What is Dual-Band Wi-Fi?
To provide the highest possible speed wireless connectivity for the widest range of devices, both new and old, Wi-Fi routers and Access Points often transmit and receive radio signals on two separate frequency bands. This capability, which can now be found in most advanced Wi-Fi equipment, is known as dual-band Wi-Fi. The frequencies of these bands are 2.4 and 5 GHz respectively.
If your Wi-Fi access devices and your Wi-Fi access points (or wireless routers) both support dual-band Wi-Fi, but the latter are not equipped with Client Steering technology, you may still be able to improve the performance and reliability of your wireless network by manually selecting the band chosen by each of your access devices. For short distances with relatively few physical obstructions to the signal path (such as walls or ceilings), then the 5GHz band, since it allows for multiple channels to be bonded together, provides a faster connection and thereby offers more bandwidth to the user. The 5GHz band also has the advantage of being less susceptible to interference from non-Wi-Fi devices such as wireless phones, cameras, or microwave ovens – most of which operate across the 2.4GHz band. At longer distances however, especially where the signal must traverse multiple obstructions, and where interference from other devices is at a minimum, then the 2.4GHz band may ultimately offer a more reliable connection. In such cases, the easiest way to force connection at one band or another is to set the access points' SSIDs to separate identifiers for each band and to then configure each client device’s WLAN preferences to first attempt connection to the preferred band.802.11ac vs 802.11n? Which Wi-Fi technology should I use?
With its higher capacity and speed (currently up to 1.75Gbps), 802.11ac is generally recommended for any new deployment where usage is typical of today’s modern multi-media web applications. Even in cases where lower speed is adequate for the time being, the current exploding demand for Wi-Fi bandwidth will almost certainly necessitate an upgrade in the not too distant future.However, faster Wi-Fi does not always translate to faster performance for users of the network. For example, if the applications and data being accessed are located at the other end of a 500Mbps pipe, then there is no benefit in connecting to that pipe at a rate any faster than 500Mbps. Similarly, if none of the critical applications require more than 2 or 3 Mbps, and the number of concurrent connections is less than 100, again there would be no discernable speed advantage to deploying 802.11ac. What is Client Steering? Band Steering?
To maximize throughput and performance for the maximum number of wireless devices, without having to resort to manual band selection (see 802.11ac vs 802.11n? Which Wi-Fi technology should I use?), the more advanced dual-band Wi-Fi routers and Access Points are able to intelligently allocate bands based upon the capabilities of each client and its apparent signal strength. This capability is known as client steering.What is beamforming?
Beamforming is a technology common to all 802.11ac access points which focuses radio coverage in the direction of their connected devices. Traditionally, Wi-Fi access points radiate their Wi-Fi signals in just one pre-defined pattern. Typically, this pattern is more or less spherical (or hemispherical for ceiling-mounted units), providing roughly equivalent signal strength in all directions. This works fairly well in situations where the access point can be located in the middle of a large unobstructed area with relatively few sources of competing interference. However, in most real-world situations, such a static beam pattern is inefficient and leads to inconsistent performance and connectivity across the full distribution of access devices. By using a phased array of multiple antennas and varying the signal phase of each so that amplitudes combine at the precise locations of connected devices, signal strength is increased for those devices, with a resulting improvement in connectivity and throughput. This capability is known as beamforming.How much signal attenuation (loss) should I expect from walls and floors?
Signal attenuation will vary according to the material, thickness and construction of any barrier, as well as the band being used (2.4GHz or 5GHz), but the following provides a rough guide:
- Dry wall: 2 – 4 dB
- Brick wall: 6 – 10 dB
- Glass partition: 8 – 12 dB
- Cubicle wall (fabric): 18 – 30 dB
- Concrete wall: 18 – 30 dB
- Floor: 30 – 40 dB
Will a wireless network allow us to install less network cabling in a building?
Generally, no; We feel that it may be short-sighted not to install the minimum recommended amount of copper data wiring into every room in the building.How does wireless work?
Basically, it's a radio signal between a transmitter and a receiver, which provides users access to the Internet and network resources. The Wireless LAN Card replaces the Ethernet cable, so you do not need to be plugged into a network socket. For wireless cards to work, users must be within the range of a Wireless Access Point. One of the main advantages of the wireless network is that it provides mobility, allowing movement around the campus while still connected to the network. Students can study together in groups where access to the network is usually unavailable. You will be able to carry out research, study, access the internet, check your mail & obtain your files using your own Laptop, PDA or Tablet anytime, anywhere.What is a Wireless site survey?
