NXP SA606 RF-IF ICs can connect cardiac patient's implanted device to clinic or doctor's office via standard phone line or cellular phone. Monolithic FM IF system incorporates mixer/oscillator, 2 limiting intermediate frequency amplifier blocks, quadrature detector, logarithmic Received Signal Strength Indicator (RSSI), voltage regulator, and audio and RSSI op amps. Remote monitoring receiver operates from 60–80 kHz, and MCU has DSP for resolving and outputting pertinent information.