选用SDR
FM Radio一般是80Mhz-110Mhz，然而每款SDR覆盖的频段都有所侧重，这里为了实现一个FM Radio系统首先需要注意SDR的频段。
| SDR型号 | 频段 |
|---|---|
| E312 | 60Mhz-6Ghz |
| N210+SBX | 400Mhz-4.4Ghz |
| N210+WBX | 70Mhz-2.4Ghz |
| BladeRF | 230Mhz-3.8Ghz |
GQRX组件
GQRX组件是GNURadio中一个全频段的接收机模块，可以直接实现频谱的查看。
NBFM和WBFM
窄带FM和宽带FM的主要差别在于频偏。
Gnuradio的一些log信息.
"u" = USRP
"a" = audio
"O" = overruns -- getting more samples than your CPU can process
"U" = underruns -- getting lesser samples thatn your USRP needs to run the process
Combining the flags above results in a specific indication of PC to USRP communication status. For example :
"aUaU" = audio underrun (PC is not providing samples rapidly enough to the soundcard)
"uOuO" = USRP overrun (PC is not keeping up with the sample rate of USRP), so USRP samples are being dropped
"uUuU" = obvious :) i.e. USRP Underruns