Security mon that shows #lines or fh

[cctvfan 0]

Hi, are there good security monitors that indicate the vertical resolution (or #TV lines) of the video signal currently being displayed?

 

Even if it does not show the #lines directly, the horiz frequency (fh) it's currently locked to would be good enough. (I'm tying to get a good mon for benchmarking my cameras, so I can confirm if a cam is indeed generating 480 lines, etc.)

 

If the above features are not for end users, are there service engineers out there who can tell me if we can get, say Sony monitors to go into "service mode" and show the above info?

 

Cheers.

[Cooperman 0]

The standardised method for testing whether a camera is resolving its claimed resolution figure, is to use a test chart.

If you set up the chart at the correct distance in front of the camera under optimised conditions, provided you are displaying the image on a significantly higher resolution monitor, you should be able to see which of the smallest set of resolution bars are still clearly definable.

Although camera manufacturers quote resolution figures (bench tested) for their products, it's usually the poor optical performance of the lens which has an immediate effect on reducing the quality; of course, if the camera is working in low light, or is generally producing a noisy picture, this will also have an effect on resolving detail.

Engineers, particularly in the Broadcast TV industry can certainly use 'scopes', test signal generators, vectorscopes and goodness knows what else to measure and optimise set ups, but for general CCTV work, excessive comparisons can eventually make you paranoid.

Come to think of it, I've just realised why whenever somebody mentions lines, I immediately think back to my school days!

[cctvfan 0]

Cooperman, thanks for your tips!

 

Actually I am not after the *resolution* being accomplished by a camera setup. As you said, many factors come into play that could affect the ultimate "ability to resolve picture details". Test charts are certainly the proper way.

 

Rather, I'm just trying to achieve a much less ambitious goal of performing a quick sanity check on the cameras to see if they are meeting their claim about *electrical* characterisitics, i.e. #TV lines generated (again, nothing to do with resolution).

 

Some cameras with generic brand names (mostly imported) have poor documentation or even inadequate marking on the camera itself. I'm just trying to get some peace of mind in case, say, they mix up a 330-line unit and a 480-line at the factory (the two look identical in some cases).

 

Cheers!

[Cooperman 0]

cctvfan

 

I think I've been spending too much time in the sun (yes we do get some sun in the summer, here), because you are getting me confused now.

 

Just to clarify, the only two 'lines' that are referred to by manufacturers, are either a) the 'TVL' which directly relates to the number of pixels in the imager, and hence the number of equivalent lines that can be resolved (i.e. image resolution), or b) the number of lines making up the picture, which is a function of the scanning system, e.g. NTSC or EIAJ (525 lines); PAL, Secam or CCIR (625 lines). If you tried an NTSC camera on a PAL monitor, you wouldn't get a picture!

 

If you want to do a simple visual check on a cameras performance, set up the best camera you can, so that looking at a torn out page from a newspaper the page fills the screen on your monitor. If you then test any other camera it's relatively easy to see whether it is comparable or inferior.

 

If you need to actually measure the frequency response, you'll have to buy a half decent oscilloscope, learn to use it properly, and then become a braver and more patient man than I. If you're interested in a thirty five year old Tektronix dual beam scope (with valves!) ...... I should really donate it to a museum!!

 

If none of this makes sense, you can send the men in the white coats over to visit me.

[cctvfan 0]

Cooperman. Sorry for the confusion.

 

After second thoughts, I agree with you there is no short-cut to verifying the advertised TVL of a camera (without resorting to the standard resolution test procedures). An NTSC signal is an NTSC signal, one can't expect the monitor to be able to back out the CCD resolution from the signal.

 

Thanks!

[Cooperman 0]

No problem, I can cut down on my medication now!

 

Talk about coincidence; I just opened a mag. this morning and what did I see?

 

A handheld test monitor used in the broadcast TV industry.

I wouldn't dare ask the price, but it looks good though

 

http://www.hamlet.co.uk/products/Flexiscope/inst/menu/frame.html

[rory 0]

If you are use to using 480TVL color cameras, and then go an use a 330 or 350TVL camera, you will easily notice the difference. There is a huge difference in clarity, especially in playback on a DVR. For example, use it indoors on a cash register or capturing customers faces, or an exview outdoors in low light.

 

Rory

[Cooperman 0]

Rory,

I recently saw a demo of a 'leading manufacturers' wide dynamic CMOS camera which they claimed was 480 lines, but basically looked as if it was struggling to reach 330. Have you come across any examples where, what the manufacturer claims, and what the eye tells you, are no way the same?

[rikky 0]

Cooperman,

Which CMOS camera are you talking about?

[rory 0]

Rory,

I recently saw a demo of a 'leading manufacturers' wide dynamic CMOS camera which they claimed was 480 lines, but basically looked as if it was struggling to reach 330. Have you come across any examples where, what the manufacturer claims, and what the eye tells you, are no way the same?

 

 

How did I miss this reply?? Anyway ...

 

Nope, so far I have only used Phillips, GE (Kalatel), Provideo (they claim 420TVL and it looks like 480TVL, in BW, rouch stuff!), Samsung, COP USA, ExtremeCCTV, and a couple others.

 

Phillips & GE (Kalatel), what they claim on different cameras match what I have seen, great pictures.

 

Samsung, I have only used a Zoom camera, 3 different models, same thing, if you use manual zoom, then you can geta a high res from it, if auto focus, looks more like 350TVL.

 

Provideo, found so far, whatever they claim, you get, they are impressive for cheaper cameras, bullet cameras. They havent lied to me yet! Their 420TVL BW cameras are almost comparable to 480TVL cameras from kalatel & Phillips, obviously not color.

 

COP usa, one or 2 of their cameras are ok, others have such bad color production I cant get into clarity, as it makes no sense. I dont use them anymore, though installed a few for a client recently who bought them himself.

 

Extreme CCTV, never been lied to, they are impressive, though pay for them hefty.

 

So basically no, havent come across any yet that claim it but dont do it

Even with bad color production COP USA cameras I used never claimed to have a high res on the ones we used, or they were used in low light when we did.

 

I dont know of any manufcaturers I use, that still have CMOS cameras..

 

Rory

[Cooperman 0]

Rikky,

 

The unit they demo'd was a very late pre production prototype. If I named the manufacturer, I'd probably never work again!, or walk come to that!!

 

Rory

 

I'm amazed you have the time to test out so many cameras (I must be doing something very very wrong!!).

Quite a few of the cameras you mentioned are not readily available in the UK, and would I be right in guessing that the US sourced models you use, are all NTSC?

I've noticed that although the technology in a couple of 'wide dynamic' models is clearly CMOS, the manufacturers are very reluctant to come clean; their is still something of a stigma attached to CMOS, particularly as the earliest examples were absolutely dreadful. As I said before, the sneak preview I had of one model, I'd quite happily have missed out on.