The Baseband Channel / Brickwall Filter is designed for use with the Time-Division Multiplexer, Model 9460, the Time-Division Demultiplexer, Model 9461, and the T1/CEPT PCM Transceiver, Model 9462. Other modules that can be used with the Baseband Channel / Brickwall Filter are the Line Coder, Model 9464, and the Line Decoder, Model 9465.

The Baseband Channel section of the module provides the frequency characteristics of a twisted pair of wires. The line length simulated is selectable between 0.15, 0.30, 1, and 2 kilometers. An auxiliary noise input is provided for noise injection. Input and output impedances are 120 S and coupling is either DC or AC (10 kHz). When AC coupling is selected, both the input and output connectors have a balanced (ungrounded) characteristic.

The Brickwall Filter creates heavy intersymbol interference (ISI) conditions. The filter has a very sharp low-pass characteristic that cuts off at 60 dB per decade. Again, input and output impedances are 120 Ω and can be either DC or AC (balanced) coupled.