diff --git a/recv.py b/recv.py
index 406a325..5265172 100755
--- a/recv.py
+++ b/recv.py
@@ -186,7 +186,8 @@ def main(fname):
             f.write(data)
 
 if __name__ == '__main__':
+    import sys
     logging.basicConfig(level=logging.INFO, format='%(asctime)s %(levelname)-12s %(message)s')
-    main('rx.int16')
+    main(fname=sys.argv[1])
     if pylab:
         pylab.show()
diff --git a/send.py b/send.py
index c09a033..4aeb270 100755
--- a/send.py
+++ b/send.py
@@ -42,11 +42,11 @@ def modulate(sig, bits):
         if all(symbols == 0):
             break
 
-def main():
+def main(fname):
     import ecc
     log.info('Running MODEM @ {:.1f} kbps'.format(sigproc.modem_bps / 1e3))
 
-    with open('tx.int16', 'wb') as fd:
+    with open(fname, 'wb') as fd:
         start(fd, sym.carrier[carrier_index])
         for c in sym.carrier:
             training(fd, c)
@@ -55,5 +55,6 @@ def main():
         modulate(fd, bits)
 
 if __name__ == '__main__':
-    logging.basicConfig(level=logging.DEBUG, format='%(message)s')
-    main()
+    import sys
+    logging.basicConfig(level=logging.INFO, format='%(asctime)s %(levelname)-12s %(message)s')
+    main(fname=sys.argv[1])
diff --git a/test.sh b/test.sh
index 09f7f42..2ba37fc 100755
--- a/test.sh
+++ b/test.sh
@@ -3,17 +3,18 @@ set -u
 set -e 
 
 dd if=/dev/urandom of=data.send bs=1024 count=1
-./send.py
+./send.py tx.int16
+
+killall arecord aplay || true
 
 ./wave.py record rx.int16 &
-PID=$!
-
 ./wave.py play   tx.int16
 sleep 1
-kill -INT $PID
 
-./recv.py
+killall arecord aplay || true
+
+./recv.py rx.int16
 ./errors.py data.* 
 if [ -z $? ]; then
 	./show.py tx.int16 rx.int16
-fi
\ No newline at end of file
+fi
diff --git a/wave.py b/wave.py
index c5402ea..af6f6d2 100755
--- a/wave.py
+++ b/wave.py
@@ -7,13 +7,15 @@ import logging
 log = logging.getLogger(__name__)
 
 from common import Fs
-Fs = int(Fs)
+Fs = int(Fs) # sampling rate
+bits_per_sample = 16
+audio_format = 'S{}_LE'.format(bits_per_sample) # PCM signed little endian
 
 def play(fname, **kwargs):
-    return launch('aplay', fname, '-q', '-f', 'S16_LE', '-c', '1', '-r', Fs, **kwargs)
+    return launch('aplay', fname, '-q', '-f', audio_format, '-c', '1', '-r', Fs, **kwargs)
 
 def record(fname, **kwargs):
-    return launch('arecord', fname, '-q', '-f', 'S16_LE', '-c', '1', '-r', Fs, **kwargs)
+    return launch('arecord', fname, '-q', '-f', audio_format, '-c', '1', '-r', Fs, **kwargs)
 
 def launch(*args, **kwargs):
     args = map(str, args)
@@ -41,4 +43,11 @@ if __name__ == '__main__':
     p = args.func(args.filename)
 
     import sys
-    sys.exit(p.wait())
+    exitcode = 0
+    try:
+        exitcode = p.wait()
+    except KeyboardInterrupt:
+        p.kill()
+        exitcode = p.wait()
+
+    sys.exit(exitcode)