Ale

I have a Zmod DAC 1411 connected to an Eclypse Z7 board. The Eclypse board is powered by its original power supply, housed in its enclosure, and the DAC is connected to a spectrum analyzer with a BNC cable. When connecting the DAC output to the spectrum analyzer, I observe an interference between 16 and 19 kHz. In this case, the FPGA on the Eclypse is programmed only to send a constant signal to the DAC. Is the disturbance at 16-19 kHz a known issue? Do you know what might be causing it?