Pat

Whoa. Do you know what ExviewHAD is?? There seems to be some people saying that Exview and SuperHAD are poor quality. If so please tell me one mainstream CCTV CCD imager that is better. Most of the good day/night cameras will use ExviewCCDs. There is mention of a Sony I.T chip. Can someone tell what it is.

ILT - interline transfer is by far the most common.

FT - Frame transfer

FIT - Frame interline transfer

IT - ?? Is this a mistake

Exview is Sonys 'best' CCD. It has better sensitivity, reduced smear, improved dynamic range (not WDR) and has better spectral response in the IR wavelengths. Please tell me why it wouldn't be good for day/night cameras?

The comment Exview day images can be poor and pixelated. There is something not right here. The best CCD day or night is Exview. Please tell me of a better one.

Exview is the most expensive chip used in CCTV. No surprise it is in most high end cameras. Pelco best box camera uses which CCD?

Rikky, I do not know what the test equipment is that you are refering to but at a guess if it is used to sync cameras then it sounds like a means to set line lock. The above are right that digital equipment such as multiplexers do not require the cameras to be in sync as they use framestores to line up each video source. However there are a lot of small and large matrixes that would benefit from correctly adjusted line lock.

I can give the theory and background but not practical experience. New technology, the chipset is from a company called Pixim Inc. based in the USA. The technology is called the Digital Pixel System (DPS). It is (hopefully) one big advance for CCTV. The main advantage is the increased dynamic range. Each pixel has its own analogue to digital converter (ADC), conventional CCDs have one. DPS can read out any pixel independantly from the others. DPS reads out the pixels at 5 different exposures field. This greatly expands the dynamic range. After that it has a number of other advantages that come from it being a progressive scan imager. It isn't the be all and end all though (yet). It isn't as sensitive as a 1/2" exview. Put it in a room looking inside and out on a sunny day and nothing will hold a candle to it. It has a dynamic range well beyond any current wide dynamic camera.

There will be other manufacturers releasing cameras with this. JVC TKC-WD310, Baxall HyperD, GE and possibly two more.

Also

Milestone Xprotect www.milestonesys.com

VCS www.vcs.com

IndigoVision www.indigovision.com

These are all high end IP solutions that offer advantages (cost savings!) over conventional systems. These really come into their own on large scale instalations where the decentralised nature of IP brings savings. If you are looking to replace a small system with true IP then the cost may be prohibitive.

I would say that the DVR v NVR comparison is biased and misleading. It does not give the whole story and is very unbalanced.

Honestly I think it does more harm than good to push a solution in this way. I work with coax and IP and each has its advantages. This NVR v DVR comparison is useless at best.

Do you know the specification of your switcher. In particular for this problem there are two features to look out for a switcher

Vertical Interval Switching (VIS)

Blank Field Insertion (BFI)

Vertical interval switching should stop roll on a monitor

BFI will stop the monitor rescanning for another input.

Bear in mind that the monitor must be detecting video loss and scanning the other channels within a frame for the described problem to occur.

If the video signals in to the switcher are synchronised then the switch between cameras should be less than a frame. So BFI would most likely solve your problem but it costs. Have to tried synchronising the cameras?

In the UK try a company called SNT they have a products one called Duo link that can combine multiple video stream, power and RS485 onto one coax. You can find them in the Norbain cataloge

I kind of have one. The kind of is that at present we have a progressive scan imager but we currently take two captures per frame. However the hardware can support outputting both fields from the same image capture I just haven't enabled this yet as not many people currently have the requirement. It is PAL or NTSC (got to love progressive imagers), 1/3" colour. It is based on the DPS system from Pixim Inc. If you are interested pop a post and we can talk. Unfortunately it would not be in production with this feature until May. I could provide beta test units though.

Line lock is used to synchronise multiple cameras on an instalation. If a camera is powered of AC and set to linelock the camera is triggered off the mains (line). Most cameras with line lock also have phase adjust so you can alter the point on the mains cycle that camera triggers, this is for three phase installs. Why would you use it? If all cameras are triggered at the same point in time you stop image roll on analogue switchers. Another way to do this is Genlock but that is almost never used. FYI you get a better picture in internal sync than in line lock. Look a edges of objects in line lock and you will see more colour roll (like barbers pole) than when the camera is in internal.

This is quite handy for explaining camera functions http://www.baxall.com/pdf/guide.pdf I could be biased as I wrote most of it! It is pretty generic.

I agree with AV. A multiplexer is a digital device not an analogue one. A mux takes in multiple video feeds. It places an image from each one into a frame store, digitise and tags it and then sequentially outputs each frame to the recording media be that a tape or a standalone singe channel digi recorder.

A combined mux / dvr is the same as a mux and a digi recorder but in one box. The advantages of the combined unit over the two boxes are;

There is no D>A A>D conversion between the mux and the hard drive on an all in one unit. So no coax or S-Video (not S-VHS) cable.

You are not limited to 50 or 60 fps (video recorder) you can record at higher frame rates and so get a faster update rate on you cameras but you use more disk space as you are recording more images.

Couple of questions.

How are the cameras sync'd. Are they line-locked or running on internal? Kind of suspect this could be an LCD monitors version of image roll when switching between cameras that are out of sync.

What happens if you switch between cameras manually?