Camera Power Considerations

CCTV cameras are available with various voltage requirements. These include 12VDC, 24VAC, and 115/230VAC. 115/230V models are rarely used, due to the expense of providing local high-voltage power. 24VAC models are quite common in that they can tolerate greater wire distances than their 12VDC counterparts, and are generally more immune to ground-loops. A significant portion of cameras today are wide-ranging in that they can operate on 12VDC or 24VAC.

12VDC Operation
Should the camera operate off of 12VDC only, special considerations must be taken to ensure correct operating voltage. These considerations include short wire runs, thick wire gauge, or slightly increasing the power supply voltage to achieve the correct voltage at the camera. Another consideration is that 12VDC cameras often connect the power supply return lead to the camera’s ground. The result can be that current from the power supply may flow through the shield of the video path, a recipe for ground-loops. For this reason, it is recommended that 12VDC cameras be powered from a local 12VDC supply that has a floating (not grounded) output.
Some products that allow 4-pair UTP wire to be used to deliver camera Power, Video, and if necessary, telemetry Data. Some “cable integrator” pass-through devices that allow the use of an external power supply and RJ45 connectorisation for in-house wiring. This allows for inter-operability with external low voltage power supplies, including those that deliver 12VDC. An example might be a 4 watt 12VDC camera, which is limited to a wire distance of 43ft (13 meters). This is not a particularly impressive distance, but a better solution is listed below after we discuss 24VAC operation. 

24VAC Operation
Also in the UTP range are cable integrators that have built-in individually floating 24 or 28 VAC power supplies. The 28 Volt setting allows 24VAC cameras to operate at extended distances over 4-pair UTP wire. Here, a 4 Watt 24VAC camera with a ±10% tolerance can operate up to 1,047ft (319m). 

Dual Voltage 24VAC/12VDC Operation
Many 24VAC and 12VDC cameras are specified to be powered from a source that is ±10%, which is a range of 21.6 VAC to 26.4 VAC or 10.8 VDC to 13.2VDC, respectively. To reduce the number of camera models, most camera manufacturers incorporate a switching power supply that will operate comfortably off any voltage from 10.8 to 30 volts AC or DC. These wide-ranging switchers can therefore operate off 24VAC or 28VAC at very long wire distances, allowing cameras to be powered from the head-end control room. This allows for the entire system to operate off of one UPS. Here, a 4 Watt camera can operate off a 28VAC supply but tolerate a voltage of 14 VAC, yielding 1,467 feet (447 meters). A 2.75 Watt camera can go over 2,000ft (600m).
12VDC Cameras Powered from a 24VAC Supply Should the camera not operate over this wide range, consider using Converter the camera to convert from 24VAC to 12VDC. Easily operate off a voltage as low as 12VAC, allowing it to be powered from a 24VAC or 28VAC source. When calculating distance, set the Camera Minimum Voltage parameter to 14V (half the 28VAC value is where we get maximum power transfer), and set the Camera Power parameter to be 10% higher than the camera’s published rating. The camera current should not exceed 400mA. A 4 Watt 12VDC camera can be 1,336ft (407m) away from the power supply. a 2.75 W 12VDC camera can be 1,942ft (592m).

If you are design analog based CCTV projects, consider per camera per power supply. Always power cameras from a local power source such as a small transformer / SMPS. This is a simple way to do it and will require less cable having to be run which may be fine in a small / Big installation. Do not used Multi-Camera power supply, sometimes called a PDU (power distribution unit) to provide power for the cameras.

So how do you determine the correct CCTV power supply for your security camera system?

There are two main selection criteria.

1. The number of cameras to be powered.
2. The total current draw.

You will need to get the power requirements of the camera from the spec sheet or from the camera itself. Typically the measurement you need to know is how many amps the camera will draw for AC or DC power. If you don’t know the amps you can divide the watts or VA by the voltage to find out. 

As an example a camera my show 5W at 24 VAC. How many amps is that? Based on the chart you would divide 5 by 24 for approximately 0.200 amps or 200 mA (milliamps).

If you have 4A Power Supply then see what happend as in below exp:

Example 1: You have 2 domes drawing 1 Amp each and 6 cameras, drawing 150mA each. Your total current draw is 2.9 Amps, well within the total available current of 4 Amps. This is OK.

Example 2: You have 5 domes, drawing 1 Amp each and 3 cameras, drawing 150 mA each. Your total current draw is 5.45 Amps, exceeding the total available current of 4 Amps. This in not OK. Your installation will not work.

Practically Major Camera showing Video Loss due to use of multi camera power supply (8 in 1, 4 in 1, etc) in India. Maximum Indian (Mainly Stores, Hospital, Small Office, Hotels etc) used multi camera power supply due to low price (In 2012 you can get 12V@5A Power  supply Rs. 1200/-). Where as Power Plant, Big Organization etc used 12V@1A power supply per camera (In 2012 you can get it Rs. 300.00/-) Just Imagine if you have more then 08 nos of camera.

