What is the use of the DECT sync in/out connections on the EQUE card?

In some large multi-studio FreeSpeak or CellCom installs it maybe necessary to have antennas connected to one Eclipse matrix located in the same area (corridors, reception areas) as another set of antennas from a different Eclipse matrix.
Typically this maybe the case Studio-1 matrix including EQUE card for CellCom operation has antennas in the main scenery corridor Studio-2 matrix including EQUE card for CellCom operation has antennas in the same main scenery corridor
Therefore we have two independent DECT systems operating in the same RF space. DECT is designed to handle this situation with best selection of clean RF channels and auto handover between best available RF channels. However there is some loss in RF channel efficiency
When multiple Eclipse frames operate antennas in the same DECT space in order to provide the best carrier frequency efficiency the DECT sync of the different matrices should be locked together so that antennas connected to the Studio-1 matrix EQUE card  do not RF drift over other antennas connected to Studio-2 matrix EQUE cardFor this reason the EQUE card does provide for an external DECT sync in / out connectors 

See this FAQ for the DECT Sync IN / OUT pinout details https://clear-com.atlassian.net/wiki/spaces/SF/pages/158719564

What if any system issues might one expect with the wireless operation of each frame if the DECT sync connection is ignored?

a) If the antennas for the two different matrices are in the same RF space it would limit the number of beltpacks as there was less available carrier room and handovers would happen more often with a risk of higher audio drop out as carrier channels collide.

b) If the matrices are in two separate RF spaces (they are RF separated)  – no consequence.

Can the DECT sync signal be transported over fibre (FIM-202?) and routed across and reconverted back on the other frame?

The 100Hz sync signal uses pulse code width to determine synchronisation values. Customers have used both the fiber splitter and RS422/485 media converters to carry DECT Sync.
However, since this is only necessary when the antennas are using the same RF DECT space it is unlikely to be required.

If a CAT-5 run is the only solution for the DECT sync connection, what is the practical limitation on length of this CAT-5 connection between frames?

We use the same driver as the E1 signals from the RJ-45 connectors. upto 1000m using 24AWG CAT5 cable