Recently I found some unwanted behaviour of iio_device_create_buffer function in fmcomms2 reference design:
When I create a Tx buffer, a carrier frequency appears on the spectrum analyzer. When I push any data, this frequency disappears and I see the spectrum of the transmitted signal. The amplitude of the carrier frequency is of the order of the transmitted signal on the spectrum analyzer. The dds scale is 0 all the time. If I set the buffer to non-cyclic, this carrier frequency appears again when the transmission ends.
Is there a way to produce no output signal at all when buffers are not pushed?