Signals are for example the grouping of individual currency strength indices. For a longer period the currencies may move along the same path and look as if they are attached to each other. Which is in a sense true because of tight correlations and speculation on relevant pairs.
As UJ is all about USD devaluation, the opening bell is the start of the reversal of USD. The slow descent becomes even more visible once the currency groups with its strong correlating economies of JPY and CAD.