3 Packet Format

A 5 byte preamble is used for testing and this is programmable. The payload in DSSS mode is byte oriented. Definition of packet lengths, headers, CRC, whitening follow the same rules as in the standard CC13x2 Generic FSK modes. The entire packet structure is illustrated in Figure 3-1.

Figure 3-1 WB-DSSS Packet Structure

The payload is encoded first by FEC and then spread through the DSSS block, as described in Section 2. In order to terminate the sequence, the modem automatically inserts four termination bits at the end of the payload with each termination bit resulting in 2*DSSS transmitted over-the-air symbols.

The relationship between data rate (the actual amount of information bits available to the higher protocol layers) and the symbol rate (the actual modulation rate used in the radio) can be expressed as:

Equation 1.