I have a pic in the VLF band at 1.5 kHz. What would be the origin of this peak?

The graph was obtained by running display_qt in Linux from a laptop.

enter image description here

  • $\begingroup$ Hi, and welcome to ham.stackexchange.com! We recommend all new users take the tour to get the most from the site. $\endgroup$
    – rclocher3
    Jan 5, 2017 at 18:59

1 Answer 1


display_qt is a GNU Radio example program. It does not display any actually existing electromagnetic signal but internally generates a 1500 Hz sinusoid.

The code creates a sine source and a noise source,

// Source will be sine wave in noise
src0 = analog::sig_source_f::make(rate, analog::GR_SIN_WAVE, 1500, 1);
src1 = analog::noise_source_f::make(analog::GR_GAUSSIAN, 0.1);

then sums them and sends that to the displays.


You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .