I'm doing a reversing camera project. It went wrong. Any ideas?


Captain Jack Sparrow

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I have been planning this project for quite a while because I keep bumping into things while reversing (yes, Jack Sparrow has a license!).

The solution I've come up with is to purchase a reversing camera and a motorized monitor which flips itself up when the vehicle is in reverse gear and tucks itself away when in any other gear or neutral.

Screen arrived a few months ago, I connected that to an ATX PSU and connected the video input to my old Sky SD box, just to check that it works. Screen works fine (although with 1 stuck red pixel) and I was happy.

Next, I looked for the camera. I chose one that replaces the license plate lamp because I can change the other one to LEDs while I'm there, so I can have LED license plate lamps.

Brace yourself, it's all down hill from here!!

Hooked the screen up to the ATX PSU and connected the camera to a switch and then to the ATX PSU (to simulate going into reverse).

I turn the switch on which turns the camera on. The monitor flips itself up. It shows a very distorted image with large amounts of static. For a split-second. The screen then goes blank. Ummm what? Also tried the non-reverse camera input on the monitor with the same results.

So I tried connecting Sky box back up to the monitor as mentioned previously. Again, the monitor appears to work perfectly.

So it must be the camera that must be faulty, right?

WRONG!

I connected the reversing camera to my Hauppage PCI-E capture card, to see if the same behaviour occurs. But this time, the image was displayed perfectly! So now, I have no idea what the problem is - the monitor or the camera.

This is really odd, it seems that neither items are faulty, they just aren't comaptible with each other. Does anybody have any ideas which I can try? Just so you know, both the monitor and camera use a 12v DC power input and exchange video signals with composite. My only idea is that the camera is a NTSC version which has been mislabelled as a PAL version, I know that the mointor requires a PAL signal.

For reference, the monitor (external link, AliExpress - exact model no longer available, here's an equivalent) was from Aliexpress and the camera (external link, eBay UK) was from eBay.

- Capt. Jack Sparrow.
 
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Ian

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There's nothing that springs to mind on this one - but I guess there are a few things you could try out of curiosity:
  • What happens if they're both powered independently (not from same PSU)?
  • Could it be interference from the PSU or wiring setup? I have a Raspberry Pi cam on my 3D Printer, which would often produce a purple image and then cut out - it turns out that it was interference from the printer causing the problem, so I improved the wiring setup and it fixed it.
Maybe the screen isn't as forgiving with the signal as the PCI-E Capture card, so the two things are not compatible :(. That shouldn't be the case, but the quality of AliExpress stuff can be pretty variable.
 

Captain Jack Sparrow

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There's nothing that springs to mind on this one - but I guess there are a few things you could try out of curiosity:
This one's a bit of a strange one. I haven't been able to conclusively narrow down the cause of the problem, whether it's the monitor or the camera itself.
  • What happens if they're both powered independently (not from same PSU)?
I tested with the monitor connected to the ATX PSU and with the camera connected to a small, low amperage 12v plug type power supply I use for my LED moodlighting. The results were identical with the same split-second images and poor quality video.
  • Could it be interference from the PSU or wiring setup? I have a Raspberry Pi cam on my 3D Printer, which would often produce a purple image and then cut out - it turns out that it was interference from the printer causing the problem, so I improved the wiring setup and it fixed it.
Not sure how to test this one. I don't think it's an issue with the PSU, I used the FSP FSP350-60EPN which I normally use to power the car stereo that I'm currently using as a really ghetto multimedia amplifier.
FSP PSUs are quite reliable, with good noise regulation, so I doubt it's a PSU issue. I bet that the 12v low amperage plug type PSU I used in the previous test has poor noise regulation. Plus, if the PSU was causing that much noise problems, wouldn't this be apparent when I tested the monitor with the Sky box?
Maybe the screen isn't as forgiving with the signal as the PCI-E Capture card, so the two things are not compatible :(. That shouldn't be the case, but the quality of AliExpress stuff can be pretty variable.
This is the only explanation that I can think of. There are many different varients of PAL and NTSC signals and I guess it could just be that the monitor doesn't support all of them, whereas a capture card is designed to capture video signals, so by nature it supports all worldwide NTSC and PAL signals.
Bit of a stretch but it could be dodgy cables. :blush:
I'd like to think I've eliminated that when I found that the monitor works with the Sky box, but the camera works with the PCI-E capture card. Thanks for your input but I really don't know what to think at this point. :confused:

I have an old laptop which has an analog TV output, so I'll try hooking this up to the monitor and then forcing the graphic card to output each available varient of NTSC and PAL signals. This will hopefully tell me what this monitor supports and what it doesn't.

TL;DR - As for the camera, I ended up sending it back while I still can, once I know what video signals the mointor definitively supports, then I'll look for an alternative camera.

- Capt. Jack Sparrow.
 
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Ian

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As for the camera, I ended up sending it back while I still can, once I know what video signals the mointor definitively supports, then I'll look for an alternative camera.
I think that's the best way to be honest, I imagine it'll be some tiny tiny problem causing the incompatibility - at least this way should be much easier :).
 

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