Siglent SDS800X HD 12 bit DSO's

[rf-loop]

Thank you for the list.  But it confuses me to no end.  For example, take the Siglent PP215 probe.  Siglent advertises it as 6Mhz Bandwidth with no attenuation and 200 Mhz with 10x attenuation. (https://www.tequipment.net/Siglent/PP215/Standard-Passive-Oscilloscope-Probes/)   But your list shows it with 200 Mhz bandwidth, which I presume is only for 10x attenuation.  In other words, your list does not show the bandwidth at 1x attenuation.  Is that correct?

Yes.

Tip capacitive loading is such that only low impedance signal sources can overcome the loading at 1x without impact on waveform integrity and for higher BW use it is normal to use a 10x probe/setting that imposes low loads (pF's) which affects signal integrity much less.
There is much truth in the statement every measurement affects the measurement.

Many only use probes on 10x for this very reason.

I would like to add to this (for @whodiini) that when talking about the frequency range of the probe, we need remember that it is relative to the impedance of the source being measured.
If the bandwidth of the measuring head is said to be, for example, 6MHz with 1:1 attenuation. It is not really independent of the "source impedance" of the measured signal. If the source impedance were 25 ohms, you would get a completely different frequency range than if the source impedance were 1000 ohms or if it were 2 ohms. The frequency response of oscilloscope probes is typically specified for a 25 ohm source impedance.
The reactance of the probe does not change. When the source impedance of the measured signal changes, the frequency response also changes.

Here I mention the Keysight N2870A probe. It's a 1:1 probe. Its capacitance is stated to be 39pF and its frequency range is stated to be 35MHz. It's not exactly cheap either. DC impedance 1Mohm when connected to the oscilloscope's 1M ohm input.
I note here that the 39pF reactance is of the order of 116ohm at a frequency of 35MHz. That also gives some direction.

Siglent normal probes input capacitance is around 85 - 120pF when 1:1
In practice they -3dB BW is more than 6MHz
Just measured one individual random Siglent PB470 (10x 70MHz probe)
1x it has -3dB point around 10MHz measured from source impedance 25ohm

[mawyatt]

When it comes to scope probes one thing that might not be obvious to the casual observer/user is what capacitance you "see" at the probe tip at 1X is effectively the cable and scope input capacitance in parallel.

To put this in perspective, if one considers using a 1.2 meter RG58 cable (typical scope probe/cable length) as a "scope probe" connected to the scope (1Mohm/18pF), then expect to "see" 98pF (RG58 82pf/m) + scope input capacitance, or ~116pF at the cable end. That's quite a lot of capacitance to be hanging on a circuit being probed, and one might expect the circuit to "react" to this added "probe" capacitance and effect the measurements.

When using a 10X probe (or setting probe to 10X) one "sees" a much lower capacitance at the probe tip due to the complex passive network within the probe which "hides" the long cable capacitance, and the circuit/measurements benefit from less probe induced perturbations.

Best,

[mawyatt]

Had a few moments to play around with our new 814 and created a Curve Tracer for npn and pnp transistors and Bode Plot of Wein-Bridge RC filter.

The first plot shows an 2N3904 (npn) in both forward and reverse states, note the gain difference between forward and reverse!! Second is a 2N3906 (pnp).

Last plot shows the Wein-Bridge RC filter utilized in the classic Wein-Bridge Oscillator HP made famous. The R is 10K and the C is 0.01uF, so the peak should be ~1.59KHz and the peak amplitude should be 1/3 or -9.54dB.

Gotta love these little 12Bit Instruments Rigol and Siglent have introduced

Edit: Everyone's bitching about minor DSO details and such, the real issue is this damn site keeps scrambling the image inserts

Constantly having to go back and forth with editing to get the images corrected, when is this going to ever get fixed


Another edit: Just for fun used the Wein-Bridge RC network in a classic Wein-Bridge Oscillator. As shown it works like a charm and very close frequency to where the Bode Plot predicted

Best,

[tautech]

Edit: Everyone's bitching about minor DSO details and such, the real issue is this damn site keeps scrambling the image inserts

Constantly having to go back and forth with editing to get the images corrected, when is this going to ever get fixed

Nice work as always Mike.

For some things SMF is broken  however other forum SW can be worse. 
If like me you use Attachments/Choose File always omit the first and use only 'more attachments' and files will remain in the order uploaded.

