I am trying to generate a chirp at a carrier frequency of 310Mhz. The chirp would be sent out at a regular interval. Chirp signal is generated from xilinx DDS. However i could see that the carrier which is fixed at a frequency of 310Mhz is always present in the output. Ideally the carrier should not appear in output based on the maths shown here (https://wiki.analog.com/resources/eval/user-guides/ad-fmcomms1-ebz/math ). Here is a pic of signal capture.
Could anyone explain why does carrier appears in the output and how can i avoid it?