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BTSC encoder achieves stereo audio sans alignment

Posted: 31 Jan 2008 ?? ?Print Version ?Bookmark and Share

Keywords:integrated alignment-free? digital BTSC? stereo encoder? digital STBs? digital video recorders?

Asahi Kasei EMD Corp. has launched an integrated alignment-free digital Broadcast Television Systems Committee (BTSC) stereo encoder targeting digital STBs, digital video recorders and RF modulator converter boxes in the United States, Canada, Mexico, Brazil and Taiwan.

Asahi has expanded its Audio4home family with the launch of its AK4145 encoder. Packaged in a 16-pin TSSOP, the AK4145 encoder enables stereo audio transmission over the same RF signal that is used for cable and antenna inputs. AKEMD's new digital BTSC encoding process achieves high audio performance without alignment of external components. Audio characteristics include 0.01 percent S/(N+D), 82dB SNR, and 47dB stereo separation.

The AK4145 outputs digital PCM data as a baseband composite (MPX) audio signal, which includes L+R, L-R, and a Pilot signal by BTSC encoding. It supports video/27MHz input for synchronization of the pilot signal and video system signals.

Additional integrated functions such as soft mute, digital volume control and de-emphasis allow for a constant signal level setting corresponding to the audio source, and the composite output level can be adjusted by the baseband composite volume control.

The AK4145 audio data interface supports MSB-first, LSB-first or I?S formats. The master clock supports 256-, 384-, 512fs and externally supplied 768fs, which are typical frequencies for digital audio equipment. The sampling rate can be 32-, 44.1- or 48kHz, making it possible to use the AK4145 in the same system configuration as existing audio DAC products. The operating voltage range for the digital section is 1.7V to 1.9V, and 2.7V to 3.6V for the analog and interface sections.

Evaluation boards and samples are already available.

- Gina Roos

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