Products > Test Equipment
12 bit Keysight... when?
nctnico:
--- Quote from: David Hess on January 15, 2024, 10:08:15 pm ---
--- Quote from: EE-digger on January 15, 2024, 07:44:29 pm ---4MPts memory depth? C'mon Keysight. That's like making us use a 4 function calculator instead of Matlab or other.
--- End quote ---
Memory depth is usually more important for marketing than engineering. What matters more is the ratio between memory depth and bandwidth which determines how quickly the memory can be processed. Previous HP DSOs had limited acquisition memory because they had a custom ASIC for processing, and users seem to have loved the fast processing that allowed.
--- End quote ---
That depends on what you are doing. For circuits with microcontrollers / processors you'll need all the memory you can get. I used to have an Agilent model with the 8MPts Megazoom ASIC and that was not enough in many cases. Keep in mind that with the Keysight scopes you'll have 1/4th or even 1/8th of the memory available because it is shared amongst all channels (analog and digital).
2N3055:
I have both MSXO3104T and several long memory scopes (2 x Siglent and Picoscopes).
While Keysight is really fast to react to user controls, it really is very limited in some ways.
As long as you reach certain time-bases sampling rate drops quickly.
If you use it as you would a smarter CRT scope then it is fine.
But very small memory is very limiting for some use cases.
David Hess:
--- Quote from: nctnico on January 16, 2024, 01:22:44 pm ---That depends on what you are doing. For circuits with microcontrollers / processors you'll need all the memory you can get.
--- End quote ---
I would agree that in some cases record length is everything, but more often it is just for marketing where more is better. Record length can be objectively advertised, but how can fast response of the user interface and ease of use advertised?
It is like how every new DSO is now advertised as "low noise", whether it really is or not.
EE-digger:
I had several occasions where tens of megabytes of memory depth were needed for SPI to prove existence of processing glitches in a commercial chip. For this we switched to a Saleae 16 analyzer which filled the bill nicely. We performed rapid searches on the PC and proved the problem to ADI at the time. So this created a dividing line for which I no longer blame the Keysight scopes. Having this ability in the scope may have given completeness but not the best place for it to reside given PC speeds and space.
2N3055:
--- Quote from: EE-digger on January 17, 2024, 03:30:12 am ---I had several occasions where tens of megabytes of memory depth were needed for SPI to prove existence of processing glitches in a commercial chip. For this we switched to a Saleae 16 analyzer which filled the bill nicely. We performed rapid searches on the PC and proved the problem to ADI at the time. So this created a dividing line for which I no longer blame the Keysight scopes. Having this ability in the scope may have given completeness but not the best place for it to reside given PC speeds and space.
--- End quote ---
There are many occasions where you have glitches because of EMC, or some chip acting up. Some chips will react to very fast pulses and get confused.
Using protocol/logic analyser is fine to find the erroneous message but will not explain why message is wrong. On CAN you can have bus collisions that will show as bad message. But you don't know why. That is why deep memory scope that will keep sampling rate in long captures, and be able to decode is useful..
It really depends on what you do.
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