diff --git a/test_monitor_tshark.sh b/test_monitor_tshark.sh
index 28dd282..ff09336 100755
--- a/test_monitor_tshark.sh
+++ b/test_monitor_tshark.sh
@@ -196,7 +196,11 @@ fi
 # Now parse the pcap file to extract fields
 # Only extract 802.11 header fields - data payloads are encrypted
 # Include PHY rate and MCS for histograms
+# Note: Some fields may not exist for all frames - tshark will output empty values
 CAPTURE_OUTPUT=$(tshark -q -r "$TEMP_PCAP" -n -T fields \
+    -E occurrence=f \
+    -E separator='\t' \
+    -E header=n \
     -e frame.number \
     -e frame.time \
     -e wlan.ra \
@@ -212,7 +216,7 @@ CAPTURE_OUTPUT=$(tshark -q -r "$TEMP_PCAP" -n -T fields \
     -e radiotap.mcs.index \
     -e wlan_radio.data_rate \
     -e wlan_radio.mcs.index \
-    2>&1 | grep -v "^tshark:" | grep -v "^Running as" | grep -v "^Capturing" || true)
+    2>&1 | grep -E '^[0-9]' | head -1000000 || true)
 
 # Clean up temp file (unless KEEP_PCAP is set)
 if [ -z "$KEEP_PCAP" ]; then