I am writing a novel and need help me with some technical GPS questions.
Here is the situation: A man dies in a single-car crash (murder). He was driving a high-end Audi. The GPS tracker is removed from the car in order to see where it has been. Here are some questions:
—am I correct in thinking the tracker stores information for a long period of time? The detective is looking at details for the past month. Would that be realistic?
—the detective is not tech oriented. Is it possible for him to be given a printout of the GPS message format that would be easily understandable? If so, what would the information show? Time, date, longitude and latitude? Would he be able to know the exact address of each destination?
—is there specific terminology that should be used? Is it possible to see a sample of an easily understandable readout?
I feel like I’m working in the dark at the moment, so thank you for any assistance.
I’ll give an initial stab at answering some of your questions:
A GPS sensor will get LATitude and LONgitude and inferred ALTitude information coupled with the time (assume in this case it is UTC (Universal Time Coordinated)). The altitude accuracy is highly dependent upon how many satellites the GPS can “see” and is much less accurate than the position computed with the LAT and LON values. Driving next to a mountain, where one side is obstructed by the hillside, will result in a less accurate estimate of altitude.
Usually the number of readings that the device stores is dependent upon what the intended purpose is. Assuming that the GPS is used to feed an on-board navigation system, that system will most certainly store many data points - showing a route driven. Whether all 4 pieces of information (LAT, LON, ALTitude and time) are stored for the entire route is highly dependent upon what system is used - but for purposes of a novel one can assume anything from all (assume 1 reading per second) to little (only start time, end time and total distance).
With modern software technology, a printout of a list of these 4 values can easily be converted to display on a map using freely available software. Anyone with a PC and that list can get it to display on a Google-Maps type object.
There are several standards for displaying tracks. “GPX” is a commonly used and recognized format.
Kathy:
The GPS tracker is removed from the car in order to see where it has been.
'Tracker,' to me, would mean a device added on an aftermarket basis. For example, they're often used by vehicle dealerships to facilitate repossession in the event of non-payment. They're also sometimes installed by a car owner for theft recover (Lo-jack is a common one), though this technique is basically a homing beacon and doesn't use GPS or send coordinates. Tracking devices are useful for fleet management. All of these give real-time data over the air.
They’re also sometimes used by people to figure out travel patterns on a surreptitious basis. For example, law enforcement (or a stalker, for that matter) may install a device on a vehicle that can transmit coordinates similar to the types above or simply record coordinates that the vehicle had been for later examination. Of course, the latter would require retrieval of the device.
If you intended some OEM component (meaning, installed by Audi on the new vehicle), whether and how anything is stored is entirely dependent on its design. A fictitious vehicle computer could easily store weeks of GPS data as well as things like cabin audio and video from a collision avoidance or semi-autonomous driving cameras.
It doesn’t need to be a tracker for nefarious purposes. In some countries devices are installed that measure GPS coordinates along with 3-axis acceleration and send the data to the insurance company. These telematics are done so that young drivers, whose insurance costs are prohibitively expensive, can get a cheaper rate if they drive carefully. The collected data is used to drive algorithms that rate driving - using factors such as time-of-day (and night), type of roads driven, acceleration and deceleration and other factors. This data is sent every 15 seconds except when an “event” occurs (e.g. 10g deceleration to 0 speed which can indicate an accident) when data is sent even more frequently. These devices are installed in the car and most often the drivers don’t know where.
I know this because I worked as a consultant for a long time for a big insurance company which offered these telematics rates to young drivers and part of I did was big data warehousing and analysis on the huge amounts of data streaming in from these devices (just imagine the volume of data involved in 100K+ devices sending GPS coordinates, DOP, x-y-z axis acceleration and some other data in a block every 15 seconds!).
Thanks for your helpful response. So, would the inspector get the GPS information from the victim’s insurance company (he was an older man) or from the team doing the forensic examination of the vehicle?
In this case the tracker doesn’t store much data, it all resides with the insurance company. The data is stored indefinitely and can be accessed by the insured person upon request (as is often done in the case of accidents - the data from the insurance company can be used in court) or upon receiving a court order.
I was always amazed at the amount information one can infer from these car trackers and wouldn’t really want one in my car, even if the insurance gets a lot cheaper. Although I was cleared to access the data and did quite a bit of analysis for the fraud detection and accident departments even a small seemingly innocuous query such as “what is Car X’s location at 2AM on successive nights?” can lead to a serious breach of information. Imagine querying the database for all vehicles that are stationary more than 10KM away from the home address at 2AM whose owners are married. Guaranteed to find a number of vehicles whose insured are having an extramarital affair - with just a bit of additional correlation those can be detected and are open to blackmail. Or imagine what a marketing company could do with all that data - determine who drives how far at lunchtime to which fast-food restaurant? Luckily, data security laws for this type of data is quite tight, particularly in Europe.
I can’t edit my post - so I’ll add that while at that insurance company I supplied tracking data for a specific period of time to the police after getting a court order. This also included analysis as to whether the person driving during this period was likely to be the insured or another party. While the tracks aren’t accurate enough to determine whether the person driving was drunk or under the influence, but just like fingerprints, retinal scans and walking gait the style of driving is somewhat personalized.
Great info. Thanks. My novel is still in the VERY early draft stage. I’m copying and pasting your comments so I can study all the info. Would I be able to send you the small section that concerns the GPS to have a look at and make sure I’ve understood things correctly?
:oops: Looks like I posted without checking to see if this forum allows PMs. It doesn’t; which means that one of the two options I wrote aren’t available. But you still have a choice , just like Mr. Ford’s customers did when it came to their color scheme…
