The Si100x/1x transceivers support three different modulation options: Gaussian Frequency Shift Keying (GFSK), Frequency Shift Keying (FSK), and On-Off Keying (OOK). GFSK is the recommended modulation type as it provides the best performance and cleanest modulation spectrum. The figures shown illustrate the different modulation techniques. The GFSK figure also shows the modulated figure passed through the Gaussian filter. It can be seen that the time domain plots show a decrease in the edges of the signal which reduces spectral content.