 added a check to not thrown errors if there is no elevation data
 added a check to not thrown errors if there is no elevation data

SuperDARNCanada/realtimedisplay,SuperDARNCanada/realtimedisplay,SuperDARNCanada/realtimedisplay,SuperDARNCanada/realtimedisplay,SuperDARNCanada/realtimedisplay,SuperDARNCanada/realtimedisplay,SuperDARNCanada/realtimedisplay