Audio Scrambler and Sub-Audio Signalling Processor 3 CMX138 Block Diagram Transmit Functions Sub-audio Signalling Pre-programmed 51 tone CTCSS encoder Programmable CTCSS tone encoder Programmable 23/24bit DCS encoder In-band signalling Mux MOD Programmable In-band encoder Audio processing MIC Voice Filter Compressor (Optional) PreEmphasis (Optional) Scrambler (Optional) Soft Limiter Channel Filter Receive Functions Audio Processing DISC Voice Filter De-Scrambler (Optional) De-Emphasis (Optional) Expander (Optional) sw AUDIO VBias Sub-audio signalling Pre-programmed 51 tone CTCSS decoder LPF Programmable CTCSS tone decoder Programmable 23/24bit DCS decoder In-band signalling HPF Programmable tone decoder System Control Auxiliary Functions AVdd VBias Auxiliary System Clocks Bias Programmable PLL Clock Clock O/P AVss I/O configuration DVdd VDec Tx Enable Bias I/O Clock/Xtal XtalN Rx Enable Clock Select DVss Crystal oscillator Main clock PLL Auxiliary DAC Ramp profile RAM DAC 1 DAC O/P IRQ Reply Data CSN Auxiliary ADC C-BUS Interface CMD Data Serial Clk Thresholds Power control ADC Registers sw ADC I/P Averaging Figure 1 Block Diagram © 2008 CML Microsystems Plc Page 6 D/138_FI1.0/6