Memdepth : It´s manual selectable...That sounds very promising. Does it always stay that way?AFAIK this is misunderstanding or careless expression. (nice to see you also ask this question even when you know answer already)I don't know the answer and that is why I ask the question. To me it is utterly and totally unclear on whether this oscilloscope can be set to have a fixed memory depth or not (without needing to resort to workaround by using zoom mode c.q. even if that results in data being outside of the display). The original incarnation of this oscilloscope would revert back to automatic memory depth in many cases which was very annoying. In later incarnations the memory depth seems to be always automatic according to your information. Waiting for Martin to (finally) get a clear answer on this topic....
Or perhaps you think this can just change suddenly as some random small FW fix... No.
On the RTB you can say 10(20)M memory and even at 1ns timebase it'll capture that amount of memory at 2.5gs/s. So you can single capture then pull the timebase out and see more data.
For me it seems "normal" that memdepth will reduce the shorter the timebase is.
Before the asian low cost scope came up, I´ve done measurings with lecroy models only, so I don´t care about the memdepth "problem" of the siglent.
But....
Having 200mpts memory is somekind of worthless, when you can use it very limited.
You only got it in ms-ranges….
The selectable maximum memdepth is only vaild for slower timebases - above it´s functionless….
Before the asian low cost scope came up, I´ve done measurings with lecroy models only, so I don´t care about the memdepth "problem" of the siglent.
But....
Having 200mpts memory is somekind of worthless, when you can use it very limited.
You only got it in ms-ranges….
The selectable maximum memdepth is only vaild for slower timebases - above it´s functionless….Why? I'm not suggesting it is a good thing.. but if you want to record all that data why not zoom out, capture and zoom back in.
This is the point where I get a little bit confused today.
Obviously lecroy, a "A-Brand", does the memory thing handle like siglent ( and for what they´re "blamed") for decades.
I did a capture of a 1Mhz sine in ms-range and zoomed in with no problems because 200mpts memory was active.
But in reverse this wouldn´t go on the siglent because of the memory decreasing.
Is this a really problem....
All lecroy models [...] got one thing in common:
Same behaviour as the siglent scope….memdepth will decrease when the timebase becoming shorter.
My Tektronix MDO3k seems to capture the full memory depth that you set regardless of time-base. I guess that is the point to setting the memory in the first place.. since that setting would serve no purpose if it was time-base dependent.
Of course you could argue whether acquiring offscreen data after the trigger event is always more interesting than offscreen data before the trigger event. So if capturing offscreen data was supposed to be an important feature, you'd also need a setup that allows to somehow define a maximum pre/post trigger offset. I would think that no scope on the market offers something like that.
This is the point where I get a little bit confused today.
Obviously lecroy, a "A-Brand", does the memory thing handle like siglent ( and for what they´re "blamed") for decades.
I did a capture of a 1Mhz sine in ms-range and zoomed in with no problems because 200mpts memory was active.
But in reverse this wouldn´t go on the siglent because of the memory decreasing.
Is this a really problem....
1. Time offset mode from center of screen.
2. Fixed horizontal (memory/display) position mode and because display width from left border to right border in Siglent = acquisition length aka memory length it can say that trigger can set to fixed position in currently used memory length. Of course if then user do other settings and memory length change its proportional position in memory length stay same. With this feature it can set even for " analog scope" style where trigger stay start of sweep (exept amount of fixed (if not adjustable in some specials...) trig delay what normal analog scopes have)
1. Time offset mode from center of screen.
2. Fixed horizontal (memory/display) position mode and because display width from left border to right border in Siglent = acquisition length aka memory length it can say that trigger can set to fixed position in currently used memory length. Of course if then user do other settings and memory length change its proportional position in memory length stay same. With this feature it can set even for " analog scope" style where trigger stay start of sweep (exept amount of fixed (if not adjustable in some specials...) trig delay what normal analog scopes have)
Do you mean when Delay displayed in the top left corner (see attached picture)? Hmm, this sounds great then.
It would be good to know which model/firmwares support this.
All lecroy models [...] got one thing in common:
Same behaviour as the siglent scope….memdepth will decrease when the timebase becoming shorter.The better Lecroys (e.g. Waverunner 6zi) offer a selection between "Maximum Memory" and "Fixed Sample Rate" (in real-time sampling mode).
In the "maximum memory" setting, you select the "maximum sample points" and the scope adjusts the sample rate when changing the time scale (or pre/post trigger delays) to make use of the given sample points.
In the "fixed sample rate" setting, you select the sample rate which is kept whatever time base you select.
Anyway, note that when using a fixed memory length, even if this means that your record length is ten times longer that what you seen on the screen, this also decreases the update rate and increases the dead time. So while it can be handy to force a scope into doing so, this is usually not what you want as only or even default setting in normal trigger mode. In single trigger mode though, there is no real reason to not fill the whole memory. So when comparing the behavior of different scopes, the trigger mode could make a difference.
Of course you could argue whether acquiring offscreen data after the trigger event is always more interesting than offscreen data before the trigger event. So if capturing offscreen data was supposed to be an important feature, you'd also need a setup that allows to somehow define a maximum pre/post trigger offset. I would think that no scope on the market offers something like that.
And Keysight proves that it is perfectly possible to have high update rates AND deep memory at the same time.
And Keysight proves that it is perfectly possible to have high update rates AND deep memory at the same time.Keysight own Salesmens University have perhaps own basic math book. 1M memory need one M samples to fill. If sampling speed is 1GSa/s it takes 1ms and even with zero blind time (impossible) 1kwfm/s. But when deep memory is selected and scope is running for high update rates it can not capture deep memory, but salesmens forget to tell it.... Yes there can do example last acquisition trick.... and fool users (I do not know what is Keysight salesmens trick for this).
But how about deep full mem measurements during this high speed update rate with deep memory, how salesmens jump over this lazy fox. Oh... they never promised...
1. Time offset mode from center of screen.
2. Fixed horizontal (memory/display) position mode and because display width from left border to right border in Siglent = acquisition length aka memory length it can say that trigger can set to fixed position in currently used memory length. Of course if then user do other settings and memory length change its proportional position in memory length stay same. With this feature it can set even for " analog scope" style where trigger stay start of sweep (exept amount of fixed (if not adjustable in some specials...) trig delay what normal analog scopes have)
Do you mean when Delay displayed in the top left corner (see attached picture)? Hmm, this sounds great then.
It would be good to know which model/firmwares support this.