I.T.: Networking: wireless frequencies & possible noise sources.

I.T.: Networking: wireless frequencies & possible noise sources.  

Within the computer itself, which may have a poor design physically or logically that may be used post manufacture to tweak settings and eliminate the interference between it's own components.
An update to the (bios/firmware) programmable chips is often part of the solution.

A couple examples have been illustrated in the new Raspberry Pi 4 Model B (Released 2019-August):

• 24 June 2019 – Raspberry Pi 4 Model B launched.[314]
• 10 December 2019 – 30 million units sold;[315] sales are about 6 million per year.[316][317]

******************
HERE ARE SOME SNIPPETS FROM ARTICLE HITS ON MY GOOGLE SEARCH:

Causes of WiFi Interference

Problems associated with WiFi interference can be broken down into some main keys areas:

Physical Barriers

Regularly you will find that there is a certain spot within a building or area where you cannot seem to reach any reliable WiFi signal, no matter where you place your device. Physical barriers, such as the materials that a building is constructed with, is one of the most likely reasons for a WiFi signal being unable to reach your device. Here is a list of common building materials and the level of likely interference they are causing you:

The best way to combat a physical barrier interfering with your signal is obviously to move the router or wireless access point to a better location so the signal does not have to go through the barrier. You could also try broadcasting the signal using the 5GHz frequency, which if available will be an option with the device’s settings, but this tends to only be available on higher end equipment.

Finally, a physical barrier to a WiFi signal that most people never consider is…themselves! More specifically, your hand when holding a mobile device. Trying changing your grip for a better signal.

Frequency Interference

Frequency interference is when another signal crosses paths with your signal on a similar bandwidth and corrupts or overpowers it. Unfortunately the list of devices that has been known to cause this form of bandwidth interference is almost never ending, but here we provide a list of the common ones:

Wireless Devices – Technically speaking, any other devices that transmits or receives a wireless signal is capable of causing an interference to signal, so look to things like wireless speakers, baby monitors, walkie talkies, garage door openers.

Microwaves – Most microwaves operate on the 2.4GHz spectrum, which is the same as a lot of wireless devices, especially older or less expensive models, so massive network interference will often be experienced while a microwave is in operation.

Cordless WiFi Phones – Cordless phones also commonly operate on the 2.4GHz spectrum, so while you are talking on the phone or the phone is ringing, you will most likely see signal interference. This does not include standard DECT cordless phones, only the WiFi variety.

Satellite Dishes – If a satellite has been wired up incorrectly or the wiring is old and deteriorating, it is common for them to leak signal interference into the vicinity.

Neighbouring WiFi Network – Powerful WiFi networks, especially those seen in large corporate environments, in a close proximity to your own can affect your signal and performance, and vice versa. Installing WLAN controllers with rogue detection functionality can help detect this.

Hearing Aids – If a person with a hearing aid is in very close proximity to a wireless broadcasting device, signal disruption can be experienced.

Refrigerators – the motors on the inside of a fridge can cause disturbance with WiFi signals, as well as the fact that they are packed with ice, which can act as a barrier. Keeping WiFi broadcasting devices away from fridges is always a good idea.

External Monitors & Displays – Certain displays can emit harmonic interference, especially within the 2.4 GHz band between channels 11 and 14.

Christmas Tree Lights / Fish Tanks – both of these oscillate on the same frequency as WiFi signal and are known to be common causes of interference, not just to WiFi signal but internet connectivity in general. Avoid having internet based equipment near either of these.

Poorly Shielded Cabling – External hard drives or other devices you are connected to with poorly shielded cabling can interfere with a wireless signal and you can of course test this by temporarily removing the device to see if the signal improves. Try replacing the cable(s) that connect into the troublesome device.

In most instances, altering the broadcast channel on your WiFi device will solve a frequency interference issue. Typically a channel can be set between 1-13, try a few different ones to see which works best. Typically the best ones to use in the UK are channels 1, 7 or 13. Run a WiFi scanning tool in your vicinity (WiFi Analyzer is a good free one, available for mobile devices), check out which channel of those three is most commonly used in your area and pick one of the others. Higher end routers will allow you to broadcast on the 5GHz frequency which helps eradicate a lot of frequency issues and is the most effective solution at present.

