I'm no expert but this seems to split up the data correctly:

use utf8;

my $data = 'M02 1731580851ç? æµ· WBPXæ·±å?³é¾?å??å??ä¸?æ??é??å?¬å?¸ 99
+9999321';
my @chars = $data =~ /(.)/sg;
[download]

With the utf8 pragma I get 41 chars, without it I get 65.

-Blake