TVL Measuring

[Soundy 1]

Either way it matters little to me. You're attempts to prove me wrong, and my attempts to ensure you were knowledgable about what you were argueing, is what pulled this thread so far. Had you not said anything the first post would have been my last, but then you had to argue an after thought like I said it was the word of god and then continued to argue, unsuccessfully, anything else I said in response to your arguements because you invisioned yourself as being more knowledgeable.

 

Erm... it was Alex who first questioned your claim. So far, nobody else has disagreed with him, or me.

 

You're the one making these claims, yet you leave it up to us to prove them via YOUR methods... then when those methods don't work, you claim it's because we're incompetent.

 

So... it's YOUR claim, so YOU back it up, using YOUR methods. Then nothing can possibly go wrong, right? You say it works, so show us how it works.

 

Or will you continue to try to weasel out of it?

[Scott Broscious 0]

Erm... it was Alex who first questioned your claim. So far, nobody else has disagreed with him, or me.

Noone else besides you him and cirrvine ahs disagreed with me either so does that mean the other 3 that have posted automatically agree with me? You're logic is flawed....as usual.

 

You're the one making these claims, yet you leave it up to us to prove them via YOUR methods... then when those methods don't work, you claim it's because we're incompetent.

First there is no these claims. There was one claim that youv'e been argueing. Quit making **** up. Secondly you've already shown how it proved my "theory" (as you say). You're the one that said you were incompetent when you said "I can't get it to work" after informing me (and everyone else here) that your 470 tvl camera spit out a resolution of 720*480. No need to continue further until you can show me a camera with say 320 tvl that spits out a resolution of 720*480.

 

So... it's YOUR claim, so YOU back it up, using YOUR methods. Then nothing can possibly go wrong, right? You say it works, so show us how it works.

I'm not the one worried about an after thought, or proving it right. The only reason I continue posting in response to you is because, as of this post, every arguement you've presented has been incorrect and I felt the need to correct you way of thinking because you were so confident in the way you answered that it made me think you actually believed the bs that was coming out of your mouth.

 

Or will you continue to try to weasel out of it?

There's nothing to weasel out of.

[Soundy 1]

First there is no these claims.

 

Damn, boy... you dance like a drunken cowboy at Stampede.

 

Fine... THIS claim:

 

I need to know if there is any CCTV testing device that can measure the resolution or TVL of the camera, due to some exageration from some suppliers about their cameras' resolution and picture quality.

 

A less technical, less accurate way, would be to take the recording from your video cameras, get it onto your computer and use a program like vlc (or maybe windows media player...i dont really use it though so im not sure) to view the video.

[Scott Broscious 0]

I dance around? Lol you've gone from tvl to vlc to image sensors to oscilloscopes thru this whole thread and when one of your claims to discredit me blows up in your face you try to find something else or fall back to one you've already shown worked once.

 

Dancing around the subject would be me outright ignoring it. Sorta like how you've done in every instance I've proven your statements false or when I've asked you a question. How about quoting the entire idea expressed?

 

First there is no these claims. There was one claim that youv'e been argueing.

 

You like to take things out of the context they're said in to make it sound like you're correct. pfft danced. I know what you're arguing and have acknowledged it more than once. If you ask me its you that are dancing and you that have shown insufficient knowledge to back any of your claims.

 

I'm supposed to believe you know what you're talking about when you didn't even know that a spec anni is an oscilloscope? I'm supposed to believe you know what you're talking about when you say the tvl of a camara comes from an image sensor? You tried to explain ntsc broadcast signal to me like it was a SIGNAL...ntsc is a format present in the signal, learn what a carrier wave is and everything that may be transmitted it on it before you try to explain signal to me. I'm supposed to believe you know what you're talking about for what? You've given me no reason to think you possess anything more than a passing familiarity with what we've been talking about thru the course of this thread. You may have dazzled these guys, ak didn't know a spec anni was an oscope either so your bs may have had him shaking his head up and down in agreeance, but I don't fool so easily.

 

I'm supposed to play your game and prove a suggestion, I made as an after thought, correct when you've done nothing but try to prove me wrong with complete and utter bs? Why? Either use the suggestion or don't. I don't care, its inaccurate anyway.

