Sony STR-DA7100ES 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 time-
base 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
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 jitter-
free signal at the full quartz-crystal accuracy of the receiver's master clock. You
ES Receivers v1.0
STR-DA7100ES
Page 24