Sony STR-GX80ES Technical Background - Page 24

Controlling the signal flow with HATS The design of the interface is exceptional because communicating six streams of 2.8224 MHz digital samples raises exceptional challenges. Conveying 1-bit signals at such high data rates and synchronizing the signals with the receiver's master clock would normally expose the signal to the timebase errors called jitter. Jitter translates directly into time-based distortion of the audio waveform. Sony overcame this challenge with the High quality digital Audio Transmission System (HATS). HATS uses "command-based rate control of isochronous data flow" to solve the problem. The system incorporates three principal elements. 1. Variable-speed transmission from the player. 2. Buffer memory in the receiver. 3. Command signals from the receiver to the player, controlling transmission speed. DVP-NS9100ES STR-DA7100ES With Sony HATS, audio data flows from the player to the receiver's buffer memory, according to rate control commands from the receiver. Reproduction in the receiver achieves the full time base accuracy of the receiver's quartz crystal master clock. The receiver continually monitors the amount of audio data in its buffer memory. When the buffer memory reaches its lower limit, the receiver commands the player to increase data transmission speed. When the buffer memory reaches its upper limit, the receiver commands the player to decrease transmission speed. And when the buffer memory is between the upper and lower limits, the receiver commands the player to transmit at normal speed. In this way, HATS makes it unnecessary to synchronize a jitter-prone signal with the receiver master clock. Instead, the buffer memory outputs a jitterfree signal at the full quartz-crystal accuracy of the receiver's master clock. You ES Receivers v1.0 Page 24