VIANC/xfer_tracer/script.py

#!/usr/bin/env python3

import pyvisa
import time

import pyaudio as pa
import numpy as np
import scipy as sc


current_phase = 0.0
normalized_f  = 0.0 # in cycles per sample : f = normalized_f * f_sampling

trans_len = 2000
intro = 0.5 * (1 - np.cos(2 * np.linspace(0, np.pi/2, trans_len)))
outro = 0.5 * (1 + np.cos(2 * np.linspace(0, np.pi/2, trans_len)))

intro = np.append(intro, np.ones(1024))
outro = np.append(outro, np.zeros(1024))

change_f = True
trans_done = False
new_f = 0.0
fade_time = 0


def audio_callback(in_data, frame_count, time_info, status):
	global fade_time
	global change_f
	global new_f
	global current_phase
	global normalized_f
	global trans_done

	if change_f == True:
		change_f = False
		trans_done = False
		fade_time = 0

	if(fade_time != 2*trans_len):
		if(fade_time < trans_len):
			last_fade = fade_time + frame_count
			envelope = outro[fade_time:last_fade]
			fade_time = min(last_fade, trans_len)
		elif(fade_time >= trans_len and fade_time < 2*trans_len):
			normalized_f = new_f
			if(new_f == 0):
				current_phase = 0. # Avoid weird sub-audio behavior
			last_fade = fade_time + frame_count
			envelope = intro[fade_time - trans_len:last_fade - trans_len]
			fade_time = min(last_fade, 2*trans_len)

	if(fade_time == 2*trans_len):
		trans_done = True

	sine = np.sin(2 * np.pi * (current_phase + np.arange(frame_count)*normalized_f))
	delta = frame_count*normalized_f
	delta -= np.floor(delta)

	if(delta + current_phase > 1):
		current_phase += delta - 1
	else:
		current_phase += delta

	if(fade_time != 2*trans_len):
		sine *= envelope

	return (sine.astype(np.float32).tobytes(), pa.paContinue)

paudio = pa.PyAudio()

audio_strm = paudio.open(format=pa.paFloat32,
	channels=1,
	rate=48000,
	output=True,
	input=False,
	stream_callback=audio_callback,
	start=True)

def acquire_samples(sc_frequency, oscillo):
	global new_f
	global change_f
	global trans_done
	new_f = sc_frequency
	change_f = True
	while (change_f == True) or (trans_done == False):
		time.sleep(0.05)
	time.sleep(0.2)

	oscillo.write("acquire:state run")
	oscillo.write("data:source CH1")
	input_ch = oscillo.query_binary("curve?", container=np.array)
	oscillo.write("data:source CH2")
	output_ch = oscillo.query_binary("curve?", container=np.array)

	return input_ch, output_ch
	#return (input_ch, output_ch)

def manage_measures(f_list, oscillo): # These are NOT normalized frequencies
	hscales = [25e-3, 10e-3, 5e-3, 2.5e-3, 1e-3,
	           500e-6, 250e-6, 100e-6, 50e-6, 25e-6, 10e-6]

	hscale_index = 0
	current_hscale = hscales[hscale_index]

	cal_A = []
	cal_B = []
	cal_done = False

	H = []

	W = sc.signal.windows.flattop(2500)

	for f in f_list:
		sc_frequency = np.round(2**20/48000 * f)/2**20
		num_periods = f * 10 * current_hscale
		while(num_periods >= 5 * 2.5):
			hscale_index += 1
			current_hscale = hscales[hscale_index]
			num_periods = f * 10 * current_hscale
			oscillo.write("horizontal:main:scale " + str(hscales))
			cal_done = False

		print(f, " : ", current_hscale,"s/div, ", num_periods, " periods")
		A, B = acquire_samples(sc_frequency, oscillo)
		if not cal_done:
			cal_A, cal_B = acquire_samples(0., oscillo)
			cal_done = True

		A, B = (A - cal_A)*W, (B - cal_B)*W
		f_acq = 250./current_hscale
		rel_f = f / f_acq

		# Obtain the Fourier transforms of A, B @ rel_f, with flattop windowing 
		V = np.exp(-2.0j * np.pi * np.arange(2500) * rel_f)
		h = np.sum(B*V)/np.sum(A.V)
		print("H(", f, ") = ", h)
		H.append(h)
	return H

def find_oscillo():
	rm = pyvisa.ResourceManager()
	R = rm.list_resources()
	print(R)
#	if R.empty():
#		print("No device found")
#		exit(1)
	return rm.open_resource(R[0])

osci = find_oscillo()
print(osci.query("*IDN?"))

osci.write("*RST")
time.sleep(5)

osci.write("ch1:scale 1.0e-1")
osci.write("ch1:bandwidth ON")
osci.write("ch1:coupling AC")
osci.write("select:ch1 1")

osci.write("ch2:scale 5.0e-2")
osci.write("ch2:bandwidth ON")
osci.write("ch2:coupling AC")
osci.write("select:ch2 1")


osci.write("trigger:main:edge:source LINE")
osci.write("trigger:main:mode NORMAL")
osci.write("trigger:main:type EDGE")

osci.write("acquire:mode sample")
osci.write("acquire:stopafter sequence")
osci.write("data:encdg ascii")
manage_measures([330., 470., 680., 820., 1000.])