SWRA122D January 2007 – September 2018 CC1100 , CC1100E , CC1101 , CC1101-Q1 , CC1110-CC1111 , CC1131-Q1 , CC1151-Q1 , CC430F5123 , CC430F5125 , CC430F5133 , CC430F5135 , CC430F5137 , CC430F5143 , CC430F5145 , CC430F5147 , CC430F6125 , CC430F6126 , CC430F6127 , CC430F6135 , CC430F6137 , CC430F6147
Section 5 shows plots of sensitivity versus frequency offset for different data rates. The required crystal accuracy is calculated from the total frequency offset as
| Case | Figure | 3-dB Bandwidth (Total Frequency Offset) | Crystal Accuracy (868 MHz) |
|---|---|---|---|
| 4.8 kbps, 2FSK, 25 kHz deviation, DC filter,
RX filter bandwidth = 101 kHz |
Figure 4 | 50 kHz | ±14 ppm |
| 4.8 kbps, 2FSK, 25 kHz deviation, no DC filter,
RX filter bandwidth = 101 kHz |
Figure 5 | 50 kHz | ±14 ppm |
| 10 kbps, 2FSK, 19 kHz deviation, DC filter,
RX filter bandwidth = 101 kHz |
Figure 6 | 70 kHz | ±20 ppm |
| 10 kbps, 2FSK, 19 kHz deviation, no DC filter,
RX filter bandwidth = 101 kHz |
Figure 7 | 70 kHz | ±20 ppm |
| 38.4 kbps, 2FSK, 20 kHz deviation, DC filter,
RX filter bandwidth = 101 kHz |
Figure 8 | 110 kHz | ±32 ppm |
| 38.4 kbps, 2FSK, 20 kHz deviation, no DC filter,
RX filter bandwidth = 101 kHz |
Figure 9 | 120 kHz | ±35 ppm |
| 76.8 kbps, 2FSK, 32 kHz deviation, DC filter,
RX filter bandwidth = 232 kHz |
– | 230 kHz | ±66 ppm |
| 76.8 kbps, 2FSK, 32 kHz deviation, no DC filter,
RX filter bandwidth = 232 kHz |
– | 260 kHz | ±75 ppm |
| 100 kbps, 2FSK, 47 kHz deviation, DC filter,
RX filter bandwidth = 325 kHz |
– | 220 kHz | ±63 ppm |
| 100 kbps, 2FSK, 47 kHz deviation, no DC filter,
RX filter bandwidth = 325 kHz |
– | 180 kHz | ±52 ppm |
| 250 kbps, MSK, DC filter,
RX filter bandwidth = 541 kHz |
Figure 10 | 200 kHz | ±58 ppm |
| 250 kbps, MSK, no DC filter,
RX filter bandwidth = 541 kHz |
Figure 11 | 220 kHz | ±63 ppm |
| 500 kbps, MSK, DC filter,
RX filter bandwidth = 812 kHz |
Figure 12 | 120 kHz | ±35 ppm |
NOTE
The ADC spectrum in the RX chain consists of a significant DC component. This puts a lower limit on the IF frequency that can be used. For optimum sensitivity, a digital DC filter can be enabled (MDMCFG2.DEM_DCFILT_OFF =0), and the ADC DC output is attenuated. This opens for selection of lower IF frequencies thereby lower noise floor and improved sensitivity. As an example, for 868 MHz, 250 kbps 2-FSK, enabling the DC filter gives 2 dB better sensitivity, at the expense of an increased current consumption of 2.3 mA.