This reminds me of those stickers that one could put on your GSM a hundred years ago which lit up when there was an incoming call. Similar principle at work in this demonstration: https://youtu.be/CNJVhzOjWgU?t=12s
Wow the comments on that video, my eyes , my eyes!
I got a nice EMC probe for my oscilloscope (so that I could look at the effectiveness of my bluetooth antenna trace) and it provides a nice way to scan a phone for all of the various RF frequencies its putting out. One thing I thought was interesting is that when you put your phone in a shielded box (so that you're only seeing the phone's radiated signals) it bumps up the xmit power in the GSM bands trying to talk to a cell tower it can't reach. Seems a little mini StingRay on your dresser to reassure your phone that cell service is nearby would help its battery life :-)
I got a nice EMC probe for my oscilloscope (so that I could look at the effectiveness of my bluetooth antenna trace) and it provides a nice way to scan a phone for all of the various RF frequencies its putting out. One thing I thought was interesting is that when you put your phone in a shielded box (so that you're only seeing the phone's radiated signals) it bumps up the xmit power in the GSM bands trying to talk to a cell tower it can't reach. Seems a little mini StingRay on your dresser to reassure your phone that cell service is nearby would help its battery life :-)