1) By measuring the travel times for multiple skips, it should be possible to remove center-to-limb effects in place rather than referencing north-south times to east-west times. 2) Instead of using quadrants (4 sectors), it may be advantageous to use more, like 12 or 16. 3) To learn more about center-to-limb effects, it is useful to measure the temporal frequency dependence. Tests of 1)-3) have been done using 1-year of HMI data and Thomas Hartlep's simulations including a center-to-limb effect.