-
公开(公告)号：US5416524A
公开(公告)日：1995-05-16
申请号：US894388
申请日：1992-06-05
CPC分类号： H04N5/126 , H04N5/4401 , H04N5/52 , H04N7/56
摘要： A digital television signal includes data sent as multilevel symbols in successive data segments each including a synchronizing sync character. The detected synchronizing sync character produces a characteristic having two opposite polarity levels separated by a zero reference level, with the levels occurring at successive sampling points of the television signal, and a detection signal that has a peak occurring in time coincidence with the zero reference level. The detection signal controls sampling of the received television signal. The gain of the received signal is controlled by an AGC circuit that also responds to the detection signal.
摘要翻译： 数字电视信号包括在包括同步同步字符的连续数据段中作为多电平符号发送的数据。 检测到的同步同步字符产生具有由零参考电平分开的两个相反极性电平的特性，电平在电视信号的连续采样点处发生，并且具有与零参考电平在时间上一致的峰值的检测信号 。 检测信号控制接收到的电视信号的采样。 接收信号的增益由也对检测信号作出响应的AGC电路控制。
-
公开(公告)号：US5016100A
公开(公告)日：1991-05-14
申请号：US453525
申请日：1989-12-20
摘要： A method of transmitting a video signal includes separating one or more parts of the video signal into a high frequency component and a low frequency component, encoding the low frequency component using an adaptive delta modulation process and transmitting the encoded low frequency components during non-active intervals of the high frequency component. In one embodiment, the high frequency component is encoded using an entropy code. A receiver is provided for reconstructing a video signal in response to the received encoded signals.
摘要翻译： 一种发送视频信号的方法包括将视频信号的一个或多个部分分离成高频分量和低频分量，使用自适应增量调制过程对低频分量进行编码，并在非活动期间发送编码的低频分量 高频分量的间隔。 在一个实施例中，使用熵码对高频分量进行编码。 提供接收机，用于响应于所接收的编码信号重构视频信号。
-
公开(公告)号：USRE36992E
公开(公告)日：2000-12-19
申请号：US194301
申请日：1994-02-09
CPC分类号： H04N7/0803 , H04N11/006 , H04N5/21 , H04N5/4401 , H04N5/455 , H04N11/002
摘要： A television signal transmission signal comprises a suppressed carrier, VSB signal having respective Nyquist slopes at the lower and upper edges of a 6 MHz television channel, the center frequency of the Nyquist slope at the lower edge of the channel being substantially coincident with the frequency of the suppressed carrier, and a pilot signal in quadrature relation with the suppressed carrier. The suppressed carrier is modulated by an N-level digitally encoded signal having a sample rate fs substantially equal to three times the NTSC color subcarrier frequency, with the frequency of the color subcarrier being less than the co-channel NTSC picture carrier by an amount equal to about fs/12. The received signal is demodulated by a synchronous detector in response to the received pilot signal and interfering NTSC beat components are attenuated by a linear filter having notches at fs/12, 5fs/12 and fs/2. The output of the filter comprises an M-level signal, where M is greater than N, which is converted to a N-level output signal representing the televised image.
-
公开(公告)号：US4876718A
公开(公告)日：1989-10-24
申请号：US221166
申请日：1988-07-19
CPC分类号： H04L9/0891 , H04L9/3226 , H04N7/1675 , H04L2209/34
摘要： A bit packet communication system includes a head-end having a software implemented 16 bit shaft register with a plurality of feed-forward taps and a different plurality of feed-back taps for simultaneously dividing and multiplying the input data bit packet to provide an output bit packet that is both encrypted and error protected. Dynamic encryption is provided by utilizing an initial preset for the software corresponding to a preset encryption key for the shift register. Authorized subscriber terminals are provided with memories and decryption keys are downloaded. The bit packets are assembled with a global bit packet encrypted with a global encryption key and subsequent individually addressed bit packets encrypted with address keys. The address keys and terminal addresses are permanently stored in the subscriber terminal memories. The global encryption keys are changed periodially. Means are provided in each subscriber terminal for storing a number of global decryption keys which are cycled through in attempts to decrypt the global packets. One of the global decryption keys is a permanent default key associated with the subscriber terminal to assure that communication with that terminal is possible despite a lack of knowledge of the terminal address or the other global decryption keys in its memory.
