EEVblog Electronics Community Forum

Products => Test Equipment => Topic started by: xcalibur on June 19, 2021, 09:10:15 am

Title: UNI-T UTG962 - How do I generate an AC signal with a 0V "pulse"
Post by: xcalibur on June 19, 2021, 09:10:15 am
This one is breaking my brain a bit, and I hope you guys can help.

I want to generate a 2.4Vpp, 50Hz sinewave with a 0V "pulse" for 80ms every 3 seconds.  (Basically, a continuous sinewave that stops (0V) for 80ms every 3 seconds)

Is this possible using the UTG962 / arbitrary capability of the UTG962?
Title: Re: UNI-T UTG962 - How do I generate an AC signal with a 0V "pulse"
Post by: tttonyyy on June 19, 2021, 03:43:12 pm
Have you tried looping the second channel output to the TTL level FSK input on the side and using that second channel signal to "gate" the first one?

I don't own one of these but I've been reading about them with a view to purchasing. If I ever figure out what the difference is between UTG962 and UTG962E.
Title: Re: UNI-T UTG962 - How do I generate an AC signal with a 0V "pulse"
Post by: 2N3055 on June 19, 2021, 04:23:28 pm
This one is breaking my brain a bit, and I hope you guys can help.

I want to generate a 2.4Vpp, 50Hz sinewave with a 0V "pulse" for 80ms every 3 seconds.  (Basically, a continuous sinewave that stops (0V) for 80ms every 3 seconds)

Is this possible using the UTG962 / arbitrary capability of the UTG962?

You AM modulate 50 Hz carrier with a pulse that has shape of 0 for 80 ms and some voltage for 2,92 sec..
I don't know if UTG962  can do that (internally or using second channel looped into external modulation input) but that is how you do it...
Title: Re: UNI-T UTG962 - How do I generate an AC signal with a 0V "pulse"
Post by: tttonyyy on June 19, 2021, 05:38:48 pm
From the manual, internal modulation by square wave is fixed at 50% duty cycle. It's unclear if the external FSK modulation can be set for frequencies that result in the carrier being 0Hz for a while, or if you can have a 0Hz carrier (maybe 1uHz) modulated up to 50Hz.
Title: Re: UNI-T UTG962 - How do I generate an AC signal with a 0V "pulse"
Post by: 2N3055 on June 19, 2021, 09:02:48 pm
From the manual, internal modulation by square wave is fixed at 50% duty cycle. It's unclear if the external FSK modulation can be set for frequencies that result in the carrier being 0Hz for a while, or if you can have a 0Hz carrier (maybe 1uHz) modulated up to 50Hz.
Use external AM modulation then if it exists...
Title: Re: UNI-T UTG962 - How do I generate an AC signal with a 0V "pulse"
Post by: tttonyyy on June 19, 2021, 09:49:26 pm
Use external AM modulation then if it exists...

It's FSK only on a TTL logic input.
Title: Re: UNI-T UTG962 - How do I generate an AC signal with a 0V "pulse"
Post by: DL2XY on June 20, 2021, 10:38:28 am
You don't need fancy modulations or second channels, just use burst with 2920ms (or 146 cycles) ontime in 3000ms period.

Title: Re: UNI-T UTG962 - How do I generate an AC signal with a 0V "pulse"
Post by: tttonyyy on June 20, 2021, 11:03:53 am
Now I'm sold on buying one of those.

Since you're familiar with it, is there any way to make it single burst N cycles on an external trigger?
Title: Re: UNI-T UTG962 - How do I generate an AC signal with a 0V "pulse"
Post by: xcalibur on June 20, 2021, 08:29:21 pm
Looks like I have a lot more studying to do. Up until recently I "faked" signals using my old trusty Arduino, simply programming the signals (or close to the signals) I wanted. I decided to get a dedicated signal generator to make this part of my tinkering easier.

Your comments definitely gave me some direction and made me realise that, other than the straightforward configuration of signals via the UI, I really have to delve deeper into how this all works, i.t.o external triggers etc. 

@DL2XY - Now that looks like an interface I can work with. Yes, the UTG962 comes with some software, but it doesn't look anything close to what you get with the Siglent (as per your screenshot). My initial thought was also "burst", but I simply can't find a burst feature in the software. I've downloaded a simple sinewave signal in CSV format (using the Uni-t software) and I'm trying to see if I can modify it to do what I need it to do. 

So, talking as a complete sig-gen noob, what would you guys recommend I do to generate that signal?


Title: Re: UNI-T UTG962 - How do I generate an AC signal with a 0V "pulse"
Post by: tttonyyy on June 20, 2021, 09:04:44 pm
Ah, looking at DL2XY's post history, he is using a SDG6052X which is ~40x more expensive than the UTG962, so I suspect offers features that the Uni-T device doesn't - like bursts within a period.
Title: Re: UNI-T UTG962 - How do I generate an AC signal with a 0V "pulse"
Post by: bdunham7 on June 21, 2021, 12:07:24 am
So, out of boredom and curiosity, I tried some of mine.  The Siglent SDG2042X will do this easily (burst mode--I have literally never pressed that button until today) and the FeelTech FY6900 will do it with a few more button pushes using the burst modulation feature and a pulse on CH2 as the trigger set to 00,000.000,333,333kHz, in typical FeelTech fashion.  Any PC with a line or speaker out should do this as well with the right software. 
Title: Re: UNI-T UTG962 - How do I generate an AC signal with a 0V "pulse"
Post by: tttonyyy on June 21, 2021, 10:00:53 am
The PC is a good idea.  Though on mine there must be some hardware output filtering as this is supposed to be silent for 4 cycles (80ms) starting at a zero crossing.   :o
Title: Re: UNI-T UTG962 - How do I generate an AC signal with a 0V "pulse"
Post by: ledtester on June 21, 2021, 10:54:36 am
Quote
Any PC with a line or speaker out should do this as well with the right software.

Here's some example Python code to generate a WAV audio file:

https://stackoverflow.com/a/33913403/866915

Then just play the file with any audio player.
Title: Re: UNI-T UTG962 - How do I generate an AC signal with a 0V "pulse"
Post by: xcalibur on June 21, 2021, 01:07:41 pm
Been in contact with UNI-T support and their response was:

"UTG962E has no burst function. Our UTG2000A, UTG2000B, UTG4000A series have burst function."

So it looks like I'll be hand-coding a CSV file to achieve this using the UTG962. (My knowledge on the subject is definitely letting me down)

I'll play around with this later, for now the WAV file is probably the quickest method. Thanks @ledtester