WWVB 's low frequency signal tends to propagate better along the ground , the signal path from transmitter to the receiver is shorter and less turbulent than WWV 's shortwave signal .
Which is strongest when it bounces between the ionosphere and the ground .
Since WWVB 's low frequency signal tends to propagate better along the ground , the signal path from transmitter to the receiver is shorter and less turbulent than WWV 's shortwave signal , which is strongest when it bounces between the ionosphere and the ground .