Pie Shaped Coverage Areas

Here we go again, another software product arbitrarily showing cell tower coverage as a pie shape.

In cell phone forensics, data provided by the network operator in a Call Detail Record report provides the tower and antenna sector that the phone utilized for a voice call, SMS text and data session. It also typically provides the location of the tower and the antenna direction. It does not provide any information about the coverage area of the tower.

In a previous blog The ZetX H-Plane - Let's put this to bed, ZetX created an "H-Plane" shape to depict coverage. I have come across another software product called Geotime that also creates a shape for the coverage area. At least ZetX comes up with some method to their madness. Geotime just plots a pie wedge shape for coverage without any explanation of how they came up with that. Geotime was purchased by Penlink a few years ago.

Here is a Geotime plot from a recent case I worked on. It shows a pie shaped wedge as the coverage of the tower sector antenna. Magically, the target location falls directly within the "coverage area". The prosecution team offers no explanation of how they came to decide that this pie wedge was the actual coverage area. They offered no data source for the determination of this area. They just arbitrarily drew it and presented it to the jury.

Here is another plot from the same case. This one shows multiple pie slices from multiple towers. It also shows what looks to be a phone location. This phone location was not in the supporting CDR, so I have no idea why these phones are shown in these spots in this map.

Both of these maps have terrible resolution and are very difficult to read. It adds additional vagueness to the presentation of the data.

The judge in this case allowed the prosecution to show these maps and the defendant was convicted. We are attempting to obtain a new trial mainly based on this false evidence.