Linear vs Switch Mode Power Supply

Linear vs Switch Mode Power Supplies

The Power Guy (Electrical Engineer) focuses on modern switch-mode power supplies and converters for powering Video Surveillance Camera.

Introduction

Linear power supplies were the mainstay of power conversion until the late 1970’s when the first commercial switch-mode became available. Now apart from very low power wall mount linear power supplies used for powering consumer items like cell phones and toys, switch-mode power supplies are dominant.

What are the differences and how do they work?

Linear power supplies have a bulky steel or iron laminated transformer. It provides a safety barrier between for the high voltage AC input and the low voltage DC output (Step Down Transformer). The transformer also reduces and the AC input from typically 115V or 230VAC to a much lower voltage, perhaps around 16-30VAC. The lower voltage AC is then rectified by two or four diodes (Full Wave rectifier) and smoothed into low voltage DC by large electrolytic capacitors. That low voltage DC is then regulated into the output voltage by dropping the difference in voltage across a transistor or IC (the shunt regulator).

Switch-mode supplies are a lot more complicated. The 115V or 230VAC voltage is rectified and smoothed by diodes and capacitors resulting in a high voltage DC. That DC is then converted into a safe, low voltage, high frequency (typically switching at 200kHz to 500kHz) voltage using a much smaller ferrite transformer and FETs or transistors. That voltage is then converted into the DC output voltage of choice by another set of diodes, capacitors and inductors. Corrections to the output voltage due to load or input changes are achieved by adjusting the pulse width of the high frequency waveform.

Comparisons of both technologies

Size: - A 50W linear power supply is typically 3 x 5 x 5.5”, whereas a 50W switch-mode can be as small as 3 x 5 x 1”. That’s a size reduction of 80%.

Weight: - A 50W linear weighs 4lbs; a corresponding switcher is 0.62 or less. As the power level increases, so does the weight. I personally remember a two-man lift needed for a 1000W linear.

Input Voltage Range: - A linear has a very limited input range requiring that the transformer taps be changed between different countries. Normally on the specification you will see 100/120/220/230/240VAC. This is because when the input voltage drops more than 10%, the DC voltage to the shunt regulator drops too low & the power supply cannot deliver the required output voltage. At input voltages greater than 10%, too much voltage is delivered to the regulator resulting in over heating. If a piece of equipment is tested in the US and shipped to Europe, Asia and Mexico in some cases, the transformer “taps” have to be manually changed. Forget to set the taps? The power supply will most certainly blow the fuse, or may well be damaged.

Most switch-mode supplies can operate anywhere in the world (85 to 264VAC), from industrial areas in Japan to the outback of Australia without any adjustment. The switch-mode supply is also able to withstand small losses of AC power in the range of 10-20 milliseconds without affecting the outputs. A linear will not. No one will care if the AC goes missing for 1/100th of a second when charging your cell phone, it will take 100 of these interruptions to delay the charge by one second. However, having your computerized equipment shutdown or reboot 100 times a day will cause a great deal of heartburn.

Efficiency:

A linear power supply because of its design will normally operate at around 60% efficiency for 24V outputs, whereas a switch-mode is normally 80% or more. Efficiency is a measure of how much energy the power supply wastes. This has to be removed with fans or heat-sinks from the system.

As a quick note, in Europe, they are trying to limit those losses of all power supplies used by consumers particularly when operating in the “Off” mode (as many products are left plugged in 24 hours a day). Imagine 350 million power supplies eating up a couple watts. That equates to the output of a whole power station.

4K Resolution TV Everything You Need to Know

4K Resolution TV Everything You Need to Know

 

4K technology is quickly taking over the mainsteam of the digital video world, from TV screens to computer monitors to cameras and projectors, 4K screen resolution and all of its accompanying features are now no longer just bleeding edge technologies but becoming positively mainstream, particularly when it comes to TV displays and the video recording that creates their content.

With four times the resolution of traditional HD displays, 4K Ultra HD offers a massive improvement in picture clarity over existing HD resolutions.

The reason for this has to do with the amount of pixels a 4K TV contains. Whereas traditional HD is limited to 1920 vertical columns and 1080 horizontal rows of pixels, Ultra HD has a total resolution of 3840 pixels by 2160 – a slightly smaller resolution than the 4,096 x 2,160 resolution seen on cinema screens (that, for the record, is called Cinema 4K).

