Hi, Recently, I am confused about the process from baseband signal to RF transmission. I know that baseband signal is sent to USRP through UHD. If the signal amplitude exceeds 1, what will happen? I looked up some mailing lists and mentioned nonlinearity. I wonder what this nonlinearity means? There are many nonlinear devices in RF, such as ADC, amplifier, etc. which is the specific one? As I understood it earlier, suppose a baseband signal sample (0.8+0.8i) becomes Udacmax* (0.8+0.8i) when it enters the USRP. Udacmax is the maximum voltage. When a signal sample is (2+2i), it becomes udacmax* (1+1i)?Amplitudes exceeding 1 are forced to be limited to 1 and multiplied by the maximum voltage?
When the baseband signal has a high PAPR, it will affect the RF operation. A high amplitude will bring nonlinear distortion to the power amplifier. Is this nonlinear distortion the same as the nonlinearity brought by the amplitude exceeding 1 mentioned above? If it is the same, can I evaluate the impact of high PAPR by changing the value of the "multiply const" module (the scaling factor before the baseband signal enters the USRP sink) to make the signal enter nonlinearity? Finally, I would like to know the whole process from baseband signal to RF electromagnetic wave (on USRP). Is there any website you can recommend? I have some fragmentary knowledge of signal processing, but I can't combine them to figure out the whole process. Looking forward to your reply, thanks in advance?? Sincerely, Regards linge93
