On 02/11/2016 03:07 PM, Zhihong Luo via USRP-users wrote:
Hi All,
Can we get the power of the signal on transmitter output and receiver
input (X300)?
If there is a function for that, please help point it out. Thanks in
advance.
Zhihong Luo
For measuring TX power, you need a calibrated RF power meter, that can
usefully measure at the desired frequency.
On RX, the power across the bandwidth represented by the sample stream is:
power ~= AVG(II + QQ)
Now, notice this isn't absolute power. The sampled signal will contain
voltage estimates that are proportional to the instantaneous voltage
as seen at the antenna terminals, but given that there are several
stages of (mostly-linear) transforms (gain, mixing, digital and analog
filtering transforms), the only way to relate what appears in the
sample stream with voltages as seen at the antenna input is to use an
external calibration source that produces a known power at the
desired frequency.
On 02/11/2016 03:07 PM, Zhihong Luo via USRP-users wrote:
> Hi All,
>
> Can we get the power of the signal on transmitter output and receiver
> input (X300)?
>
> If there is a function for that, please help point it out. Thanks in
> advance.
>
> Zhihong Luo
For measuring TX power, you need a calibrated RF power meter, that can
usefully measure at the desired frequency.
On RX, the power across the bandwidth represented by the sample stream is:
power ~= AVG(I*I + Q*Q)
Now, notice this isn't absolute power. The sampled signal will contain
voltage estimates that are *proportional* to the instantaneous voltage
as seen at the antenna terminals, but given that there are several
stages of (mostly-linear) transforms (gain, mixing, digital and analog
filtering transforms), the only way to relate what appears in the
sample stream with voltages as seen at the antenna input is to use an
external calibration source that produces a known power at the
desired frequency.
