Thursday, February 14, 2013

Arguments against Video Surveillance



As the use of CCTV cameras increases across the United States and globe, so does the debate over their numbers and motives. In a previous post, Arguments for Video Surveillance, we looked at four arguments for video surveillance. These arguments included peace of mind, loss prevention, crime deterrent, and crime solving.
But what about the other side of the fence? The ACLU has an entire Web site, You Are Being Watched, devoted to the “high costs of camera surveillance systems, both in terms of money and civil liberties,” and there are a large number of individuals and other groups out there that oppose “big brother” watching our every move.
So, what are some of the arguments against the use of CCTV surveillance systems?
  1. Invasion of Privacy – This is the most common argument against surveillance systems. While video surveillance is more commonly accepted in public areas, this sentiment comes into play with the use of covert and hidden cameras in almost every case.
  2. Mistrust – The use of security cameras in your home or business can make its occupants feel mistrusted. If your family members or employees are under constant surveillance, there is likely to be hostility and animosity in the air.
  3. Not Proven Effective – Studies done in California and London have found that security cameras had little to no effect on reducing the crime rate. With an increase in the sheer number of cameras in many large cities, many replacing human security guards, this is a strong argument that will be the main target of many opposing groups.
  4. Misuse and Abuse – The footage captured by CCTV cameras becomes susceptible to abuse and misuse by those who have access to it. For instance, the footage can be used to discriminate against people and for voyeurism. In the age of the internet, this is another huge deal, as can be seen by all of the “hilarious” YouTube videos out there. I doubt the subjects would find most of them as funny.
All of these reasons are valid arguments against CCTV surveillance. There are many cities and countries that have massive surveillance systems, and we will likely see a large increase in public monitoring in future, so the more the public knows about the industry and their rights, etc, the more everyone can prepare for when it happens in your little corner of the globe.
Do you have any additional arguments against the use of security camera systems? What are your thoughts? Will you fight them, or open your “public” life up willingly to being observed? Let us know – we’d love to hear from you.

Saturday, January 26, 2013

How fiber optic cabling combined with PoE converters allows long-distance IP camera placement



Power over Ethernet (PoE) technology enables powering IP surveillance cameras through the transfer of DC electrical power along with data over standard unshielded twisted pair (UTP) cabling. This cabling connects to a network device through an RJ-45 port that injects the power from power sourcing equipment such as a PoE switch or midspan PoE injector. PoE provides a flexible and convenient means of powering devices that are located in out-of-the-way locations, and saves money by eliminating the expense and difficulty of direct electrical wiring. A challenge with PoE is reaching remote locations outside the distance limitation of UTP cabling. According to the TIA/EIA 568-5-A standard for category 5e cable, the maximum length for a cable segment is 100 meters (328 ft), and PoE power injectors or midspans do not increase the distance of the data link.



So, how do you get beyond that 100-meter limit? Once answer is through fiber optics. Fiber optic cabling is an effective method to overcome the distance and bandwidth limitations of UTP, and media converters are a commonly used to integrate copper network equipment and fiber. Since DC power cannot be conducted over fiber, PoE media converters are the solution to extend network distances via fiber to remote IP cameras. A PoE media converter converts the fiber to copper, and sends DC power to the camera over the UTP cabling.

How PoE Media Converters Work
On the main article image/PoE schematic that appears at right, an Ethernet switch with RJ-45 ports resides in a control room or data closet. The copper UTP cabling is converted to fiber with a standard media converter. The fiber is run a long distance to the PoE media converter located near a convenient AC or DC power source, where it converts the fiber back to copper UTP. The PoE media converter also functions as a power-sourcing mini switch, and injects PoE (DC power) over the UTP cable. At the other end of the UTP cable is the IP camera, located up to 100 meters away from the PoE media converter.
PoE media converters are available with Gigabit Ethernet and Fast Ethernet data rates and can support PoE (15.4 watts) or PoE+ (25.5 watts). PoE media converters function like PoE mini-switches, and are available in a variety of multi-port configurations, including dual RJ-45 and dual fiber ports. They can support fixed fiber connectors or small form pluggable transceivers.
To understand those power specifications, it’s worth knowing that in 2003, the IEEE ratified the 802.3af PoE Standard. That standard provides up to 15.4 watts of power per port. Late in 2009, the IEEE ratified the 802.3at PoE Standard known as PoE+ that provides up to 25.5 watts of power for each port. PoE+ can be required to power IP cameras with Pan-Tilt-Zoom (PTZ) / Speed Dome Camera capabilities, and weather-hardened cameras used in cold environments that feature blowers and de-icers.

