The MX469 is a full-duplex pin-selectable 1200/2400/4800bps Minimum Shift Key (MSK) Modem for FM radio links. The mark and space frequencies are 1200/1800, 1200/2400, and 2400/4800Hz respectively. Tone frequencies are phase continuous; transitions occur at the zero crossing point. The use of a common Xtal oscillator with a choice of two clock frequencies (1.008MHz or 4.032MHz) provides data-rate, transmit frequencies, and RX/TX synchronization. The transmitter and receiver operate entirely independently including individual section powersave functions. The MX469 includes on-chip circuitry for Carrier Detect and RX Clock Recovery, both of which are made available at output pins. RX, TX, and Carrier Detect circuits contain bandpass filters to provide high quality signals in their respective paths. The carrier detect time constant is set by an external capacitor, whose value should be arranged as required to further enhance this product's performance in high-noise environments. The MX469 demonstrates high sensitivity and good bit-error-rate under adverse signal conditions. This low-power device requires few external components and is available in the following packages: 24-pin SOIC (MX469DW), 22-pin PDIP (MX469P), and 20-pin SOIC (MX469D3). 1998 MX-COM, Inc.