Entering the address into a smartphone that the Raspberry Pi is connected to, via hotspot, produces a simple website that can control location transmission.
The first button, on the left, allows users to switch between the high and low accuracy options of the Geolocation API. Based on testing, there appears to be little to no difference between the two options, so it is recommended to use the (default) low accuracy option as the high accuracy option should consume more power. The second button on the right starts/stops location collection and transmission.
If at any point the app/tab is switched, or the screen turns off, while collection and transmission are running, coordinates will no longer be transmitted. Thus, when the start button is pressed, the web app will request a wake lock in an attempt to at least keep the screen on for the user. This is one of many reasons why an alternative Expo app was pursued, as it would allow for location information to be collected in the background with the screen off—saving power—or with another app/tab active; a web API for background location has been discussed for years but has never been implemented due to a variety of battery/privacy/etc. reasons. When a user does leave the web app, the portable system with the CsI detector, as well as the portable NaI detector system, will continue to record the latest pair of coordinates for up to one minute. After one minute, both systems will record the “default” location, (0, 0), as the current location, so it should be obvious that up-to-date coordinates were no longer available as (0, 0) is in the South Atlantic Ocean, off the African coast.
