Correct the output format:

1. omit the empty obsrvation.
2. correct the match rule of
   signal.

Readme.md

@@ -21,10 +21,13 @@ do not modify the information.
 ![image](Convert_chart.png)
 
 ### About Project ###
-At present, the RINEX2.xx format conversion has been fully supported,
+2024/11/14: At present, the RINEX2.xx format conversion has been fully supported,
 the format output error of the previous version has been modified,
 and the conversion from 2.xx to 3.xx is currently supported.
 
+2024/11/15: Correct the output format, omit the empty observation and change the
+rule of match.
+
 ### Update plan ###
 1. 2.xx and 3.xx versions are fully supported, and support mutual conversion.
 2. Gradually introduce the conversion support for RTCM files.