Coverage Mapper is designed to run in the background on your phone while you're moving around, so that it can log the signal strength at various locations, for the purposes of generating an accurate cellular coverage map. A screenshot of the main screen is shown below.

If the application says your screen is off, try restarting your device. Devices running Android 1.5 and 1.6 can have issues with detecting the screen's state. If rebooting your device does not fix the issue, or you are using Android 2.1 or later, and you are still experiencing this issue, please request help on the forum or through the contact form.

Coverage Mapper is free to download and use. If you enable "Only Use Wifi" in the settings, then regardless of any other settings in Coverage Mapper or in your device's system settings, Coverage Mapper will never cost you any money to use. It collects all its data from the GPS (which is free, courtesy of the United States Department of Defense) and from your cellular radio. It simply measures the signal strength when your device is connected to a tower, but it does not use any data, make or receive any phone calls, send or receive any text messages, or do anything else that could result in a charge from your cellular carrier.

Under normal circumstances, usage is fairly simple. You start the application, tap "Start Logging", and then you go about your day. When you want it to stop, you tap "Stop Logging". You can upload all your data to the server by tapping "Upload Data". If you want to view a coverage map for the network you're using, you can tap the "View (Cell Carrier) Map" to open a browser and load the map. It will default to your current location. The mobile version of the map does not have nearly as many features as on a computer, due to screen size limitations. To access all the features, view the map on your computer.

When you first run Coverage Mapper, you will see a message about keeping the screen on. The application is unable to record signal strength data when the screen is off, so it must be kept on. If at any time, while Coverage Mapper is running, the screen is turned off, it will simply stop recording data until the screen is turned back on. At this time, there is no way around this. If you use Coverage Mapper mainly in your car, when your device is plugged in (possibly while using other software such as Google Maps Navigation), then this should not be an issue for you. However, if you do not have it plugged in, this could result in some battery life issues. If you have the device in your pocket, it's possible that some buttons could get pressed while the screen is on. Some safeguards for this are being worked on, but they are not yet ready. Keep in mind that Coverage Mapper will keep the screen on (but dim), which will prevent the timeout from sending the device to sleep. However, it will not prevent you from manually turning off the screen by pressing the power button.

At the bottom of the main screen is some status information that updates as the application is running. It is meant mostly for debugging, since Coverage Mapper is still in a beta stage, and it can be useful for reporting issues to include the last status message that was displayed here.

If you press the menu key, the menu will pop up, with two options: "Settings" and "About". The "About" option displays some information about Coverage Mapper, and provides a link to this website. The "Settings" option opens a new screen that allows Coverage Mapper to be configured to better suit your usage pattern.

Enable While Charging: When this option is enabled, connecting your device to a power source will enable Coverage Mapper, and disconnecting it will disable Coverage Mapper. This is very useful if you have a car charger, as it will ensure that while you're driving around, you're always logging data.

Automatic Uploading: When this option is enabled, whenever the device has 25 data points stored, it will initiate an upload. This is a good way to ensure you don't forget to upload any data.

Only Use Wifi: When this option is enabled, no data will be uploaded (automatically or manually) unless you are connected to wifi. This option is meant for people without cellular data plans, or with very small plans.

Log While Roaming: When this option is enabled, you will still log coverage data while roaming onto another carrier's network (in or out of country). This data will be used for that carrier's coverage map (not your home carrier's). This option will not cause you to incur any additional costs, as no data is used for Coverage Mapper operation. If you have automatic uploading enabled, however, you should verify the "Data roaming" setting in your device if you do not want to use data while roaming.

This is by far the most frequently requested feature. However, the answer is, unfortunately, no. The Android developer guide for "App Install Location" has a section called Applications That Should NOT Install on External Storage. The first item in the list is "Services". Coverage Mapper is a service, and it could cause problems for users if it were allowed to install on the SD card.

Unfortunately, there appears to be a bug in Android. It may be designed this way intentionally, but it is undocumented, which would be odd for a "feature" like this. If the screen is off, the signal strength will not update. With the screen on, it does update. Thus, Coverage Mapper requires the screen on, or the signal strength will never update.

Up until Android 2.1, there was no good way to tell if a device's screen is on. Coverage Mapper uses a trick that usually works on devices with 1.5 and 1.6. On devices with 2.1 and later, Coverage Mapper uses the proper method. If you have a device with 2.1 or later, and it says the screen is off, please contact us or post a message in the forum. If you have a device with Android 1.5 or 1.6, the first step is to reboot your device. This fixes the problem almost every time. If this does not work, then unfortunately, Coverage Mapper will probably not work on your device.

Technically, it doesn't. This is how the Android process lifecycle works. Coverage Mapper remains in memory, even though it is no longer running. It does not use the CPU, and it does not use your battery. It will only be completely removed from memory if the operating system needs memory for something else. Coverage Mapper behaves exactly how it should, and there is no need to worry. When you tap "Stop Logging", it stops.