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Some knowledge accumulated about timestamping
=============================================
The meaning of the timestamps changed between v2.3.1 and v3.0.0, this document gives some guidance about the interaction between different settings.
The following table tries to summarise the differences.
+-----------------------------+----------------------------------------------+-------------------------------------+-----------------------------------------------+
| ODR-DabMux version | Meaning of timestamp inside EDI | ODR-ZMQ2EDI wait time w | Offset that should be set in the mod |
+=============================+==============================================+=====================================+===============================================+
| Up to and including v2.3.1 | t_frame = t_mux (No offset in mux available) | positive, meaning delay after t_mux | Something larger than w + mod processing time |
+-----------------------------+----------------------------------------------+-------------------------------------+-----------------------------------------------+
| Later than v2.3.1 | t_frame = t_tx = t_mux + tist_offset | negative, meaning delay before t_tx | Something larger than mod processing time |
+-----------------------------+----------------------------------------------+-------------------------------------+-----------------------------------------------+
The edilib tool decodes both EDI timestamp and MNSC, and can be used to verify both are identical.
Issues in ODR-DabMux v2.3.1
---------------------------
Running ODR-DabMux against the absolute timestamp firmware has uncovered a few issues:
* At startup, the UTCO was not properly applied to the EDI seconds. This offset was 5 seconds (TAI-UTC offset - 32s, see EDI spec);
* odr-zmq2edi did not compensate for UTCO, hiding the above issue;
* ODR-DabMux needs a configurable offset;
* (minor) MNSC and EDI timestamps did not use the same internal representation, making it difficult to prove that they encode the same value;
* (minor) odr-zmq2edi swapped endianness when regenerating EDI from ETI (minor because only ODR-DabMod considers MNSC, and usually isn't used with EDI);
**Important** Do not combine odr-zmq2edi with odr-dabmux of a different version!
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