PDU格式短信解码出错,高手请进!

Question

接收到PDU编码“4F60597D”,通过以下函数解码出现乱码"O`Y}"（原码为：你好）,请高手赐教.function DecodePDU(var s:String):string;
var
  i:Integer;
  str:string ;
  len1,len2:integer;
begin
    i:=1;
    str:=s;
    while i < length(str) do
    begin
      len1:=strtoint('$'+str[i]+str[i+1]);
      len2:=strtoint('$'+str[i+2]+str[i+3]);
      result:=result+chr(len1)+chr(len2);
      i:=i+4;
    end;
end;

Answer 1

function UCS2ToASC(Src:String):String;
var i:Integer;
    S:String;
    D:WideChar;
    ResultW:WideString;
begin
  for i:=1 to Round(Length(Src)/4) do  begin
    S:=Copy(Src,(i-1)*4+1,4);
    D:=WideChar(StrToInt('$'+s));  //此处是重点，用delphi提供的widechar可以转换
    ResultW:=ResultW+D;
  end;
  Result:=ResultW;
end;

Answer 2

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Answer 3

function TProtocolDataUnit.UnpackUCS2(UDInfo:string):WideString;
var
  i,j:Integer;
  CharTotal:Integer;
  CharUnicode:Integer;
begin
  Result:='';
  try
    CharTotal:=StrToInt('$'+Copy(UDInfo,1,2));
    if CharTotal mod 2<>0 then
      CharTotal:=CharTotal div 2 +1
    else
      CharTotal:=CharTotal div 2;
  except
    Exit;
  end;
  j:=3;
  for i:=1 to CharTotal do
  begin
    try
      CharUnicode:=StrToInt('$'+Copy(UDInfo,j,4));
      Result:=Result+WideChr(CharUnicode);
      Inc(j,4);
    except
      Exit;
    end;
  end;
end;