Case study:

20x Freespeak beltpacks on a 1.9GHzsystem. 5 antennas on a CAT5-connected splitter (Area 1).  Another 5x antennas via a fibre-connected splitter (Area 2). RF coverage areas for both splitters are overlapping (i.e. a beltpack can see antennas from both splitters simultaneously). 

Initially with all antenna cable lengths at minimum, a beltpack could roam from Area 1 to Area 2.  However they could not go back...the beltpack stayed connected to the Area 2 and the only way to get them back to Area 1 was to cycle power on the beltpack. 

Adjusting various antenna cable lengths as high as 300 m gave no results. We did notice that setting a fibre antenna at 1540 m would help the beltpack roam back to the Area 1.  We set all the fibre-splitter antennas at 1000 m and then they began to sync properly with the CAT5-splitter antennas. It seems that the fibre conversion probably introduces more latency than a CAT5 cable would.  

Answer from Clear-Com hardware engineering:
When using a fibre splitter the conversation from conversion optical/electrical or fibre/CAT5 does add a delay to the DECT sync pulse, which needs to be compensated for using the antenna compensation. The DECT sync pulse is sent from the basestation/ matrix to all antennas in order to keep them aligned and help with roaming between antennas. The conversation from fibre to CAT5 adds an extra 200m to the overall cable distance. This needs to be added in to cable compensation. You only need to add the fibre conversation (FC) value once.
 

When using a Freespeak II (FSII) system (matrix or base) you enter the actual cable lengths between the matrix/base and the antenna. Note that the difference between DECT-sync propagation speed for fibre vs. CAT5 is negligible. Treat cable lengths the same for both.  

Base/matrix <---> CAT5-A <---> FSII-Splitter  <---> CAT5-B <---> Antenna : Total distance to enter (m) = A+B

Base <---> Fibre-A <---> FSII-splitter <---> CAT5-B <---> Antenna : Total  distance to enter (m) = FC + A + B ,where FC =200 (conversion factor optical/electrical)

Note:

• A =  Length of Fibre

• B =  Length of CAT5 

Base <---> CAT5-A <---> FSII-splitter <---> Fibre-B <---> FSII-splitter <---> CAT5-C <---> Antenna = Total  distance to enter (m) = FC +A + B+ C

where FC =200 (conversion factor optical/electrical)

Note:

• A = Length of CAT5

• B = Length of Fibre

• C = Length of CAT5 

To adjust the antenna compensation value for

Matrix: Goto EHX > cards ports > Eque splitter FSII > advance settings

FSII Base II: Go to FSII base CCM (web browser) > overview > click on the antenna 

In summary The antenna compensation values are used to minimise the handover error between antennas. Handover errors can be experienced as loss of connectivity on the beltpacks, (BP screen shows searching), audio pops as you move from RF zone one to another or inability to roam between antennas.

This is especially important when adjacent antennas have overlapping RF coverage zones and have very different cable lengths. The antenna compensation length should be entered when usingCAT5 only systems or when using a fibre splitter When using the fibre port of the FSII splitter the conversion optical/electrical (or fibre/copper) requires the addition of 200 m to the total length of fibre cable plus all CAT5 cables 

See attached for examples.