 

Also you don't know enough about me to call me a blowhard. that would suggest I'm either boasting or bragging. If you think I'm boasting with what I've said here then once again you're wrong I could come up with better crap to "impress" you with than telling you what my job title is or telling your friend about my education when he informs me of his 2 years of electronics schooling in an attempt to show me just how much he knows, and then continued with belittling me for the merchandise I sold like it proved anything in regards to technical knowledge. So yeah I guess depending on how you look at it you could say I did measure myself...but I used the ruler you handed me because you wanted to know how big I was.

 

Hell, you were lost when I was just explaining that an spec anni is an oscilloscope and I wasn't even trying to confuse you. Why would I want to impress you? Up until I posted from the wiki you swore you were right, even to the point of trying to prove it. There's no reason for me to try and impress you by boasting, you've yet to show me your worth impressing. I'm also not bragging...that implies exageration and that's not here either.

 

I can call you a blowhard though. Hell you've been pushing your incorrect information hard as hell like it was 100% accurate and bullet proof.

Edited July 6, 2009 by Guest

[dopalgangr 1]

http://www.youtube.com/watch?v=HcOZ6xFxJqg

[cctv_down_under 0]

Wow what a response - would have loved to read it all but would take so long.

 

To measure accurately you are correct an oscilloscope could be used, to measure roughly though you could use a TV Line generator or a still image with tvline measurement......there is one on the back of the best CCTV book ever written ironicaly called "CCTV".

 

You would need a larger one for testing but you will see that there are vertical and horizontal lines making a triangle shape......where the lines can no longer be seen as seperate lines is where the the TVL resolution is limited to.I purchased a larger version of this to test all new cameras on and it is a damn bit cheaper than an oscilloscope

 

There are a multitude of ways to test TVL but this is the most basic way.

 

I suggest all CCTV experts read and purchase this book....it is my Bible...there is a newer and an older version...its not light reading but covers everything you would ever need to know.

 

http://www.cctvlabs.com/orderbookmagschart.pdf

[ak357 0]

 

To measure accurately you are correct an oscilloscope could be used, to measure roughly though you could use a TV Line generator or a still image with tvline measurement.

 

how do u use TV Line Generator in your example ?

Thx

[cctv_down_under 0]

You get a large version of that chart ...focus the camera onto it and look at the video on the other end, you need to ensure that the screen you use to measure it on can handle, more than the TV lines you are trying to measure, you dont allow it to be compressed, just analogue signal - by visualising the chart you can (although not perfectly clearly) visualise where the TV lines will stop on both Vertical and Horizontal.

 

If you look at that link, you will see that the chart has an x and y triangle shape with lines coming together at the tip of each triangle, where you can no longer visualize the independant lines is where the TVL stops and looking at the shart at that point you can read the TVL.

 

I admit it isnt perfect but it is fairly accurate - I dont think a lot people realise that the difference perception to the human eye of 50TVL or so is so minimal that it isnt worth regarding really.

Not to mention the tricks that are used to reach that TVL spec in the first place

[ak357 0]

You get a large version of that chart ...focus the camera onto it and look at the video on the other end, you need to ensure that the screen you use to measure it on can handle, more than the TV lines you are trying to measure, you dont allow it to be compressed, just analogue signal - by visualising the chart you can (although not perfectly clearly) visualise where the TV lines will stop on both Vertical and Horizontal.

 

If you look at that link, you will see that the chart has an x and y triangle shape with lines coming together at the tip of each triangle, where you can no longer visualize the independant lines is where the TVL stops and looking at the shart at that point you can read the TVL.

 

I admit it isnt perfect but it is fairly accurate - I dont think a lot people realise that the difference perception to the human eye of 50TVL or so is so minimal that it isnt worth regarding really.

Not to mention the tricks that are used to reach that TVL spec in the first place

 

thx for info

but I was asking how TV Line generator fits in your example ?

of TV line measuring

 

I do have real EIA1956 chart

[cctv_down_under 0]

Bad wording......on my part, but assume you can get a signal generator for that test pattern

[crirvine 0]

cctv down under you need to read all the post it all started with scotts wonderful usb dvr to test test with. Hey scott you not gonna attack this man. I still do not sell off my web site it is for my customers for info not sells like yours buy adds you have a nice ebay looking site also scott.

[Scott Broscious 0]

cctv down under you need to read all the post it all started with scotts wonderful usb dvr to test test with. Hey scott you not gonna attack this man. I still do not sell off my web site it is for my customers for info not sells like yours buy adds you have a nice ebay looking site also scott.

