Using SI Units

[jhillairet]

• use Hz instead of GHz as new default
• use second instead of nanosecond as new default

[jhillairet]

Any comments on this PR? Did I miss something somewhere?

[capn-freako]

What is the default frequency unit in v0.30.0, Hz or GHz?

[jhillairet]

Since this PR has been merged and version 0.29.0, it should be SI (Hz). Did you meet an issue?

[capn-freako]

Since this PR has been merged and version 0.29.0, it should be SI (Hz). Did you meet an issue?

Yes, but I think one of my co-developers has answered it:

Hi @capn-freako ,

If we see the touchstone.py file here & the Network read_touchstone call here ;

if I interpret it correctly; the S-Parameters frequency unit gets passed to the Network Object regardless of the SI unit standardization. e.g.: If your Touchstone file has the following header # GHz S DB R 50.0 , then the Network Object created will inherently carry the unit of GHz.

I'm checking to see if this is my problem, now.

Thanks for responding so quickly!
-db

[capn-freako]

Nope, that wasn't it.

I'm able to fix things, by making this change to my code:

@@ -1255,11 +1256,11 @@ def interp_s2p(ntwk, f):
     assert rs == cs, "Non-square Touchstone file S-matrix!"
     assert rs == 2, "Touchstone file must have 2 ports!"

-    extrap = ntwk.interpolate(f, fill_value="extrapolate", coords="polar", assume_sorted=True)
+    extrap = ntwk.interpolate(f*1e-9, fill_value="extrapolate", coords="polar", assume_sorted=True)
     s11 = cap_mag(extrap.s[:, 0, 0])
     s22 = cap_mag(extrap.s[:, 1, 1])
-    s12 = ntwk.s12.interpolate(f, fill_value=0, bounds_error=False, coords="polar", assume_sorted=True).s.flatten()
-    s21 = ntwk.s21.interpolate(f, fill_value=0, bounds_error=False, coords="polar", assume_sorted=True).s.flatten()
+    s12 = ntwk.s12.interpolate(f*1e-9, fill_value=0, bounds_error=False, coords="polar", assume_sorted=True).s.flatten()
+    s21 = ntwk.s21.interpolate(f*1e-9, fill_value=0, bounds_error=False, coords="polar", assume_sorted=True).s.flatten()

Is it possible that the interpolate() function is still using GHz as its default?
(I perused your source a bit and it doesn't look like that should be the case.
But, I'm not sure what else to suspect.)

I've checked the f argument.
And it is correct and has units: Hz.

[capn-freako]

Sorry, please ignore my comments above.
The error is somewhere on my end. :(