better more or less overwhelming first of all the technology we have mobile phones actually not suited for this purpose so bluetooth is only able to mesh you're only able to measure the signal strength for Bluetooth you're not able to measure distance so first of all we had to overcome the technical problems associated and they are still not solve to be very clear I mean the technically say workaround is first of all when measure or at the contact which is relevant for this disease is combined of two parameters which is time and