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Can anyone clever enough please tell me what's wrong with this camera.

First of all in this setup

I mean in dark room with camera lens pointed to a black box...

... I get this whashed out image on my video recorder...

although this is not a real-life situation, it's quite representative for problems i've been having with this camera.

...while the camera is producing this on the scope...

waveform.jpg

this is line no. 4 of the white image above

I mean, when I connected it to the scope I was hoping to see the waveform shifted upwards (as it's supposed to range from 0 to sth. about 1V, right? But as you can see its almost symmetrical -0.5 / +0.5V.

The camera is SONY 1/3 Super HAD taken out from a cctv dome.

What kind of circuit I need to add to the video output from the cam to get at least the right voltages (I am begginning to be afraid that I will never get a decent saturated picture from this cam).

EDIT:

Now I checked the picture from my DV cam. It shows up good on the same video recorder the previous cam did not. The strange thing is, it also produces a waveform in the same volt range (-0.5 to +0.5V), although somewhat weaker.

waveform2.jpg

(the picture was nearly the same - as whit as I could quickly get - switched on nightshot and pointed lenses at the lamp) Can not make anything out of it....

BTW: 75 ohm resistor added between video and gnd changes nothing

Edited by mieczotronix

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I was hoping to see the waveform shifted upwards (as it's supposed to range from 0 to sth. about 1V, right? But as you can see its almost symmetrical -0.5 / +0.5V.

Your video signal is AC coupled (a traditional thing), so it will not be referenced to 0V DC.

I get this washed out image on my video recorder...although this is not a real-life situation, it's quite representative for problems I've been having with this camera.

It would be helpful to see the the video waveform when the camera is aimed at a bright light source. But, in absence of more info, I would say that the camera's AGC is too aggressive. I suppose that it is trying its best to see in the dark, but does not have enough dynamic range to make you proud. It may be best to use it as a surveillance camera instead of for FPV.

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ok, thanks,

I still wonder if this is AGC because the same thing happens in broad daylight, everything igets overexposed.

While observiing the waveform on scope I also discovered that when I move the cam towards/away bright light source, the whole waveform shifts up and down by some 0.1-0.2 V. A

I think the waveform is clipped at the same height when the cam points to a bright source, the clipping is already visible on the right side of the first picture, I manipulated the cam to get as much clipping as possible. I'll try this evening to connect a 100k pot across gnd and cam_Vid-out to see if it helps to darken the image as I remember it did help a little. What should I do not to mess up the impedance completely?

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I think the waveform is clipped at the same height when the cam points to a bright source,

Sure sounds like an AGC issue to me (and the camera's dynamic range seems to be low).

What should I do not to mess up the impedance completely?

Don't worry about that, it is the least of your problems at this point. Frankly, it does not appear to be a good camera for our R/C model application.

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Frankly, it does not appear to be a good camera for our R/C model application.

Well, your probably right about that.

But I just made one more test before I give up on it.

Here it is:

When I added a 10k pot across gnd and vid out, even the slightest movement of the pot makes the signal fed to my monitor drop to 0.3V

And here is the difference it makes:

before (bare camera)

cam1v.jpg

img1v.jpg

and after

cam03v.jpg

img03v.jpg

obviously the 0.3V signal is not that transmitter or osd likes, but this somehow leads me to believe that AGC is not the real cause here. If the washout would be due to AGC, when I reduce the voltage the clipping should still be on the picture, yet in this case you can see that details in the previously washed out area start to appear (quite a lot of detail). The camera hasn't moved and lighting conditions hasn't change either.

Well... what do you thing

I also pointed the cam directly at my halogen desk lamp. I actually put it to the glass in front of the bulb. The lcd screen was completelly white, yet the clever cam managed to see some details. Anyway those flat areas on the graph below indicate the maximum level achievable. So it seems it is indeed -0.5 + 0.5 V range.

maxlight.jpg

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When I added a 10k pot across gnd and vid out, even the slightest movement of the pot makes the signal fed to my monitor drop to 0.3V

A 10K ohm pot will act like an on/off switch in this situation. I would have recommended a 500 ohm pot with a 100 ohm resistor in series with it. However, since the camera appears to observe the 1V video standard, the external attenuation will not really offer much help in a typical application.

If the washout would be due to AGC, when I reduce the voltage the clipping should still be on the picture, yet in this case you can see that details in the previously washed out area start to appear (quite a lot of detail). The camera hasn't moved and lighting conditions hasn't change either.

To me, both are the same waveform, but one is severely attenuated. Neither is fully saturated (I don't see any obvious clipping). The last scope waveform definitely is saturated and has clipped video. Your camera limits the whites to 1V, so despite its other shortcomings, it is at least observing the video standard's levels.

If I was forced to guess, I would say that the original video level was pushing the video display's dynamic range and the lower video level had better gamma because the signal was not as close to white saturated levels. But even if we confirmed an actual cause, the only solution I can come up with is to replace this camera with something that is better suited for your application. Otherwise, just use it as-is and ignore its problems.

Operating voltage and the camera's voltage specs have not been discussed. Have you confirmed that you are using the camera at its recommended voltage? Undervoltage can cause weird operation (and overvoltage can cause death).

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But even if we confirmed an actual cause, the only solution I can come up with is to replace this camera with something that is better suited for your application. Otherwise, just use it as-is and ignore its problems.

Operating voltage and the camera's voltage specs have not been discussed. Have you confirmed that you are using the camera at its recommended voltage? Undervoltage can cause weird operation (and overvoltage can cause death).

I already purchased a kx-131 clone and put it on pandora, but I miss resolution of this cam that's why I've been still thinking about it. I've had also an opportunity to see this cam's waveforms hoping they will point me to some kind of solution.

Supply-wise I run the cam of 3s lipo. It is rated 12V and it manages to work with unchanged signal parameters until something in the range of 9.6V then it just shuts off. So I guess power supply is not the issue here.

The cam has CXD3141R sensor onboard, I've see someone posting CXD3142R datasheet in another post. The cam has its chip's serial lines output on 4 pads on the PCB so it can be easily reprogrammed to aonther gamma / dynamic range if anyone knows how to do it (as it seems it is now tuned to cctcv purposes - to render well human faces). So I put it back in the box or install it back in the dome and on the wall of my home until better times come.

Anyway thank you for your valuable insights.

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