diff --git a/ofdm/ofdm_rx.m b/ofdm/ofdm_rx.m
index c2fd3ae..dc08088 100644
--- a/ofdm/ofdm_rx.m
+++ b/ofdm/ofdm_rx.m
@@ -1,9 +1,9 @@
-function [sym_out, H, W] = ofdm_rx(filename, foff, SNR, with_cir, show_H)
+function [sym_out, H, W] = ofdm_rx(filename, foff, flip_spec, SNR, with_cir, show_H)
 %
-% [sym_out, H, W] = ofdm_rx(filename, foff, SNR, with_cir, show_H)
-% Example: ofdm_rx('drm-15435-if.wav', -174.65, 400, 0, 1)
-% Example: ofdm_rx('xv.wav', 0, 400, 0, 1)
-%       or ofdm_rx('yv.wav', 0, 400, 0, 1)
+% [sym_out, H, W] = ofdm_rx(filename, foff, flip_spec, SNR, with_cir, show_H)
+% Example: ofdm_rx('drm-15435-if.wav', -174.65, 0, 400, 0, 1)
+% Example: ofdm_rx('xv.wav', 0, 0, 400, 0, 1)
+%       or ofdm_rx('yv.wav', 0, 0, 400, 0, 1)
 
 close all;
 
@@ -45,7 +45,11 @@ end
 if with_cir
     x = filter(h_cir, 1, x);
 end
+
 x = x - mean(x);
+if flip_spec
+	x = conj(x);
+end
 x = x./max(abs(x));
 xout = [real(x) imag(x)];
 wavwrite(xout,fs,nbits,'ofdm_rx.wav');