公开(公告)号：WO1997004412A2

公开(公告)日：1997-02-06

申请号：PCT/US1996011416

申请日：1996-07-08

Applicant: CABLE TELEVISION LABORATORIES, INC.

Inventor： CABLE TELEVISION LABORATORIES, INC. ,  WILLIAMS, Thomas, H. ,  BAGGETT, Claude, T.

IPC: G06K00/00

CPC classification number: G06F21/123 ,  G06F2211/007

Abstract: A system for protecting software from copying wherein the software to be protected is placed on the computer system in two parts. A first part (120) is stored in non-volatile storage, such as a hard disk or floppy disk within the computer system (100), and a second part is stored and executed in a "hardware key (122)", which is attached to the computer system (100). The second part is stored in volatile RAM (206) and will be erased when electrical power is removed from the hardware key (122), or when the software stops execution. This requires that the second part of the software be reloaded each time the hardware key (122) is powered up. Typically, the second part of the software will be loaded from a network (130), or from a cable network, thus reloading of the second part into the hardware key (122) is a trivial matter, so long as the user is an active subscriber to the network (130) or cable network.

Abstract translation: 一种用于保护软件免于复制的系统，其中待保护的软件以两部分放置在计算机系统上。 第一部分（120）存储在诸如计算机系统（100）内的硬盘或软盘的非易失性存储器中，并且第二部分被存储并执行在“硬件密钥（122）”中，即“硬件密钥 连接到计算机系统（100）。 第二部分存储在易失性RAM（206）中，并且当从硬件钥匙（122）去除电力时，或当软件停止执行时将被擦除。 这要求在硬件密钥（122）上电时重新加载软件的第二部分。 通常，软件的第二部分将从网络（130）或有线网络加载，从而将第二部分重新加载到硬件密钥（122）中是一件简单的事情，只要用户是活跃的 用户到网络（130）或有线网络。

公开(公告)号：WO1995002290A1

公开(公告)日：1995-01-19

申请号：PCT/US1994007679

申请日：1994-07-08

Applicant: CABLE TELEVISION LABORATORIES, INC.

Inventor： CABLE TELEVISION LABORATORIES, INC. ,  WILLIAMS, Thomas, H.

IPC: H04L05/06

CPC classification number: H04L27/2601 ,  H04L27/2623 ,  H04N7/08 ,  H04N7/088 ,  H04N7/0882

Abstract: A system is disclosed which provides a significantly enhanced transmission rate for digital data transmitted over a television channel, while also providing immunity to signal interference caused by multipath reception. One embodiment of the system transmits a signal containing digital data in the vertical blanking interval of a television signal. Before being transmitted, the digital data is modulated (105, 110, 115) by a process called orthogonal frequency division multiplexing, or OFDM. Each block of digital data to be transmitted is transformed (105) by using an inverse discrete Fourier transform which produces a block of data (110) that is used to modulate a single carrier signal. The modulated carrier signal has a plurality of mutually orthogonal components, each of which has a lower frequency (data rate) than the original digital data signal. The single carrier signal can be viewed as being comprised of a plurality of mutually orthogonal carrier signals which have lower frequencies than the original signal. These lower frequency "carrier signals" can be transmitted with more immunity from phase and amplitude distortion than a single modulated higher-frequency signal. Even though interference-induced distortion of the transmitted signal may be relatively large when viewed across the entire transmission (broadband) channel, the distortion is relatively small across each of the limited-bandwidth carrier channels. Therefore, the transformed signal has a high immunity to multipath interference, even when the phase of the received multipath signal is time-varying. A guard interval (217) is optionally prefixed to the front end of the data signal to provide additional immunity to multipath interference. A further feature of the present system is the optional inclusion in the transmitted signal of an error correcting code which allows detection and correction of multiple sequential data transmission errors.

Abstract translation: 公开了一种系统，其提供了通过电视频道发送的数字数据的显着增强的传输速率，同时还提供对由多路径接收引起的信号干扰的抗扰性。 系统的一个实施例在电视信号的垂直消隐间隔中发送包含数字数据的信号。 在传输之前，通过称为正交频分复用或OFDM的过程对数字数据进行调制（105,110,115）。 通过使用产生用于调制单载波信号的数据块（110）的逆离散傅里叶变换来变换（105）要发送的每个数字数据块。 调制载波信号具有多个相互正交的分量，每个分量具有比原始数字数据信号更低的频率（数据速率）。 单载波信号可以被看作是由具有比原始信号低的频率的多个相互正交的载波信号组成的。 这些较低频率的“载波信号”可以比单个调制的较高频率信号以更大的抗相位和幅度失真的抗扰度被传输。 即使在整个传输（宽带）信道上观察时，即使发射信号的干扰引起的失真可能相对较大，在每个有限带宽载波信道上的失真相对较小。 因此，即使接收的多路径信号的相位是时变的，变换信号对多径干扰具有高的抗扰性。 保护间隔（217）可选地前缀到数据信号的前端，以提供对多径干扰的附加抗扰性。 本系统的另一个特征是在传输信号中可选地包括允许检测和校正多个顺序数据传输错误的纠错码。