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11. 发明授权

EP0548205B1 RECEPTION OF ORTHOGONAL FREQUENCY DIVISION MULTIPLEXED SIGNALS 失效
标题翻译： RECEIVING正交频率复SIGNALS
公开(公告)号：EP0548205B1
公开(公告)日：1997-11-19
申请号：EP91916674.4
申请日：1991-09-13
申请人： DIGI-MEDIA VISION LIMITED
发明人： GLEDHILL, Jeffrey John , ANIKHINDI, Santosh Vasudev , AVON, Peter Anthony
IPC分类号： H04L5/06 , H04L7/033
CPC分类号： H04N21/2383 , H04L27/2602 , H04L27/2657 , H04L27/2662 , H04L27/2679 , H04N7/0803 , H04N21/4382
摘要： In an OFDM signal individual OFDM carriers are modulated by samples of signals which can only take a limited range of allowed values and a block of samples modulates the group of carriers during a time period T. In a receiver, the signal modulating an individual OFDM carrier may be demodulated by estimating the position of reference axes serving as the frame of reference against which the allowed modulating values are defined, and multiplying the value of the demodulated samples by the complex conjugate of a point on one of the estimated reference axes. The spread of the groups of samples demodulated from each OFDM carrier gives an indication of whether the receiver is synchronised to the block boundaries. Preferably spread of the complex samples is evaluated in the radial direction only and used to steer the sample clock frequency. Phase drift of the demodulated samples from one block to the next indicates the degree of local oscillator frequency error. Preferably phase drift is assessed by multiplying complex values by the complex conjugate of an earlier sample demodulated from the same OFDM carrier and using the resulting measure to steer the local oscillator frequency via a frequency locked loop.

12. 发明公开

EP0759667A2 Statistical multiplexing 失效
标题翻译： Statischer多路复用器
公开(公告)号：EP0759667A2
公开(公告)日：1997-02-26
申请号：EP96305955.5
申请日：1996-08-14
申请人： DIGI-MEDIA VISION LIMITED
发明人： Budge, Michael Richard Joseph , Jagger, Jonathan Rodney Bull , Stedman, Robert Julian
IPC分类号： H04J3/16 , H04N7/58
CPC分类号： H04N21/4347 , H04J3/1688 , H04N19/115 , H04N19/146 , H04N19/152 , H04N19/154 , H04N19/172 , H04N19/182 , H04N19/61 , H04N21/234354 , H04N21/2365 , H04N21/23655 , H04N21/2385
摘要： The present invention relates to a transmitter for transmitting a plurality of digital signals through a plurality of channels, the channels having a predetermined total bitrate allocated to them, comprising a plurality of encoders one associated with each channel; a multiplexer for receiving the encoded digital signal and transmitting them as a stream of data and capable of adjusting the distribution of the bitrate allocation between the encoded signals; and processing means for providing an indication of a target quality and an actual quality for each channel and causing the multiplexer to repeatedly adjust the distribution of the bitrate allocation in response to differences between the indicated actual quality and the indicated target quality for each channel so as to tend to equalise the difference between the actual and target quality across some or all of the channels.
In principle, by grouping encoders together in what will be termed herein "statistical multiplex groups", and making real time decisions about the bitrate requirements for those encoders, bitrate can be allocated to maximise picture quality for the group. The theory is that for a variety of different picture sources in a statistical multiplex grouping, to achieve a target picture quality the bitrate requirements of each will vary with coding difficulty. Thus a channel within the statistical multiplex group that is experiencing little difficulty in encoding its picture can free bits to channels that are having greater difficulty. The effect is to smooth the picture quality and to subjectively improve it.
摘要翻译：本发明涉及一种用于通过多个信道发送多个数字信号的发射机，所述信道具有分配给它们的预定总比特率，包括与每个信道相关联的多个编码器; 多路复用器，用于接收编码数字信号并将其作为数据流发送并且能够调整编码信号之间的比特率分配的分布; 以及处理装置，用于提供针对每个信道的目标质量和实际质量的指示，并且使多路复用器响应于指示的实际质量与每个频道的指示目标质量之间的差异重复地调整比特率分配的分布，以便倾向于平衡部分或所有渠道的实际和目标质量之间的差异。原则上，通过将编码器分组在这里将被称为“统计多路复用组”，并对这些编码器的比特率要求做出实时决定，可以分配比特率以最大化该组的图像质量。理论是针对统计多路分组中的各种不同的图像源，为了实现目标图像质量，每个的比特率要求将随着编码难度而变化。因此，在对其图像进行编码时几乎没有困难的统计多路复用组内的信道可以对具有更大困难的信道进行空闲比特。效果是平滑画面质量，主观改善。