[KungFuJosh]

Constantly having to go back and forth with editing to get the images corrected, when is this going to ever get fixed

Maybe it was fixed? The board's SMF version is 3 years out dated. 🤷

[tautech]

Constantly having to go back and forth with editing to get the images corrected, when is this going to ever get fixed

Maybe it was fixed? The board's SMF version is 3 years out dated. 🤷

IIRC Dave rolled it back as later version did not play well with some of the patches he'd installed. 
Then other patches later install provided a workaround for the Attachments bug: Drag n Drop etc.

[mawyatt]

Added Wein-Bridge Oscillator, see post #1127 above.

Best,

[Performa01]

I would like to know why the incorrect spelling of the well-known Wien bridge is so widespread in the English-speaking part of the world?

https://en.wikipedia.org/wiki/Wien_bridge

[whodiini]

Thank you for the list.  But it confuses me to no end.  For example, take the Siglent PP215 probe.  Siglent advertises it as 6Mhz Bandwidth with no attenuation and 200 Mhz with 10x attenuation. (https://www.tequipment.net/Siglent/PP215/Standard-Passive-Oscilloscope-Probes/)   But your list shows it with 200 Mhz bandwidth, which I presume is only for 10x attenuation.  In other words, your list does not show the bandwidth at 1x attenuation.  Is that correct?

Yes.

Tip capacitive loading is such that only low impedance signal sources can overcome the loading at 1x without impact on waveform integrity and for higher BW use it is normal to use a 10x probe/setting that imposes low loads (pF's) which affects signal integrity much less.
There is much truth in the statement every measurement affects the measurement.

Many only use probes on 10x for this very reason.

I would like to add to this (for @whodiini) that when talking about the frequency range of the probe, we need remember that it is relative to the impedance of the source being measured.
If the bandwidth of the measuring head is said to be, for example, 6MHz with 1:1 attenuation. It is not really independent of the "source impedance" of the measured signal. If the source impedance were 25 ohms, you would get a completely different frequency range than if the source impedance were 1000 ohms or if it were 2 ohms. The frequency response of oscilloscope probes is typically specified for a 25 ohm source impedance.
The reactance of the probe does not change. When the source impedance of the measured signal changes, the frequency response also changes.

Here I mention the Keysight N2870A probe. It's a 1:1 probe. Its capacitance is stated to be 39pF and its frequency range is stated to be 35MHz. It's not exactly cheap either. DC impedance 1Mohm when connected to the oscilloscope's 1M ohm input.
I note here that the 39pF reactance is of the order of 116ohm at a frequency of 35MHz. That also gives some direction.

Siglent normal probes input capacitance is around 85 - 120pF when 1:1
In practice they -3dB BW is more than 6MHz
Just measured one individual random Siglent PB470 (10x 70MHz probe)
1x it has -3dB point around 10MHz measured from source impedance 25ohm

Thank you.  Since you have so much knowledge, what would you recommend in my situation. I am trying to measure the noise level of some power supplies.  I understand that a standard way to measure is to put a load on the power supply, then measure the voltage across the load with a probe.  Noise measurements are typically taken to 20Mhz so I thought that a 1:1 probe with bandwidth to 20Mhz would be needed.  Then I put the scope in FFT mode, AC coupled mode. If I use a 10:1 probe then I lose 10x sensitivity.  Since I am measuring noise I want the most sensitivity as I can get. I was considering a single switchable probe so I could have multiuse, but other people recommend buying a 1x probe only because it would not have compromises that a switchable probe would. I am not really sure why I care whether the probe goes cleanly out to 20Mhz vs 6 MHz, since I am most interested in noise in the audio region (using these power supplies for audio equipment). 

[tautech]

If I use a 10:1 probe then I lose 10x sensitivity.

Yes but consider at max sensitivity using a 10x probe you will have a 5mV/div sensitivity and only if that is insufficient for your needs/measurement do you need use a 1x probe.

Typically a PSU rail cares little if you instead use a 1x probe as it is a stiff source that will not be loaded materially with a 1x probe.

[whodiini]

If I use a 10:1 probe then I lose 10x sensitivity.

Yes but consider at max sensitivity using a 10x probe you will have a 5mV/div sensitivity and only if that is insufficient for your needs/measurement do you need use a 1x probe.

