gstlal_ll_dq: reduce the upper frequency for the horizon distance calculation

gstlal-ugly/bin/gstlal_ll_dq

@@ -82,7 +82,7 @@ class PSDHandler(simplehandler.Handler):
 		del kwargs["instrument"]
 		del kwargs["agg_sink"]
 		simplehandler.Handler.__init__(self, *args, **kwargs)
-		self.horizon_distance_func = reference_psd.HorizonDistance(20., 2048., 1./16., 1.4, 1.4)
+		self.horizon_distance_func = reference_psd.HorizonDistance(15., 900., 1./16., 1.4, 1.4)
 
 		self.routes = ("noise", "range_history")
 		self.datatypes = (("min", min), ("median", aggregator.median), ("max", max))