 

Lol attack who? cctv down under? why he was trying to help. Sorta like you said you were yet you have yet to help. There have been a total of 3 or 4 people that have tried to help in this thread, you soundy and ak are not included in that number as you've contributed nothing worth much to the OP. Oddly enough if you take the time to go back and read thru the thread instead of picking out bits and pieces, I haven't attacked anyone that didn't attack me first. Remember what I told you the first time you slung an insult my way? I'm a marine you're not going to offend me...you'll only get return fire.

 

On another note - if you sell nothing on your site why are there links for sales and billing? I have an ebay looking site? My site looks nothing like ebay. Know what? It doesn't matter what you think of my site. At least my site doesn't look like it was thrown together by a 13 year old learning html. Before you want to toss insults at other peoples sites...ensure yours doesn't look like you threw up on the screen and just decided to leave it because it was better than what you could come up with. Have fun with your site....its looking soooo good.

 

You keep talking about my merchandise like it makes you, ak or soundy look technically proficient. Again I'll say my merchandise means nohtimg more than what I can get ahold of. Thats not even what I'm going to sell 5 years from now, just the first thing I could ahold of. If my website showed how technically inept I was why was I the one to correct soundy's thoughts that tvl came from an image sensor? Why was it me that corrected the though both ak and soundy had regarding spec anni's not being oscilloscopes? Why was it me that corrected him when he thought the only thing present in the analog signal coming from your camara was the ntsc/pal format? Why was it me that had to break down what a carrier wave was to a bunch of cctv "gurus"? Hell you yourself actually had the nerve to say I was "blinding with bs" when I broke that down to soundy to show him how there was more on that analog signal than ntsc format and you claim to have taken 2 years of your liife to study electronics....horrible, waisted 2 years is more like it! But your right, my website tells you I suck at being an electronics technician (lol)....wonder what it makes you when I've corrected you guys? Can you guess what you're website tells me? Nothing other than your skill with html...which is the only thing you can learn about me from my site. If I take the cameras down and start throwing up slides for 5 year olds does that make me less of an electronics technician? Your logic is flawed.

 

I think you have nothing worth argueing so you decide to pull my website into the conversation like it has any weight. I could sell lipstick and still be more technically proficient than you 3 have shown yourselves to be in this thread so far. Hell even my wife knows that a spec anni is an oscope yet 3 grown men who have a combined total of over 50 years working with these tools didn't know that. Laughable.

 

Again ill tell you im not in cctv. Im an electronics technician. Heres a link to a basic job description http://www.schoolsintheusa.com/careerprofiles_details.cfm?CarID=1590 the only issue i find with that description is the third paragraph and its descriptions of what electronics technicians can do. it's a bit misleading because it makes it seem as if a comp tech is an electronics technician. the only way a comp tech is an electronics tech is if he's taken a soldering iron to a circuit board in order to repair the pc, otherwise he's just a comp tech but its still a pretty good job description.

 

Here's the real issue:

scotts wonderful usb dvr to test test with

First noone said anything about a usb dvr, both you and soundy need to read thru the thread again. I said usb ADAPTER. Nothing more than an electronic circuit (hey sound...consisting of nothing but filters and drivers) to turn your analog signal into a format your usb port in your computer would accept.

 

Second it wasn't a way to test anything, it was a way to get the resolution of the image. The guy asked for resolution OR tvl. I added in your could use the known resolution to get an inaccurate measurement of tvl after I thought about the fact that he may not have/know how to use an oscilloscope...which was my only real method. The other was an inaccurate after thought that you all have been harping on like I said it was the coming of christ. Like I told soundy, either use the suggestion or dont i dont care its inaccurate either way.

 

You guys dance around semantics, but expect others to be semantically accurate, and add things into the conversation that were never there better than anyone I've ever met in my life.

 

Again, the biggest drawback to my suggestion, besides it being inaccurate, is your usb PORT on your computer as it is the ONLY LIMITING factor in my suggestion. Nothing is changed apart from an analog signal being converted digitally

That adapter has no way of knowing the TVL of the camera's sensor, it's just reading the NTSC output of it, 525 lines, 30 times per second (substitute appropriate numbers for PAL, if that's what you're using).

