Re: [Discuss-gnuradio] Gain ahead of Basic RX?

[Matt Ettus]

John Ackermann N8UR wrote:
> As mentioned earlier, I'm working on a front-end board for the Basic-RX
> to provide some gain and selectivity for HF use.
>
> Question -- has anyone figured out what sort of gain is optimum ahead of
> the the Basic-RX for use as an HF receiver?  I can easily tweak the
> front-end design to provide anything from about 8 to 18 dB gain; more
> than that might require adding a second amp stage, which is doable if
> necessary.
>   

Using an BasicRX on a USRP with the PGA turned all the way (+20dB) up is
roughly like having a 35dB noise figure.  Based on that and your desired
system noise figure, you can tell how much gain you need ahead of it. 

On the high side, with the PGA turned down (0dB), the ADCs will clip at
2Vpp.

Matt