Leverage the Benefits of Fiber
There are several solutions available to extend the distances of PoE network links, including LAN extenders that convert Ethernet to DSL, UTP to coax converters and wireless technology. When you’re going long distance, however, fiber optic cabling provides several advantages over these technologies.
Unlike copper, fiber extends network distances up to 87 miles (140 kilometers) per link with no data deterioration over distance (signal deterioration is to be expected in copper cabling). LAN extenders can only extend network distances about 3,300 feet, but a data rate of 100 Mbps can drop by 70 percent at longer distances.
Fiber cabling provides security benefits as well. It is a secure medium that generates no electro-magnetic emission and is very difficult to tap. Fiber is also very reliable because it is not susceptible to electrical interference, or data loss due to temperature or atmospheric conditions.

Wednesday, January 23, 2013

Analysis and Comparison of 1G, 2G, 3G, 4G, 5G and 6G Telecom Services

Until the controversial spectrum scams were brought up in the lime light many were ignorant of what 1G, 2G or 3G stood for and all of a sudden a hike was found out amongst laymen so as to be knowledgeable about it. Still a number of people are unaware of 1G or 2G when the world has moved on to 4G.

The telecommunication service in World had a great leap within a last few year. . 6 billion people own a mobile phones so we are going to analyze the various generations of cellular systems as studied in the evolution of mobile communications from 1st generation to 5th generation .Now almost all the service providers as well as the customers seek for availing these 3G and 4G services.

We can analyze that this could be due to increase in the telecoms customers day by day. In the present time, there are four generations in the mobile industry. These are respectively 1G the first generation, 2G the second generation, 3G the third generation, and then the 4G the forth generation. Ericson a Swedish company is launching this high tech featured mobile into the market. It is being first introduced in the Swedish Capital city, Stockholm.

Present Status of Telecommunication Services in Asian Countries

Now we are in the midst of 4G. In China, the 3G service came into existence only by last February. Therefore, that it may take time for exposing to other states. But we should also realize many other countries such as the Asian countries were using these services since last decade. Due to these reasons, we can hope that the 4G may enter within a few years. The 3G (Third Generation) had also reached India recently. There is no doubt that within a few years India will be the first in telecom users also.

What is 2G ?

Second Generation (2G) wireless cellular mobile services was a step ahead of First Generation( 1G) services by providing the facility of short message service(SMS) unlike 1G that had its prime focus on verbal communication. A typical 2G G.S.M network service ranges from 800/900MHz or 1800/1900 spectrum. The bandwidth of 2G is 30-200 KHz.

Let us examine what these 3G & 4G have rather than that of 1G and 2G.

Analysis of 1G and 2G services

In 1G, Narrow band analogue wireless network is used, with this we can have the voice calls and can send text messages. These services are provided with circuit switching. Today’s the usual call starts from the beginning pulse to rate to the final rate. Then in case of 2G Narrow Band Wireless Digital Network is used. It brings more clarity to the conversation and both these circuit-switching model.

Both the 1G and 2G deals with voice calls and has to utilize the maximum bandwidth as well as a limited till sending messages i.e. SMS. The latest technologies such as GPRS, is not available in these generations. But the greatest disadvantage as concerned to 1G is that with this we could contact with in the premises of that particular nation, where as in case of 2G the roaming facility a semi-global facility is available.

2.5 Generation

In between 2G and 3G there is another generation called 2.5G. Firstly, this mid generation was introduced mainly for involving latest bandwidth technology with addition to the existing 2G generation. To be frank but this had not brought out any new evolution and so had not clicked to as much to that extend.

What is 3G Generation

But to overcome the limitations of 2G and 2.5G the 3G had been introduced. In this 3G Wide Brand Wireless Network is used with which the clarity increases and gives the perfection as like that of a real conversation. The data are sent through the technology called Packet Switching .Voice calls are interpreted through Circuit Switching. It is a highly sophisticated form of communication that has come up in the last decade.

