the toss

I viewed the camera (standing on a ladder right next to it) with my wrist monitor and it was clear. The interference wouldn't effect it the same way?

Not if your plugged directly into the camera when the interference is entering via the coax run.

In that case there is not much you can do cable wise. I would be looking for external sources of interference that the cable is running close to like fluoro lights , high power switching power supplies , sodium lamps, refridgeration units, RF transmitters etc

Like Boogie says - cheap cameras struggling with low light/IR conditions. When operating under IR there is a sweet spot. Any closer causes over exposure and a white "Casper the ghost" effect while any further away the IR is not up to it. When there is not enough light entering the camera lens the AGC (automatic gain control) winds up to increase the signal level BUT in doing this it also increases the noise level which is what your seeing. Add to this that the stated IR range of a camera can usually be halved to get an accurate range as against the "salesman range"

Just to re-iterate ----->

It is RG59 & NOT RG6 or RG58

It is copper conductor /shield and NOT copper clad steel/aluminium

It is woven shielding and NOT wrapped foil

can you clarify on these three questions

I'm wondering if the existing cable is the thin pre-made stuff that comes with pre-packaged kits. If it is then most likely it is NOT RG59 at all but simply a screened (not shielded) audio cable. The fact that it has BNCs on the ends doesn't mean it is RG59 coax. As a CCTV proffessional I will give this bit of advice. The coax run is usually the most labour intensive part of the job. Cheap cables may or may not give satisfactory results. You can scrimp on the other parts but NOT the cable as it takes to much time/effort to replace it.

Take the cameras off the coax & see if the problem is still there. If it is (my guess) then your interference is getting in on the coax. Being an AC (balanced) power feed it is unlikely (but not impossible) to be an earth loop.

Are the cameras at the mounting point isolated from any building metal structure?

BUT is it copper or copper clad steel/aluminium?? Also what sort of coverage does the shielding provide ??

The only difference with plenum cable is the non combustable insulation so that wont help.

What do you mean by a "splitter"

Some information as to what type of cable is being used would help. SMPS are a possible source of interference as are fluro lights if the cable is run colse to them

Shows the quality of "Tech Support" that you get now days.

Yes. The power supply specs are simply a statement of what it is capable of doing if called upon.

It all comes down to the lens you use and of course the screen size you view it on. Most packaged cctv systems will use a wide angle (2.4 - 3.5mm) lens. This will give a wide picture but specifics within the picture are small. Going to something like a 12mm lens will bring everything up closer but the picture wil not have as broad coverage.

If your looking at something like a driveway then try getting something like a 5 - 25 mm varifocal lens

carinlynchin you are right in your understanding that current , resistance & voltage are all inter-related. But its not that hard to understand. Think of your power supply as a water tank on a stand connected to a hose. The higher the stand is above ground (voltage) then the higher the amount of the water (current) that comes out the hose (resistance). Changing the height (voltage) or pipe diameter will cause a change in flow(current).

Now with your camera you have a power supply that is 12V and CAN DELIVER 2Amps. Now lets say your cable has a "return" resistance of 3 ohms and the camer a requires 0.4A (400mA) then the voltage that will be dropped over the cable length will be current x resistance 0.4A x 3^= 1.2V. So now the voltage at the camera is only 10.8V instead of 12V. The camera may well work at this voltage BUT things get worse when the IR comes on.When the IR comes on the camera may now require 0.8A (800mA) to function. 400mA for the camera AND 400mA for the IR. Do ing the same calculation the voltage drop over the cable run is now current (0.8A) X resistance (3^) = 2.4V. Now the voltage at the camera is only 9.6V.

The problem with having a higher voltage power supply to compensate for the voltage drop when the IR is ON is that when the IR is OFF the voltage will be high at the camera and may cause a problem.

Hope this helps

"The cable was installed about 6 years ago" by you or by someone else. I'd ALMOST bet my bouncys that it has been joined somewhere in the run either using proper BNC fittings or (yuk) by soldering and a bit of tape. If that is the case then pull it out and replace it. Otherwise if it is short circuit it could be determined by a return resistance measurement if you know the cable type & specs. If it is open circuit it could be determined by a "time domain reflection" reading.

Sometimes when people try that trick you need to call their bluff. That is a fairly big job & if your not going to make anything from it you'd be better off staying in bed

Get your friend involved it is his sister-in-law

Can of spraypaint ??

get it replaced, it should have a warranty unless you've bought it on fleabay

Your microphone output will be in the microvolt range and as has been stated will need amplification. The DVR wil act as a pre-amplifier and give you a standard line output level of 1Vpp. This level is still pretty unuseable aecept as an input for other electronic devices. You will still need further amplification if you want to hear it. This could be via a TV/monitor/stereo etc

How hot does is get in your attic. Here in Australia it regularly gets over 110*F outside in open air. I've been in ceiling spaces in summer where the temp is reaching 140*F. Not much different to a sauna. If you have any doubts then simply check the specs of your cable.

Doesn't matter , it is more important to ensure the conductors are pure copper & not copper clad steel or aluminium.

What lens you need is governed by what picture you want. 2.8mm will give a wide field of view with little detail while a 12mm would give a narrower field of view with appreciably more detail. The difference between 2.8mm & 4mm is fairly negligable.

You get what you pay for. If you want to self monitor then you have the problems you have identified. You need to understand the basic concepts of electronic security and the various levels of risk abatement involved. Anyone relying only on cctv is their own worst enemy. It has very little deterent value given the use of hats , hoodies & dark glasses and is primarily used for evidence gathering AFTER the event. Used in conjunction with a security system which has real-time deterent value you are moving in the right direction. Then if video monitoring is employed for event affirmation you are starting to get serious about security. It all comes down to how much money you're prepared to spend and what risk you perceive to be applicable.

There is no difference between the Tx & Rx function of baluns. ALL they are is an impedance matching device

( 75^ - 100 ^ - 75^ ) , the better ones having some filtering incorporated.

If it is mounted to the back of the eve ( ie near the wall ) and is looking "out" more than "down" then you are likely to suffer from IR reflection off the eve. A very common problem experienced by the uninitiated.