public Function LongLatToString( ByVal lat as Double ) as string
  Dim i as Integer = lat * 100000
  Dim b() as byte = BitConverter.GetBytes( i )
  return Convert.ToB64String( b )
End Function
 
public Function StringToLongLat( ByVal s as string) as Double 
  Dim b() as byte Convert.FromB64String( s )
  Dim i as Integer = BiConverter.ToInt32(b)
  Dim d as Double = i
  return d / 100000
End Function