Measurement of transmit power for USRP 2922

[Payal12]

hello,

I am working on 2X2 MIMO system with Almouti coding.For that I am using 2 USRPs as Tx and 2 USRPs as rX. When I refer the data sheet of USRP 2922 there i find that the maximum o/p power range is in between 50mw to 100mw. My question is this the transmit power of USRP?. and next question is that how can i measure the transmit power of USRP 2922 ?so that i come to know that the USRPs I am using transmits power at this value particulary.

[vvkakade]

Hi,

USRP 2922 is a uncalibrated device so there is no way to determine the output power without actually measuring it.

One way to do it is by connecting it to a RF power meter and then sweeping through the Tx gains on the USRP 2922 and measuring the power at the same time. This will give you a kind of working calibration table which will look like this:

USRP Gain   Output Power

1                          x1 dBm

2                          x2 dBm ...

Then you can use this table to reverse calculate the gain required for a requested power.

Note that the output power will also depend on the base-band sinusoid amplitude.

A sample power meter that you can use:
http://www.ni.com/en-us/support/model.usb-5680.html

There might be a few cheaper ones out there too.