3 Data Protocol and Signal Timing

The remote sensor sends an RF data telegram with the temperature data for every 10s or when the user presses the SW1 or the SW2 button. The base station receiver is polling for this data telegram on RF channel 433.92 MHz in regular intervals of 5 ms. The RF transmission and data protocol of the remote sensor and the base station is using the following settings:

• Transmission order is MSB first for preamble and data section
• RF channel – 433.92 MHz
• Data rate – 8 kbit/s with FSK modulation and Manchester encoding
• Deviation – ±8 kHz

Each data packet uses two bits before and after the data telegram to force a Manchester code violation, which the receiver detects to separate the data packets and to restart the synchronization procedure of the receiver.