13. 发明公开

EP0757499A2 Method and apparatus for testing the signature of decoders of compressed digital television signals 失效
标题翻译：的方法和装置，用于检查压缩的数字电视信号的解码器签名
公开(公告)号：EP0757499A2
公开(公告)日：1997-02-05
申请号：EP96305412.7
申请日：1996-07-23
申请人： DIGI-MEDIA VISION LIMITED
发明人： Bock, Alois
IPC分类号： H04N17/00
CPC分类号： H04N17/004
摘要： A method of testing a digital decoder which decodes a compressed digital television signal including a test bit stream. The decoder is connected to a signal analyser which checks whether the decoder provides an expected signature of bits from the test bit stream. The signal analyser has to be clocked by gating pulses which must be fixed in relation to the test bit stream. In order to supply the gating pulses, the invention includes a trigger signal in the television signal which is detected at the output of the decoder, the gating of the signal analyser being determined by reference to the detected trigger signal.
摘要翻译：测试一个数字解码器，其压缩的数字电视信号包括测试比特流进行解码的方法。解码器被连接到检查是否解码器提供从测试比特流的比特的预期的签名的信号分析仪。信号分析器必须由选通脉冲，它必须是固定在相对于测试比特流提供时钟。为了供给该选通脉冲，本发明包括在电视信号中的触发信号检测到的所有这是在解码器的输出端，信号分析器是确定性的通过参考检测到的触发信号开采的门控。

14. 发明公开

EP0356055A1 Interference suppression for transmitted signals and demodulation of vestigial sideband signals 失效
标题翻译： ÜbersprechstörungfürübertrageneSignale und Demodulation von Restseitenbandsignalen。
公开(公告)号：EP0356055A1
公开(公告)日：1990-02-28
申请号：EP89307988.9
申请日：1989-08-04
申请人： DIGI-MEDIA VISION LIMITED
发明人： Beech, Brian Herbert
IPC分类号： H03D3/00
CPC分类号： H03D3/002 , H04N7/045
摘要： A vestigial sideband (VSB) signal is demodulated by separately a.m. and f.m. demodulating the signal, triangulating the a.m. demodulated signal, i.e. processing the a.m. demodulated signal to produce an output whose magnitude is a function of the frequency of the a.m. demodulated signal, and combining the result with the f.m. demodulated signal; the output signal is substantially free from the usual distortion which arises due to the absent sideband.
The same technique is used to suppress adjacent channel interference (ACI) affecting a signal on one side of its carrier frequency.
ACI affecting a signal on both sides of its carrier frequency is suppressed as above in some cases if the polarity and/or magnitude of the triangulated a.m. demodulated signal is adjusted dependent upon the value of the f.m. demodulated signal.
ACI is also reduced by filtering a signal to remove one sideband containing interference and then demodulating the filtered signal as a VSB signal by the above technique.
摘要翻译：残留边带（VSB）信号分别在上午和下午5点解调。对所述信号进行解调，对所解调的信号进行三角测量，即处理所述解调后的信号以产生其幅度是所述解调信号的频率的函数的输出，并将所述结果与f.m. 解调信号; 输出信号基本上没有由于没有边带而产生的通常的失真。相同的技术用于抑制影响其载波频率一侧的信号的相邻信道干扰（ACI）。如果三角测量的解调信号的极性和/或幅度取决于f.m的值，则如上所述，影响其载波频率两侧的信号的ACI被抑制。解调信号。通过对信号进行滤波以除去包含干扰的一个边带，然后通过上述技术将经过滤波的信号解调为VSB信号也减少了ACI。

15. 发明授权

EP0563167B1 COMPATIBLE NON LINEAR PRE-EMPHASIS FOR COMPOSITE VIDEO SIGNALS 失效
标题翻译：方法和装置非线性加重和去加重的复合视频信号
公开(公告)号：EP0563167B1
公开(公告)日：1997-08-27
申请号：EP92901581.6
申请日：1991-12-20
申请人： DIGI-MEDIA VISION LIMITED
发明人： BEECH, Brian, Herbert 10 Darlington Road
IPC分类号： H04N5/21 , H04N9/77 , H04B1/62
CPC分类号： H04N5/21 , H04N5/205 , H04N5/208 , H04N5/38 , H04N7/015 , H04N11/16
摘要： When a video signal including a component modulated onto a subcarrier (such as a PAL signal) is subjected to a non-linear pre-emphasis known for MAC signals, with the object of reducing the effects of noise encountered in transmitting the composite signal through an f.m. channel, problems of noise and differential gain remain. These problems are overcome by subjecting the composite signal to a filtering step, before application of the non-linear processing, so as to filter out the subcarrier, the chrominance subcarrier in a PAL signal, and to compand the chrominance sidebands. Preferably a notch filter is used which has a notch shaped as a Gaussian curve.

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