Questions about the output after character transcoding

Questions about the output after character transcoding
Header ("content-type:text/plain;charset=gb2312");
Header ("Content-disposition:attachment;filename=". Date ("Ymdhis"). " Test.xls ");
echo iconv ("UTF8", "gb2312", "Weibo id\t");

Why is there no data in the exported Excel table?

If you rewrite the UTF8 in the Iconv function to Utf-8, there is no problem.

Please explain why, thank you.

------Solution--------------------
UTF8 is UTF8 encoded in MySQL. PHP is utf-8.
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1 Floor Positive Solution


But on someone else's machine (ubantu), there is no problem with the test, there is a problem on my machine (win7).

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