def init_vna():
ref_freq = 40e6
vna = VNA()
source_freq = 6.0e9
lo_freq = source_freq - 2e6
vna.set_tx_mux('iq', sample_input='adc')
vna.lo.freq_to_regs(lo_freq, ref_freq, apwr=0)
vna.source.freq_to_regs(source_freq, ref_freq, apwr=0)
#vna.dither_en(1)
#vna.set_tx_mux('samples', sample_input='adc')
vna.write_sample_time(int(40e6 / 1000 + 100))
#vna.write_sample_time(110000)
vna.write_io(pwdn=0, mixer_enable=0, led=1, adc_oe=0, adc_shdn=0)
vna.write_pll_io(lo_ce=1, source_ce=1, lo_rf=1, source_rf=1)
vna.write_att(0.0)
vna.write_switches(tx_filter=source_freq,
port=2,
rx_sw='rx2',
rx_sw_force=False)
vna.write_pll(vna.source)
vna.write_pll(vna.lo)
vna.write_pll(vna.source)
vna.write_pll(vna.lo)
vna.read_iq()
vna.read_iq()
return vna
def sw_terms(iqs, freqs):
"""Switch terms from IQ"""
sparams = []
for f in xrange(len(freqs)):
sw_f = iqs[f][('rx2',1)]/iqs[f][('b',1)]
sw_r = iqs[f][('rx1',2)]/iqs[f][('a',2)]
sparams.append( [[sw_f, 0], [0, sw_r]] )
return skrf.Network(s=sparams, f=freqs, f_unit='Hz')
ref_freq = 40e6
vna = VNA()
ports = [1, 2]
sw_correction = True
freqs = np.linspace(30e6, 6e9, 801)
vna.set_tx_mux('iq', sample_input='adc')
vna.write_att(7.0)
vna.write_sample_time(int(40e6/1000+100))
vna.write_io(pwdn=0, mixer_enable=0, led=1, adc_oe=0, adc_shdn=0)
vna.write_pll_io(lo_ce=1, source_ce=1, lo_rf=1, source_rf=1)
iqs = [{} for i in xrange(len(freqs))]
time.sleep(0.5)
