def calibrate():
logging.info("[CALIBRATION] Starting calibration procedure")
global ADC
target_coeff = 1
max_amp = 2**30 #Maximum signed int value / 2
target_snr = 2
parameters = {'bc': [], 'tx': []}
args_adc = config.hardware['ADC'].copy()
args_adc.update({'selected_freq': config.test_params['tx_freq']})
zero_gains()
analogue_IO.enable(**config.hardware['IO'])
calib_metadata=dict()
for chan in ["X", "Y", "Z"]:
logging.info("[CALIBRATION] - Calibration, searching channel %s", chan)
ADC = follower.follower()
ADC.power_on()
noise_level = get_trimmed_mean_amp(args_adc, chan, samples=10, max_dev=1.0)
ADC.stop()
logging.debug("[CALIBRATION] - Noise level = %f", noise_level)
logging.debug("[CALIBRATION] - Find tx_coeff (what's the read amplitude it the current channel for a tx gain of 1)")
tx_coeff = get_tx_coeff(args_adc, 0.0001, max_amp, 'tx', chan, noise_level)
test_tx_gain = min(target_coeff, 0.3 * max_amp / tx_coeff)
logging.debug("[CALIBRATION] - test_tx_gain = %f, tx_coeff = %f", test_tx_gain, tx_coeff)
ADC = follower.follower()
ADC.power_on()
waveform_tx_only = ADC.get_sample_freq(**args_adc)
ADC.stop()
AWG.setGain('tx', 0, oneshot=True)
logging.debug("[CALIBRATION] - Find bc_coeff (what's the read amplitude it the current channel for a bucking gain of 1)")
bc_coeff = get_tx_coeff(args_adc, 0.0001, max_amp, chan, chan, noise_level)
test_bc_gain = min(target_coeff, 0.7 * test_tx_gain * tx_coeff / bc_coeff, 0.3 * max_amp / bc_coeff)
logging.debug("[CALIBRATION] - test_bc_gain = %f, bc_coeff = %f", test_bc_gain, bc_coeff)
logging.debug("[CALIBRATION] - Use the coefficients we've found to find the best phase shift")
AWG.program()
AWG.setGain('tx', test_tx_gain)
AWG.setGain(chan, test_bc_gain)
AWG.run()
best_phase = phase_min(args_adc, chan, samples=5)
logging.info("[CALIBRATION] - Channel %s first pass results: tx=%f, bc=%f @ %f deg", chan, test_tx_gain, test_bc_gain, best_phase)
# Now for the fine tuning:
old_res = max_amp
sig_test = -1
for iter in range(10):
if tx_coeff <= bc_coeff:
tx_gain = target_coeff
bc_gain = target_coeff * tx_coeff / bc_coeff
else:
bc_gain = target_coeff
tx_gain = target_coeff * bc_coeff / tx_coeff
logging.debug("[CALIBRATION] - Fine tuning, bc_gain = %f, tx_gain = %f", bc_gain, tx_gain)
AWG.program()
AWG.setGain('tx', tx_gain)
AWG.setGain(chan, bc_gain)
AWG.setPhaseShift(chan, best_phase, deg=True)
AWG.run()
current_amp = get_trimmed_mean_amp(args_adc, chan, ref_sample=waveform_tx_only)
logging.debug("[CALIBRATION] - Bucking gain = %f, TX gain = %f, residual amp = %f" , bc_gain, tx_gain, current_amp)
if abs(old_res) < abs(current_amp):
sig_test *= -1
old_res = current_amp
if abs(current_amp) > target_snr * noise_level and iter < 10:
#We still have work to do then...
if tx_coeff <= bc_coeff:
bc_coeff = (abs((target_coeff * tx_coeff) + sig_test * current_amp) / bc_gain + bc_coeff) / 2
else:
tx_coeff = (abs((target_coeff * bc_coeff) + sig_test * current_amp) / tx_gain + tx_coeff) / 2
logging.debug("[CALIBRATION] - tx_coeff = %f, bc_coeff = %f", tx_coeff, bc_coeff)
else:
#We found acceptable parameters!
logging.info("[CALIBRATION] - Channel %s residual signal amplitude: %f with tx=%f and bc=%f %f deg", chan, current_amp, tx_gain, bc_gain, best_phase)
parameters['tx'].append(tx_gain)
parameters['bc'].append({'gain': bc_gain, 'ps': best_phase})
break
# Record some metadata:
if not calib_metadata.has_key("noise_level"):
calib_metadata["noise_level"] = dict()
if not calib_metadata.has_key("coeffs"):
calib_metadata["coeffs"] = {'tx': dict(), 'bc': dict()}
calib_metadata["coeffs"]["tx"][chan] = tx_coeff
calib_metadata["coeffs"]["bc"][chan] = bc_coeff
calib_metadata["noise_level"][chan] = noise_level
if not calib_metadata.has_key("no_bucking_ps"):
calib_metadata["no_bucking_ps"] = dict()
for rec_chan in ["X", "Y", "Z"]:
calib_metadata["no_bucking_ps"][rec_chan] = waveform_tx_only.get_phase_shift(ord(rec_chan) - ord('X'), deg=True)
parameters["metadata"] = calib_metadata
params = print_parameters(parameters)
filename = time.strftime(str(config.test_params['tx_freq']) + "Hz_%Y%m%d-%H%M%S.calib")
f = open(filename, 'w')
f.write(str(params))
f.close()
if os.path.isfile('current.calib'):
os.remove('current.calib')
os.symlink(filename, 'current.calib')
def zero_gains():
AWG.program()
for chan in AWG.REGISTERS_GAIN:
AWG.setGain(chan, 0)
AWG.setPhaseShift(chan, 0)
AWG.run()