Wide-Band DSSS Mode for FCC Digital Transmission Systems Using CC13x0

This application report describes a wide-band modulation scheme to comply with the requirements of FCC section 15.247 for non-frequency hopping digital modulation systems utlizing datarates below 500kbps. The scheme is implemented with an MCE patch, which is a standalone program that implements the various options of the Wide-Band Direct Sequence Spread Spectrum (WB-DSSS) scheme. The patch is included in the CC1310 SDK and can be setup to be imported in the final application by Code Export option of SmartRF™ studio. This SDK can be downloaded from: http://www.ti.com/tool/SIMPLELINK-CC13X0-SDK.

The implementations and summary of performances measured on CC13x0EM ^[5] are provided in this document.

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1 Introduction

WB-DSSS uses a well-known method to obtain sensitivity gains by means of coding and spreading the information bits into a series of transmitted symbols.

The transmit spectrum requirements of FCC Section 15.247 for digital transmission systems operating in the 902 MHz - 928 MHz band are as follows:

The minimum 6 dB emission bandwidth of the signal shall be at least 500 KHz.
The maximum peak conducted output power for transmitter is +30 dBm (1 Watt).
The maximum power spectral density is limited to 8 dBm in any 3 KHz band segment within the emission bandwidth during any interval of continuous transmission.