Smooth TTFF process

Bug: 161589960
Change-Id: I16bb3027fba4c243b745cf1bea0c7c92f55582d6
diff --git a/acts/framework/acts/test_utils/gnss/gnss_test_utils.py b/acts/framework/acts/test_utils/gnss/gnss_test_utils.py
index cca5417..6cb25c5 100644
--- a/acts/framework/acts/test_utils/gnss/gnss_test_utils.py
+++ b/acts/framework/acts/test_utils/gnss/gnss_test_utils.py
@@ -827,13 +827,11 @@
                                     "message in logcat. Abort test.")
         if not ad.is_adb_logcat_on:
             ad.start_adb_logcat()
-        logcat_results = ad.search_logcat("write TTFF log", begin_time)
+        logcat_results = ad.search_logcat("write TTFF log", ttff_loop_time)
         if logcat_results:
+            ttff_loop_time = get_current_epoch_time()
             ttff_log = logcat_results[-1]["log_message"].split()
             ttff_loop = int(ttff_log[8].split(":")[-1])
-            if ttff_loop in ttff_data.keys():
-                continue
-            ttff_loop_time = get_current_epoch_time()
             ttff_sec = float(ttff_log[11])
             if ttff_sec != 0.0:
                 ttff_ant_cn = float(ttff_log[18].strip("]"))