Technical data

www.asti-usa.com ASTi DACS: Operation & Maintenance Manual (Version 4, Rev. B.1)

Instead of providing analog interfaces local to the card, however, the TDM Controller forms a

base driver for a Time Division Multiplex ring. This ring carries digital audio to and from Remote

Interface Units populating the ring. The RIUs in turn provide the analog to digital interface at

remote sites along the ring. See the next section for more information on the RIU.

The TDM Controller has two RJ-45 connectors for connection of standard Category 5, UTP net-

work cables. To form the TDM ring, cabling is run from the TDM controller card to the ﬁrst

Remote Interface Unit. Subsequent RIUs are daisy chained together with the ring eventually ter-

minating back at the TDM Controller (see Figure 2). Rings can be conﬁgured to a maximum

length of 100m.

Within the Model Builder software environment, a TDM controller looks exactly like a Waveform

Synthesizer. Sound and communications models are developed in the same fashion. The main dif-

ference is that models generated for a TDM Controller allow up to 24 audio ins and outs as

opposed to 8 ins and outs with the Waveform Synthesizer.

Figure 2: TDM Ring Distributing Digital Audio

Audio interface within the TDM architecture is via the Remote Interface Unit (RIU). RIUs con-

tain both signal conditioning circuitry as well as the necessary A/D and D/A converters for con-

version of audio between the digital and analog domain. Audio sampled by RIUs distributed on

the TDM ring is passed back to the main TDM controller for control and manipulation by the

local sound model. Sounds and audio mixed and generated in the TDM controller can in turn be

sent out in a digital format to the RIUs, which convert them back to analog audio signals.

This architecture allows the user to place the analog/digital interface close to an audio source such

as a headset, reducing susceptibility to noise and crosstalk typically generated by long analog

cable runs. The TDM ring allows for up to 14 RIUs driving up to 24 audio Input/Output channels.

Multiple TDM rings can also be installed within a single DACS. This provides the user with a

highly ﬂexible and expandable architecture.

DACS

RIU 1 RIU 2

Cat 5

Cables

RIU 3 RIU 14