What is 4K?

Pure and simple, 4K means a clearer picture. It's more pixels (8,294,400 to be exact) on the screen at once that creates images that are crisper and capable of showing more details than standard HD.

What is the resolution of 4K?

4K resolution, at least the way most TVs define it, is 3840 x 2160 or 2160p. To put that in perspective, a full HD 1080p image is only a 1920x1080 resolution. 4K screens have about 8 million pixels, which is around four times what your current 1080p set can display.

Think of your TV like a grid, with rows and columns. A full HD 1080p image is 1080 rows high and 1920 columns wide. A 4K image approximately doubles the numbers in both directions, yielding approximately four times as many pixels total. To put it another way, you could fit every pixel from your 1080p set onto one quarter of a 4K screen.

Why is it called 4K?

Because the images are around 4,000 pixels wide. And before you ask, yes, the industry named 1080 resolution after image height, but named 4K after image width. For extra added fun, you also might hear this resolution referred to as 2160p. Welcome to the future. It's confusing here.

Do all those extra pixels matter?

They matter very much. More pixels means more information. More information means sharper pictures. Sharper pictures are more engaging. More engaging content is more fun. And fun... well fun is the thing, isn't it?

Moving 4K into Home Theater

While the origins of 4K film go back quite a ways and have their roots in theatrical releases of films such as Blade Runner: The Final Cut back in 2007, it wasn’t until James Cameron filmed his now famous “Avatar” in 4K resolution that the projection platform itself was widely introduced in many theaters eager to please audiences with beautiful crystal screen clarity.

However, going from theaters to something like home entertainment is a big leap and it wasn’t until just within the last couple of years that both projectors and the already mentioned TVs became widely available for home theater system set up that would let consumers enjoy UHD clarity in their houses.

Now, in terms of TV 4K systems, this resolution isn’t even entirely noticeable unless you enjoy a very large and thus very expensive screen or are sitting abnormally close to your TV. However, when it comes to projectors, the power offered by 4K really does become visible.

Sitting close enough?

Yup. Remember when Apple made a big fuss about "retina" displays a few iPhones back? "Retina" refers to screens that have sufficient resolution that at a normal viewing distance your eye can't make out individual pixels. Get far enough away from a 1080p set and, hey presto, It's a retina display! More importantly, at that same distance, your eyeballs won't be able to squeeze any more detail out of a 4K image than a 1080 one. If you're at "retina distance" from your 1080p set now and don't plan on moving your couch closer, upgrading to 4K may not make a big difference to your experience.

So I should sit closer?

Oh my yes. The ability to get up close to the screen without the image breaking down is one of the most intoxicating things about 4K. Sitting closer allows the same sized screen to fill more of your visual field, which yields greater immersion. The up-close factor is one of the reasons 4K computer monitors have become one of the technology's fastest growing sectors. 4K monitors remain pin-sharp even when you're just a foot or two from the screen, as you are when you're sitting at your desk. 

Streaming 4K Content

While 4K content for home theater systems such as projectors and TVs is still pretty scarce on the ground, it is making ground as streaming content. YouTube has had a 4K channel running since as early as 2010 and other developments are definitely on the horizon, especially in countries or regions with excellent internet connectivity that goes above the normal speeds available to most people.

The broadcast industry as a whole is offering the promise of a steadily more established standard in streaming content compression during transmission, called H.265 or HVEC (High Efficiency Video Codec). With the implementation of HVEC, broadcasters are assuring the buying public that 4K content will become easy and economical to stream into home theater systems and thus will become much more common. TV manufacturers themselves have been keeping up to date with this promise and have ensured that every new 4K TV to be released since 2015 and today, as well as for the foreseeable future, is fully capable of decoding the HVEC standard for its users.

Furthermore, other competing standards of 4K video compression are being developed, though with less ecosystem traction. One that has gained some headway is Google’s VP9 4K video compression codec, which the company still uses in compressing the 4K content streams found on its YouTube video service. Most premium 4K TVs today are compatible with both VP9 and H.265, though not all models offer both.

