We use ADRV9008-1 in our board. Our fundamental modulated waveform frequency is in C-Band frequency and is 5700MHz. Our sample rate is 122.88 MHz, and the maximum bandwith is our design is about 30 MHz. The problem is that if there is an another signal near our main carrier, it reduces the SNR and creates Bit Errors on our waveform design at spesific frequencies. To test this situation we created a setup and gave an another carrier near our main carrier by changing it's frequency and we saw that SNR decreases and creates bit errors at some frequencies. For example there is no error if the unwanted signal frequency between 5.42 GHz - 5.56 GHz or 6.04 GHz - 6.1 GHz. However if the unwanted signal frequency is between 5.56 GHz - 5.7 Ghz or 5.36 GHz - 5.28 Ghz, we saw that SNR decreases and creates bit errors at our waveform design. How can we eliminate this affect to our main carrier if there is an another carrier or unwanted signal in our inband C-band frequencies ?