I’m trying to get a feel for how to simulate some passive LC filter circuits… the long-term plan is to design some filters to use with an RTL-SDRv3 dongle in direct-sampling mode which has a Nyquist frequency of 14.4MHz.
As a first step I thought I’d try to simulate something that would put a notch at around 14.4MHz (in hindsight, probably not the holy grail I’m after, but let’s just run with it for the sake of a simulation exercise).
This is the circuit, and its simulation:
This is both good and bad. Good in that it’s built into the schematic capture package and produces a nice looking graph. BUT there’s no grid showing the variances in frequency. I can guess the big notch at the bottom is at 14.4MHz, but where are those two peaks? I have no clue.
Is there a way to make it plot steps X axis which show finer graduations than what is “standard”?
I am not aware of a possibility to set the x or y scales manually. However you may switch on a cursor to (manually) shift it and read the x-y-values per each graph.
In the ‘Signals’ window right click onto a signal and set ‘Show cursor’. The cursor then may be manually shifted along the graph to the point of interest.
It seems that frequency markers are only drawn when the most significant digit changes.
Your schematic is a bit hard to read. Is your simulation parameter line:
.ac lin 100 12000k 16000k
In that case the nearest frequency markers will be at 10MHz and 20MHz.
It took me some experimenting to find the cursor that holger mentioned, but I managed to find them and it does work for me. After enabling a cursor I can drag the white dashed line over the screen and it shows Frequency and Gain.
This may help… Using your mouse, you can Window-Zoom (i.e., window a box at the point of interest). It will Zoom and auto adjust the Axis scaling. It works on my Mac…