Typically a PSU rail cares little if you instead use a 1x probe as it is a stiff source that will not be loaded materially with a 1x probe.

For linear regulated PSU, noise is typically .5mV so I do need at 1x probe to get down to .5mV/div. That is what makes a 12Bit DSO so nice. Some low noise PSUs claim .005 mV, which seems low to me. I would like to verify.

[tautech]

If I use a 10:1 probe then I lose 10x sensitivity.

Yes but consider at max sensitivity using a 10x probe you will have a 5mV/div sensitivity and only if that is insufficient for your needs/measurement do you need use a 1x probe.

Typically a PSU rail cares little if you instead use a 1x probe as it is a stiff source that will not be loaded materially with a 1x probe.

For linear regulated PSU, noise is typically .5mV so I do need at 1x probe to get down to .5mV/div. That is what makes a 12Bit DSO so nice. Some low noise PSUs claim .005 mV, which seems low to me. I would like to verify.

Quite difficult.
Eg, Siglent SPD1000X linear PSU's claim better than 350uV ripple and noise which even with a 1x probe and 500uV/div is difficult to quantify, yes I've tried. 

[rf-loop]

Thank you for the list.  But it confuses me to no end.  For example, take the Siglent PP215 probe.  Siglent advertises it as 6Mhz Bandwidth with no attenuation and 200 Mhz with 10x attenuation. (https://www.tequipment.net/Siglent/PP215/Standard-Passive-Oscilloscope-Probes/)   But your list shows it with 200 Mhz bandwidth, which I presume is only for 10x attenuation.  In other words, your list does not show the bandwidth at 1x attenuation.  Is that correct?

Yes.

Tip capacitive loading is such that only low impedance signal sources can overcome the loading at 1x without impact on waveform integrity and for higher BW use it is normal to use a 10x probe/setting that imposes low loads (pF's) which affects signal integrity much less.
There is much truth in the statement every measurement affects the measurement.

Many only use probes on 10x for this very reason.

I would like to add to this (for @whodiini) that when talking about the frequency range of the probe, we need remember that it is relative to the impedance of the source being measured.
If the bandwidth of the measuring head is said to be, for example, 6MHz with 1:1 attenuation. It is not really independent of the "source impedance" of the measured signal. If the source impedance were 25 ohms, you would get a completely different frequency range than if the source impedance were 1000 ohms or if it were 2 ohms. The frequency response of oscilloscope probes is typically specified for a 25 ohm source impedance.
The reactance of the probe does not change. When the source impedance of the measured signal changes, the frequency response also changes.

Here I mention the Keysight N2870A probe. It's a 1:1 probe. Its capacitance is stated to be 39pF and its frequency range is stated to be 35MHz. It's not exactly cheap either. DC impedance 1Mohm when connected to the oscilloscope's 1M ohm input.
I note here that the 39pF reactance is of the order of 116ohm at a frequency of 35MHz. That also gives some direction.

Siglent normal probes input capacitance is around 85 - 120pF when 1:1
In practice they -3dB BW is more than 6MHz
Just measured one individual random Siglent PB470 (10x 70MHz probe)
1x it has -3dB point around 10MHz measured from source impedance 25ohm

Thank you.  Since you have so much knowledge, what would you recommend in my situation. I am trying to measure the noise level of some power supplies.  I understand that a standard way to measure is to put a load on the power supply, then measure the voltage across the load with a probe.  Noise measurements are typically taken to 20Mhz so I thought that a 1:1 probe with bandwidth to 20Mhz would be needed.  Then I put the scope in FFT mode, AC coupled mode. If I use a 10:1 probe then I lose 10x sensitivity.  Since I am measuring noise I want the most sensitivity as I can get. I was considering a single switchable probe so I could have multiuse, but other people recommend buying a 1x probe only because it would not have compromises that a switchable probe would. I am not really sure why I care whether the probe goes cleanly out to 20Mhz vs 6 MHz, since I am most interested in noise in the audio region (using these power supplies for audio equipment).

How accurately and with what level of confidence do you need to measure.

If you start being really precise, the source impedance at different frequencies will also start to be taken into account. So many DC/Audio people might say that the impedance of the DC power supply is low. Yes, when looking at DC. Just to stimulate thought: 20cm 2.5mm diameter copper wire. Its self-inductance is about 200nH. Its inductive reactance is about 25 ohms at 20MHz frequency. But at DC its resistance is about 0.0007 ohm.

