scripts init

scripts/condense.py

@@ -0,0 +1,69 @@
+#!/usr/bin/env python
+
+"""
+Condense a raw sample file generated by USPR, removing idle periods.
+"""
+
+import os
+import argparse
+import scipy
+import itertools
+import struct
+
+WINDOW = 80
+
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument('file', help="Raw sample file")
+    parser.add_argument('--thres', type=int, default=1000, help="Power threshold")
+    parser.add_argument('--out', help="Output file")
+    parser.add_argument('--skip', type=int, default=int(0.1*20e6),
+                        help="Inital samples to skip (USRP stabilization period)")
+
+    args = parser.parse_args()
+
+    wave = scipy.fromfile(args.file, dtype=scipy.int16)
+    raw_samples = [complex(i, q) for i, q in
+                   itertools.izip(wave[::2], wave[1::2])]
+    print "%d raw samples" % (len(raw_samples))
+
+    if args.out is None:
+        args.out = '_condensed'.join(os.path.splitext(args.file))
+
+    fh = open(args.out, 'wb')
+
+    state = 'idle'
+    count = 0
+    countdown = 0
+    for i in xrange(0, len(raw_samples), WINDOW):
+        if i < args.skip:
+            continue
+
+        if state == 'idle':
+            if any([abs(c.real) > args.thres for c in raw_samples[i:i+WINDOW]]):
+                state = 'trigger'
+                countdown = 80*10
+                count += 1
+
+        if state == 'trigger':
+            if countdown > 0:
+                do_write = True
+            elif any([abs(c.real) > args.thres for c in raw_samples[i:i+WINDOW]]):
+                do_write = True
+            else:
+                do_write = False
+                state = 'idle'
+
+            if do_write:
+                for c in raw_samples[i:i+WINDOW]:
+                    fh.write(struct.pack('<hh', int(c.real), int(c.imag)))
+                countdown -= WINDOW
+
+    fh.close()
+    print "%d packets" % (count)
+    print "Output written to %s" % (args.out)
+
+
+if __name__ == '__main__':
+    main()