Cooperman

For one dreadful moment, I thought I'd suddenly woken up from a very long sleep .... about twenty years at least If you think the information looks familier (I did), have a look at this one:- http://www.cctv-information.co.uk/cgi-bin/index.cgi?url=http://www.cctv-information.co.uk/constant2/introctv.html A useful site, but certainly not the most informative (IMHO) If you're bored, you could also have a look at this one:- http://www.techstore.ie/hometech/Closed-Circuit-television/

My 'puter's gone mad...just posted twice and I wasn't even touching it

They've offered a £ 2 million (that's almost US$ 3.5 million) reward, so I'd be surprised if the police don't get a fairly quick result. With a carrot that size, it will be interesting to see what crawls out of the woodwork.

Is that the £ 50 million one your talking about? The police have just announced two arrests, but they won't be releasing any CCTV recordings just yet (that's assuming they have some recordings )

I always design out ground loop problems, but used to spend quite a bit of time sorting out other peoples! Oh lucky me!! It's far more common on larger industrial sites where the earthing points can be quite some distance apart.

I always find a mild tap on the nose with a tightly rolled umbrella, seems to do the trick

Everything rory said (although keeping clear of HV cables is more to do with induced hum, than ground loop) , and also consider using a 12vDC powered camera mounted on an insulated platform / bracket .... or fibre optic transmission .... or wireless ..... or .....

sf 1964, Just a quick suggestion for you; in the cameras present location (although to be honest, I'm not absolutely convinced that's the best place for it), if you tilt the camera down perhaps a further 15 degrees, you should loose the top 25% of the picture, which also contains a significant amount of your 'light' sources. You'll have far more (better) foreground coverage, although if you do get any 8' basketball players walking in, you might just miss the top of their heads.

gadgetguy, As they are hot filament light sources, LV Halogens spew out lots of Infra Red light, so although they may not look particularly bright to an observer, a half decent B&W or Day/ Night camera should be able to exploit the near IR component to help produce a resonably bright image. As with any lighting, the quantity and location will be key , as to whether you get a nice well illuminated image. As regards lenses, exactly the same principles apply for CCTV lenses, as they do for photographic optics. That said, photo. lenses are generally much better corrected, and the level of distortions and definition issues, are actually far less than you would normlly experience with some average jobbing CCTV offerings. Where a "zoom" type lens adjustment is indicated as either Far or Near, it is almost certainly a Varifocal lens, and not a zoom. In practical terms, you will almost always get better performance from fixed focal length lenses than you will from "zoom" types. If you have experience of using photographic cameras, it is relatively easy to relate CCTV lens coverages, to (for example) 35mm optics; although in practice, using larger format lenses on smaller format imagers, will always offer the best return in terms of overall image quality. Simple example, a 50mm lens on a 35mm SLR, would have an equivalent coverage to an 8mm on 1/3", or 12mm on 1/2". In each example, an 8 or 8.5mm (2/3" lens) on 1/3", and 12.5mm (1 inch lens) on 1/2", would cost slightly more for the optic, but the lens (and picture) quality would be significantly better.

Couldn't agree more Thomas!! If the case hinges on the video recorded evidence, then the defence attorneys key objective will undoubtedly be to get the recordings thrown out of court. jisaacmagee, you have to provide sufficient assurance that the DVR's were functioning correctly at all times, that they were not accessible to unauthorised personnel, and that they could not have been tampered with by anyone, authorised or not. Is there a log of recorder operations?; can you adequately describe the security features of the DVR's if challenged?, was there any motion triggered recording, in which case can you prove beyond doubt that the motion activation was working correctly at the time of the theft. The defence may well bring in their own 'CCTV expert' to cast doubt on the integrity of the system. They may ask how many of these DVR's you've used on other sites, to try and cast doubt on the equipments overall reliability in operation. If this case were in the U.K., there would be a number of possible legal challenges, which fortunately you don't have to worry about in the States.... at least, not yet!