Capacity & Coverage

A problem that often occurs, especially in corporate environments, is that there simply aren’t enough wireless broadcast devices available for users to connect to, causing overload issues in capacity. A wireless device is only capable of serving a finite amount of bandwidth, regardless of how fast the internet connection into the building is, and that amount is divided amongst the number of people connecting to it. So if for example you have an office with 50 people all connecting to the same access point, the amount of available bandwidth from that access point is divided by 50. Ensure that you don’t have one device or access point serving a high density of people in a certain area.

Coverage also plays a very important part here, so consider the distance that people are having to connect across. Signal is always stronger and more reliable the closer you are to a device, so don’t leave users a long distance away from a device they are trying to connect to. Also consider the manner in which your wireless devices are installed to provide that coverage. Wireless broadcast devices are designed to shoot their signal in a specific direction and the problem is that you can’t the radio signal to see which direction it is going. If you have access points that are lodged in the ceiling tiles or buried on a shelf in the back of a room, this is not the way they were intended to be used. Check the manufacturers guide that came with your device and the aerials to determine the intended coverage pattern and ensure they are installed correctly.

Conclusions & Resolutions

There has been large strides in recent years that has closed the gap a fair bit, but as a rule WiFi performance will always be inferior to wired performance.

To increase your chances of having a more reliable WiFi service, look primarily at the kit providing those services. Consider upgrading your kit to a device that is capable of using the 802.11ac frequency and has dual band functionality i.e. that broadcasts on both the 2.5Ghz and 5GHz spectrum. For current devices you have, never overlook the importance of a firmware upgrade. Manufacturers are constantly finding ways of enhancing the capability and performance of their devices by developing new software that runs them, so check regularly on their website for your model number and the latest firmware releases. These updates will nearly always be completely free of charge.

Metal and concrete are most certainly the highest level of obstruction risk so ensure that whatever devices you have that are broadcasting your WiFi signal are placed strategically to avoid the most amount of metal and concrete in your building.

Always carefully consider the design of your WiFi network so that capability and coverage are sufficiently catered for. If you are in doubt, consider speaking to us about having a WiFi survey or audit, more details of which are available here: https://activereach.net/solutions/converged-networks/data/wireless/

Dos and Don’ts of Wi-fi connectivity: Maximizing Range and Reception

While installing Wi-fi solutions, a user may come up with a few impediments; specifically w.r.t the range and reception. It is very important to be aware of these impediments and see how they could affect the installation, before going in for a wireless solution.

Walls

The first thing to do is to check the construction of the walls. In theory, Wi-Fi signals are capable of passing through walls and other obstacles relatively easily. However, in reality, some walls are thicker or use reinforced concrete and may block some of the signals. Materials such as drywall, plywood, other kinds of wood and glass can be easily penetrated by wireless signals. However, materials such as brick, plaster, cement, metal, stone, and double-glazed glass may cause problems. The following facts should therefore be kept in mind:

• Metal bodies absorb Wi-Fi signals. Therefore, wireless surveillance solutions do not guarantee connectivity between floors of buildings and between thick reinforced concrete walls
•  If the walls are made of non-porous materials, your wireless connection may have a shorter range or a slower speed
• Elevators block Wi-Fi signals to a great extent. When placing an IP camera; make sure the elevator does not come between the camera and the Wireless Access Point
•  Tinted glass panes carry metal constituents. So if you have tinted glasses anywhere between WAP and the camera, you can expect a drop in signal strength.

Interference

The other thing to check for is potential interference with the Wi-Fi network’s frequency range. The 802.11 wireless standards communicate in the 2.4, 3.6 and 5 GHz frequency bands.

Interference can slow down a network significantly and reduce its range as well. The two most common sources of wireless network interference are wireless telephones and microwave ovens. Existing previously installed 802.11 networks can also cause interference.