Sorry the second your analog signal hits a digital format it is no longer ntsc or pal format, it is a digital format. The adapter is what converts this analog signal into digital. Noone said anything about the adapter knowing anything about tvl...again its digital so tvl (which is analog) means nothing. 1's and 0's, off or on...that's all the analog signal is after it leaves the adapter. Sorta the same as how it starts with the image sensor storing voltage in capacitors (not having tvl capabilities soundy...pixel resolution...yeah...tvl...not so much) Edited July 6, 2009 by Guest

[Soundy 1]

Well, I see Scott's gonna do everything he can to avoid actually showing us how to magically determine a camera's TVL using VLC. Of course, everyone ELSE here knows that it can't be done... and I suspect Scott knows that it can't be done either, but rather than just say he made a mistake, he's going to continue to dance around the subject and insist that everyone else is incompetent for not being able to make it work.

 

You guys have fun with him, but until I see a video from him documenting this procedure, I'm outta this thread.

[cctv_down_under 0]

Last time I looked this site was called CCTV Forum .....not CCTV argument...lets keep it a little mature shall we.

 

Look I know I should have read it all...I am sorry but I am far too busy.......(read that as Lazy)

 

TV Lines in CCTV can be very confusing indeed - especially these days as we are not necessarily talking about standard video anymore so it really depends on what medium you are talking about...Digital or Analogue.

 

When discussing Analogue Vertical Resolution is the maximimum number of horizontal lines that a camera is capable of resolving..... this is limited in Analogue to the CCIR/PAL (in my country) standard to 625 horizontal lines and in your native USof A EIA/NTSC recommendations to 525 horizontal lines....however the REAL vertical resolution for both standards in analogue is much less.

 

If you take into consideration the vertical sync pulses, equation lines etc the maximum would be 575 for PAL and 470 for NTSC this then needs to be further corrected by the Kell factor of 0.7 to get a more realistic vertical res of 400TVL PAL......... A similar deduction applied to the NTSC signal would render the maximum realistic resolution at 330TVL

 

Horizontal Resolution is the maximum number of vertical lines that a camera can resolve and this figure is only limited by the technology and the monitor quality. Horizontal resolution is usually 75% of the number of horizontal pixels on any given CCD chip this is a direct result of the 4:3 aspect ratio.

 

When counting or measuring vertical lines in order to determine horizontal resolution you only count the horizontal width equivelant to the vertical height of the montior used to measure..this ensures that you have an equal thickness of lines both vertically and horizontally so then when you measure the total number of vertical lines accross the width of the measuring monitor you have multiply this by 3/4 which is equal to 0.75 and because of the unusuall counting .....horizontal resolution is always reffered to as TV Lines and not just Lines...this is WHERE the measurement comes from...measuring lines on a TV (Yes Analogue).

 

In answer to your questions there are many ways to test a cameras perfomance in this way and one of the best ways is as I mentioned before the CCTV Test chart ...as one of our colleagues pointed out ....this is for your people called a EIA RETMA chart but this by no means makes it the only testing device - however this chart is designed for CCTV measurement unlike some others that are available.

 

To test on a chart like this you need to focus a camera to the best possible focus (usually a middle F-stop, 5.6 or making the test chart fully in the feild of view, you also need to turn off all other features of the camera - like AGC etc.

 

Now this is where the oscilloscope comes in.....you can measure on this chart where the lines in the shape of a sharp triangle come in contact but if this is only measured by a human eye it will only give an approxamite (usually fairly accurate) however for a more accurate testing you can use the oscilliscope...especially if the one you use for testing supports a TV Line function (some do) the measurement is then narrowed down to selecting a line where the four lines of marking making the triangle modualtion depth is equal to or better than 5% by doing this you can measure by disregarding the moniutors resolution limits.

 

Although resolution is closely related to the signal bandwidth a camera may generate it is not the defining characteristic.

 

I may stand corrected but once you are taking the analogue signal which can be defined and creating a digital signal then you are no longer measuring TV Lines as TV Lines are a measurement based on analogue environments.

 

I think you may be confusing resolution and TV Line measurement and you need to know in which medium you are measuring this and in what context...you firstly need to quantify to medium you are testing as you seem to be crossing between different types of measurements.

 

I am sorry if any of this is off the mark

[Soundy 1]

To test on a chart like this you need to focus a camera to the best possible focus (usually a middle F-stop, 5.6 or making the test chart fully in the feild of view, you also need to turn off all other features of the camera - like AGC etc.

