公开(公告)号：EP1898630A2

公开(公告)日：2008-03-12

申请号：EP07114687.2

申请日：2007-08-21

Applicant: STMicroelectronics Pvt. Ltd

Inventor： Mohan Sharma, Vivek ,  Kumar Jain, Sheetal

IPC: H04N5/00

CPC classification number: H04N21/2368 ,  H04N5/40 ,  H04N21/2383

Abstract: The present invention provides a digital radio frequency (RF) modulator for providing modulation for base-band TV signals. The RF modulator provides direct conversion of digital base-band audio and video signals to a desired RF channel frequency, without any analogue up conversion. The RF modulator in the present invention includes an audio module, a video module, and a RF converter. The audio module includes a pre-emphasis filter, a multi-stage audio interpolator and a complex frequency modulator to generate frequency modulated (FM) audio signals. The video module includes a complex VSB filter, a group-delay compensation filter and some processing logic to generate a filtered output video signal. The RF converter includes a complex adder, a complex multiplier and a RF interpolator to construct the base band TV signals and to shift the base band TV signals in a frequency domain to the desired RF channel frequency. The exponential video carrier is generated at baseband and has a frequency whose value is in the range of +/-13.5MHz. The RF interpolator includes a zero pad logic followed by a quadrature band pass filter (BPF), and an optional second stage of another zero-pad logic followed by a real band pass filter (BPF). The second stage is optional in the sense that it is required only if the desired RF channel is in the higher VHF band.

Abstract translation: 本发明提供一种用于提供基带电视信号调制的数字射频（RF）调制器。 RF调制器可将数字基带音频和视频信号直接转换为所需的RF信道频率，无需任何模拟上转换。 本发明的RF调制器包括音频模块，视频模块和RF转换器。 音频模块包括预加重滤波器，多级音频内插器和复频调制器以产生调频（FM）音频信号。 视频模块包括复合VSB滤波器，组延迟补偿滤波器和用于产生经滤波的输出视频信号的一些处理逻辑。 RF转换器包括复数加法器，复数乘法器和RF内插器，以构建基带TV信号并将频域中的基带TV信号移位到期望的RF信道频率。 指数视频载波在基带处产生，其频率范围为+/- 13.5MHz。 RF内插器包括跟随正交带通滤波器（BPF）的零焊盘逻辑，以及随后是实数带通滤波器（BPF）的另一零焊盘逻辑的可选的第二级。 在第二阶段是可选的，只有当所需的RF信道处于较高VHF频带时才需要。

公开(公告)号：EP1898630A3

公开(公告)日：2010-04-28

申请号：EP07114687.2

申请日：2007-08-21

Applicant: STMicroelectronics Pvt. Ltd

Inventor： Mohan Sharma, Vivek ,  Kumar Jain, Sheetal

IPC: H04N5/00 ,  H03C1/60 ,  H03D7/16 ,  H04N5/40

CPC classification number: H04N21/2368 ,  H04N5/40 ,  H04N21/2383

Abstract: The present invention provides a digital radio frequency (RF) modulator for providing modulation for base-band TV signals. The RF modulator provides direct conversion of digital base-band audio and video signals to a desired RF channel frequency, without any analogue up conversion. The RF modulator in the present invention includes an audio module, a video module, and a RF converter. The audio module includes a pre-emphasis filter, a multi-stage audio interpolator and a complex frequency modulator to generate frequency modulated (FM) audio signals. The video module includes a complex VSB filter, a group-delay compensation filter and some processing logic to generate a filtered output video signal. The RF converter includes a complex adder, a complex multiplier and a RF interpolator to construct the base band TV signals and to shift the base band TV signals in a frequency domain to the desired RF channel frequency. The exponential video carrier is generated at baseband and has a frequency whose value is in the range of +/-13.5MHz. The RF interpolator includes a zero pad logic followed by a quadrature band pass filter (BPF), and an optional second stage of another zero-pad logic followed by a real band pass filter (BPF). The second stage is optional in the sense that it is required only if the desired RF channel is in the higher VHF band.