Camera van and dashcam disagree |
Camera van and dashcam disagree |
Thu, 1 Mar 2018 - 13:53
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Member Group: Members Posts: 12 Joined: 1 Mar 2018 Member No.: 96,812 |
I was surprised to receive an NIP in the post alleging that I had been travelling at 83mph on a 70mph NSL road and photographed by a manual camera van. I had seen the van, and was travelling in the flow of traffic. I have a GPS 'satnav' map device and a GPS-linked dashcam and so downloaded the data from both. The video clearly shows the camera van on the other side of the road, and that my speed is 69.3mph. While the satnav measures in legs of a few hundred yards rather than instantaneously it is in agreement with the dashcam.
This is where it gets interesting. The safety partnership have kindly sent two stills of the car. However, the time printed on the picture is some 30 seconds after I passed the van - and the car is about half a mile away. I asked a police friend of mine what to do, and he suggested writing to the safety partnership to tell them that I had evidence from two devices that agreed with each other but disagreed with theirs. I did so, and got a rapid reply to say that GPS devices were inaccurate and affected by the weather so they were still going to prosecute. I have returned the RK form - I was driving and that is not in dispute, but I do dispute their data. Firstly, the two devices agree with each other on time, place and speed. They have no connection with each other apart from a power supply from the car. Furthermore, while I am well aware that the speed measured can fluctuate, it depends on the number of satellites used for calculation and the variation is not great - ceratinly not 14mph for a sustained peiod. 8 satellites were being used. Even more pertinently, the timekeeping by the GPS system is incredibly accurate. The devices keep good time even when not able to see satellites, but when they can see them it is accurate to milliseconds. I'm pretty confident in the time and speed records I have and have preserved. I am minded to defend this, as something has clearly gone wrong at their end. I have no idea what, and it isn't my role to speculate. Please can I seek advice on this course of action? This post has been edited by stethoscope: Thu, 1 Mar 2018 - 13:53 |
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