Warning: if this doesn't put you to sleep, you have been drinking entirely too much coffee.
The following is based on Paul Rowlette's Power Point slides and discussion about cell towers in the Courtland area. Four towers come into play. Each was used by multiple cell phone companies, and not all companies used all towers. The tower locations in question are: two towers in Batesville (north of Courtland), one tower in Pope (south of Courtland), and one tower actually in Courtland on Shiloh Rd, the "Shiloh" tower. Jessica Chambers cell phone was with Verizon, and it used all four towers. Quentin Tellis' cell phone was with AT&T which only used the two in Batesville and one in Pope.
Recall the term used by Verizon, RTT or Range-to-Tower, which was an estimate by a tower at a given point in time when it was in contact with a cell phone as to the distance to that cell phone. There was another term used by AT&T with the same meaning. The accuracy of those distance estimates varied depending on such things as: number of cell towers involved, weather, topography (including presence of skyscrapers), and location within each cell tower's sectors or arcs of strongest reception. In addition to the distance, each data point would include an angle or compass bearing (azimuth) from the tower. So for example, looking from a tower for a given data set, one would first draw a line from the tower in the direction of the signal, then mark off the estimated distance along that line to arrive at the approximate cell phone location after correcting for difference in tower antenna and cellphone elevations.
Using the raw RTT data, Rowlette was able to process it and plot multiple estimated points of each cellphone's location. Although the phones may have been stationary at one location for a given period, the corresponding cell tower estimated locations would be scattered point clusters due to variations in the RTT distance estimates. But by plotting the patterns of those points along with the actual known locations of each phone (known locations based on things like CCTV, or testimony a person was home at the time) a correction or shift could be determined to better center those clusters of estimated locations around the actual known locations, thereby improving the distance estimates. Rowlette stated the correction was about a 1/2 mile toward the east. Once that was done, the scattered points for JW's phone were centered around her home when she was there using her phone, and around the crime scene further to the west on Herron Road later on.
There is another way to estimate a location, but it only works if two or more towers are receiving the cellphone signal. By plotting a line from each tower in the direction of the signal, where the two lines intersect is the approximate location and does not require using the distance estimate from either tower. This is called triangulation, because it typically involves trying to resolve a location from three different directions. Those three different lines would invariably intersect at three slightly different points. Those three points are the corners of a triangle that surrounds the "average" intersection of all three lines, hence the term triangulation. This is a much better way to determine a location, in fact it is how ships used to navigate before GPS.
So, given that there were so few towers in the area, what if another tower could have somehow been introduced that could improve the accuracy of those locations? Well, turns out it could have been, if a device called a Stinger was being used by LE at the time to monitor illegal drug activity in the area. It acts exactly like a cell tower, and can be used to intercept cellphone calls the same as a cell tower, collecting all the same data with something called a pin register. However it is something small enough to fit inside a van or car, so very useful for LE surveillance because it can be easily transported from one place to another if needed to avoid arousing suspicion of those being monitored.
What if such a device was being used in the Courtland area at the time of Jessica's murder? We do not know. LE agencies who use the equipment are required to sign a non-disclosure agreement with the manufacturer. If one was in use, the data it collected might have significantly enhanced the analysis of the cell tower data from the phone companies, especially around Courtland where Tellis' phone was only served by one tower while Jessica's was served by two.
JM(yawn)O...
Clouseau