How can I measure the advertising intervals of a peripheral?

[Malvin2000]

I would like to know how frequently my peripheral is sending advertising and data packets. I've tried using ble-sniffer-osx but it doesn't actually reveal any device names for some reason, so it's not trivial to use. Is it possible to do this using Xcode's Bluetooth Explorer utility to do this?

[endnode]

I've updated my answer. As Petter mentioned this indication is only measured and displayed by Android app. There is no way to find out Adv. Interval, app is just measuring deltas between received events from lower Android BT stack (through API) and it displays it. As explained if you want exact value you either need to know it from app developer or you need to run some larger statistics (dozens of packets) and precise time measurement with some more professional 2.4 GHz (BLE PHY enabled) analyzer ("sniffer" if you want) and take average value (assuming interval is not changing over time and that you don't miss any packet).