Add subsample delay compensation (untested)

1 files changed, 25 insertions, 22 deletions

diff --git a/align/GenerateExampleTxRxIQ.py b/align/GenerateExampleTxRxIQ.py
index fc105fd..03c79b6 100755
--- a/align/GenerateExampleTxRxIQ.py
+++ b/align/GenerateExampleTxRxIQ.py
@@ -30,19 +30,6 @@ import scipy
 import scipy.signal
 import numpy as np
 
-## Configuration
-# whether to correct for delays larger than one sample
-# Not necessary unless you have delay larger than oversample/2
-do_integer_compensation = 0
-
-# by how much to oversample the signal before applying the delay
-oversample = 8
-
-# Add a delay of delay/oversample samples to the input signal
-#delay = 7
-
-do_plot = False
-
 def gen_omega(length):
     if not length % 2 == 0:
         raise ValueError('Needs an even length array.')
@@ -53,8 +40,9 @@ def gen_omega(length):
     omega[halflength+1:] = 2*np.pi*( np.arange(halflength+1, length)-length )
     return omega / length
 
-def gen_signals(delay):
-    ## Generate signal
+def gen_signals(oversample, delay):
+    """Generate a signal that is delayed and a bit noisy. Returns a tuple
+    (original signal, shifted signal)"""
 
     iq_file = "/home/bram/dab/aux/odr-dab-cir/phasereference.2048000.fc64.iq"
 
@@ -137,13 +125,28 @@ def delay_signal(sig, delay):
 
     return np.fft.ifft(sig_fft * rotate_vec)
 
-for d in [2, 5, 9, 15, 34, 120]:
-    a, b = gen_signals(d)
-    delay = arg_max_corr(a,b)
-    print("{} {}".format(d / oversample, delay))
+def fftplot(sig):
+    plt.plot(np.abs(np.fft.fftshift(np.fft.fft(sig))))
+
+if __name__ == '__main__':
+    # Add a delay of d/oversample samples to the input signal
+
+    # by how much to oversample the signal before applying the delay
+    oversample = 8
+
+    do_plot = False
+
+    for d in [2, 7]:
+        a, b = gen_signals(d, oversample)
+        delay = arg_max_corr(a,b)
+        print("{} {}".format(d / oversample, delay))
 
-    print("{} {}".format(d / oversample, arg_max_corr(a, delay_signal(b, delay))))
+        print("{} {}".format(d / oversample, arg_max_corr(a, delay_signal(b, delay))))
 
+        if do_plot:
+            plt.figure()
+            fftplot(a)
+            fftplot(a-b)
 
-if do_plot:
-    plt.show()
+    if do_plot:
+        plt.show()