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Hi,
For 500kHZ HSDC, what is the cut-off frequency?
And what is that for 6.25 Mhz?
Best,
Fei
Hi Fei,
The 500KHz HSDC uses an ADC that samples at 500,000 samples/second. There is a hardware antialiasing filter on that ADC at 200KHz. On top of that, some data types have additional low pass filters or lower filters (X, Y sensors for example).
The 6.25MHz HSDC uses an ADC that samples at 50,000,000,000 samples/second. There is no antialiasing filter for this ADC, but there is a high pass filter at ~200Hz.
Hope that helps!
--Bede
Hi Bede,
Thanks for your reply.
In the Veeco diNanoscope V Contorller Manual (Rev.B ,page 41), it is said that General I/O Input1 and 2 has bandwith from DC to 100kHz.
It seems there is a hardware filter. Can you tell me the specification of the filter?
This is crucial for my application. I want to sample the vertical deflection signal with 500khz HSDC from a cantilever via General I/O. The resonant frequency of the cantilever is about 120Khz.
If I know the filter specification, then I can compensate compensate the effect from the filter.
My AFM is Multimode with Nanoscope V controller.
Thanks.
Fei,
The general IO outputs (via the front panel) are bandwidth limited because the signals get sampled and then written back out.
This is a different signal path from HSDC. If you sample deflection directly from HSDC (selecting it as a data type) then it has the bandwidth that Bede describes.
-Ben
Hi Ben,
I see what you and Bede mean now. Thanks a lot.
It means I should not use the front panel General IO input to sample signal, which has frequency more than 100Khz, which is out of banwidth.
The problem is I have done so.
So can you tell me the specification of the filter with General IO input? With the specification of the filter, the power spectrum of the signal may be corrected.
Thanks a lot. Without correction of the power spectrum, my half-year work is to be useless.
The front panel outputs are updated at 100KHz, but the inputs (1 and 2) are read at 500,000 samples/second with the usual 200KHz antialiasing second order lowpass filter.