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Siglent SDS2000 new V2 Firmware

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Performa01:
Another Trigger Jitter Test.

I just came across a scenario which I thought might be worth sharing.

Fast Acquisition, Peak Detect, Sin(x)/x, 35Mpts.
Display Type Vectors.

Ch. 3: 60 MHz Sine, 1.2 Vpp
Ch. 4: 1 MHz Sine, 1.2 Vpp

Edge Triggering on CH. 4, rising edge, 20mV.

The first time I've ever seen some jitter on this scope, but that is to be expected when triggering on a really slow edge like this (Trig_Sine_Vectors):



We see a jitter of about 5ns, which is still very impressive!

The trigger edge rises less than 17mV within 5ns, so that is also the uncertainty of the trigger level, which in turn causes the jitter observed on the Ch. 3 waveform. As the vertical gain setting is 200mV/div; that means the uncertainty is just about 8% of a division, which in turn corresponds to exactly 2 LSB of the ADC. That is about as good as it gets.  :-+

Changing the signal on trigger channel 4 to a squarewave with a rise time of about 13ns, all the jitter disappears as expected (Trig_Square_Vectors):



This is just another proof  that the most important part of any scope – the trigger system – really is as good as it gets on the SDS2000.  :-+

tautech:

--- Quote from: Performa01 on December 16, 2015, 02:19:19 am ---XY Display.......

Once the signals are properly set up in Y-t mode, we can actually get a nice Lissajous figure in X-Y mode (XY_Display_2):
--- End quote ---
Dots?
I ask because the waveform looks "grainy"


--- Quote ---Couldn’t resist creating a new Siglent logo (XY_Display_3) ;)
--- End quote ---
:-+

Performa01:
History Display.

One of the really nice features on the SDS2000 is the history display. This is a very useful analysis tool as it allows the examination of not just the current screen but also a bunch of acquisitions that have been taken in the past. The good thing is it doesn’t need to be enabled explicitly, it’s just always there and can be accessed whenever it is needed.

Of course, for this feature to be useful we need deep memory, and that’s where the 35/70 Mpts now available with V2 FW really help. On the other hands, restricted acquisition modes like Average and Eres, where there is no memory available, are pretty much ruled out by that.

For this test I’ve just setup two arbitrary signals on channels 3 and 4 and used peak detect mode with max. memory.

Ch. 3: 50MHz, 1.2Vpp sinewave, 100% amplitude modulated at 1kHz.
Ch. 4: 10MHz, 1.2Vpp squarewave.

The first screenshot shows the signals in Run mode (Hist_Sig):



Once we hit Stop (or access the history menu, which also stops the scope), we can either manually scroll through the individual acquisitions or automatically playback the entire history buffer in either direction at almost any interval we like. In this scenario, we got 80000 history frames and we can turn on a list display that shows the history frames including number, timestamp and time difference of the respective acquisition.

In manual mode, we can just scroll through the list, which can be very time consuming if there are 80000 entries, just as in this scenario. The list as well as the screen display is updated accordingly.

Just two examples for manual mode:

First, I manually selected a random acquisition where the amplitude modulated signal on Ch. 3 was at a minimum (Hist_Display_Min).



Second is an acquisition where the amplitude modulated signal on Ch. 3 was at a maximum (Hist_Display_Max).



We can also start history playback in either direction and hit the pause button anytime, and then continue with manual mode for instance. Playback interval can be anything from 1µs up to 1s. This means the interval at which the individual history frames are displayed and of course 1µs isn’t a realistic number, as the scope just isn’t capable of displaying frames nearly as fast as 1 million per second. The fastest I could get was about 2000 frames per second, which means we can playback 80000 frames within some 40 seconds. The amplitude modulated waveform looks almost like in run mode, just the screenshot doesn’t exactly show that as the playback slows down a bit when hitting the print button (Hist_Playback).



BUG Alert: While playing with the history mode, I tried to playback the history buffer at maximum speed, i.e. with an interval setting of 1µs. Of course it wasn’t nearly as fast as that, and after several thousand frames, playback suddenly stopped and then scope would respond to keystrokes only with a lag of several seconds. History mode was not operative any more. See screenshot (Hist_Frozen).



After hitting the Run/Stop button, the scope came back to live after several seconds. I tried it one more time, and it happened again, even with an interval setting of 10ms. After several attempts I finally managed to get it to playback the entire history buffer at an interval of 10ms. I did not need to restart the scope to get there, but it happened again and again, so history mode certainly is not yet reliable in operation yet.


Conclusion:
Apart from the bug described above, I think history mode can be extremely useful in general and even though there is no means for quick navigation within the history buffer, i.e. a jump function or something similar, it is still very usable. 

rf-loop:

--- Quote from: Performa01 on December 16, 2015, 04:27:24 am ---
BUG Alert: While playing with the history mode, I tried to playback the history buffer at maximum speed, i.e. with an interval setting of 1µs. Of course it wasn’t nearly as fast as that, and after several thousand frames, playback suddenly stopped and then scope would respond to keystrokes only with a lag of several seconds. History mode was not operative any more. See screenshot (Hist_Frozen).

--- End quote ---

I can repeat this with next notes.

I can not repeat this if trigger source is CH1 or 2.
I can repeat this error if trigger source is CH3 or CH4

Independent of how many channels are acqured.
I'm not sure but looks like that also independent of history playback interval time setting.
Also looks like independent of if history playback display mode is dots or lines and Sin(x)/x on or off what also affect playback max speed.
Also looks like this problem is independent if math, including FFT or measurements or cursors are used in history playback mode or history is horizontally zoomed or horizontally shifted.
My rest life is not enough for test all possible settings combinations but strogly it looks this error is somehow connected to trigger source used in acquisition(?).
(also I have tested 1,2,3 or 4 channels on separately and 1+2 or 3+4 and also used every channel for trigger source. But every time if trigger source is CH3 or 4 in acquisition then history playback suddenly stop to random position and after then history freeze until run scope agen using run/stop or other things like default or autoset. (it looks like there is least less this problem if timestamp table is off during playback)


My version is
FW: 1.2..1.28.1
FPGA: 15.11.17-15.11.17-15.11.26
HW: 3-3
Model: SDS2304

Performa01:

--- Quote from: tautech on December 16, 2015, 03:03:04 am ---Dots?
I ask because the waveform looks "grainy"

--- End quote ---

Yes, it certainly was dots display, as this is my default setting.

I know, I could (should?) have changed it to vectors for the new Siglent Logo at least ;)

In general, I don't mind a little 'grain' and only switch to vectors display if it really is required to aid in visibility.

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