In this article, we examine the intradaily Euro-dollar exchange rate volatility persistence result from the dissymmetric impact of monetary policy signals stemming from the ECB Council and the FOMC. A model is constructed by extending the AR(1)-GARCH (1,1) to an exponential process EGARCH (1,1), using high-frequency data (five minutes frequency) which integrates a polynomials structure depending on signal variables, starting from the deseasonalized exchange rate returns series.