A wireless site survey, sometimes called an RF site survey or wireless survey, is the process of planning and designing a wireless network, to provide a wireless solution that will deliver the required wireless coverage, data rates, network capacity, roaming capability and Quality of Service (QoS). The survey usually involves a site visit to test for RF interference, and to identify optimum installation locations for access points. This requires analysis of building floor plans, inspection of the facility, and use of site survey tools. Interviews with IT management and the end users of the wireless network are also important to determine the design parameters for the wireless network.
As part of the wireless site survey, the effective range boundary is set, which defines the area over which signal levels needed support the intended application. This involves determining the minimum signal to noise ratio (SNR) needed to support performance requirements.Wireless site survey can also mean the walk-testing, auditing, analysis or diagnosis of an existing wireless network, particularly one which is not providing the level of service required. What are the types of wireless site surveys?
There are three main types of wireless site surveys: passive, active, and predictive.
During a passive survey, a site survey application passively listens to WLAN traffic to detect active access points, measure signal strength and noise level. However, the wireless adapter being used for a survey is not associated to any WLANs. For system design purposes, one or more temporary access points are deployed to identify and qualify access point locations. This used to be the most common method of pre-deployment wifi survey.
During an active survey, the wireless adapter is associated with one or several access points to measure round-trip time, throughput rates, packet loss, and retransmissions. Active surveys are used to troubleshoot wifi networks or to verify performance post-deployment.
During a predictive survey, a model of the RF environment is created using simulation tools. It is essential that the correct information on the environment is entered into the RF modellinging tool, including location and RF characteristics of barriers like walls or large objects. Therefore, temporary access points or signal sources can be used to gather information on propagation in the environment. Virtual access points are then placed on the floor plan to estimate expected coverage and adjust their number and location. The value of a predictive survey as a design tool versus a passive survey done with only a few access point is that modelleded interference can be taken into account in the design.Additionally, some survey applications allow the user to collect RF spectrum data using portable hardware spectrum analysers, which is beneficial in case of high RF interference from non-802.11 sources, such as microwave ovens or cordless phones. .
What is a PTZ camera?
PTZ stands for Pan, Tilt, Zoom. A PTZ camera can be remotely controlled allowing it to move up and down as well as zoom in on potentially important targets. You can also program a tour between pre-set points. In theory PTZ cameras sound great, they can cover large areas and even zoom in when more detail is required.
There are 2 frequencies in use, 2.4GHz and 5.8GHz. In theory 5.8 GHz wireless transmission is supposed to suffer less interference than 2.4 GHz but that is changing as more and more devices switch to the higher frequency. The higher frequency also tends to be blocked more readily by solid objects such as walls. Whether you choose 2.4 or 5.8 GHz there is one thing which is unavoidable, the power limit imposed on unlicensed wireless devices in the UK. Keep this in mind if you ever watch a demonstration of wireless CCTV technology, was it made in the UK using unlicensed equipment or overseas where no such limitations exist?What is a NVR?
A network video recorder (NVR) is a software program that records video in a digital format to a disk drive, USB flash drive, SD memory card or other mass storage device. An NVR contains no dedicated video capture hardware. However, the software is typically run on a dedicated device, usually with an embedded operating system. Alternatively, to help support increased functionality and serviceability, standard operating systems are used with standard processors and video management software. An NVR is typically deployed in an IP video surveillance system.
Network video recorders are distinct from digital video recorders (DVR) as their input is from a network rather than a direct connection to a video capture card or tuner. Additional processing may be done at the NVR, such as further compression or tagging with meta data.How does motion detection work? Through the camera or software?
Motion detection works through the software in the NVR system by recording video when pixels in the image change. Most Security NVR’s offer a sensitivity scale so the user can set the sensitivity of the motion detection.What's the difference between Hardware Compression and Software Compression?
Hardware Compression: Both Capturing Video Signal and Compressing Video Signal are done by DSP chipset integrated on NVR Board. It doesn't need the computer's CPU to do this work. It's low cost of CPU and RAM resources. In this system the computer CPU's task focus on answering network request, streaming the video/audio to network and saving recorded data to local hard disk.
