Two-dimensional ‘Time vs DM’ dependences (±0.1 pc/cm³ by DM and ±400 ms – by time). In the left panel, the candidate-signals found in the Survey are shown. In the right one – ‘Time vs DM’ – are dependences for the ‘inverse’ dispersion measure (the dispersion delay is proportional to − f ⁻²). Candidate signals are characterized by the presence of an inclined oval of high intensity in the centre. Such a wide maximum is not observed in the case of ‘signals’ found during the inversion of the spectrograms (adapted from Zakharenko et al. 2018 and Kravtsov 2018).