- screens.fields.theta_grid(d_eff, mu_eff, fobs, dtau, tau_max, dfd, fd_max)[source] [edit on github]¶
Make a grid of theta that sample the parabola in a particular way.
The idea would be to impose the constraint that near tau_max the spacing is roughly the spacing allowed by the frequencies, and near the origin that allowed by the times. In practice, one needs to oversample in both directions, by about a factor 1.3 in tau (which makes some sense from wanting to sample resolution elements with about 3 points, not just 2 for a FFT), but by about a factor 1.6 in f_d, which is less clear.
Effective distance. Should be constant; if different for different points, no screen-to-screen scattering is taken into account.
Effective proper motion (
v_eff / d_eff), parallel to
Mean frequency for which the doppler factor should be calculated.
Requested spacing in delay (typically should somewhat oversample the spacing in the secondary spectrum).
Maximum delay to consider. Can be up to the value implied by the the frequency resolution (i.e.,
Requested spacing in doppler factor (typically should oversample the spacing in the secondary spectrum).
Maximum doppler factor to consider. Can be up to the value implied by the time resolution (i.e.,