But as you told you are not doing "rocket science" level lab work.
------------

Back to hobby lab.

For linear regulated PSU, noise is typically .5mV so I do need at 1x probe to get down to .5mV/div. That is what makes a 12Bit DSO so nice. Some low noise PSUs claim .005 mV, which seems low to me. I would like to verify.

With SDS800X HD and normal passive probe you are in big difficulties with this kind of noise levels.

But before go further, why you need x1 normal probe. You can take example 50cm RG59 (or other 75ohm coaxial) and its capacitance is about 34pF and for this kind of frequencies and this purpose it can use instead of x1 probe. If you think its bandwidth it is sure better than normal 1/10 probe in x1 mode) (If use 50cm RG58 (50 ohm coax) it have higher capasitance, around 50pF.   If you can reduce length you reduce also capasitance what goes parallet with scope input cap.)

But then, you have other problem if you want really verify this level of noise. Even when SDS800X HD is very good in its base noise but now you talk about 0.005 mV(rms I think) noise. Perhaps using this scope and probe you can detect or somehow quess it is there. If you want measure it, well which one uou measure, oscilloscope or Device Under Test (DUT). And if not think this 0.005 mVpeak or rms..  even if think 0.5 mVpeak or rms still reliable measurement...

Lets looks some realities.

Here attached images.
Oscilloscope base noise (input open but most sensitive when probe is set for x10 and then set to x1.
There can see (of course) FFT drops 20dB and normal scope xt display stay same.
Then last image is (now more carefully measured) Siglent PB470 set for x1  frequency response when source impedance is 25ohm.
Swept from 150kHz to 60MHz. Probe tip "coaxially" (BNC - Probe adapter) connected to generator what have external 50ohm Tektronix feed thru in its output so source is now 25 ohm.






Probe set x1 (no probe connected, input open, 20M  BW)
If calculate these FFT levels to Vrms...  no need even try measure power supply 0.005mVrms... difficult to get any really reliable results.

But if do lot of work and then take this base noise FFT and then run other FFT same time (I have no time now to do demonstration if this may use but based to thinking it may be useful to try)
But you or someone can try: Channel 1  FFT just for reference (scope base noise)... and then Ch2 FFT (same settins) connected to DUT... perhaps it give some image about noise  levels over measured BW.

If look image there is FFT level -100 dBVrms. Level responds Sine wave about 28.3 uVpp,  10 uVrms. (0.01 mVrms)


But then, with good low noise preamplifier. With these can do lot of for these measurements - only "sky or money book is limit" how deep can go. 






Probe set x10 (no probe connected, input open, 20M  BW)
If calculate these FFT levels to Vrms...  this is whuy it can say. No way.
If look image there is FFT level -80 dBVrms. Level responds Sine wave about 282.8 uVpp,  100 uVrms. (0.1 mVrms)



Siglent PP470 probe set for x1, Scope BW FULL (200MHz) Signal Source "25 ohm".
Sweep from 150kHz - 60MHz.  FFT Window Flat Top.  FFT in Max-Hold mode.
Sweep time 600 sec.

If use this kind of probe and then FFT for analyze noise....  just then this response curve can use for corrections when need of accuracy is not so high

[egonotto]

I would like to know why the incorrect spelling of the well-known Wien bridge is so widespread in the English-speaking part of the world?

https://en.wikipedia.org/wiki/Wien_bridge

Hello,

es ist zum weinen. (in english: it makes you cry)

Best regards
egonotto

[mawyatt]

I would like to know why the incorrect spelling of the well-known Wien bridge is so widespread in the English-speaking part of the world?

https://en.wikipedia.org/wiki/Wien_bridge

Just my bad spelling as usual, always have mixed up "e" and "i"

Best,

[rf-loop]

When I previously told FFT can use so that one FFT is somehow as reference and other connected to DUT

Here is not going on any serious measurement. Just example how it may look.

F1 is as reference. FFT from Ch3 base noise. Ch3 have 50 ohm external termination (and forget it to DC coupling).
F4 is FFT from Ch4. Ch4 (1M ohm, AC coupling) is connected to some 24Vdc source using 80cm coaxial cable (like 1:1 probe).
Both FFT and both input channels all settings are equal. (note I forget Ch3 to DC)
FFT mode Max-Hold, 150 kHz to 60 MHz
If I disconnect this DUT both FFT looks "same".