摘要翻译： 位分组通信系统包括具有软件实现的具有多个前馈分接头的16位轴寄存器和不同多个反馈抽头的头端，用于同时分割和乘法输入数据位分组以提供输出位 数据包被加密和错误保护。 通过利用与移位寄存器的预设加密密钥相对应的软件的初始预设来提供动态加密。 授权用户终端设有存储器，下载解密密钥。 位分组与通过全局加密密钥加密的全局比特分组和后续单独寻址的用地址密钥加密的比特分组合组合。 地址键和终端地址被永久存储在用户终端存储器中。 全局加密密钥周期性地改变。 在每个用户终端中提供用于存储在尝试解密全局分组时循环的多个全局解密密钥的装置。 全球解密密钥之一是与用户终端相关联的永久默认密钥，以确保与该终端的通信是可能的，尽管缺乏对其存储器中的终端地址或其他全局解密密钥的了解。
-
公开(公告)号：US5136375A
公开(公告)日：1992-08-04
申请号：US553822
申请日：1990-07-17
CPC分类号： H04N19/00 , H04N5/4401 , H04N7/015 , H04N19/30
摘要： A spectrum compatible HDTV data transmission system includes an adaptive delta modulator for producing 12-bit packets comprising direction and slope components of successive groups of three samples of removed low frequency video siganl. The 12-bit packets are compressed by a lookup table to four-bit output codes prioritized according to the statistical likelihood of occurrence of the 12-bit packet in a typical video signal. The 15 most likely to occur 12-bit packets are mapped to four-bit output codes 1-15 and the remaining 4080 12-bit packets are mapped to a common four-bit linking code. The next 255 most likely to occur of the remaining 4080 12-bit packets are further mapped to eight-bit output codes. All of the remaining 12-bit packets are mapped to the common remaining state of the eight-bit output codes. The compressed output codes are correlated with the constellation states of a quadrature modulator, with the constellation states requiring the least transmission power corresponding to the most likely to occur of the four-bit output codes. The output codes are multiplexed with the high frequency video before application to the quadrature modulator. The output of the modulator is transmitted at RF frequencies.
摘要翻译： 频谱兼容的HDTV数据传输系统包括一个自适应增量调制器，用于产生12位数据包，其中包括已删除的低频视频信号的三个样本的连续组的方向和斜率分量。 根据典型视频信号中出现12位数据包的统计可能性，12位数据包被查找表压缩为4位输出代码。 15个最可能发生的12位数据包被映射到四位输出代码1-15，其余的4080个12位数据包被映射到一个通用的四位链接代码。 剩下的4080个12位数据包中最可能出现的255个进一步映射到8位输出代码。 所有剩余的12位数据包都被映射到8位输出代码的公共剩余状态。 压缩的输出代码与正交调制器的星座状态相关，其中星座状态需要与四位输出码最可能发生的最小发射功率。 在应用到正交调制器之前，输出代码与高频视频复用。 调制器的输出以RF频率传输。
-
6.发明授权
公开(公告)号：US5087975A
公开(公告)日：1992-02-11
申请号：US611236
申请日：1990-11-09
CPC分类号： H04N7/0803 , H04N11/006 , H04N5/21 , H04N5/4401 , H04N5/455 , H04N11/002
摘要： A television signal transmission signal comprises a suppressed carrier, VSB signal having respective Nyquist slopes at the lower and upper edges of a 6 MHz television channel, the center frequency of the Nyquist slope at the lower edge of the channel being substantially coincident with the frequency of the suppressed carrier, and a pilot signal in quadrature relation with the suppressed carrier. The suppressed carrier is modulated by an N-level digitally encoded signal having a sample rate fs substantially equal to three times the NTSC color subcarrier frequency, with the frequency of the color subcarrier being less than the co-channel NTSC picture carrier by an amount equal to about fs/12. The received signal is demodulated by a synchronous detector in response to the received pilot signal and interfering NTSC beat components are attenuated by a linear filter having notches at fs/12, 5fs/12 and fs/2. The output of the filter comprises an M-level signal, where M is greater than N, which is converted to a N-level output signal representing the televised image.
摘要翻译： 电视信号传输信号包括抑制载波，在6MHz电视频道的下边缘和上边缘具有相应奈奎斯特斜率的VSB信号，在该信道的下边缘处的奈奎斯特斜率的中心频率基本上与 抑制载波和与抑制载波正交关系的导频信号。 抑制载波由具有基本上等于NTSC彩色副载波频率的三倍的采样率fs的N电平数字编码信号调制，彩色副载波的频率小于同频道NTSC图像载波的量相等 到约fs / 12。 所接收的信号由同步检测器响应于接收到的导频信号进行解调，并且干扰的NTSC拍频分量由具有fs / 12,5fs / 12和fs / 2的陷波的线性滤波器衰减。 滤波器的输出包括M电平信号，其中M大于N，其被转换为表示电视图像的N电平输出信号。
-
公开(公告)号：US4802213A
公开(公告)日：1989-01-31
申请号：US019445
申请日：1987-02-26
CPC分类号： H04N7/167
摘要： A TV scrambling system includes means for scrambling a TV signal by phase reversing the carrier at a horizontal rate. A sound masking circuit includes a phase locked loop which operates at five times the horizontal frequency. The program sound signal is used to frequency modulate the VCO in the phase locked loop and the output is added to the regular program sound for modulation onto an RF carrier to create an interfering sound signal. Detection of the program sound signal in an unauthorized receiver is accompanied by beating between the 5 H harmonic of the phase reversal frequency and the interfering sound signal, which masks the program sound.
