Just one question about these 'recorders' (actually just crude segmented memory)
Depends how you define it. 10 years ago it would be sufficient to have that kind of segmented memory implementation,
today it's not. Today segmented memory is not only a "recorder" capturing data based on interval you set, but on trigger data.
Sure, it is not that one could not measure once time between two events and setup then the interval, but that's is good
for few things only. The better way is to capture one event (or even none) and start then segmented memory cature - when there
is an event it will get captured. And exactly here it does make sense, as we don't have any pre-selected interval between frames,
to have time tag implemented.
The time-tag need of course good resolution (accuracy is anyway different story, one have to calcutate the deviation
by themselves based on measured time-tag stamp and typical timebase/trigger accuracy).
Something like 10-100ps is common usefull value for resolution.
EDIT: Agilent can e.g 10ps best case, see 5989-7833EN
since the Rigol DS1000 series also has the feature: do they have time tags for the 'frames'?
from a hardware point of view DS1000, (and all these who copied that hw design, like Siglent/ATTEN/UNI-T etc. )
does not have RTC on board, so no way to have time tag (and yes i know, there could be a counter running in
FPGA/CPLD and the latency between µC and FPGA could be calibrated out, but this is not the case for these DSO here).
Rigol changed that in DS2000, so it does have external RTC (ISL1208), but no matter how good the counter/interrupt/rtc/rtos
combination works, you will not get real ps resoultion on processor running at 400MHz. I don't have DS2000, so can't test anything.
All i found in user manual and pictures was like 1us timetag resolution. On the other side Rigol does not speak about
"segmented memory" but "recorder", so that ok, the timetag (independant on the given resolution) is then an small extra,
but not a real feature. I haven't found anything about when DS2000 is saving frames (except the interval setting, but i don't saw
anything trigger related). So when it can't be set to save on trigger event, then it is only recorder (or old school segmented memory).
Of course i might be wrong, maybe Rigol implemented the timetag counter (and on-trigger input) into the second FPGA (which is afaik
from the memory speed/size the recordig FPGA), so they could get best case 2ns resolution.
Anyway, you have DS2000, you can check that.
Regards Tekway, it does have internal RTC and enought counters to get 100-500ns resolution, but there is not RTOS
but Linux running. Sure, with proper device driver and changes to fw they could for sure do 1us or so, but that's would
be not a real timetag (or not what timetag have to be). Maybe i should ask them to see what they can implement, but yeah,
i didn't expect much from 400MHz ARM with Linux on it. Here, as on the DS1000E (and it's hw clones), the FPGA is too
small and timing already too hard on limit to have a way to implement timetag into FPGA, so as said above probably
1us could be the max (if they would implement it). And yeah, Tekway is based on interval as well, so no way to save
frame on each trigger event, so typical recorder and not segmented memory.
Because without that, IMO, there usefulness decreases.
as said above, without resolution (and accuracy of course) timetag is exact that good as manually counting seconds
on fingers between two nanosecond pulses.