TDS380 Jerky Response with Measurements Turned On


Richard Peterson
 

I've noticed that that the trace on my TDS380 works great and responds immediately to incoming signal changes but when I turn any of the measurements on, it appears jerky. Any ideas about why that would be and how i can eliminate it? I've played around with the settings, but nothhing seems to make any difference. Here's a link to a video i made of the response to a function generator with measurements turned off and then turned on: https://youtu.be/kH2E1isGD9I

Thanks in advance.

Rich


Richard Peterson
 

Any thoughts? Normal?


Dave Voorhis
 

I don’t own a TDS380 so I don’t have a basis of comparison, but it looks completely normal to me. I would expect measurements to consume some CPU horsepower, with a corresponding slowdown or latency elsewhere.

On 21 Jan 2022, at 20:11, Richard Peterson <saaber1@comcast.net> wrote:

Any thoughts? Normal?


Harvey White
 

Shouldn't be a factor, adding an extra display that exactly replicates the internal display is just paralleling signals.

If the external display could be written to separately, then it would be CPU intensive.

Harvey

On 1/21/2022 5:15 PM, David Templeton wrote:
How are you displaying on that monitor? , I presume it must have a secondary output, could that be a factor?





Richard Peterson
 

My scope has Option 14 which includes the display output. I did have to construct a converter to 'translate' the Tek pinout to a VGA input but running with that disconnected doesn't affect the latency. I've stumbled across a thread on eevblog complaining about the slow update rate of this scope especially with measurements on, so I guess this is normal. Still a nice scope, so I'll just live with the lag.

Thanks for the feedback

Rich


Kevin Wood G7BCS
 

Yep, that looks normal in my experience. If you watch closely, the trace update pauses briefly before each measurement update, so it probably spends a little time capturing some samples for the measurement, then processing them to compute the measured value.

Kevin
G7BCS

On 22/01/2022 15:42, Richard Peterson wrote:
My scope has Option 14 which includes the display output. I did have to construct a converter to 'translate' the Tek pinout to a VGA input but running with that disconnected doesn't affect the latency. I've stumbled across a thread on eevblog complaining about the slow update rate of this scope especially with measurements on, so I guess this is normal. Still a nice scope, so I'll just live with the lag.
Thanks for the feedback
Rich


Richard Peterson
 

I agree. I found it odd as well. I have a TDS210 on the shelf. I'll have to dig it out and see how that performs in comparison.

Rich