In addition to verbal communication it includes data services, access to television/video, categorizing it into triple play service. 3G operates at a range of 2100MHz and has a bandwidth of 15-20MHz. High speed internet service, video chatting are the assets of 3G.

How is 2G different from 3G?


  • In comparison to 2G customers will have to pay a relatively high license fee for 3G.
  • The network construction and maintenance for 3G is much expensive than 2G.
  • From the point of view of customers, expenditure will be excessively high if they make access to various facets of 3G.

What is Packet Switching

This is actually done by supplying various addressed packets, which will be interconnected to have the conversation. It is not necessary to create a new dedicated path for sending the data. It had been modified in such a way that the data can be send through any path; hence, this data will be received at a less time as compared to that of voice calls.

Packet Switching in Computer networks

The data packs are also used in computer that is when we connected with internet this data pack helps to download the web pages that is being displayed in the monitor. For a Data Pack it does not need any separate path for downloading or displaying any objects in the computer or any other equipment. This is due to the reason that by networking, separate paths are being created and after analyzing each, the data are being transferred to the correct access point.

Main 3G Services

With the help of 3G, we can access many new services too. One such service is the GLOBAL ROAMING. Another thing to be noted in case of 3G is that Wide Band Voice Channel that is by this the world has been contracted to a little village because a person can contact with other person located in any part of the world and can even send messages too. Then the point to be noted is that 3G gives clarity of voice as well can talk with out any disturbance. Not only these but also have entertainments such as Fast Communication, Internet, Mobile T.V, Video Conferencing, Video Calls, Multi Media Messaging Service (MMS), 3D gaming, Multi-Gaming etc are also available with 3G phones.

Main 4G Features

When It is still to estimate as to how many number of people have moved on from 2G to 3G , technology has come up with the latest of its type namely 4G.A successor of 2G and 3G, 4G promises a downloading speed of 100Mbps and is yet to shower its wonders on. then with the case of Fourth Generation that is 4G in addition to that of the services of 3G some additional features such as Multi-Media Newspapers, also to watch T.V programs with the clarity as to that of an ordinary T.V. In addition, we can send Data much faster that that of the previous generations.

What is the reason for delay in implementing 3G and 4G Mobile services?

It is very sad to say that the 3G services had only reached with in some towns of china, so that it may take time to reach to Other countries. Another major defect of this is that Wide Band Frequency Spectrum, which is needed for 3G, is lacking. Another reason for this is that it a cost bearing item especially for sending data. So for us it is a higher one which could be used only by upper classes. If it should be accepted among all customers, firstly it should be availed at a lower rate, for which the rate of spectrum should be declined.

What is 5G Technology

5G Technology stands for 5th Generation Mobile technology. 5G mobile technology has changed the means to use cell phones within very high bandwidth. User never experienced ever before such a high value technology. Nowadays mobile users have much awareness of the cell phone (mobile) technology. The 5G technologies include all type of advanced features which makes 5G mobile technology most powerful and in huge demand in near future.

The gigantic array of innovative technology being built into new cell phones is stunning. 5G technology which is on hand held phone offering more power and features than at least 1000 lunar modules. A user can also hook their 5G technology cell phone with their Laptop to get broadband internet access. 5G technology including camera, MP3 recording, video player, large phone memory, dialing speed, audio player and much more you never imagine. For children rocking fun Bluetooth technology and Piconets has become in market.

What is 6G technology ?

1. Increase performance and maximize your data throughput and IOPS
2. Protect your system and secure your data
3. Ease your service and build efforts and expand your data center configuration options

The 6G technology haven't been fully revealed yet but the search phrases like what is 6g mobile technology, 6G technology, 6G mobile, 6G network, 6G wiki, 6G technology ppt are getting more familiar with new mobile technology getting evolved. The Google hot trends has rated the term 6g as the 17th most searched word in the search engines. iPod nano 6G is available in 8GB and 16GB versions and carries the price tag of $149 and $179 respectively.

Tuesday, January 22, 2013

New Security Design Guidelines for Healthcare Facilities


The International Healthcare Security & Safety Foundation (IHSS) has released the 2012 edition of the Security Design Guidelines for Healthcare Facilities. The guidelines are intended to be used by security and design professionals for renovations and new construction.

