my @data = qw ( 01 b2 01 00 b6 81 81 01 b4 0a 01 01 01 01 00 01 00 00 01 00 c7 82 82 01 b2 01 00 b8 );

for ( my $i = 0; $i < $#data; $i++ ) {
        if ( $data[$i] eq "81" ) {
                if ( $data[$i+1] eq "81" ) {
                        print "match 81 starting at index $i\n";
                }
        }
        elsif ( $data[$i] eq "82" ) {
                if ( $data[$i+1] eq "82" ) {
                        print "match 82 starting at index $i\n";
                }
        }
}