Over such a short distance, if you use a very good quality double screened co-ax, it shouldn't be a problem (seperate cable for 12v). For a bit of cable costing next to nothing, it wouldn't hurt to try it.

Just a quick suggestion, but if you mount the camera on the 'top left' corner of the building (rather than top right), zoom in to a longer focal length, you'll then have more time and more images recorded, to allow identification of the vehicle.

Our legal system tends to work somewhat differently from yours, but one point that may be worth thinking about is multiple copies. Where interviews are conducted for possible court use, it is becoming increasingly common to find three recordings being made at the same time ( one identical master each for the police, prosecutor and defence ). Normal DVD recorders with a seperate TDG could be suitable, although I recently saw a DVR which had 3 DVD drives built in as standard.

There used to be an old saying about the proof of the pudding is in the eating, and in a funny way both of you guys, rory and cctvgeeknz, are actually arguing your positions simply based on having had similar experiences. Rory, you don't trust the specs that manufacturers publish and prefer to see the proof for yourself, in the field - who could possibly disagree with that eminently sensible position. cctvgeeknz, you've settled on a product that you confidently feel wipes the floor with most of the opposition, so why bother changing - why indeed? If it works for you, as we say over here, more power to your elbow! The Bosch argument amuses me, only because I remember what happened when RCA became Burle Industries, which was then taken over by Philips, who eventually succumbed to Bosch. At each stage of the company's evolution, they produced world class products .... albeit at world class prices. I always tend to put the argument about camera specs. the other way around; if either of you guys were given a basic piece of kit to work with, I'd confidently predict you'd both manage to get the very best out of it. If on the other hand you give a mega bucks camera to someone that doesn't know what they're doing, the results would almost certainly be significantly inferior.

Just to add a few more comments to what Flip-Top has already said. Over here, IP is being touted as the future of surveillance, and many in the industry are incorrectly forecasting the imminent demise of conventional CCTV. Just in passing, there is actually a very important IP Security event on this week in the U.K. (IIPSEC). Anyone that I've spoken to, that have been in the industry for more than twenty years, tend to have a similar outlook. IP can undoubtedly offer more impressive technical solutions for high end users in certain applications, but the momentum that is driving the sales pitch for all things digital, tends to come down to a more fundamental issue at present. Manufacturers can't make the margins on conventional gear, but they can make a few extra bucks selling IP / Digital solutions. There is some very good IP gear on the market, and a lot better to come, but it's still going to be some years before we see conventional gear being replaced completely with IP systems. For the next few years, on a simple cost / technical comparison, conventional CCTV will dominate the lower end of the market, hybrid CCTV / IP systems will increase in the middle sector, and complete IP networked systems will increasingly replace top end conventional installations. The general consensus is that IP isn't quite there yet, and anyone that says otherwise, is a brave person indeed.

Hi kaysadeya, Long time no hear - welcome back! If you do have "...free time to focus on more interesting topics", we won't be discussing CCTV then!

Singlemode fibre then (sorry, couldn't resist it!). Back in the '70s, there weren't any training courses; you just had to use your common sense, or learn about CCTV the hard way. Just last week, I went round to a client that was using a 15+ year old TOA line powered Vidicon tubed camera, that was not producing a picture (referred by a friend of a friend, so no chance to make any decent money out of it). I whipped off the covers, tickled the circuits, and they said the picture was way better than they'd ever seen it before. I happened to mention that if another engineer were to look at it now, 95% would say it's old technology and can't be repaired, when in fact there wasn't anything fundamentally wrong with it (other than the circuits needed recalibrating). Surpsise, surprise, they admitted that another "expert" had already looked at it, and said precisely that - it would cost them hundreds for a new camera as their old museum piece couldn't be repaired. The moral of this silly story (if there is one) is that you can only learn so much from a training course, but you can't learn what they don't teach you - most of the courses I've seen have a lot of useful information, along with glaring deficiencies in areas that they don't tell you about. For someone who doesn't have an interest or passion for learning about technology, any knowledge is better than nothing, but a little knowledge can ultimately be a dangerous (and expensive) thing.