Software Compression: The NVR Board only capture video signal but doesn't compress it, it is the computer CPU and RAM to do this compression work. It's high cost of CPU and RAM resources. In this system the computer CPU and RAM are often overloaded. It is easier to crash than hardware compression system.Why do I have a clear sharp picture during the day and it is out of focus at night?
This is due to the depth of field changing as the light conditions change and can be easily overcome by following set procedures.Does the 'f' stop matter when choosing a lens?
Yes, lenses are usually specified as having a minimum and maximum 'f' stop rating; the 'f' stop is a measure of how efficiently the lens allows light from the scene, to pass through the lens and onto the camera CCD sensor. The maximum aperture (when the lens is fully open), is the minimum 'f' stop number and the minimum aperture, (just before the lens completely closes) is the maximum 'f' stop number.ONVIF
Open Network Video Interface Forum is a global and open industry forum with the goal of facilitating the development and use of a global open standard for the interface of physical IP-based security products – or, in other words, to create a standard for how IP products within video surveillance and other physical security areas can communicate with each other. ONVIF is an organization started in 2008 by Axis Communications, Bosch Security Systems and Sony.
It was officially incorporated as a non-profit Delaware corporation on November 25, 2008. ONVIF membership is open to manufacturers, software developers, consultants, system integrators, end users and other interest groups that wish to participate in the activities of ONVIF. The ONVIF specification aims to achieve interoperability between network video products regardless of manufacturer.What camera housing should I use and at what IP Rating?
Camera housings come in various shapes and sizes. With regard to the correct IP rating protection, this will range from dust and water ingress. This system is governed by a number of European and British standards.IP55
Protected against dust - limited ingress. Protection against low-pressure jets of water.IP65
Protection against low pressure jets of water from all directions - limited ingress permittedWhat is a ground loop?
An AC current that can be produced in a cable. This is usually caused by parts of the system being fed from different electrical sources resulting in different earth potentials at each end. The result is interference on the signal, usually in the form of dark bands across the monitor and on occasion tearing in the top third of the image.How can I eliminate ground loop faults?
This can be achieved in a number of ways, the easiest of which is the installation of a Ground Loop Isolation Transformer. This is best installed at the monitor or recording end of the system.
What is access control?
Directing who is admitted into your building or office, which areas they are allowed in and at what times defines the process of access control.
Managed access control allows the user to keep their focus on their work, not their doors and alarms.
Basic access control systems can be purchased and installed by a vendor, or self-installed, but are not supported by a service staff. With managed access control, a company assists you in running everything access control related at your property.
A managed access control provider walks you through each step of the process and continues to work with you throughout the life of your system. In addition to the installation and maintenance of your system, managed access control provides programming assistance (activating and de-activating credentials, changing permission levels, hours, etc.) and monitors your doors and office space.What are key fobs?
Key fobs are small, plastic devices individually programmed with your access privileges. It has a small hole to fit on a key ring. Treat your key fob like you would a regular key—because it is a kind of key!Will my key fob be okay going through airport security?
Yes, your key fob can go through security and it won’t get deprogrammed. Do keep it with your other keys and personal items in the basket when you go through screening.How many people can i control?
From one person to thousands of people. There is no limit, in terms of technology, to how many people, or how many doors you want to control.Who can access the secure information?
Anyone who has access to your network with the correct level of authority.PC Controlled Access Control Systems
There are many manufacturers of these systems, and a wide variety of ‘bolt on’ options. It’s critical to choose the right system or ‘platform’ as you will be stuck with it in the future. Once you have made the investment in the software, training, badge technology and hardware, it’s prohibitive, in terms of cost to switch to another manufacturer.
The principle of these systems is that from a central location, you can truly control who goes in or out of any door, anywhere on the system, during what hours. There are a variety of alerts that can be enabled, such as if a door has been held open, or forced open, or if the emergency break glass has been broken.
Typically, there is a reading device at each door, which accepts swipe cards, or more typically is a proximity reader. This device can ‘read’ the information on a badge or fob from 2 or 3 inches. There are other readers with a longer read range, that help people comply with the Disability Discrimination Act.What are the limitations of Access Control?
It is often wrongly considered that Door Access Control will always provide full secure control of who is restricted and who is granted access through doors. A door can be held open for someone or it is sometimes impractical to control a very busy door that sees a lot of pedestrian traffic. Only the use of pedestrian turnstiles and barriers can physically limit the number of individuals who pass through at one time and can allow provision for accurate control/monitoring. Depending upon what is trying to be achieved, an Access Control system needs to be planned and given consideration.I only want to control some of my doors? What are my options?
