Verilink Red Zone Encryption (REMS) (880-502423-001) Product Manual - Manual (Page 34)

Theory of operation
3-8 Red Zone Encryption Management System (REMS) User Manual
6. As the near-end DTE transmits its D4/ESF framed signal, the near-
end FBR extracts information about the location of the D4/ESF
framing bit.
7. The near-end FBR sends an FBR code that is aligned with the DTE
framing. This means, actually, that the FBR code is inserted into the
DTE framing bit position.
The far-end FBR identifies the FBR and BRC frame bit positions and
calculates an offset count.
8. The near-end FBR repositions the DTE framing bit, which contains
the FBR code, by an amount equal to the offset count. Only the
framing bit itself is repositioned, and the end-to-end (encode/decode)
delay of the entire signal is a maximum of one bit. The FBR code
and BRC framing bits now correspond to the same time slot.
Time
I BRC
DTE F
I = BRC inserted bit
F = D4 framing bit
Time
I BRC
DTE F
FBR code FBR
offset = x
I = BRC inserted bit
F = D4 framing bit
FBR = FBR code
F 0 1 2 3 191
0 1 2 F 3 191
offset = x