An alternate way of looking at this (but more complicated) is to look at this relative velocity change over time. This second diagram shows all the time differences, day-by-day, for both Voyager 2 and Voyager 1. Red means the distance is increasing, blue is decreasing. Each year is plotted vertically, with January at the top and December at the bottom. The years increase to the right, so launch (1977) is farthest left in both panels. We can see from Voyager 1 that there is a slow settling to a regular pattern. Voyager 2 is more complicated, but we can see that each planetary encounter altered the pattern considerably. The brighter yellow areas show when the Voyagers are barely moving with respect to Earth, and we can see that this happens earlier in the year for Voyager 1 than for Voyager 2. Look for Voyager 2's day-to-day change to decrease slowly too over the next few weeks! Voyager 1 won't start making up lost 'ground' until sometime in April.