3.1.2.1 Telegram Structure

The ATA8510/15 supports the transmission and reception of a wide variety of telegrams and protocols. Generally, no special structure is required from a telegram to be received or transmitted by the ATA8510/15. However, designated hardware and software features are built in for the blocks that are depicted in the following figure. Using this structure or parts of it can increase the sensitivity and robustness of the broadcast.

Desync:

The de-synchronization is usually a coding violation with a length of several symbols that provokes a defined restart of the receiver. The use of a de-synchronization leads to more deterministic receiver behavior, reducing the required preamble length. This can be favorable in timing-critical and energy-critical applications.

Preamble:

The preamble is a pattern that is sent before the actual data payload to synchronize the receiver and provide the starting point of the payload. A very regular pattern (e.g., 1-0-1-0...) is recommended for synchronization (“wake-up pattern, WUP”, sometimes also called “pre-burst”) while a unique, well-defined pattern of up to 32 symbols is required to mark the start of the data payload (“start frame identifier, SFID” or “start bit”). In polling scenarios, the WUP can be tens or hundreds of ms long.

Data Payload:

The data payload contains the actual information content of the telegram. It can be NRZ or Manchester-coded. The length of the payload is application-dependent, typically 1..64 bytes.

Checksum:

A checksum can be calculated across the data payload to verify that the data were received correctly. A typical example is an 8-bit CRC checksum. Data bits at the beginning of the payload can be excluded from the CRC calculation.

Stop Sequence:

The stop sequence is a short data pattern (typically 2 to 6 symbols) to mark the end of the telegram. A coding violation can be used to prevent additional (non-deterministic) data from being received.