Specific 4K display-related technologies

Moving along into some particular features of current 4K display features in TVs and other devices, we come to a few very particular specs and technologies which are redefining the quality of both the TV display viewing experience and how rich the consumer content experience can become. In particular, high dynamic range and wide color gamut are playing a crucial role in making 4K TVs into displays of previously unparalleled richness and quality.

High Dynamic Range

High dynamic range technology is the Big New Thing in the world of 4K TV displays and with good reason. What HDR essentially does is expand the range of both bright and dark levels a 4K TV can show on the screen. At the same time, highlights of color vibrancy and richness are also expanded by this same wider dynamic range. The result is a more realistic, much more sharply detailed picture quality in comparison to what you’d see with standard dynamic range (SDR).

Of particular interest to TV makers (and consumers once they get to experience the realism produced) is the ability to develop HDR that can come as close as possible to simulating the brightness and darkness of the real world. Thus, while we already have 4K TVs that can create essentially “perfect” darkness with no notable light emission, in the form of OLED technology, the brightest consumer HDR 4K televisions, even for 2016, can only manage something between 1000 and 2000 nits of brightness, when in the real world, even the sky on a sunny day is seen by our eyes at about 20,000 nits. Thus you can see the dramatic difference at work here.

However, the aim of 4K TV makers and the companies behind HDR technology is to create displays which can even reach 10,000 nits. This is what one HDR standard bearer called Doby Vision is aiming for. Current HDR standards like “UHD Premium” from the UHD Alliance call for at least 1100 nits of maximum brightness in LCD 4K TVs but more on that shortly.

Wide Color Gamut

Another crucial aspect of modern 4K TV content is color gamut technology, or the ability to deliver the largest possible range of rich colors for the greatest possible realism and vibrancy. Currently, many 4K TVs are thus starting to offer color ranges that conform two two particularly broad gamuts called DCI P3 (which is frequently used in commercial cinematic display) and REC.2020, which is the current “Wide Color Gamut” gold standard for 4K ultra HD. However, not all 4K content fits these higher quality standards and much of the video and 4K TV display technology still on sale is REC.709, which was developed for older HDTV display technology.

Devices, such as 4K HDR TVs

• ·       Display resolution: minimum of 3840 x 2160 pixels
• ·       Color bit depth: 10-bit signal
• ·       Color Palette: (Wide Color Gamut)
• ·       Signal Input: BT.2020 color representation
• ·       Display Reproduction: More than 93% of the DCI P3 color spectrum
• ·       High Dynamic Range
• ·       SMPTE ST2084 EOTF
• ·       Both Peak Brightness and deep black levels of either more than 1000 nits and less than 0.05 nits of black, OR more than 540 nits of peak brightness and less than 0.0005 nits of black level. (This dual contrast standard is likely a direct sop to LG’s OLED technology, which can’t match the high nit levels of LCD/LED displays but can completely outmatch them in terms of how dark their blacks go, thus re-bracketing the range which constitutes HDR and deep contrast.

 My friend told me about 4K OLED. What's that?

More acronyms! Isn't this fun? OLED - organic light emitting diodes - have been around for some time, but producing big screens using this technology has proven to be prohibitively expensive, something which has so far prevented OLED television from being a mainstream proposition.

It's a real shame because OLED technology can be stunning, offering vibrant colors, deep blacks and bright whites. But don't give up hope just yet. Several companies (most prominently LG) are laboring away to bring OLED to 4K televisions. We recently took a look at LG's new 4K OLED sets, but while they're gorgeous, pricing remains sky high. Hopefully that will change soon, though. "I believe the price and yield rate will be higher immediately and the price will be down," Mr K I Kwon, president of LG Electronics UK, told recently. We hope his predictions hold and we aren't ruling out OLED as a big player in the next generation of televisions.

What about 4K content? Can I get that?

Yeah, about that... There's actually not much 4K broadcast content to be had right now. That said, if you're willing to shell out for it – e.g. buy a 4K UHD Blu-ray player and several 4K Blu-ray discs or purchase digital UHD movies outright from services like Sony's Ultra Streaming Service or UltraFlix – there are plenty of other options out there.

Why isn't broadcast TV in 4K?

