USRP -> 3318PA -> DB4090 -> 20' LMR-400 -> （避雷针）lightning arrestor -> 20' RG-8X -> 9 dBi 天线
One problem to note is that the USRP puts out spurs and noise in the rx band, about 80 dB down from the tx signal, but still high enough to be a problem without good duplexing isolation.
With cable losses the EIRP of the antenna was about 39dBm.
9 dBi天线 -> 20' RG-8X ->（避雷针）lightning arrestor -> 20' LMR-400 -> DB4090 ->（前置放大） preamps -> rx filter（滤波） -> USRP
The Rx chain of the USRP was set to maximum gain, so the RF amp was set to the max of 70dB, and the programmable gain amp in front of the A/D was set to 20dB. According to the USRP RFX900 specs, the low-pass filter has a notch about 50-55 MHz from the center freq. So we twiddled with the RFX900 receive LO, so that our transmit frequency fell into this notch, giving us more transmit isolation. That feature would not work, however, in a multi-ARFCN system.
注： OpenBTS Burning Man 2008 RF Chains（原文出处，翻译整理仅供参考!）