Re: [Discuss-gnuradio] ADC calibration

[Daniel Halperin]

On Tue, 10 Aug 2010, Matt Ettus wrote:
> When using a BasicRX or LFRX with the PGA set at 0dB gain (USRP1 only), 
> +10dBm is full scale on the ADC.  On the USRP2 full scale on the ADC is full 
> scale when it gets back into gnu radio.  On the USRP1 full scale on the ADC 
> is (1.67/2) times full scale due to the gain of the CORDIC.
>
> +10dBm = 2Vpp = 1 Vpeak = 0.7 Vrms
>
> With other daughterboards you will need to calibrate at the frequency of 
> interest.

Thanks, that's helpful.  However, I can't quite make the math work:

P = V^2/R ; 0.01 W = (1 V)^2/R ; R = 100 Ohms.

But we're using SMA connectors which are 50 Ohms right?  Or should I be
putting 1 Vpeak I *and* 1 Vpeak Q and getting the 100 Ohms from the
combination of the two 50 Ohm connectors?

Thanks,
Dan

(forgot to reply all first, sorry for the double-msg Matt)