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Glossary of Technical Terms

Denon Original Technologies

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DENON LINK 4th

What is DENON LINK 4th?

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Digital Audio Signal

Sound that reaches human ears is made up of vibrating air that continually exists over time. Audio devices transform these vibrations into an electric signal. Sometimes the signal is an analog audio signal (smooth waveform), and sometimes it is quantified to become a digital audio signal (staircase waveform).

The digital audio signal samples the waveform of the analog audio signal at fixed intervals as it passes continuously over time and quantifies it into binary values consisting of 1 and 0. Since quantification enables the digital audio signal to be expressed as a waveform, it is negligibly affected by noise; as can be heard when listening to a CD, the sound of the music is very clear and virtually noise-free. The digital audio signal also suffers little degradation when edited and is therefore easily processed for use on various media such as CD, DVD, and Blu-ray disc.

In reality, however, digital audio signals are not entirely free of noise, as they have a distortion known as clock jitter that affects sound quality.

The Existence of Jitter

Digital audio devices are equipped with a clock that generates a time axis for quantized digital signals. The clock generates a time axis for use when signals are converted from digital to analog or from analog to digital. Jitter occurs when intervals along the time axis (the samples) fluctuate. The fluctuations along the time axis cause distortion in the sound.

Jitter mainly occurs due to a lack of accuracy in the clock itself and along the signal transmission path. To support media such as Blu-ray and DVD (video + audio), players need to have multiple clocks, and with Blu-ray and DVD, the video and audio signals need to be synchronized.

Generally, PLL is used to generate clock signals, but they are easily affected by noise during transmission which in turn causes jitter and degrades sound quality.

In recent years, greater attention is being focused on the importance of a master clock for the constant management of sampling at fixed intervals.

Conventional Jitter Suppression

In conventional jitter suppression, the digital audio signal (data) was temporarily stored in the front-stage memory of the audio circuit and output after being synchronized with the clock to achieve low-jitter digital signal transmission.

This method, however, was limited to audio sources on CD. There were basically two reasons for this. The first reason was that the clock frequencies of audio circuits were different from those of video circuits, and the second reason was that while the quantity of audio-only data was not that large and could be stored in memory, the quantity of video data and multi-channel audio data on DVD or Blu-ray disc is too large to store in memory.

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The Advent of DENON LINK 4th, the world's first jitter suppression technology to include video signals

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We have succeeded in using DENON LINK (a digital interface) as a dedicated clock signal transmission line to transmit high-grade digital signals in high speed and with negligible influence from external noise. Previously, the purpose of DENON LINK was to transmit the digital audio signals themselves, but the purpose of DENON LINK 4th is to control the clock.

DENON LINK 4th uses the master clock in the A/V surround receiver as the reference for controlling the video circuitry and the disc drive in the player, and the digital video and audio signals from Blu-ray disc are transmitted to the A/V surround receiver via an HDMI cable. This is how our DENON LINK 4th works.

DENON LINK 4th is able to transmit digital audio signals with negligible jitter because it has audio devices share the same clock. In addition, DENON LINK 4th has achieved a world first by suppressing jitter to an absolute minimum even for the playback of Blu-ray discs that include video signals.

Jitter suppression brings exceptional results to three-dimensional playback in such areas as sound localization, sound spaces and sound images. The sound space of a concert hall, for instance, is reproduced so clearly that it feels as though the artists are performing in very close proximity to the listener.