SPIRIT1 is a low-data-rate, low-power sub-1GHz transceiver that supports 2-FSK, GFSK, MSK, GMSK, OOK and ASK modulation schemes, air data rates from 1 to 500 kbps, has excellent receiver sensitivity (-120 dBm), selectivity and blocking characteristics, very low power consumption (RX is 9 mA, TX is 21 mA, transmit power is programmable up to +11 dBm), fast start-up, and short frequency synthesizer settling time (6 µs), and has frequency offset compensation, integrated temperature sensor, battery indicator and low battery detector, RX and TX FIFO buffer (each 96 bytes), configurability via SPI interface, automatic acknowledgement, retransmission and timeout protocol engine, AES 128-bit encryption co-processor, antenna diversity algorithm, fully integrated ultra low power RC oscillator, internal timer wake-up and wake-up on external event, flexible packet length with dynamic payload length, sync word detection, address check, automatic CRC handling, FEC with interleaving, digital RSSI output, programmable carrier sense (CS) indicator, automatic clear channel assessment (CCA) before transmitting (for ISM band).