Because every 4K frame contains four times the information of HD, 4K content is four times more bulky than regular HD content in terms of its raw file size. That makes it a challenge to get it to you. Broadcast TV hasn't made the 4K switch yet (indeed, it's only recently that hard drive sizes have gotten big enough to manage DVRing HD programs comfortably).

But you can get 4K Blu-ray discs should you decide to buy a Ultra-HD Blu-ray player.

What about gaming in 4K?

We've had 4K gaming on the PC for a while now, but this year at E3 2016 4K took off in a big way with the announcement of Microsoft's 4K Xbox code-named Project Scorpio. Alongside the Scorpio, Microsoft also has the Xbox One S which will upscale HD content to 4K as well as play Ultra HD Blu-ray discs.

Microsoft isn't the only console manufacturer with a 3840 x 2160 resolution on its mind, however. Sony just announced a 4K console of its own called the PS4 Pro that not only plays 4K Ultra HD movies and TV shows from streaming services like Netflix, but can play games in 4K, too.

What kind of cables will I need for 4K?

The two standard cables you're most likely to use are either a standard HDMI or if you're connecting a PC to a Ultra HD monitor, Display Port.

HDMI cables now come in four flavors: high speed with ethernet; high speed without ethernet; standard speed with ethernet and standard speed without Ethernet. Standard speed cables are capable of 1080i, but aren't able to handle the bandwidth of 4K. High speed cables can do anything higher than 1080. Now, as long as you're using the same class of cable, there is no distinguishable difference in terms of performance between one manufacturer's set of cables and another's.

The speed of your connection will depend on the types of connectors, which includes HDMI 1.4, HDMI 2.0 and HDMI 2.0a. HDMI 1.4 connectors support a 3820x2160-resolution at 30 frames per second, while HDMI 2.0 is the latest spec and can output video at Ultra HD resolution at 60 frames per second. (But more on that below!) HDMI 2.0a is capable of HDR, which is limited to a very specific range of televisions from each manufacturer.

The other type of cable you can use is DisplayPort. DisplayPort carries 4K image and audio signal from most high-end graphics cards to monitors without any noticeable artifacts or delays.

So should I buy a 4K set now or should I wait?

It depends. If you want the absolute best TV you can get right now and don't mind paying a premium for it, it's a 4K set. If you're buying from one of the top tier manufacturers, you're going to get a good product that's reasonably future-proofed. As we said before, the sets look great. However, don't expect to be watching most of your video content in 4K for another two to three years. And make sure any set you buy has HDMI 2.0 ports (the first wave of 4K TVs used the previous HDMI 1.4 standard).

On the other hand, if you're price sensitive or want to wait until the content side of the equation is a bit more solved, it absolutely makes sense to wait. The UHD Premium specification is still in its infancy, and although we're moderately sure and it remains to be seen if the entire industry will eventually adopt it.

In terms of content you're not missing out on much at the moment. There are incredible values to be found in generously-sized 1080p sets right now. And 4K sets are only going to get cheaper.

What’s the Bottom Line, Is 4K Here to Stay?

This certainly looks to be the case. Current 4K UHD trends are developing at a much faster and steadily more affordable pace than what we’re seeing with plasma TV and the still incredibly expensive OLED display technology. In fact, plasma TVs, which for a time were thought to be the next wave in Ultra HD TV display technology are failing completely so far. With Their main manufacturer having ceased production this year.

This means that 4K is almost certainly going to have its large space on the TV market as new UHD content emerges, and the technology is already well established as the latest and possibly best in cameras and film projectors.

Yes, major manufacturers are already working on experimental development projects in the even more powerful 8K resolution technology but many of the problems that already exist with displaying and streaming 4K will need to be worked out even further before 8K ever becomes a commercial product. So for now, it seems that 4K is here to stay at least for the next few years and getting ready for it is a great idea now that prices for TVs, cameras and even projectors are dropping.

Pros

1) The 4K TV is gorgeous because of its resolution 3840×2160 which gives perfect image clarity. The pictures are more detailed with sharpness.

2) The image depth is so nice that it overcomes the problem of some people who feels that the image is getting flattened. Every image is clearly seen in this 4K TV.

3) 4K TV can handle the perfect color of an image. Even if the picture is heavily compressed the color won’t change. Color resolution plays good in 4K TV.

