CCTV Infrastructure

Cable quality versus CCTV image quality

Graham is the project manager for a CCTV systems integration company in Johannesburg. While trying to commission a CCTV system Graham just couldn’t get the cameras into focus. The cameras were all focused on a test monitor at the camera and they all appeared to be in-focus, yet at the recorder the cameras were all out-of-focus. The more puzzling question Graham had was, why were the Pan-Tilt-Zoom (PTZ) cameras out of focus? The PTZ cameras all had auto-focus lenses and no matter what the PTZ cameras were looking at they looked out-of-focus.

Graham was at his wits’ end. He had replaced the PTZ cameras, then he replaced the Digital Video Recorder (DVR) along with the monitor and still the camera images were out-of-focus.

Graham then decided to bench test the equipment. He removed the PTZ cameras, a few static cameras, the DVR and the monitor and plugged the systems together at his office on short fly-leads. Surprise, surprise, all the components worked and Graham had a fully operational system. The cameras, the DVR and the monitor were not at fault.

After much testing and investigating we found that Graham had two “challenges” with this installation:

1. Graham had used poor quality video baluns

2. Graham had installed poor quality cable

The solution to the above challenges was resolved by doing the following:

1. The video baluns were replaced with BFR Digital’s Video CAT products and the video image improved but was still out-of-focus.

2. It was only after the installation was re-cabled that the problem was successfully resolved.

What Graham learnt from this experience can be summed up in one sentence. Even if you use high quality equipment such as BFR Digital’s Video CAT with a leading brand camera and DVR, connecting these components with a poor quality cable will always result in a poor quality video image.

Do IP CCTV systems fail to deliver when poor quality CAT5 or CAT6 is used?

Absolutely! The digital high-speed data stream will experience signal attenuation and crosstalk just like an analogue video signal did on poor quality cable. This always results in reduced data throughput on that particular cable.

Remember, using good quality components installed correctly will produce superb video images every time.

Fibre Lite Plus

Here we have it! Fibre Lite Plus is now available. Fibre Lite Plus has been designed to transmit Video, Data, Contact Closures and Audio over multimode fibre optic cable. Fibre Lite Plus has ample power budget to achieve a cable distance of 6km.

Fibre Lite Plus transmits at 1300nm and features the same AGC functions as our popular Fibre Lite products.

32 channel Fibre Lite video receiver

Here we have it a Fibre Lite card cage populated sixteen 2 channel video receiver cards.

Fibre Lite 2 channel receiver card

Hi there,


Sorry I’ve been out of the loop the last couple of months. I’ve been busy developing a new product range with my team. This is our first product introduction this year and in true BFR tradition it's built to last.

I’m proud to introduce the Fibre Lite 2 channel video receiver card. With this unit it is possible to populate the 2U Fibre-Lite cage card with up to 32 channels of fibre optic video receivers.

This receiver has Automatic Gain Control with a range of ±6dB and normalizes the video to a standard 1Vpp level no matter if the device connected to its composite video output is terminated at 75ohm or hi-impedance.

Keep watching this space for new procucts.

Digitally Controlled AGC

AGC (automatic gain control) is nothing new and is used in a variety of equipment from CCTV cameras to fibre optic transmission equipment. When it came time to implement AGC in our Fibre Lite range of products we decided to do something really special with the AGC.

We analysed the sort comings of traditional Gain Control on analogue fibre optic equipment and found that the biggest problem was video drift. Simply put this is when the image starts losing its contrast, colour and eventually video sync (the image rolls on the screen). Video drift is caused by a number of factors like; cable aging, electronic component aging, large temperature fluctuations, additional losses on the cable due to the cable being damaged and requiring some splicing work, etc.

The Gain Control is there to compensate for all these variables but it’s normally a manual adjustment. This means that the system requires regular servicing by a qualified technician to maintain a crisp high resolution image.

We thought that in today’s world of high labour costs and the low cost digital microprocessors; why not have a microprocessor continually sampling, analysing and adjusting the gain control? This is how we come up with the idea of Digitally Controlled AGC. In our Fibre Lite range each fibre optic video receiver has its own dedicated microprocessor continually sampling, analysing and adjusting the gain control. Below is a simple diagram of how it’s done.

This is the magic behind Fibre Lite and what makes the product range adjustment free without digitally encoding the video as is the case with our Fibre Pro range.

http://www.bfrdigital.co.za/fibrelite.html

Why AM modulated analogue multimode fibre optic video transmitters are smaller than digitally encoded multimode fibre optic video transmitters?

I think the best way to explain this is with a few block diagrams and some photos. The block diagram below shows the basic design of a simple AM modulated fibre optic transmitter.



Our first fibre optic transmitter released in 2002 ran on this exact design and below I include a photo of this product’s PCB (Printed Circuit Board).

As you can see the design is so simple that the product is a mere 35mm in length.

A digitally encoded fibre optic transmitter is more complicated because all the video and data signals have to be converted into digital signals before they are processed and transmitted. The block diagram below shows the basic system design for this type of product.

As you can appreciate this is a far more complex design. The picture below is of our VTXD-030-SMM. When we designed the VTXD-030-SMM we decided to make the video transmitter and the video/data transmitter a one PCB design and only populate the component required for the particular model. It is for this reason that our video and our video/data units are the same size. This was done to simplify the product range and to decrease the cost of the product.

This product is 133mm in length, which is 98mm longer than the simple analogue design.

http://www.BFRDigital.co.za/fibre.html