On Mon, Aug 16, 2021 at 12:09 PM, Syd wrote:
In the manual there is a Transform setup for the bandpass mode and here is the
picture of the results attached. I think this setup is strictly for measuring
band pass filters, correct me if I'm wrong. From the pix I can see that the
time being scanned from the frequency setup is from 0 ns to 43 ns shown on the
bottom. From what I am seeing I think ch0 shows the pulse being generated and
ch1 is showing the results from the BPF. The 20.0n/-0.14 and 10.0n/-0.02
scaling for ch0 and ch1 at the top I thought was showing the scaling per
division and the level, but now I am not sure what it is telling me. Then
again the white marker notation is showing 4ns 0.4m? How do I interpret that?
Additionally, what is the TDR measurement of a band pass filter giving me
information wise that I can't get from scanning the BPF and looking at the
logmax output over a span of frequencies? At least from the logmax method I
can see the characteristics of the filter, and I don't see anything like it
with this method since it is in the time domain.
syd/wt1v
This feature is not restricted to measuring bandpass filters.
The TDR mode uses an IFFT algorithm on VNA frequency data to get a time domain display. This is useful when finding distance to a fault or the length of a transmission line When measuring a device under test (DUT) it gives the impulse response which is the time domain equivalent of the frequency response. Selecting "bandpass" mode is useful when measuring transmission lines with DC blocking or filtered transmission lines. It is the mode to use when setting a stimulus frequency well above DC.
You can read more about this in this app note by Agilent. The bandpass mode is described on page 13.
Roger
Roger Need