4) 4K TV will make the view of 3D better because of its bigger screen resolution. You may feel real 3D image with this TV.

Cons

1) You may only feel 4K presence if the screen you choose is big.

2) 4K TV is more expensive and we need to buy some extra devices based on the purpose.

3) 4K TV sources are still short due to the broadband and Blu-ray disc connectivity  problems.

Visit: http://arindamcctvaccesscontrol.blogspot.de/2015/07/difference-between-1080p-and-2160p.html
https://arindamcctvaccesscontrol.blogspot.de/2015/01/720p-and-1080p-explained.html?m=0
https://arindamcctvaccesscontrol.blogspot.in/2014/12/to-4k-or-not-4k-video-or-ultra-hd.html?m=0

Guide to High Security SpeedGate

A guide to High Security SpeedGate/Flap Barrier 

As per Form No. 209 Issue 1.1

1. Introduction

A turnstile or entrance control system is designed to deter or completely stop unauthorised entrants, whilst enforcing the use of an access control system to ensure the ‘one token one person’ rule applies. Security levels vary depending on style and type of the products.

2. Scope

This guide provides details of the different style and type of turnstile systems, along with an indication of installation, interconnectivity and interoperability of available systems. Comparisons between styles and types are included to help in the specification of the correct product.

3. Terms and Abbreviations

Anti-pass back: Where the turnstile provides a return signal to the Access Control System to signal that user A has entered or exited the building. If user A then passes his proximity card to user B the access control system will know that this entry is potentially fraudulent and prevent access/egress.

Anti-piggybacking: Where methods have been put in place to avoid unauthorised people gaining access to a secured area by passing through in collusion with another person who does have authorisation.

Anti-tailgating: Where measures have been taken to avoid an unauthorised person following another through a secured entrance way, therefore achieving access without the authorised person’s knowledge or consent.

Biometric Control: The use of biological features i.e. Fingerprints, eyes, voice etc to ensure that the user is carrying their access control card and that fraudulent entry is not being gained by a 3rd party.

Breakaway force: The level of force, required by the turnstile user, to collapse the turnstile barrier or barriers to allow emergency escape.

DDA Compliance: Indicates whether a particular product is capable of allowing use by a disabled person. Previously this related to The Disability Discrimination Act, 1995. The applicable Act (except in Northern Ireland) is now The Equality Act 2010. For further information refer to BSIA Form 173, An Access Control Guide to Disability Discrimination.

DDA Disability Discrimination Act (see DDA Compliance)

Egress: The exit of a user from a building through a turnstile.

Fail safe: The turnstile will collapse or release all locking to allow non-secure egress during an emergency situation. Used in the majority of situations as part of a cohesive fire strategy.

Fail secure: During an emergency situation the turnstile will ensure that any user is not `trapped’ within the unit before locking to ensure that security is maintained in all situations.

Ingress: The entry of a user into a building through a turnstile.

Optical turnstiles: Turnstiles that monitor the number of transactions, and detect unauthorized entry and signal this through an alarm of some form rather than a physical barrier.

Return signal: A signal or pulse from a turnstile to signify that a user has activated/used/or carried out an unauthorised passage through the units.

Volumetric security: A security measure (normally used to prevent piggy-backing) where the physical volume of the turnstiles user is measured rather than purely the weight.

Weight sensing: A method of preventing piggy-backing by the turnstile weighing the occupant(s) of the turnstile during operation. If the weight exceeds the permissible weight of user, access will be denied.

4. Types

5. Security levels

The majority of waist height turnstiles are reliant on the user responsibility to prevent collusion between users enabling unauthorised ingress/egress.

Key:

1 Indicates whether a product of this type is typically DDA compliant. Products vary and compliance can be dependent on other circumstances 

2 Level of physical security in comparison with other types

3 Speed measured in persons per minute

4 Level of emergency access for this type of product 

5 DDA access possible depending on diameter

6. Typical Locations & Example Use

7. Systems Integration

Security turnstiles can be integrated with the following peripherals, with many physically integrated within the body of the units:

• Card readers; proximity and swipe, smart cards etc.

