电路设计_CC11xx灵敏度与频率偏移和晶体精度的关系

1、If the crystal frequency has an error of ±X  ppm (parts per million) the RF frequency also has an error of ±X ppm.

2、The signal bandwidth has to be less than the receiver channel filter bandwidth.

3、Conversely , if the receiver has an error of +X ppm and the transmitter an error of -X ppm the IF frequency will have an error of -2·X ppm.

4、BWchannel = BWsignal + 4 · XTALppm · fRF

BWsignal = Data rate + 2 * frequency deviation

 

Note that the frequency offset between Rx and Tx needs to be taken into account when selecting the Rx filter bandwidth.

 

3dB带宽指幅值等于最大值的二分之根号二倍时对应的频带宽度幅值的平方即为功率，平方后变为1/2倍，在对数坐标中就是-3dB的位置了，也就是半功率点了，对应的带宽就是功率在减少至其一半以前的频带宽度，表示在该带宽内集中了一半的功率。