[whodiini]

How accurately and with what level of confidence do you need to measure.

If you start being really precise, the source impedance at different frequencies will also start to be taken into account. So many DC/Audio people might say that the impedance of the DC power supply is low. Yes, when looking at DC. Just to stimulate thought: 20cm 2.5mm diameter copper wire. Its self-inductance is about 200nH. Its inductive reactance is about 25 ohms at 20MHz frequency. But at DC its resistance is about 0.0007 ohm.

But as you told you are not doing "rocket science" level lab work.
------------

Back to hobby lab.

For linear regulated PSU, noise is typically .5mV so I do need at 1x probe to get down to .5mV/div. That is what makes a 12Bit DSO so nice. Some low noise PSUs claim .005 mV, which seems low to me. I would like to verify.

With SDS800X HD and normal passive probe you are in big difficulties with this kind of noise levels.

But before go further, why you need x1 normal probe. You can take example 50cm RG59 (or other 75ohm coaxial) and its capacitance is about 34pF and for this kind of frequencies and this purpose it can use instead of x1 probe. If you think its bandwidth it is sure better than normal 1/10 probe in x1 mode) (If use 50cm RG58 (50 ohm coax) it have higher capasitance, around 50pF.   If you can reduce length you reduce also capasitance what goes parallet with scope input cap.)

But then, you have other problem if you want really verify this level of noise. Even when SDS800X HD is very good in its base noise but now you talk about 0.005 mV(rms I think) noise. Perhaps using this scope and probe you can detect or somehow quess it is there. If you want measure it, well which one uou measure, oscilloscope or Device Under Test (DUT). And if not think this 0.005 mVpeak or rms..  even if think 0.5 mVpeak or rms still reliable measurement...

Lets looks some realities.

Here attached images.
Oscilloscope base noise (input open but most sensitive when probe is set for x10 and then set to x1.
There can see (of course) FFT drops 20dB and normal scope xt display stay same.
Then last image is (now more carefully measured) Siglent PB470 set for x1  frequency response when source impedance is 25ohm.
Swept from 150kHz to 60MHz. Probe tip "coaxially" (BNC - Probe adapter) connected to generator what have external 50ohm Tektronix feed thru in its output so source is now 25 ohm.






Probe set x1 (no probe connected, input open, 20M  BW)
If calculate these FFT levels to Vrms...  no need even try measure power supply 0.005mVrms... difficult to get any really reliable results.

But if do lot of work and then take this base noise FFT and then run other FFT same time (I have no time now to do demonstration if this may use but based to thinking it may be useful to try)
But you or someone can try: Channel 1  FFT just for reference (scope base noise)... and then Ch2 FFT (same settins) connected to DUT... perhaps it give some image about noise  levels over measured BW.

If look image there is FFT level -100 dBVrms. Level responds Sine wave about 28.3 uVpp,  10 uVrms. (0.01 mVrms)


But then, with good low noise preamplifier. With these can do lot of for these measurements - only "sky or money book is limit" how deep can go. 




Probe set x10 (no probe connected, input open, 20M  BW)
If calculate these FFT levels to Vrms...  this is whuy it can say. No way.
If look image there is FFT level -80 dBVrms. Level responds Sine wave about 282.8 uVpp,  100 uVrms. (0.1 mVrms)

Siglent PP470 probe set for x1, Scope BW FULL (200MHz) Signal Source "25 ohm".
Sweep from 150kHz - 60MHz.  FFT Window Flat Top.  FFT in Max-Hold mode.
Sweep time 600 sec.

If use this kind of probe and then FFT for analyze noise....  just then this response curve can use for corrections when need of accuracy is not so high
[/quote]

This post was so informative.  What I take from it is 1) I dont need to get another probe, the PB470 that came with the Siglent will work just fine for me non-lab quality work. If I want to go beyond 6 Mhz to 20 Mhz, I can compensate with your response curve. 2) I do need a 1x probe - the PB470 will do fine.  I will make some measurements and post.  I dont quite understand your base noise curve.  What I did to get the base system noise was connect up to my power supply with the power supply off.  That means the probe was connected to the ends of a 25 ohm resistor and the noise level was much lower than your curve.  I will post later along with some power supply measurements.

