Remove invert flag for dfm decoder, replace with --auto flag.

auto_rx/autorx/decode.py

@@ -244,26 +244,14 @@ class SondeDecoder(object):
 
         elif self.sonde_type == "DFM":
             # DFM06/DFM09 Sondes.
-
-            # We need to handle inversion of DFM sondes in a bit of an odd way.
-            # Using our current receive chain (rtl_fm), rs_detect will detect:
-            # DFM06's as non-inverted ('DFM')
-            # DFM09's as inverted ('-DFM')
-            # HOWEVER, dfm09dm_ecc makes the assumption that the incoming signal is a DFM09, and
-            # inverts by default.
-            # So, to be able to support DFM06s, we need to flip the invert flag.
-            self.inverted = not self.inverted
-
-            if self.inverted:
-                _invert_flag = "-i"
-            else:
-                _invert_flag = ""
+            # As of 2019-02-10, dfm09ecc auto-detects if the signal is inverted,
+            # so we don't need to specify an invert flag.
 
             # Note: Have removed a 'highpass 20' filter from the sox line, will need to re-evaluate if adding that is useful in the future.
             decode_cmd = "%s %s-p %d -d %s %s-M fm -F9 -s 15k -f %d 2>/dev/null |" % (self.sdr_fm, bias_option, int(self.ppm), str(self.device_idx), gain_param, self.sonde_freq)
             decode_cmd += "sox -t raw -r 15k -e s -b 16 -c 1 - -r 48000 -b 8 -t wav - highpass 20 lowpass 2000 2>/dev/null |"
             # DFM decoder
-            decode_cmd += "./dfm09ecc -vv --ecc --json %s 2>/dev/null" % _invert_flag
+            decode_cmd += "./dfm09ecc -vv --ecc --json --auto 2>/dev/null"
 			
         elif self.sonde_type == "M10":
             # M10 Sondes