Spectrum analysis option on RTM3000 should use more advanced algorithms borrowed from realtime SA (R&S should know how that's done!) like overlaped FFT and many other tricks. I would be surprised if that one shows same problems.I'm hanging on the edge of my seat to see what Nico reports from his RTM3k. And expect to be jealous.
Spectrum analysis option on RTM3000 should use more advanced algorithms borrowed from realtime SA (R&S should know how that's done!) like overlaped FFT and many other tricks. I would be surprised if that one shows same problems.I'm hanging on the edge of my seat to see what Nico reports from his RTM3k. And expect to be jealous.No. I already did some tests on the RTM3004 and it shows exactly the same behaviour. The RTM3004 is pretty similar to the RTB2004 where it comes how the functionality is implemented.
No. I already did some tests on the RTM3004 and it shows exactly the same behaviour. The RTM3004 is pretty similar to the RTB2004 where it comes how the functionality is implemented.
The RTB2000 really needs the ability to manual control the sampling rate/timebase in the FFT mode, then there will be less problems. RTB reduces the sampling rate unacceptably low when narrowing the span, as a result, if I understand correctly, aliasing and the display of non-existent harmonics appear in some situations.
This is a payment for a user-friendly interface "like on a spectrum analyzer"
No. I already did some tests on the RTM3004 and it shows exactly the same behaviour. The RTM3004 is pretty similar to the RTB2004 where it comes how the functionality is implemented.
Do you mean the control of sampling rate in fft mode, or the spurs?
Ok, I made progress.
Something was wrong with the internal memory of the scope I guess.
I did a secure erase and times are now down to more reasonable values.
Have to do more tests.
Before I was stuck at 5ms/200Hz. I tried everything.
Boy this is implemented way too complicated.
I managed to capture now all segments. But you have to
- Have the record length in auto (ok, understood this, if you capture too much it takes too much time)
- Be in normal trigger mode (Why ?)
- Arm a single trigger
- Have the Nx set to larger or equal the number of expected segments.
- Have fast capture mode on (it does not work without even with my 10ms between segments)
I did not manage what you did in the second picture (RTB2004-PulseBurst-1-21-Sample.png), where there is 10ms delta and fast-capture off.
There, I get huge variations in trigger time.
Maybe activated measurements are to blame? They also need time and probably slow down the trigger.
Peter
@Goaty
Auto trigger mode is behaving EXACTLY as it should. It waits for trigger for some short time and then if there was no trigger event, it AUTO triggers without reason. It is equivalent of you pressing "force trigger" every few hundred milliseconds. To wait for trigger unconditionally you use NORMAL mode. (People get confused that AUTO means scope will magically discover appropriate trigger settings by itself. It doesn't. It simply takes blind capture every now and then. Purpose of that is that scope will show something on the screen even if you setup trigger wrong or there is no trigger event)
From RTB 2000 Manual:
"Auto" The instrument triggers repeatedly after a time interval if the trigger
conditions are not fulfilled. If a real trigger occurs, it takes precedence. This mode helps to see the waveform even before the trigger
is set. The waveform on the screen is not synchronized, and successive waveforms are not triggered at the same point of the waveform.
"Norm" The instrument acquires a waveform only if a trigger occurs, that is, if
all trigger conditions are fulfilled. If no trigger occurs, no waveform is
acquired and the last acquired waveform is displayed. If no waveform
was captured before, nothing is displayed.
I said on many occasions that it is unfortunate that what is called AUTO trigger should be called TIMEOUT trigger and there would be less confusion..
@Goaty
Segmented mode (fast one) is always single burst. How else would it be? You set it to capture 20 segments, and it does that and stops. Otherwise it wouldn't be 20 i you let it run forever. Also if you press SINGLE or RUN it is the same. It would capture next 20 trigger events (without screen updates) and then stop. On Keysight you can press SINGLE or RUN and it is the same.
When you use History mode (segmented with screen updates) retrigger time will be somewhat jittery. Reason is screen refresh, that happens on regular interval for screen, and it will make a scope "pause" a little while screen is being rendered. It takes time to take all that data from buffer, decimate it from megapoints to kilopixels and render it for screen. And those little "pauses" will happen at seemingly "random" intervals in correlation to your signal, because those two events are not correlated.
Because of that, there is "fast" segmented mode (one without screen updates) to make retrigger time and captures deterministic and as fast as possible.
And as Nico said, if you need retrigger time in msec, by the time you blink, you'll have hundreds of captured buffers already there waiting.
Thank you for clarifying this. I was under the impression that in Auto, if there is no trigger, I still see the waveform on the screen (capture), but it is untriggered all the time (like freerunning).
Also I do not see the trigger LED, which led me to believe, that also the history must therefore be NOT filled.
If I press SINGLE it captures what I set with Nx=..., then stops. If I press RUN, it does not stop for me, it runs continuously. Or did I misunderstand ?
I understand it will jitter because it´s probably not fully asynchronous, which it IMHO shuld be (acquisition and display processing),
but I was mislead by the "up to 50000wfms/s" which I have not been able to even closely reach.
It does not matter in most cases, but for trying to capture bursts with long pauses, one has to know the re-arm time, or use fast-capture. But then you have to know the Nx...
I guess I have a lot more reading and experimenting to do.
Thank you for taking the time to write !!