What is the difference in the impedance characteristics of the Optix OSN3500 device 2M interface boards D12B, D12S, and D75S.

Cause Analysis

The impedance characteristics of the 2M interface boards D12B, D12S, and D75S have the following differences:

The D12B interface board is compatible with 75-ohm and 120-ohm veneer boards, and can provide 75-ohm unbalanced interfaces and 120-ohm balanced interfaces, but does not have a service protection function.

The D12S interface board can only be compatible with 120 ohm veneer boards, and at the same time, it is a PDH interface inversion board with service protection function.

D75S interface board can only be compatible with 75 ohm single board, at the same time for PDH interface reversing board, with service protection function.

Attention is required:

The processing board of D12B can be PQ1A (to handle 75 ohm E1) and PQ1B (to handle 120 ohm E1), but the actual application should be based on the type of 2M header of the customer-side DDF rack to decide what kind of collocation to be used, e.g., if the customer-side DDF rack is a 2M butt header of 75 ohm, then the interface board can be D12B or D75S, and the processing board is PQ1A.

The 75-ohm 2M header that interfaces with the DDF shelf is coaxial cable, and the 120-ohm 2M header is twisted pair (i.e., network cable), and the headers connected to the interface board all have the same DB44 connector.

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