Aaahh, so that's what it is Personally I've never been the same since I had a pint of Theakstons Old Peculier

Steady on rory, now I know why my ears are burning Pretty accurate bit of posting there sir The only obvious bit I'd perhaps expand on is where you say "Without an added IR pass filter they will not pick up as much IR (Spectral Wavelengths) as would an IR Optimized camera." The only purpose for an IR Pass filter is to optimise imaging at a particular IR frequency, it won't actually increase the amount of IR reaching the imager; in fact the filter may even slightly reduce the amount of light that would otherwise get through. Most IR optimised cameras actually use a more sensitive imager capable of reproducing the higher IR frequencies, so where a normal CCD might have perhaps a 35% response at 830nM, an optimised camera could be (for example) 70% efficient at the same frequency, and extend it's response right up to perhaps 1100nM (maybe with only a 10% response). When CCD's first appeared there were actually two types in widespread use, the Interline Transfer (which we all know and love!) and the Frame Transfer type, which was seriously more IR sensitive. There were actually hybrid camera imagers engineered for the broadcast industry which were FIT (frame interline transfer) devices, which exploited the best characteristics of both designs, but never got as far as the CCTV industry (way too expensive).

and a kalik is ....?

Hi electronicsuk and welcome, You've had some good information from the chaps already, but I thought I'd just quickly mention a couple of other points that might be of interest. Here in the U.K., the two most popular "bulbed" IR illuminators are filtered for 715nM (bright red glow) and 830nM (dull red glow). illuminators providing outputs between 850 and 950 nM become increasingly covert as the number increases, and most higher frequency lighters are now LED based rather than bulb fitted. I'm guessing that if you've used a Wickes camera (without knowing which one), it is going to be fairly basic, and is unlikely to have any significant IR response. In other words, you'd probably need a reasonable quantity of IR light (even at a lower frequency), just to get anything useful on screen. As a suggestion, it may be worth considering keeping a low level maintained 'white light' illuminator on, perhaps using a 60w bulb. Hot filaments give out shed loads of IR, and whilst the surrounding area may not look terribly well lit to the human eye, the camera should see it very clearly. Certainly for such a short distance to view, you won't need anything hugely impressive.

Keep up the good work rory, just be careful you don't overdo things. As the man said, make sure you get some sleep

Whoever wrote that definition, obviously doesn't have much knowledge of photography post 1920 something. When I was a kid (no jokes please!) you were always told to take photographs with the sun behind you (flat lighting, minimal shadows). For anyone with a reasonable knowledge of picture taking, dealing with "contre jour" or against the light shots, can produce some quite startling and interesting images. That said, CCTV is a whole different ball game, but whereas engineers have long sought to use the wide dynamic range of some camera imagers to produce a usable picture in backlit conditions, the fact is that for perhaps 50 - 75% of everyday situations, you can just as easily manipulate available lighting (either visible or IR) to produce a more pleasing and evenly lit image. The idea that WDR is a new phenomenon, does somewhat overlook the fact that previous generations of Vidicon tubed cameras, had sufficient dynamic range to cope with lighting from perhaps 5 - 100,000 lux simply using a fixed iris lens (16mm f1.6 used on 2/3").

Double check that the cameras are not making contact with any metal structure. If they are, isolate them and if the problem disappears, refit with a suitable insulating material to prevent any re-occurance.

Camera 714, A quick suggestion for you. I don't know the camera or the I/R source, but it's obvious that the intense reflection off the support(?) is causing the camera to overcompensate. The IR Diode light source is not really going to provide the angle of coverage you are looking for, but you could try the following to see if it will light half the area. Move the "lamp" to a position next to the support (out of view of the camera, so it's no longer reflecting off it). Purely as an experiment, try using a thin layer of vaseline (grease) on the lamp window to see if its possible to diffuse the light output to cover a wider area. If it makes a significant difference, you can have a think about using a proper permanent glass diffuser, and if necessary, consider a second light source to achieve your 30' width of illumination / coverage.