Mobile operation is extended to a device. This device is of the double chamber type, and it detects atrial and ventricular events, provides atrial and ventricular stimulation, and delivers a ventricular stimulation pulse after expiration a programmed atrio-ventricular delay following the detection of an atrial event, and in the absence of detection of a ventricular spontaneous event within the AVD. The external working signal estimate is refreshed. The feature will default to the inactive state upon reset.