diff --git a/src/CoreParser.php b/src/CoreParser.php
index c8cbc85..16e0ac9 100644
--- a/src/CoreParser.php
+++ b/src/CoreParser.php
@@ -81,8 +81,10 @@ class CoreParser {
         $m->snr = 0;
 
         if( $m->code == CoreProtocol::RESP_CODE_CHANNEL_MSG_RECV_V3 ) {
-            $m->snr = unpack('V', substr($payload, $idx, 4))[1] / 4;
-            $idx += 4;
+            $m->snr = ord($payload) / 4;
+            $idx += 1;
+            // two reserved bytes
+            $idx += 2;
         }
 
         $m->channel_idx = ord($payload[$idx]);