[Bad_Driver]

Some years ago I also started as hobbyist with low noise measurements of power supplies.

A good starting point is the famous application note of Jim Williams (aka „Cookie Can“ setup)

https://www.analog.com/media/en/technical-documentation/application-notes/an83f.pdf

But this is another rabbit hole you will fall in…. But you will learn a lot.

[Mechatrommer]

If I disconnect this DUT both FFT looks "same".

you gave some real (or very close) example of real measurement, you deserve your nickname... i just would like to ask... are screen captures you provided from SDS800X HD? or from some other higher priced siglent's dso? (i'm impressed )

[rf-loop]

If I disconnect this DUT both FFT looks "same".

you gave some real (or very close) example of real measurement, you deserve your nickname... i just would like to ask... are screen captures you provided from SDS800X HD? or from some other higher priced siglent's dso? (i'm impressed )

The screenshots I present in this thread, unless otherwise specifically stated, are from the original SDS824X HD model.

[Martin72]

Can confirm this.
Plus: You can see it by the << >> arrows, this is something I never saw on SDS2k+ or 2K HD(because of the screensize I guess).

[rf-loop]

Some years ago I also started as hobbyist with low noise measurements of power supplies.

A good starting point is the famous application note of Jim Williams (aka „Cookie Can“ setup)

https://www.analog.com/media/en/technical-documentation/application-notes/an83f.pdf

But this is another rabbit hole you will fall in…. But you will learn a lot.

For many peoples who are starting these kind of works. 

an83f.pdf 

There is image 6a. Image description have very (very extremely) important sentence from "a true analog circuits guru" Jim Williams...  many, even educated and experienced peoples may drop to this trap...

[Martin72]

There is image 6a. Image description have very (very extremely) important sentence from "a true analog circuits guru" Jim Williams...  many, even educated and experienced peoples may drop to this trap...

Well, I fell into the trap.
And it took me almost a day to find out why.
But: once learned, always remembered.

[markone]

Hi folks,

i would need an idea of SDS 800 HD math / measure performance, a reference example could be the duty cycle analysis continously computed on full 2MSa buffers acquired @ 2MSa/s (1 second acquisitions) of 20KHz pulse width modulated signal, of course Track / Trend functions could be of interest if they cover every single pulse cycle.

I currently make use of a Picoscope 3203D with Picoscope 7 TM software, with a modest PC based on Ryzen 5600 the simple math function "duty(A)" works in realtime with acquisition buffers up to 10MS acquired @ 10MS/s, minimal specs are "almost" realtime readings with a 2MS acquisition @ 2MS/s.

I'm happy with Picoscope but there are cases where a stand alone scope would come in handy ... but only if cheap like the SDS800 HD 

I''m providing in attachment screenshots of Picoscope duty cycle analysis of 20KHz square wave pulse signal (sourced to Analog input A) modulated with 5Hz sine wave with two different acquisition settings, 2MSa @ 2MSa/s and  10MSa @ 10MSa/s, dunno if anyone here is able to perform the same task with an SDS800 HD checking if the DSO keep up the analysis in real time at least with 2MSa @ 2MSa/s.

Thanks in advance to anyone will dare to venture in this test 

[ebastler]

[...] checking if the DSO keep up the analysis in real time at least with 2MSa @ 2MSa/s.

How do you define and measure the "keeping up in real time"? Is your expectation that the waveform acquisition rate, determined by counting Trigger Out pulses, should not drop at all when you activate the Math function?

Maybe the Picoscope can achieve that since acquisition on the external unit and math computations and plotting on the PC happen in parallel. But I see little chance for the SDS800X HD, and probably most other integrated scopes.

Edit: Oh, momentary Duty Cycle is not an available math function on the 800X HD to my knowledge. So if that function is of particular importance to you, this scope is not for you. If it was just an arbitrary example -- care for a different one, say algebra, differentiation, integration of signals? 

Edit²: I stand corrected. Just tried a 1 second acquisition with 10 MPts (fixed sampling rate), and Sqrt(CH1) as a sample math function. Unless I got something wrong, the acquisition period, measured on the Trigger Out, is 1.076 seconds -- whether I enable or disable the Math function. I am impressed with that little scope!

Edit³: At 100 MPts, it's 1.302 second trigger period, whether math is on of off. Pretty neat!