摘要翻译： 电视加扰系统包括通过以水平速率相位反转载波来扰频TV信号的装置。 声屏蔽电路包括以五倍于水平频率工作的锁相环。 程序声音信号用于在锁相环中对VCO进行频率调制，并将输出添加到常规程序声音中，以调制到RF载波上以产生干扰声音信号。 在未经授权的接收机中检测到节目声音信号伴随着相位反转频率的5 H谐波与屏蔽节目声音的干扰声音信号之间的跳动。
-
公开(公告)号：US4759061A
公开(公告)日：1988-07-19
申请号：US14893
申请日：1987-02-13
IPC分类号： H04N7/167
CPC分类号： H04N7/167
摘要： A technique for toggling the coding mode in a television signal encoder comprises establishing a rectangular window defining a relatively small and substantially centrally located portion of the field image intervals of the television signal. The coding mode of the encoder is toggled whenever the APL of the television signal occurring during the window exhibits a change for successive video fields exceeding a predetermined threshold level.
摘要翻译： 一种用于在电视信号编码器中切换编码模式的技术包括建立矩形窗口，其定义电视信号的场图像间隔的相对较小且基本中心定位的部分。 每当窗口中发生的电视信号的APL对于超过预定阈值电平的连续视频场的变化表现时，编码器的编码模式被切换。
-
公开(公告)号：US5565932A
公开(公告)日：1996-10-15
申请号：US335603
申请日：1994-11-08
IPC分类号： H04N5/52 , H03G3/20 , H03G3/30 , H04L25/03 , H04L25/06 , H04L27/02 , H04L27/06 , H04L27/38 , H04N5/455
CPC分类号： H03G3/3068 , H04L27/02
摘要： An AGC circuit for a digital receiver that receives a digital television signal or the like, including a pilot, and formatted in a plurality of repetitive data segments, each data segment comprising a fixed number of multilevel symbols occurring at a constant symbol rate. The multilevel symbols are converted to corresponding digital values and the pilot (represented by a DC offset) is removed from the digital values. Every fourth symbol is sampled and the samples are accumulated and divided to derive an average symbol value. The average symbol value is compared with a reference average symbol value and the result of the comparison is an AGC potential that controls the tuner and IF gains. A cable/terrestrial input alters the sampling for cable signals to compensate for high level sweep testing in cable systems.
摘要翻译： 一种用于数字接收机的AGC电路，其接收包括导频的数字电视信号等，并且以多个重复数据段格式化，每个数据段包括以恒定符号速率出现的固定数量的多电平符号。 将多电平符号转换为相应的数字值，并从数字值中去除导频（由DC偏移表示）。 对每个第四符号进行采样，并对样本进行累积和分割，以得出平均符号值。 平均符号值与参考平均符号值进行比较，比较结果是控制调谐器和IF增益的AGC电位。 电缆/地面输入改变电缆信号采样，以补偿电缆系统中的高电平扫描测试。
-
公开(公告)号：US4885776A
公开(公告)日：1989-12-05
申请号：US159813
申请日：1988-02-24
CPC分类号： H04N7/1713 , H04N7/167
摘要： A television encoding system passes a modulated video carrier through a pair of SAW filters for attenuating and reversing the phase of the carrier during horizontal intervals. Another pair of SAW filters impart intermediate amplitude and phase changes to the video carrier during transitions into and out of the horizontal intervals to minimize switching transients and frequency disturbances in the color and audio carriers.
摘要翻译： 电视编码系统通过一对SAW滤波器传送调制视频载波，用于在水平间隔期间衰减和反转载波的相位。 另一对SAW滤波器在转换到和流出水平间隔期间向视频载波赋予中间幅度和相位变化，以最小化颜色和音频载波中的开关瞬变和频率干扰。
-
-
-
-
-
-
-
-
-
搜索结果
156 条记录 (耗时 0.017 秒)
