def getdata(self, chan=1, Nr=1, Nt=1, Nmeas=10, calibration=False, seed=0):
""" getdata from VNA
Parameters
----------
Nmeas : number of measures
chan : int
channel number
Nr : Number of receiver (used only when calibration ==True)
Nt : Number of transmitter (used only when calibration ==True)
Nmeas : Number of measurements
calibration : boolean (used only for emulation)
if True the measurement correspond to a dataset for calibration purpose
seed : In emulated mode the data are produced from random number. seed is
for reproducibility of random experiments.
Examples
--------
>>> from pylayers.measures.vna.E5072A import *
>>> import matplotlib.pyplot as plt
>>> import numpy as np
>>> vna = SCPI()
>>> vna.parS(param='S21',cmd='set')
>>> S21 = vna.getdata()
>>> vna.close()
"""
self.nmeas = Nmeas
#ipdb.set_trace()
#print "Nmeas vna",self.nmeas
if not self.emulated:
com = 'CALC' + str(
chan
) + ':DATA:SDAT?' #This command sets/gets the corrected data array.
for k in range(Nmeas):
buff = ''
while len(buff) != (self.Nf * 16 + 8):
self.trigger(cmd='test')
buff = self.read(com)
#print"buffer size :",len(buff)
#ipdb.set_trace()
S = np.frombuffer(buff[8:self.Nf * 16 + 8], dtype='>f8')
Y = S.reshape(self.Nf, 2)
H = Y[:, 0] + 1j * Y[:, 1]
try:
tH = np.vstack((tH, H[None, :]))
except:
tH = H[None, :]
tH = tH[:, None, None, :]
else:
if not calibration:
np.random.seed(seed)
tau = 300 + 10 * np.random.rand(Nr, Nt)
h = ch.TBchannel()
h.SalehValenzuela()
H = h.toFD(fGHz=self.fGHz)
EH = np.sum(H.y * np.conj(H.y), axis=1) / self.Nf
stn = np.sqrt(EH) / 10.
N = stn * (np.random.rand(Nmeas, Nr, Nt, self.Nf) +
1j * np.random.rand(Nmeas, Nr, Nt, self.Nf))
tH = H.y[:, None, None, :] + N
tH = tH * np.exp(
-2 * 1j * np.pi * self.fGHz[None, None, None, :] *
tau[None, :, :, None])
else:
np.random.seed(seed)
tau = 300 + 10 * np.random.rand(Nr, Nt)
tH = np.exp(-2 * 1j * np.pi * self.fGHz[None, None, None, :] *
tau[None, :, :, None])
dtau = 7 * np.random.rand()
tH = tH * np.exp(
-2 * 1j * np.pi * self.fGHz[None, None, None, :] * dtau)
return tH
buff = self.read(com)
#print"buffer size :",len(buff)
#ipdb.set_trace()
S = np.frombuffer(buff[8:self.Nf*16+8], dtype='>f8')
Y = S.reshape(self.Nf, 2)
H = Y[:, 0]+1j*Y[:, 1]
try:
tH = np.vstack((tH, H[None,:]))
except:
tH = H[None,:]
tH = tH[:,None,None,:]
else:
if not calibration:
np.random.seed(seed)
tau = 300 + 10*np.random.rand(Nr,Nt)
h = ch.TBchannel()
h.SalehValenzuela()
H = h.toFD(fGHz=self.fGHz)
EH = np.sum(H.y*np.conj(H.y),axis=1)/self.Nf
stn = np.sqrt(EH)/10.
N = stn*(np.random.rand(Nmeas,Nr,Nt,self.Nf)+1j*np.random.rand(Nmeas,Nr,Nt,self.Nf))
tH = H.y[:,None,None,:]+N
tH = tH*np.exp(-2*1j*np.pi*self.fGHz[None,None,None,:]*tau[None,:,:,None])
else:
np.random.seed(seed)
tau = 300 + 10*np.random.rand(Nr,Nt)
tH = np.exp(-2*1j*np.pi*self.fGHz[None,None,None,:]*tau[None,:,:,None])
dtau = 7*np.random.rand()
tH = tH* np.exp(-2*1j*np.pi*self.fGHz[None,None,None,:]*dtau)
return tH