FAQ

Some commonly asked questions.

How do I use this tool???

Although it may be daunting at first, it is rather simple to use. What to enable depends on what you want to see.
If you want to see trails that go from green to red (best to worst signal), click the Signal Trails button in the top right corner.
If you want to see details about the cells on a cell phone tower, click the Coverage button.

The tower location is way off/in the middle of the water/on top of a remote mountain

Tower locations are based purely on calculations. The reason that towers will show up over water is due to the fact that water usually doesn't contain any object that can block signals. So, to the algorithm, sitting in a building right beside a cell phone tower will appear to be the same as being 5 km away with direct line of sight. Hence, it will calculate an average of the two spots and display a marker there. The most ideal terrain to calculate a towers is a completely flat prairie with tower spaced widely apart. That being said, even that will not guarantee the location is correct if the measurements provided by the phone were not correct. For a tower to be calculated properly, you will need to travel around the tower in at least 1/2 to 3/4 of a circle near the actual location in order to determine the exact location. I have verified this with WIND Mobile in Vancouver, Canada by comparing the locations calculated to the actual licenses given for cell phone equipment to be used.

A single cell is stretching for 5/10/15 km or more!

Unfortunately, not much can be done about this. Most phones will report the same Cell ID when a call is in progress. Likewise, some phones will get "stuck" to reporting a single cell id for a certain length of time. Another possibility is that the GPS device is incorrectly reporting the position; and as a result the location may keep changing wildly before it settles down to the right location.
While the app and site try to filter this bad data, there is not much that can be done to fix it. As more data is gathered, these errors will slowly decrease until the map becomes more and more accurate.

Why isn't the uplink/downlink frequency displayed when I map a region?

The frequency can only be retrieved with a BlackBerry device for certain. Certain Windows Mobile devices (Qualcomm based HTC devices) also support this. For Android, certain Motorola MotoBlur devices (Motorola Charm) support this; as well as certain newer HTC model (LTE only).

How long does it take for my data to appear?

For live upload, it should complete within minutes if the server is not too busy. For any other methods, it may take up to an hour or so.

What are "low accuracy" towers?

Low accuracy towers are towers whose location cannot be accurately predicted given the uploaded data. Therefore, they revert to a more simple algorithm of placing the tower closest to the location of the best signal strength. This will usually be significantly less accurate than the triangulation method normally used. Some towers that only have 1 or two cells, such as omnidirectional towers, will always be low accuracy. Likewise, any towers which were detected with weaker signals will also be low accuracy until stronger signal samples are uploaded.

What is "Estimated Frequency"?

Some networks have a known sector number to frequency band mapping. If it is known, it will be displayed on the site. If you know the mapping for a certain provider, please let us know so that we can include it.

What is "Android 4.2 CellID Support? Why does it work on my devices?

In Android 4.2, the CellID API was re-written to ensure data is updated somewhat atomically to avoid bad data. Unforunately, some manufacturers, notably Samsung, have chosen not to implement this new API. You can see a list of known supported and unsupported devices on this page: Android_4.2_CellID_Support

Does CellMapper support dual-SIM phones

Yes, it does support certain dual-SIM phones. See Dual_SIM_Support for details.