Data Sheet APCM-404A-1 IRIG-106 PCM Encoder Data Sheet Download Resource The file you are trying to access requires you to be logged in as a registered user. Registration is free, sign up today. Username Enter your Curtiss-Wright Defense Solutions username. Password Enter the password that accompanies your username. Forgot password? Don’t have an account? Register here. The APCM-404A is used to encode data in an IRIG-106 Chapter 4 (Ch.4) PCM stream. APCM-404A-1 The APCM-404A is used to encode data in an IRIG-106 Chapter 4 (Ch.4) PCM stream.