Hi Zain,
As per my understanding, you are trying to set the center frequency of the SDR Pluto to 1GHz. However, the value shown in spectrum analyser is different.
According to the documentation of “sdrtx”, the default “CenterFrequency” is 2.4GHz , which matches what the spectrum analyzer shows. Therefore, the problem might be that the “CenterFrequency” isn't being modified, despite it being a tuneable parameter.
One possible workaround is to use “release” function. It releases system resources such as memory, file handles, or hardware connections, and allows you to change properties and input characteristics.
Please refer to the documentation of “release” function for more information:
Hope this helps!