You have a variety of options. Firstly, you must decide how many doors you want to control initially, and how many you are likely to want to control in the future. You need to decide if you want to link a variety of sites together, so that a person can be given access rights to a variety of doors in a variety of properties - the ‘One Badge’ principle.
What is Structured Cabling?
Structured cabling system or structured wiring refers to all the cabling and components installed in a logical and organized way. It's designed to be relatively independent of the type of equipment that uses it.
Structured cabling is the design and installation of a cabling systems that will support multiple hardware uses systems and be suitable for today’s needs and those of the future. With a correctly installed system your requirements of today and of tomorrow will be catered for and whatever hardware you choose to add will be supported.Can I use CAT 5 Cable in Power over Ethernet applications?
Cat5e and Cat6 can both effectively run POE applications up to 90m. However due to power dissipation there is better performance and power efficiently with Cat6a cabling running POE devices if being incorporated into a new design.What is a patch cable?
A patch cable is used at the cabinet end for linking the dedicated cabling port to the required equipment in the communications cabinet. For example, an outlet could be “patched” from the panel to a Data Switch, Telephone Switch, CCTV Switch, WIFI Switch Etc. The difference to standard cable is Patch cable is stranded for flexibility, whereas standard cable is solid copper.Fibre optic cabling – when is it better to use Fibre?
Fibre cable carries greater Bandwidth and over longer distances. It is not limited by the 90/100m limit of copper cable and has distance potential of 40km in some cases. It also isn’t affected by noise or outside influences as are copper cables so is a perfect solution when linking cabinets through risers in a building. As a standard guide when linking separate cabinet’s fibre optic links should be used.Should CAT 6 replace CAT 5e?
Industry predictions indicate that 80 to 90 percent of all new installations will be cabled with category 6. The fact that category 6 link and channel requirements are backward compatible to category 5e makes it very easy for customers to choose category 6 and supersede category 5e in their networks. Applications that worked over category 5e will work over category 6. Cat6A and above are also taking over specifications for new installations, especially in data centres and Audio Visual Installations.Cat5/Cat6 what’s the difference?
The general difference between Cat5e cabling and Cat6 cabling is in the transmission performance, and extension of the available bandwidth from 100 MHz for category 5e to 250 MHz for category 6. This includes better insertion loss, near end crosstalk (NEXT), return loss, and equal level far end crosstalk (ELFEXT). These improvements provide a higher signal to noise ratio, allowing higher reliability for current applications and higher data rates for future applications.Do you repair fibre cables?
Yes we can fault find to within 1.8 metres with our ODTR test equipment and repair your cable onsite with the Fusion Splicer.What's the difference between CAT 5e patch cable and CAT 5e crossover cable?
The difference has to do with the wiring of the cable and the situation in which you will use the cable. On a CAT 5e patch cable, the wiring configuration is identical on both ends of the cable. On a CAT 5e crossover cable, the wiring of pins 1, 2, 3, and 6 are "crossed-over" to pins 3, 6, 1, and 2. CAT 5e crossover cables are used in situations where two devices have the same interface, for example, connecting a hub to a hub, or a switch to a switch, or even when patching a hub or switch into a wall plate.What's the longest (maximum length) CAT 5 patch or crossover cable I can use without signal loss?
The maximum length (maximum certifiable length) for CAT 5 patch or crossover cables is 328 feet (100 meters). Beyond that, you run the risk of signal loss, attenuation and reduced data throughput.Can I join lengths of Cat5 using an RJ45 coupler?
Yes. Joining two or more lengths of Cat5 cable using an RJ45 coupler will work just fine, but it should be considered a temporary solution to whatever connectivity issue required the use of it in the first place. The more "connection points" that you have in a cable, or in a network for that matter, provide additional points where signal loss can occur. If you must join Cat5 cable using a coupler, make sure to rectify the problem with a proper length cable as soon as possible to restore maximum performance to the device using it.What is the difference between CAT 6 and CAT 5e cable?
Cat5e cable of good quality can run near or at gigabit speeds, it just cannot be "certified" for this use. By comparison, Cat6 is designed especially for gigabit use, and is certified to operate at said speed. It becomes a matter of whether you want to pay all that extra money, for little or no noticeable improvement in the performance of you network. Unless every single component in the network is gigabit rated, then you will never have a gigabit network, because your network will always run at the speed of your slowest device.