RAD FCD-20 Rate and Interface Converter for E1 Multiplexers

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FCD-2 Fractional E1 (CEPT) Rate and Interface Converter

RAD FCD-20 Rate and Interface Converter for E1 Multiplexers

FCD-20/V35/115   FCD-20/V35/230   FCD-20/X21/115   FCD-20/X21/230


The FCD-20 is a rate and interface converter for connecting E1
(2.048 Mbps) equipment to a high speed public data service that provides V.35 or X.21 link at any n x 64 kbps data rate.

The FCD-20 connects equipment providing fractional E1 (in which only some of the timeslots are being used) to data channels in which the data rate is lower than the E1 rate.

The FCD-20 keeps the fractional E1 data channelized (i.e., the exact placement of data into timeslots is maintained end-to-end). This unique feature allows connection of both multiplexers and single channel equipment to the data service.

Channelization integrity is maintained by allocating 8 kbps for synchronization between the two FCD-20s. The remaining 56 kbps in the synchronization timeslot can be used either for user data channel or for downline loading of parameters to the remote unit. The channelized E1 interface is compatible with CCITT recommendations G.703, G.704 and G.732.

Two models are available:
with V.35 link interface or with X.21 link interface. Both models provide setup and control from the front panel.

Data from the E1 multiplexer is decoded in one of two selectable methods: either as a bundle of several consecutive timeslots or in a free, user-defined timeslot allocation.

The E1 transmit clock is locked to the V.35 or X.21 trunk timing of the data service network. The E1 multiplexer should operate in loopback timing mode, or with its own timing, if it is accurate enough to prevent excessive frame slips and loss of data.

Maintenance and diagnostics capabilities include local and remote loopbacks at various points.


  • Connects E1 (CEPT) equipment to digital data services
  • Connects two PABXs through digital data services
  • Maintains fractional E1 (CEPT) integrity end-to-end
  • Link interface: V.35 or X.21
  • Front panel setup and control
  • Complies with CCITT recommendations G.703, G.704 and G.732
  • Selectable E1 framing format: two or sixteen frames per multiframe
  • Downline loading of configuration to remote sites

E1 Rate and Interface Converter

+ Specify:
V35 for V.35 link interface
for X.21 link interface

# Specify:
115 for 115 volts supply
230 for 230 volts supply
(Default is 230 volts supply)

Hardware for mounting one unit onto a 19" rack





Four Channels Transferred End-to-end through Data-service



RAD Products

For discount pricing on RAD Data Communications  
email us at sales@data-connect.com
or call 301-924-7400