Audiolink logo

Audiolink 2

The AL020 interface card.
From left to right are: power supply, ATM 155 port, two Ethernet ports, MADI in, MADI out, RS232.
Click on the pic for an enlarged view

Audiolink units connect professional audio equipment to an Asynchronous Transfer Mode (ATM) network.

The encoding of the audio on the network conforms to AES47-2002, the new standard for transmission of digital audio over ATM networks.

Audiolink 1 interfaces connect to ATM networks at 25 Mbit/s over Cat3 UTP.

AL020 specification

Internal interfaces

Two 26-way ribbon cable interfaces at the back of the board (as viewed in the picture above) each carrying the following signals; they are at TTL level and may interface with 2.5v, 3.3v, or 5v logic:
- eight audio data signals in I²S or AES3 format, configurable to be either inputs or outputs
- reference clock, word clock, and bit clock output
- word clock and bit clock input
- serial communication with "host" equipment (RS232 format)
Ribbon cable interface for separate card carrying LEDs (behind the MADI out connector)

External interfaces

From left to right along the front edge:

155 Mbit/s ATM port including audio reference signal input
two 100 Mbit/s Ethernet ports including SuperMAC sample clocks
MADI (AES10) input
MADI (AES10) output
two RS232 ports

Power supply

Any of the following options can be used:

7-60v unregulated DC input; 2.5v output available to power other cards
10-60v unregulated DC input; 2.5v and 5v outputs available to power other cards
5v regulated DC input; 2.5v output available to power other cards
2.5v and 5v regulated DC inputs

Synchronisation

The AL020 has VCXOs to generate an audio clock for 32, 44.1, or 48 kHz sampling frequencies. This clock can be locked to any of:

audio reference signal received at the 155 Mbit/s interface
8 MHz reference received from the ATM network
SuperMAC sample clock
timing information included in ATM-over-Ethernet packets
sample rate of any incoming audio signal

On the I²S interfaces, word clock and bit clock may be sourced by the AL020 or by the "host" equipment; the AL020 also sources a reference clock from which the "host" equipment can derive its bit clock.

Internal routing

Audio can be routed, as single channels or as multi-channel bundles, between any of:

AES47 audio calls on the 155 Mbit/s ATM interface
AES47 audio calls using the ATM-over-Ethernet service on either or both Ethernet interfaces
SuperMAC audio channels on either or both Ethernet interfaces
internal audio interfaces
MADI interfaces

Data messages can be routed between any of:

AES47 management calls on the 155 Mbit/s ATM interface
AES47 management calls using the ATM-over-Ethernet service on either or both Ethernet interfaces
SuperMAC data channels on either or both Ethernet interfaces
internal serial interfaces to "host" equipment
RS232 interfaces

ATM cells can be routed between any of:

the 155 Mbit/s ATM interface
either or both Ethernet interfaces when using the ATM-over-Ethernet service

This allows the Ethernet interfaces to be used to "daisy-chain" units together to share a single port on an ATM network. Because the Ethernet ports use auto-MDIX, no cross-over cables are required.

------------- ooo OOO ooo -------------