With the exception of the Digital Tachograph which only has limited GNSS (Global Navigation Satellite Systems) capabilities, most of the devices you are going to come across with plot the path of a vehicle and calculate speeds using GNSS positioning. These positions and speeds are often displayed on a map. Even better than that, we can usually extract the GPS coordinates and speeds and create our own data displays on Google Earth (as an example) and include these in our reports. But, just how accurate are those positions? Will they tell me which side of the road the vehicle was on? Are the display speeds accurate? We will explore the answer to these questions in this module.
With many of these devices we also get accelerometer data. The accelerometers are not calibrated but that does not mean we cannot use that data, we just need to know the limitations on how it can be used.
This Module starts by looking at what digital data is in its raw form. We then take a look at GNSS. We follow this by learning how to extract and display that data on a map and when we do this, just how accurate that map is (we will be using Google Earth). Having dealt with GPS we will look at the accelerometer data that we find in some devices. Finally we will take a look at digital tachograph data and how we can use the data for reconstruction and route tracing purposes.
You will be introduced to how analogue waveforms are converted to digital data, the binary number system and you will need to do revise your understanding of data sampling. You will be asked to consider differing sample rates and what the effects may be.
Block 1 - What is Digital Data
Here we look at the structure of digital data, in general terms. We follow this by looking at download and storage techniques before going on to smooth the data to reduce noise and increase the usefulness of the data. Excel is used as the smoothing tool.
GNSS and GNSS Speed
Given that so many devices these days use GNSS data and some of those devices store GNSS data which can be retrieved after a collision, we should perhaps try to understand a little more, how these devices actually work out where they are from a signal sent by a satellite. Devices that use GNSS technology that we as collision investigators are likely to come across include, late generation digital tachographs, navigation devices and cycle computers and insurance telematic boxes typically used by young drivers. The GNSS data is useful because alongside that data it often stores the speed.
Garmin, Wahoo and Other Telematic Devices
The explosion in leisure computers and wearable technology, 2024 began to see a change in emphasis on the telematics to include more about cycle computers and sports watches including Garmin and Wahoo. We look at the structure of FIT, GPX and TCX files (the raw data formats). We look at the various modes used by these devices.
We test Garmin Connect to find how it interprets and alters the data and then move away from using Connect and Strava to interpret and plot our own speeds and positions from the raw data
Wheel speed data, tachographs and route tracing for collision investigation
The first thing to grasp with wheel speed data is that it is really all about wheel rotation and so strictly is a measure of the distance travelled along whatever path the vehicle takes. The second essential point is that this is only true if the wheel remains in good contact with the ground. Locked or spinning wheels are obviously not going to indicate the true speed of the vehicle as a whole. We finish by covering route tracing.
We assume that you hold a CertHE to get the most from this module. This module can be studied as a standalone course.
Some of the assessments require the use of a spreadsheets, (Microsoft Excel) thus you will need to be able to use Excel to complete the module. Click on Entry level on the menu bar and select our free Excel course.
8 weeks distance learning.
Access to the Internet and a laptop computer. Google Earth Pro (free download) or access to the on-line version.
Your tutors will help you with your studies during the module. They will mark and comment on your final assessment and coursework.
This module is part of De Montfort university's FdSc in forensic road collision investigation.
The FdSc starts in September of each year. Apply through AiTS. If you wish to take this module without registering with the university you may do so however no university accreditation will be give. To take as a standalone check the calendar for the next presentation and contact AiTS.
| Coming on a module? | How to find us |
|---|---|
| Pricing information | Course Price List |
| Terms and Conditions | |
| Code: | ENGS2005 |
|---|---|
| Credits: | 15 |
| Level: | 5 |
| Duration: | 8 weeks |
| Type: | Distance learning |
| Assessment: | Two pieces of coursework |
| Further maths |
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| Analysis of digital data I |
| Analysis of digital data II | Computation and collision analysis |
| Motorcycle collisions |
| Pedestrian collisions |
| Vehicle dynamics - PC-Crash |