Nigel
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- Joined
- Jul 7, 2014
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A few weeks ago I was driving home in the dark and I came across a new tunnel, scratched my head and wondered why someone had built a new tunnel in the middle of a flat floodplain!
I was sure there was no mountain for it to go through, I didn't think there was a hill, I wondered if there was a new road going over it but it is too long for anything but a motorway and I knew there wasn't one of them...
I week later the same thing happened, so at the weekend I made a detour to see it in the daylight...
I was right, no mountain above it, just grass.
There is a slight hill, the Mini 0806 GPS had an altitude of 14m above sea level, but the tunnel is more or less at the top of the hill!
There is no road, to the left there is a field of grass followed by a small village, to the right a new bank which appears to be just landscaping - the tunnel would look stupid without it!
I wondered if it was for wildlife to cross the road, but there is a fence to the right big enough to stop any deer so that can't be its purpose...
Then I realised - it is for testing dashcams
daylight, darkness and street lights all at the same time to test the auto exposure and of course the thing tunnels are best at - sound quality, Top Gear style...
So here is the video:
Main view is the Mini 0806 at normal 1080 16:9 aspect ratio.
Top left is the same video but in 21:9 widescreen view. If you pause it on exiting the tunnel you can see how much of the widescreen view falls off the side of a normal 16:9 HD monitor. Pause it while entering the tunnel and you can see that there is nothing but grass either to the left or above the tunnel on the widescreen but you miss the left with the normal view.
Top right is the rear view from my Mini 0803. Notice that by the time it has adjusted to the lighting conditions in the tunnel I'm going back into the daylight while the Mini 0806 adjusts so fast that you hardly notice and due to having a wider dynamic range can display both daylight and tunnel darkness at the same time anyway.
Bottom left is the GPS speed from the Mini 0806 - showing that I did a nice steady 29 all the way through the tunnel Or maybe the tunnel is GPS proof?!
This image shows the audio levels from the Mini 0806 top and Mini 0803 bottom. The red is clipping - the 0803 is hardly coping properly with the sound outside the tunnel and is very poor inside. The 0806 has got it more or less perfect, 3db spare in the tunnel for just in case a noisy motorbike comes past and enough volume outside to hear the truck passing by on the other side of the road. (The two cameras are only synchronised to the nearest key frame as I cut the video using Registrator Viewer.)
In case anyone is interested, these images are a spectrum analysis from outside the tunnel and inside the tunnel. Not sure why the sound stops at 16 kHz when it is stored at 44 kHz but our bats are hibernating at this time of year so it's not likely to be an issue! Low frequencies work fine.
My laptop speakers are not capable of producing the low notes - it sounds very different through proper speakers!
Overall Sound quality from the 0806 is very good and considerably better than the 0803. The 0806 also responds to changing light levels very quickly and does a good job of it.
As for the tunnel, it is a nice tool for testing dashcams but it would be better without the 40 speed limit - can't do a proper Top Gear test when I can't get past 4000 rpm! Not convinced it was worth the cost and all that orange lighting can't be environmentally friendly, they could have fitted some skylights to let the natural daylight light in...
I was sure there was no mountain for it to go through, I didn't think there was a hill, I wondered if there was a new road going over it but it is too long for anything but a motorway and I knew there wasn't one of them...
I week later the same thing happened, so at the weekend I made a detour to see it in the daylight...
I was right, no mountain above it, just grass.
There is a slight hill, the Mini 0806 GPS had an altitude of 14m above sea level, but the tunnel is more or less at the top of the hill!
There is no road, to the left there is a field of grass followed by a small village, to the right a new bank which appears to be just landscaping - the tunnel would look stupid without it!
I wondered if it was for wildlife to cross the road, but there is a fence to the right big enough to stop any deer so that can't be its purpose...
Then I realised - it is for testing dashcams
daylight, darkness and street lights all at the same time to test the auto exposure and of course the thing tunnels are best at - sound quality, Top Gear style...So here is the video:
Main view is the Mini 0806 at normal 1080 16:9 aspect ratio.
Top left is the same video but in 21:9 widescreen view. If you pause it on exiting the tunnel you can see how much of the widescreen view falls off the side of a normal 16:9 HD monitor. Pause it while entering the tunnel and you can see that there is nothing but grass either to the left or above the tunnel on the widescreen but you miss the left with the normal view.
Top right is the rear view from my Mini 0803. Notice that by the time it has adjusted to the lighting conditions in the tunnel I'm going back into the daylight while the Mini 0806 adjusts so fast that you hardly notice and due to having a wider dynamic range can display both daylight and tunnel darkness at the same time anyway.
Bottom left is the GPS speed from the Mini 0806 - showing that I did a nice steady 29 all the way through the tunnel
Or maybe the tunnel is GPS proof?!This image shows the audio levels from the Mini 0806 top and Mini 0803 bottom. The red is clipping - the 0803 is hardly coping properly with the sound outside the tunnel and is very poor inside. The 0806 has got it more or less perfect, 3db spare in the tunnel for just in case a noisy motorbike comes past and enough volume outside to hear the truck passing by on the other side of the road. (The two cameras are only synchronised to the nearest key frame as I cut the video using Registrator Viewer.)
In case anyone is interested, these images are a spectrum analysis from outside the tunnel and inside the tunnel. Not sure why the sound stops at 16 kHz when it is stored at 44 kHz but our bats are hibernating at this time of year so it's not likely to be an issue! Low frequencies work fine.
My laptop speakers are not capable of producing the low notes - it sounds very different through proper speakers!
Overall Sound quality from the 0806 is very good and considerably better than the 0803. The 0806 also responds to changing light levels very quickly and does a good job of it.
As for the tunnel, it is a nice tool for testing dashcams but it would be better without the 40 speed limit - can't do a proper Top Gear test when I can't get past 4000 rpm! Not convinced it was worth the cost and all that orange lighting can't be environmentally friendly, they could have fitted some skylights to let the natural daylight light in...
