diff --git a/python/physical_layer_driver.py b/python/physical_layer_driver.py
index 7b60e3c..f59912e 100644
--- a/python/physical_layer_driver.py
+++ b/python/physical_layer_driver.py
@@ -62,7 +62,7 @@ class physical_layer_driver(gr.hier_block2):
         self._corr_est           = digital.corr_est_cc(symbols    = (preamble_samples.tolist()),
                                                        sps        = sps,
                                                        mark_delay = preamble_offset,
-                                                       threshold  = 1-math.exp(-5),
+                                                       threshold  = 1-math.exp(-8),
                                                        threshold_method = 0)
         self._doppler_correction = digitalhf.doppler_correction_cc(preamble_length, len(preamble_samples))
         self._adaptive_filter    = digitalhf.adaptive_dfe(sps, nB, nF, nW, mu, alpha)