def __init__(self, sp, port, timelen, method='estimated'):
"""Constructor
@param sp instance of class SParameters of the device
@param port integer 1 based port to calculate
@param timelen float time to peel
@param method string determining method for computing impedance profile
@remark methods include:
'estimated' (default) estimate the impedance profile from simulated step response.
'approximate' use the approximation based on the simulated step response.
'exact' use the impedance peeling algorithm.
"""
# pragma: silent exclude
if timelen == 0.0:
# if the time length is zero, make a zero length transmission line
SParameters.__init__(
self, sp.m_f,
[TLineTwoPortLossless(50., 0, f) for f in sp.m_f])
return
# pragma: include
ip = ImpedanceProfileWaveform(sp, port, method, includePortZ=False)
Ts = 1. / ip.td.Fs
sections = int(math.floor(timelen / Ts + 0.5))
tp1 = [identity(2) for n in range(len(sp.f()))]
for k in range(sections):
tp1 = [
tp1[n].dot(
array(S2T(TLineTwoPortLossless(ip[k], Ts, sp.m_f[n]))))
for n in range(len(sp.m_f))
]
SParameters.__init__(self, sp.m_f, [T2S(tp.tolist()) for tp in tp1])
def __getitem__(self,n):
"""overloads [n]
@return list of list s-parameter matrix for the nth frequency element
"""
for ds in self.m_spdl: self.m_sspn.AssignSParameters(ds[0],ds[1][n])
sp=self.m_sspn.SParameters()
if sp == 1: return sp
lp=[w+1 for w in range(len(sp)//2)]; rp=[w+len(sp)//2+1 for w in range(len(sp)//2)]
return T2S(linalg.matrix_power(S2T(sp,lp,rp),self.m_K),lp,rp)
def __getitem__(self, n):
"""overloads [n]
@return list of list s-parameter matrix for the nth frequency element
"""
# pragma: silent exclude
from numpy import linalg
from SignalIntegrity.Lib.Conversions import S2T
from SignalIntegrity.Lib.Conversions import T2S
# pragma: include
for ds in self.m_spdl:
self.m_sspn.AssignSParameters(ds[0], ds[1][n])
sp = self.m_sspn.SParameters()
return T2S(linalg.matrix_power(S2T(sp), self.m_K))
def SParameters(self,f):
"""s-parameters
@param f list of frequencies for the s-parameters
@return instance of class SParameters calculated by aggregating the list of rho
values using lossless transmission line sections with the rho calculated for each
section.
"""
N = len(f)-1
Gsp=[None for n in range(N+1)]
gamma=[1j*2.*math.pi*f[n]*self.m_Td for n in range(N+1)]
for n in range(N+1):
tacc=matrix([[1.,0.],[0.,1.]])
for m in range(len(self)):
tacc=tacc*matrix(S2T(IdealTransmissionLine(self[m],gamma[n])))
Gsp[n]=T2S(tacc.tolist())
sp = SParameters(f,Gsp,self.m_Z0)
return sp