Hi, I am trying to calculate the link budget for USRP N310.
Suppose I want a SNR of 20dB, the signal bandwidth is 10MHz, the thermal noise floor is -103.9dm. Receiver noise figure is 5.8dB (N310 datasheet 5.8dB @1.8GHz) Rx Antenna Gain 6dBi Path loss: 120dB Tx Antenna Gain 6dBi RF cable Loss (RX+TX): 1dB Then my TX power before TX antenna should be -103.9dBm + 20dB + 5.8dB - 6dBi + 120dB -6dBi + 1dB = 30.9dBm The receive signal strength at RX port of USRP = -78.1dBm The noise strength at RX port of USRP = -103.9dBm The SNR before receiver is 25.8dB, after receiver is 20dB. However, due to the sampling noise and effective bits of ADC, I doubt that the noise floor after the receiver would be much higher than -103.9dBm + 5.8dB = -98.1dBm, e.g. -90dBm?, in that case my receive SNR would be lower than 20dB. Does anyone know the output noise floor (or sensitivity) of USRP N310 receiver (e.g. RX2 port) in 500-1000MHz band? e.g. in the unit of dBm/Hz? That would help me to decide if an external LNA is necessary. If so does some typical wideband LNA with a gain of 20dB and noise figure of 3.6dB would be enough. Thank you! Regards, Zhongyuan Zhao PhD Candidate, Department of Computer Science & Engineering, University of Nebraska-Lincoln
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