Cell Coverage Map is an application for experts in cellular communication and enthusiasts that helps to create a coverage map of mobile network (GSM/UMTS/LTE) by mapping markers of a color depending on the level of the received signal at a particular location.
The application puts colored markers on a map after determining the exact location using GPS. Google Maps or OpenStreetMap can be displayed as a map.
Collected data can be exported as an image, KML or CSV file.
https://signalmonitoring.com/en/gsm-field-test