def _get_time(self):
if not self._time_valid:
log.debug('recomputing _time')
duration = self.get_current_value('trial_duration')
self._time = wave.time(self.iface_behavior.fs, duration)
self._time_valid = True
return self._time
def generate_trial_waveform(self):
# Use BBN
seed = self.get_current_value("seed")
depth = self.get_current_value("modulation_depth")
direction = self.get_current_value("modulation_direction")
fm = self.get_current_value("fm")
duration = self.get_current_value("trial_duration")
t = signal.time(self.iface_behavior.fs, duration)
# Save the actual seed that's used to generate the trial waveform
if seed == -1:
seed = int(time.time())
self.set_current_value("seed", seed)
# Do not use the self.random_generator for generating the seed. This
# generator is for use only for generating the intertrial waveform.
state = np.random.RandomState(seed)
waveform = state.uniform(low=-1, high=1, size=len(t))
# Since we are drawing samples from a uniform distribution and we wish
# to normalize for the RMS voltage, we need to divide by 0.5 which is
# the RMS value of the waveform. We could recompute the RMS value on
# each cycle; however, I think it's better to use the same value each
# time. The RMS of the waveform over time will compute to 0.5 (because
# the samples are unformly distributed between -1 and 1).
waveform = waveform / 0.5
eq_phase = signal.sam_eq_phase(depth, direction)
eq_power = signal.sam_eq_power(depth)
envelope = depth / 2.0 * np.cos(2 * np.pi * fm * t + eq_phase) + 1 - depth / 2.0
envelope *= 1 / eq_power
return waveform * envelope
