. Nice pretty sine waves increasing and decreasing in amplitude with frequency change on the scope. How do I capture and play that back w/ play/pause on the scope? Using a SigLent 1102CML+. Is there a way to download the capture to a flash drive? RTFM I know, but the manual tells you where the buttons are, not how to use them. Thanks.

Sam
 

Yaakov

Joined Jan 27, 2019
1,600
I'm working on resonant circuits and breadboarding RLC filter circuits. I'm supplying Vs at 5V and sweeping the frequency. Placing one scope channel on the Vs input and 2nd on Vo output. Nice pretty sine waves increasing and decreasing in amplitude with frequency change on the scope. How do I capture and play that back w/ play/pause on the scope? Using a SigLent 1102CML+. Is there a way to download the capture to a flash drive? RTFM I know, but the manual tells you where the buttons are, not how to use them. Thanks.

Sam
Pages 96 through 101 in the manual seem to lay out the recorder function very clearly. What are you having trouble with there?
 

Thread Starter

SamR

Joined Mar 19, 2019
1,293
OK... /Utility /Record /Mode:Record /Source:CH1,CH2,P/F-OUT?(CH 1or2 I get, not sure just what the pass fail is, but not needed ATM) Only 1 channel can record at a time? /Interval:1.00ms - 1000s how long? Interval for record frames, what is a record frame? /EndFrame:1-2500 (2500 is a LOT of knob twisting) how many record frames for a 10MHz sweep @ 50kHz/shot? 10M/50k=20? or a multiple of 20 for more than 1 sweep? /Operate:push to start, push again to stop got that one

That's just to start recording...
 

Thread Starter

SamR

Joined Mar 19, 2019
1,293
Actually, I am sweeping 100Hz to 10MHz over 60s, I was manually doing it in 50kHz jumps to record values on paper to plot...
 

Yaakov

Joined Jan 27, 2019
1,600
OK... /Utility /Record /Mode:Record /Source:CH1,CH2,P/F-OUT?(CH 1or2 I get, not sure just what the pass fail is, but not needed ATM) Only 1 channel can record at a time? /Interval:1.00ms - 1000s how long? Interval for record frames, what is a record frame? /EndFrame:1-2500 (2500 is a LOT of knob twisting) how many record frames for a 10MHz sweep @ 50kHz/shot? 10M/50k=20? or a multiple of 20 for more than 1 sweep? /Operate:push to start, push again to stop got that one

That's just to start recording...
What you are making is a Bode plot. Some scopes can do this automatically, but alas, this one can't.

P/F is a BNC connector on the back of your scope that allows you to set up conditions that will generate a pulse output if the parameters are met. It is for automated testing, I can be very useful when you need it.

Yes, it seems that scope can record the wave form on one channel.

The interval is effectively the frame rate. It specifies how often the snapshot will be taken.

The end frame is the last frame to capture. So, if you captured one frame per second for 60 frames that would be one minute of playback.

However, I think you might be better off using EasyScope software and the USB port to do waveform capture as you increment the sweep.
 

Yaakov

Joined Jan 27, 2019
1,600
Thanks Yaakov! Let me work on setting up Easyscope. Back later...
You'll have to install the LabView runtime stuff for communications. It's not obvious but if you read through the resources on Siglent's site, you'll find it.
 

Thread Starter

SamR

Joined Mar 19, 2019
1,293
You'll have to install the LabView runtime stuff
Tried that some time ago, but couldn't find a driver for the SigLent which is on the link you provided. Poked around some more on the US site and found it buried away in a not so obvious site. Back when I was googling for it I couldn't find it. After some more caffeine infusion I'll start work on it.
 

Yaakov

Joined Jan 27, 2019
1,600
Tried that some time ago, but couldn't find a driver for the SigLent which is on the link you provided. Poked around some more on the US site and found it buried away in a not so obvious site. Back when I was googling for it I couldn't find it. After some more caffeine infusion I'll start work on it.
Great, and also, look at @jpanhalt's link as well which might work for you.

The EasyScope is a good thing to have working anyway.
 

jpanhalt

Joined Jan 18, 2008
8,060
I used that method awhile back to tune some filters. One major thing it lacks is a frequency marker, but it is not hard to figure out at what frequency the peak is and the frequencies for half half height, if needed, by setting the cutoffs for your frequency generator.
 
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Thread Starter

SamR

Joined Mar 19, 2019
1,293
Looking further into the Siglent manual, I can save a .csv data file. This is the x,y coordinates of a waveform capture which can be input to a graphing application. I have looked at a couple, but any good recommendations for importing and plotting .csv data files? Preferably a free app.

Sam
 

Yaakov

Joined Jan 27, 2019
1,600
Looking further into the Siglent manual, I can save a .csv data file. This is the x,y coordinates of a waveform capture which can be input to a graphing application. I have looked at a couple, but any good recommendations for importing and plotting .csv data files? Preferably a free app.

Sam
If you just want to do something simple, a spreadsheet program will do it. You can use something like OpenOffice.

Alternatively, you can use gnuplot, but that requires programming and while it can do nice stuff, it might be more than you want to mess with.
 

Thread Starter

SamR

Joined Mar 19, 2019
1,293
Looked at gnuplot, it's a no-go. Spreadsheet plots are more designed for business graphics than scientific to me or they were years ago. Most of the free graphing software is for pre-college occasional homework. Then you get into MathLab and such which are not free... I'll keep looking... Or stick to my tried and true pencil and graph paper...
 

Yaakov

Joined Jan 27, 2019
1,600
Looked at gnuplot, it's a no-go. Spreadsheet plots are more designed for business graphics than scientific to me or they were years ago. Most of the free graphing software is for pre-college occasional homework. Then you get into MathLab and such which are not free... I'll keep looking... Or stick to my tried and true pencil and graph paper...
Many scientists and engineers use Excel to graph.
 

Thread Starter

SamR

Joined Mar 19, 2019
1,293
Yes, I'm playing w/ the latest version of Excel now and will use it since I already have it. It may have what I want hidden among all the bells and whistles since I haven't used it in many years. I'll just have to build a template... I am where I need to be for now. It's been a busy couple of days learning new tricks for this old dog. I had some funny things happening when I was manually ramping frequency and hand plotting so I need to do some more tinkering and analysis which started me down this path. I started at 100kHz @ 5VACpp and increased in 50kHz steps. I hit resonance at ~900kHz and then it plotted a straight line up to 1450kHz where I stopped. Now I want to get a good handle on it by automating the sweep, data collection, and plotting as much as I can with what I have. Thanks for all the help!
 

Yaakov

Joined Jan 27, 2019
1,600
Yes, I'm playing w/ the latest version of Excel now and will use it since I already have it. It may have what I want hidden among all the bells and whistles since I haven't used it in many years. I'll just have to build a template... I am where I need to be for now. It's been a busy couple of days learning new tricks for this old dog. I had some funny things happening when I was manually ramping frequency and hand plotting so I need to do some more tinkering and analysis which started me down this path. I started at 100kHz @ 5VACpp and increased in 50kHz steps. I hit resonance at ~900kHz and then it plotted a straight line up to 1450kHz where I stopped. Now I want to get a good handle on it by automating the sweep, data collection, and plotting as much as I can with what I have. Thanks for all the help!
Happy to help if I can. I hope you get some use out of EasyScope. It's not the most beautiful software but it's got some uses.
 
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