function getAuthorizationHeader ()
	{
		if (!$this->signed)
		{
			$this->sign($this->usr_id);
		}
		$h   = array();
		$h[] = 'Authorization: OAuth realm=""';
		foreach ($this->param as $name => $value)
		{
			if (strncmp($name, 'oauth_', 6) == 0 || strncmp($name, 'xoauth_', 7) == 0)
          	{
				$h[] = $name.'="'.$value.'"';
			}
		}
		$hs = implode(', ', $h);
		return $hs;
	}