This app was mentioned in 14 comments, with an average of 3.50 upvotes
Sensorly and Cellmapper are both really helpful. Crowdsourced maps tend to be the most accurate and one of the best ways to track network upgrade progress.
Try the ap Sensorly if you want to document and give feedback.
https://play.google.com/store/apps/details?id=com.sensorly.viewer&hl=en
Free ap, user submitted signal strength for carriers (2G/3G, LTE), my understanding is they make their money selling that data back to companies ("you should put more towers in this dead zone").
Sensorly may do what you want. You can choose from all the carriers in a given area and see their individual signal levels. Makes it easy to compare between carriers.
But note that the app only shows data from people who have used the app and allowed it to measure signals. This means it won't show coverage for every square meter but you will see very detailed results along major highways and town areas. If you get the app and use it, your results will be added to the map.
I used to run this all the time but I stopped because they do sell the data they aggregate so in a sense users are unpaid volunteers helping this company make money. That bothered me. But the app itself and the results it shows were very accurate,
https://play.google.com/store/apps/details?id=com.sensorly.viewer
Sensorly does the continuous signal tracking but not continuous speedtests. If you stop at each site and do a speedtest, it will sync it to the map. https://play.google.com/store/apps/details?id=com.sensorly.viewer
Your area could benefit from mapping on Sensorly a good bit, you should consider installing it and turning it on when you travel around the area. https://play.google.com/store/apps/details?id=com.sensorly.viewer&hl=en
When you go, could you run one (or more) of these apps in the background during your trip? :-)
I got you.
There's an app for that.
https://play.google.com/store/apps/details?id=com.sensorly.viewer
Sensorly - https://play.google.com/store/apps/details?id=com.sensorly.viewer
Exactly what your looking for with crowd-sourced coverage maps that update instantly..