• Key pads

• Biometric systems

• Cameras

• Lift destination control

• Card collection systems

• People counters

• Coin/token collection

• Building Management systems

• Fire/intruder

• Asset protection

• Metal/explosive detection

• TCP/IP Ethernet networks

Care must be taken to ensure the access control reader choice is compatible with the usage and speed of the chosen turnstile. Proximity readers will provide higher flow of traffic, whilst bio-metric readers may be deemed inappropriate for an optical type turnstile.

8. Interconnection

Most turnstile manufacturers are fully compatible with the majority of access control systems in the market today, purely requiring a two door controller to control ingress and egress through the units.

Two separate inputs are required, per barrier, to operate the unit in each direction, in the majority of cases being a normally open, going closed connection.

Other inputs may include visitor access and override + modes and operation controls. The majority of units provide a fire alarm input to allow emergency egress, either allowing break-out or providing unhindered egress if required.

Outputs will give passage confirmation in each direction for accurate occupancy counting and appropriate use of the chosen security method. Alarm state outputs are provided, either remotely or within the unit, to indicate a security breach or misuse.

All newer products are capable of direct connection, control and monitoring over existing Ethernet networks ensuring full compatibility with IP Access Control, CCTV and Building Management Systems with no need for further connection.

9. Installation Requirements

Units will require a structurally sound, level surface to allow their installation and to ensure reliable operation, but specialist fixings can be used to allow installation on raised access floor and soft screed finishes.

All units will require a number of input and outputs which are facilitated by conduits located within the floor, the design of which should always be referred to the manufacturer for details.

In existing locations, where the user does not wish to damage the existing floor, the majority of turnstile types can be installed on raised plinths which allow the units to be easily removed, and does not necessitate the adaptation of floor finishes.

Full height units can be cabled from above which make the installation easier with less disruption being required to the floor.

10. Configuration

As a rough guide when calculating the number of turnstiles required the following formula (based upon 15% of the building population entering/exiting the building in a five minute period) can be used. However, it is highly recommend that all users consult with a reputable turnstile manufacturer for an accurate recommendation.

Total Installation Capacity (per Minute) = (Building Population x 15%) / 5

Standard Width Lanes: 500 – 660mm

This dimension is critical to ensure that two users cannot enter through the turnstiles `side by side’ thereby gaining unauthorised access.

Wheelchair Accessible Lanes: 900 – 940mm

Allows passage for wheelchair users and those with other impairments or who are in need of assistance.

Side Pass Gate:

Consideration may be given to the provision of alternative, supervised access for visitors, couriers and those with large luggage or parcels.

Barriers:

Most turnstile manufacturers will provide a variety of turnstile designs to suit the individual clients’ requirements, and to provide an aesthetically seamless appearance.

Standard configurations

11. Environmental Benefits

In conjunction with an access control system and connection to buliding management system turnstiles can facilitate savings on energy loss by detecting when certain building areas are unoccupied.

Most products use steel, stainless steel and glass along with recyclable plastics so can be recycled at end of life.

  

12. Insurance requirements

Many installations will benefit from high security turnstile systems in reducing premiums against loss or damages.

13. Service and Maintenance

It is recommended that a minimum of 1-2 preventative maintenance visits per annum are carried out on all turnstiles but in areas of high traffic flow or abuse additional maintenance visits may be appropriate.

14. Standards & legislations

For European Countries all products should comply with the requirements of the appropriate European Directives and be marked with a CE mark.

For America UL 325/3295 apply.

  

15. Summary

Security management plays an increasingly important role in today’s society, and ensuring you offer your customer the perfect access control solutions to meet their security needs is vital.

With the extensive range of security turnstiles available in the market today, each designed to suit different levels of security, you are sure to find the perfect solution that fits your requirements.

Seeking professional advice from a BSIA registered turnstile manufacturer prior to specifying a turnstile system is highly advised. Not only will they will be able to advise you on the best type of product suited to your required level of security, they can also provide recommendations on installation and access control integration.

Access control provides the ability to control, monitor and restrict the movement of people, assets or vehicles in, out and around a building or site. Products range from token based systems and digital keypads, through to biometric identification systems and the associated hardware.

Access control products are subject to fast-moving technological development. A major focus of the is to raise awareness amongst end-users and specifiers of the different types of equipment that is available and the most appropriate environments for using them.

Artical published on  Safe Secure Magazine - Dec 2017 issue.