Also Visit: http://arindamcctvaccesscontrol.blogspot.in/2012/11/voltage-amperage-guide-for-your-cctv.html

CBR vs VBR Surveillance Streaming

How you stream video has a major impact on quality and bandwidth. Typically, when people think streaming or encoding, CODECs such as H.264, MPEG-4, etc come to mind. However, regardless of the CODEC, one still needs to choose how the video stream handles changes in scene complexity. This is where streaming modes such as CBR and VBR come into play. They have a major impact on quality and bandwidth consumption. In this report, we provide a tutorial and recommendation on how to optimially choose and use streaming modes.

Visit : http://www.gobeyondsecurity.com/forum/topics/cbr-vs-vbr

CBR vs VBR

Choosing between CBR and VBR modes is typically overlooked:

• CBR stands for constant bit rate and like the term implies aims for a constant or unvarying bandwidth level
• VBR stands for variable bit rate and like that term implies allows the bit rate to vary

You need to determine whether and how much you will allow the bit rate levels to vary.

Why the Difference

What you are filming can vary dramatically in complexity:

• If you have a camera zoomed in on a white wall during the day, that is a very simple scene. For a 'good' quality level, a 720p HD / 30fps stream might need 200 Kb/s for this. 
• By contrast, if you have a camera aimed at a busy intersection, this is a very complex scene. At the same exact settings as the first scene, you might need 20x the amount of bandwidth, or 4,000 Kb/s to maintain the 'good' quality level.

The more complex the scene, the more bits (i.e., bandwidth) you need to maintain the same quality level. It does not matter how 'good' or 'advanced' your codec is, this will always be the case.

Surveillance Challenges

The main practical surveillance challenge is that scene complexity can vary significantly even on the same camera and across just a few hours. Set the camera to use too little bandwidth and the image quality will suffer. Set the camera to use too much bandwidth and you will waste significant money on storage.

IP Camera Implementation Issues

Making the choice more challenging, two common issues arise:

• Camera manufacturers have widely varying defaults - both in terms of encoding modes enabled and bit rates used. As such, two different camera's efficiency in using bandwidth can vary dramatically even if the frame rate and resolution are the same.
• Manufacturers usually do not use the terms CBR or VBR, often creating novel controls or terminology that can be confusing to understand. It is easy to make a mistake or misunderstand what their controls allow.

10 Tips for Planning Perimeter Security

With inexpensive options and the improvements in technology against false alarms, more and more dealers and systems integrators are expanding their security to the perimeter. While interior protection will always be a part of a complete intrusion detection system, perimeter security allows end users, on-site guards and remote monitoring centers to know the moment an intruder steps onto the property. Below are ten tips to remember when planning a successful perimeter security system:

Stay current with technology. Your manufacturers should provide in house training at your office for your sales and installation teams at no cost while updating you on trends, technology, and the latest equipment. Successful dealers work directly with the manufacturer's sales personnel to help design, propose, train, and even close your projects for you. Including your manufacturer in the sales process, including sales calls, will lend you instant credibility and close more sales all at no cost to you.

Assess how your client intends to use the site. Make sure that your client understands how the products you are recommending work. This will help to avoid any future problems such as the client moving things around the site and accidentally blocking AIR paths or creating dead spots in front of PIR detectors.

Become certified. Many times a manufacturer will provide certification training on higher-end perimeter detectors at no cost. This not only allows you to become familiar with the product and its applications, it gives you the opportunity to offer more options to the client.

Use the tools available to you. If the manufacturer has tools/appliances recommended to use during set-up, use them. Not only will they make sure the products are set-up/calibrated correctly, they are often a huge time saver during the installation process.

Confirm your design/site plan with the manufacturer. It's important to do this before quoting your customer. Oftentimes the manufacturer will find something you missed or ways to save you money with a different design.

Use recommended manufacturing mounting hardware and accessories. When bundled with photobeam towers, premier manufacturers will mount and assemble your perimeter detectors at no additional cost. This allows for a tremendous amount of savings on labor and opportunity cost. The cost of driving to your local hardware store and standing in line to buy simple items can be saved many times over by having the manufacturer assemble and ship your equipment directly to your job site. This also provides a professional look to your installation.

Go wireless! Eliminate the additional expense of costly labor and wiring to gain more jobs and provide a better-designed system. There are many options for reliable wireless detection for outdoor/perimeter applications.

Utilize video monitoring/verification where possible. When you're dealing with outdoor systems, legitimate activations by an animal or person can often be considered "false alarms" when there is no evidence as the police or client responds 30 minutes later. The majority of photobeam and PIR detectors can easily be set up to trigger a camera.

Strategize and plan your detection coverage. Use redundant measures for true security such as double stacking your photoelectric beams to keep intruders from “jumping over” or crawling under. Along with protecting the perimeter, use rugged outdoor high mount PIR detectors with false alarm prevention technology for spot protection – they are low cost, reliable, and provide a interior trap.

Verify your perimeter's limitations. For example, when using Photobeams as a perimeter, make sure you have enough space between the wall or fence and the detector so that an intruder cannot jump over the beam and bypass the perimeter. If using PIR devices as your perimeter, allow yourself ample room to make sure there will be no bleed-thru beyond the fence line. 

Following these simple tips can mean the difference between a problem free perimeter security system and one that will cause headaches for you and your client. With the assistance of a quality manufacturer and advancement of new technologies, there is no reason to not have a successful install.