B200 mini input power full scale

[soring@ayecka.com]

The spec of B200 is maximum input power -15dbm.

However my measurements show that at 2GHz, sine input, at +10 dbm , gain 0, the sinewave amplitude is ~13400 and the maximum is 32768.

Can someone enlighten me how it is possible?

Thanks

Sorin

[keukenrol]

I've always suspected that the max power level input of -15 dBm is a safe limit for the hardware, but not for the analog to digital converter. I am working on received power calibration and wonder if this calibration will give the correct full scale behavior.

[DennisJoosens]

The -15 dBm is the most vague value and super relative to interpret in my opinion.

In terms of the USRP, we do not know:
- How is this measured?

- What is the signal that was put into it to test?

- What is the frequency?

- What is the gain set?

- Is this an average value measured over the full bandwidth?

This is not documented as far as I am aware.

However, generally I believe caution needs to be taken, if you know that the AD9361/9364 RFIC has a max. peak input level of 2.5 dBm (again no frequency/signal info).

So:

- Do you transmit a calibrated signal?
- Is your signal an RMS signal, what is the amplitude?

- What is your applied FFT window when visualising?
- How is your incoming signal connected to the B200 (wired/wireless)?

Also note that the B200 is not calibrated by default. What you measure is not necessarily the true value.

The -15 dBm (at 0 dB gain) is I believe a safe value to not damage your hardware as @keukenrol said, and to not clip your ADC in the end.