Difference between GFSK and DSSS mode

Question: What is the difference between GFSK mode and DSSS mode of communication?



WirelessUSB systems encode their data within Pseudo Noise (PN) codes in DSSS mode. The main advantage is to increase the robustness and recoverability of the signal in the presence of interference. A simple explanation is that a single data bit from the application is represented by multiple bits when sent across the air, and decoded back into the original data bit on the receiving side. One result of using PN codes is that devices in a given network must agree to use a common PN code in order to understand one another. Another advantage of this is that it increases the co-location capabilities since devices can share the same channel if they use different PN codes.

WirelessUSB LP devices also offer 1 Mbps Gaussian Frequency Shift Key (GFSK) modes that do not make use of PN codes. In this case, all devices on the same frequency can communicate with one another and co-location capabilities are potentially reduced. GFSK mode is the fastest data rate, however care must be taken in its use. By definition, this mode eliminates the advantages of DSSS technology making it much more susceptible to errors.