The AXN/ENC/401 is used to encode data in an IRIG-106 Chapter 4 (Ch.4) PCM stream.

In Ch.4 mode, parameters from any Axon module in the chassis can be placed in the Ch.4 PCM stream. Parameters from other Axon chassis and Ethernet sources can also be placed in the Ch.4 PCM stream.

Ethernet frames are input to the Axon chassis via the controller and passed to the AXN/ENC/401 across the backplane.

Multiple AXN/ENC/401 modules can be included in an Axon system and parameters can be sent to some or all encoders. The AXN/ENC/401 has differential-ended RS-422 outputs for data and clock along with buffered TTL outputs for NRZ-L, DATA, DCLK, word, minor-frame, and major-frame pulses.

The AXN/ENC/401 also has a programmable premodulation filtered analog output, which is suitable for use with a linear FM transmitter for telemetry. The cutoff frequency and amplitude can be changed to suit the bit-rate and transmitters' deviation sensitivity.

All physical outputs transmit the same payload data using independent line encoding (PCM codes) configurations.