 

Just as a point of interest, I don't know if the rule-of-thumb applies to CCTV lenses, but with most SLR lenses, "two stops down from wide-open" is generally found to have the lens's "sharpest" performance. So for a typical f/4 lens, f/8 would give the sharpest results... for an f/1.8, the "sweet spot" would be around f/3.6.

 

Of course, few if any CCTV lenses actually have aperture markings, and auto-iris ones are a lot harder to fine-tune than manual iris. Just food for thought

[cctv_down_under 0]

Fair point - I actually meant to type an eight dont know how I got the guy with the glasses LOL

 

I did say "usually" obviously there will be differences the point was that you need to set to the best focus possible for the testing, there are even better ways to do this.....but hay lets not confuse the issue, it seems pretty confused already and its nearly 1AM here......

[Soundy 1]

Oh yeah, no intention to confuse... like I say, just something as "food for thought". Two stops, btw, is equivalent to half the diameter of the aperture, so a visual approximation is fairly easy.

[nadort 0]

How to measure the tvl of a cctv camera was the first question and a read a lot of things that i never used. Wy ....when we do something we must know for sure.

I am responsible for a lot of camera's wich give legal evidence and the must work as our specs required.

TVL is nice but not the most important part.

Other things are the size of the chip 2/3, 1/2, 1/3 or and yes they sell them 1/4 inch CCD or what to think of cmos.

The choice of the lens of the camera, F rating, IR correction, zoomlens or measured and so on

The lighting outside, yes or no IR or sens-up

Than you have the DVR recording speed, resolution/compression.

Display monitor, TUBE or TFT or backbeamer projector, led or plasma

I can afford very expensive camera equipment but most of the people have to do it with the normal stock

So just make a good paper with demands what you want to see live and recorded day and/or night. Observation, Recognision or Identification, And go shopping for a good price and let the installer demonstrate if it is wat you want.

 

for the installers or big spenders on this forum who want to go profesional and want to show to non technical buyers that therre specs are right

We use for a quick checks on site the Rotakin doll. For testing the TV CCTV Test chart en checking the specs of a camera the camera analyser EWM40

[crirvine 0]

Scott this will be my last post on this. I am glad to see you no longer advertise your site in your tag line thankyou. My site links to emails for our customers we only use the web site for service links to our state info I do not have time to nitpick on things I have customers to take care off with front line equipment Sony Pelco OnSSI Axis Ademco DSC Toshiba and give free help to people on this site that need help plus I have customer that spend more than your line of credit. You might want to read your own post as you said your USB DVR can be used to test with. You also said that hardware is not the problem just write better software These are not my words they were yours before I posted. I accept your apoligy and hope you the best in your ventures.

[rory 0]

ok i will be sure to end this argument now.

best way is to use your eyes! if you cant do that then perhaps you should be out cleaning pools instead (start with my imaginary pool!)

[cctv_down_under 0]

Rory the pool Boy.....has a nice ring to it.......can see you cleaning the pools for all those rich ladies in the bahamas LOL

[rory 0]

Rory the pool Boy.....has a nice ring to it.......can see you cleaning the pools for all those rich ladies in the bahamas LOL

 

i dont know if i cud take the heat these days. i rather be inside chilling in AC with the rich ladies while someone else doing the cleaning

 

hey .. BTW my bro is moving to australia in a couple weeks.

[cctv_down_under 0]

Really - where what doing......if he needs a place to crash let me know if he is in Brisbane that is

[rory 0]

Really - where what doing......if he needs a place to crash let me know if he is in Brisbane that is

 

not sure but he has some music gigs lined up. hes going to be in the gold coast area. I think taking a trip around australia first. no work down here now. I figured id let him take the trip first ... i might check out the UK myself .. or not .. not sure. plenty ways to make money if one is in the US or Canada, but down here its like being the odd one out, they dont like us Caribbean folk.

[cctv_down_under 0]

Just come here and work for me mate.........easy peasy!!!

 

Gold coast or "the Goldie" as we call it is only about 45 mins from me.....not that any locals ever go there.....its so funny because the beaches are quite nice and you see tourists eyes light up taking pics all the time...but all the locals know......all the good beaches are not there.....but we never tell them where....no one wants to sit on the beach while there is tons of people taking pics and screaming excitedly........so we keep them secret.......clever us folk!

 

The Goldie is just for tourists...mind you I am down there this weekend for a trade show