Why Is USRP Output Power Limited at the High-Frequency Range?

Updated May 13, 2019

Reported In

Hardware

  • USRP-2943
  • USRP-2954
  • USRP-2944
  • USRP-2953

Issue Details

I am using USRP-2943R for my research.
According to the specification, the maximum output power is written as follow:

Why is the maximum output power at 3.5GHz to 6GHz lower than that at 1.2GHz to 3.5GHz?
 

Solution

The maximum output power is that USRP-2943R can transmit a single tone signal with a certain transmission power 17 dBm to 20 dBm or 7 dBm to 15 dBm across the particular frequency range mentioned.
This is the characteristics of USRP-2943R's CBX daughterboard. Therefore, the lower transmission power at the high-frequency range is the expected situation.

From USRP-2954R specification, you can find out that the maximum output power of USRP-2954R is different from that of USRP-2943R.
USRP-2954R has the following maximum output power specification:
Maximum output power (Pout) | 50mW to 100mW (17 dBm to 20 dBm)
This means that USRP-2954R can transmit a single tone signal with a certain transmission power 17 dBm to 20 dBm across the particular frequency range of 10 MHz to 6 GHz.

One of the reasons for this difference is that USRP-2943R uses a CBX daughterboard but USRP-2954R uses an UBX daughterboard.


 

Additional Information

The USRPs are not calibrated instruments, there is the performance difference among same devices due to the performance difference in the various components and PCB and manufacturing process.

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