Quantec Zombies 12xx Series, Operation Manual

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2. Menu Structure - 2.12 AES18 Config (1218 only)
ZOMBIEs 12xx
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Glossary
AES18 is an industry standard for transmitting control and signaling data using the AES3 user
channel. To block-synchronize the freely definable datagram lengths, a modified HDLC protocol is
specified. Also specified in AES18 is an access protocol to provide a fair allocation of the
transmission channel between all stations.
Messages are blocks of control and signaling data which are transmitted via the user channel. They
are sent in smaller units called packets.
Packets are sections of messages which contain a maximum of 16 signaling bytes.
A transmitter divides messages into packets and adds the target address, size, continuity index
priority and CRCC to each one. The packets are then integrated into the data stream as soon as
space is free and the priority allows it.
The receiver establishes which messages are meant for it and reassembles them according to the
continuity index. The sender is not defined in the information sent to the receiver. This can lead to
problems: if two transmitters send separate messages to one receiver at the same time this can lead
to errors in the continuity index.
The block is the basic structure used in data transfer. The number of blocks transmitted per second
can be adjusted. The size of each block varies with the number of blocks per second and the sample
rate. The minimum block size is 420 bits at 100 blocks per second and a sample rate of 42kHz. If
follows from this that the sample rate may never be permitted to drop to under 42kHz!
System Packets are packets which are always sent at the beginning of a block, from the device
which generates the blocks. They contain information regarding the size of the block and the
priority levels for all connected devices.