“In comparing the International Association for Healthcare Security & Safety (IAHSS) Basic Industry Guidelines with the Healthcare Facility Design Guidelines, readers should be aware that the Basic Industry Guidelines are more operationally focused and less prescriptive,” the guidelines claim. “By their nature, the Design Guidelines are more prescriptive and developed to assist security leaders, design professionals and planning staff to build security into each new construction and renovation project.

“By reasonably addressing security risks up front and early on during design, organizations can cost effectively address the safety and security of new or renovated space. These steps will help reduce the potential for security features either not being designed into new space or added on as an afterthought, or becoming 'value engineered' out as projects face limited budget dollars. The intent of integrating these guidelines early in the design process is to emphasize the importance, incorporate the work into other aspects of the project and ultimately to avoid expensive change orders, retrofits or other liabilities incurred by the omission of appropriate planning for a safe and secure environment.”

Monday, December 31, 2012

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

Thursday, December 20, 2012

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.

Wednesday, December 12, 2012

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.

Sunday, November 18, 2012

Understanding Power over Ethernet for video surveillance

PoE was, and is, supposed to make the powering of devices easy. You take your camera or other device that accepts power via the Ethernet port, you plug in the RJ45 jack to the port, and you walk away. Inside the head end, you plug the other end of the same Ethernet cable into a PoE switch or PoE injector and voila, power is magically delivered to the device along with the data connection. In theory, all of the normal worries are gone. AC power or DC power is irrelevant, and you don't even have to worry about over-powering a camera that, were you to fry it, could potentially set you back a few thousand dollars in equipment costs and man hours!
PoE was supposed to be this way, but practical reality has diverged from the perfect world concept in such a way that the actual installation is almost never that easy. So set aside the “perfect world” notions you have, and let’s start with the basics, so you can understand how PoE works.
There are four classes of PoE: Class 1, 2, 3 and 0. Each PoE classification denotes a range of power that is available to the end device as well as the power that must be available on the port of the power sourcing equipment (PSE):
PoE Classifications
  • Class 1 --  4.5 watts at PoE port; 3.84 watts at device
  • Class 2 --  7.5 watts at PoE port; 6.49 watts at device
  • Class 3 --  15.4 watts at PoE port; 12.95 watts at device
  • Class 0 --  15.4 watts at PoE port; .44 to 12.95 watts at device
In the world of PoE there are two kinds of switches that can provide PoE; the kind that operates with a “guarantee per port” and the kind that operates with a “total power budget”. Both kinds of switching are useful but there is a significant difference between them. If you happen to have a switch nearby, look at it and see if you can tell into which one of the above two categories your switch falls.
A switch that guarantees a certain wattage per port -- 15.4 watts per port, for example -- means that you can be sure that no matter how many Class 3 or Class 0 devices are plugged in, the switch will be able to power them. Of course, these switches tend to be bigger, more expensive and ill-suited for use outside of a nice climate controlled room, but they do prevent errors in power planning.
The second type of switch mentioned above -- the kind with a total power budget -- can only power as many PoE devices as it has power to spare. Imagine that you are working with a 4-port switch that carries a total power budget of 30 watts. This kind of switch could power four Class 2 cameras (4 devices x 7.5 watts = 30 watts needed). It could also easily power four Class 1 devices (4 devices x 4.5 watts = 18 watts needed). Continuing with that math, it would be able to power Class 3 or Class 0 devices, but it could only power two of those types of devices.
Power planning is where the rubber meets the road, and it brings up a challenge in our industry.
What happens if a chosen device (i.e., a PoE powered camera) does not clearly specify the PoE class and instead simply gives an operating wattage? You might think that this is OK since a camera which says “6.01 watts” is within the Class 2 specifications and therefore must be Class 2. But that’s where reality often diverges from common sense. In theory, what is supposed to happen is that a device is clearly labeled with a PoE classification so that when said device is plugged into a PSE device, the power budget has been worked out such that each device will receive its required PoE.
What I believe the security industry needs – right now, since PoE is happening today -- is clear labeling of the correct classification of PoE on each and every device that uses PoE. It is all well and good to place the operating or maximum wattage on the device, but industry manufacturers need to take the next step!
Manufacturers should label the device, print it on in large type and with bold colors, CLASS 1, CLASS 2, CLASS 3, CLASS 0, or whatever PoE Plus will hold as a classification. It's OK if your device actually only draws 3 watts during normal operation but for some reason is Class 0. Just tell your integrator channel partners and end users by labeling the device in the manner in which it was intended to be used. This lets system designers know the classification so that they might properly create a power plan and buy the correct devices. No one wants to be in the field trying to get a project done on time and only then realize that their switches don’t have enough power for the devices they’ve purchased.
While I am solidly standing on my PoE soapbox, let me also make a plea for PoE classification to be a priority on data sheets and marketing slicks. Some camera manufacturers make wonderful versions of these spec sheets. You’ll find photos, technical illustrations, cross reference charts, and more -- and often not a hint of PoE classification to be found anywhere. As someone who works with PoE, it sometimes seems as though PoE has become the crazy uncle that everyone has and who no one wants to invite to the party. Unfortunately for all of us, the crazy uncle could actually be the life of the party -- he makes it easy to entertain the guests and always has enough cash to pay for pizza -- but we haven't managed to take advantage of him yet!
PoE is supposed to make things easy, and between the standards bodies, the independent PoE offerings, the lack of classification usage, the errors in PoE chip usage within devices, and the propensity of some manufacturers to create Class 0 signatures in devices that draw minimal wattage, PoE's original purpose has been obfuscated in a way only rivaled by the current explanation of the financial bailout.

Why has it become so complex? Who knows! Unfortunately it has, and confusion has also shared a taxi with a lack of education on the road to PoE's widespread acceptance. People see a label on a device that says “802.af” or “IEEE Compliant” and then automatically assume that they can plug it into a PoE switch or midpsan and have it work with no problem. What makes the education problem worse is that often it does work with no problem, and this leads people to the assumption that PoE is really nothing more than Windows “plug and play” for power. Unlike Windows, however, there is no “blue screen of death” when using PoE. Instead there is a device that does not power on, or (in rare cases) a device that does power on followed by smoke, the smell of singed chip boards and fried capacitors, and then what was a very expensive security device becomes an equally expensive paperweight.

Thursday, November 15, 2012

Tips on Buying Surveillance Cameras on eBay



Until now in the world, eBay still remains one of the biggest auction websites. Millions of items are sold through eBay all over the world, including surveillance cameras.  
Although its network is huge and it is well managed, you are still not satisfied with the products you purchase form the website, especially if it is a video security camera system. According to the report of Metropolitan Police in UK, there are over 100 eBay related crimes every month.
Here are some tips for you when you are purchasing a surveillance camera on eBay, you can take a note if you think it is useful.

1. Know the seller. It is very important that you can vouch for the credibility or trustworthiness of the seller. Read the reviews. Ask for feedback straight from the buyers themselves.
2. Search extensively. There are thousands of surveillance cameras and sellers you can find in eBay. It is going to be purpose defeating if you are going to simply opt for one seller and one kind of camera. There are different ways on how to search comprehensively in eBay. You can read the tutorials or guides available in the website.
3. Determine how much you are willing to pay. You can search for surveillance cameras based on their price. Thus, it will be easier for you to purchase one that fits your budget. If the one you like does not, you can always practice the art of negotiating or haggling with the sellers. As long as they can confirm your authenticity and your faithfulness to the transaction, they may offer you with a good discount.
4. Read the descriptions. It is not enough that there are surveillance camera images. They should also have their corresponding descriptions, and they must be very detailed. This means that if there are minor defects, these should be listed to ensure that you know what to expect from the product.
5. Read the policies. Though eBay has its own general policies, every seller may implement their own. It is wise to read about their rules in shipping and purchasing before you proceed with the transaction. It is unfair to cry out fraud if the neglect is actually committed at your end.
Normally, sellers would accept cash or credit card payments. They would also send surveillance cameras for free if you are very close to the seller’s residence or business address.
6. Obtain a guarantee. Never purchase a surveillance camera if the seller cannot provide you with a warranty or guarantee. You have to remember that you cannot test the equipment before purchase. A guarantee will make sure that you can return the item if ever it does not work as expected.
7. Decide what you need. There are different kinds of surveillance cameras you can choose from. You can spend less time in eBay as well as prevent yourself from the sweet talks of sellers if you already have an idea of what you need. For instance, if you want to observe people inside buildings, you can opt for spy cameras.
Knowing well above these tips, you can have a great shopping experience on eBay, save time and money most of the times.