Potential sources of interference in the 2.4GHz ISM band:

• Microwave ovens
• 2.4GHz cordless phones, DSSS and FHSS
•  Fluorescent bulbs
• 2.4GHz video cameras
• Elevator motors
• Cauterizing devices
• Plasma cutters
• Bluetooth radios
• Nearby 802.11, 802.11b or 802.11g WLANs
• Wireless Internet Service Providers (WISPs)

Potential sources of interference in the 5GHz UNII bands include the following:

• 5GHz cordless phones
•  Radar
•  Perimeter sensors
• Digital satellite
• Nearby 802.11a or 802.11n WLANs
• Outdoor wireless 5GHz bridges

A basic wireless surveillance set-up normally consists of the wireless IP cameras, the Wireless Access Point (WAP) and the Network Video Recorder (NVR) or the media server. In addition to the above, keep the following points in mind while installing a wireless surveillance solution:

• Keep the antennas straight pointing to the sky unless told to do otherwise
• A long hallway or corridor will most likely need an indoor semi-directional antenna for coverage as opposed to an omni-directional antenna. Do check the manufacturer’s recommendations. Anytime a type of antenna that is not recommended by the manufacturer is added, do keep in mind that the signal may be getting a boost beyond the legal limits of the country.
• Weather events such as rain, snow, and even wind can wreak havoc with wireless signals
•  A high concentration of human bodies can attenuate the RF signal due to absorption
• Trees are notorious for absorbing signal energy
• Wireless Access Point (WAP)
  • Do not keep the Access Point device at a low level on the floor. If possible, try placing the WAP at a location equidistant from all the walls of the room. In other words, keep it in the middle of the room or desired area of coverage
  • As far as possible, keep the WAP above all sources of obstruction. Even if it means overruling the earlier point. For example, in an office environment, keep the WAP above the height of all the cubicles. We would recommend it to be mounted close to the ceiling
  • Try not to place the WAP near sources of heat or under the sun
  • Do not operate multiple WAPs in close proximity (<100mts apart). Especially if the same SSID is used on both.
• Wireless IP Camera
  • Once again, do not place the wireless IP Cameras at a low level. It is best placed high on the wall or nearer to the roof (to avoid all kinds of obstacles like furniture, cubicles, etc.)
  • Try not to place the cameras near sources of heat or under the sun
  • Do not keep the cameras too close to the WAP (<2mts). The camera radio may automatically turn down its transmit output power which may result in connection loss
  • Do not keep the cameras too close to each other (<2mts). This will cause signal interference between them.

Conclusion

A careful and thorough evaluation of your security requirements will help a great deal in identifying the prudence of using a wireless surveillance system.

• If you're interested in WiFi, love Christmas decorations -- or both -- you probably noticed recent reports out of the United Kingdom that your active holiday decor may be disrupting the WiFi signals in your home or business. Whether the impact is the result of shoddy electrical design by the manufacturers of the fairy lights (as they say in the UK) or a more sinister collusion between wireless router makers and the Christmas light industry to sell more wireless hardware is certainly a question that hangs in the air.

• Are ugly, light-up sweaters responsible for mobile denials of service? That one is still being investigated, but there is one clear truth that wireless experts already know regardless of the holiday light dust-up: Non WiFi products very much can make wireless life miserable.

• Without diving too deep into the technology, we can boil the problems down to a couple of regulatory realities. WiFi works in the unlicensed 2.4-GHz and 5-GHz frequency ranges. There are many other devices that also leverage the fact that you can transmit in these spectrums without expensive and complicated licensing requirements.

• In addition, all the wireless devices that tend to step on each other are required to tolerate interference, unless you can change their channel to a non-polluted one within their operational profiles. In other words, interference is a fact of life under the current rules. Now that you know about pretty lights with evil intentions, let's take a look at a number of other common interferers that you may not be aware of.

Bluetooth devices work in the 2.4 GHz spectrum, where we find 802.11b, g, and n WiFi. 

I

• Most Bluetooth devices are innocuous, and built to be good neighbors by avoiding active WiFi channels. But older versions of Bluetooth weren't so friendly and could be disruptive to WiFi users in the immediate area. And if you get a lot of Bluetooth devices all in the same room, the laws of physics say that your 2.4 GHz signal will be impacted. Whether the impact is perceptible or not will vary by individual scenario, but if your WiFi is wonky, try checking the headsets, Fitbits, and keyboards at the door.

Generally, microwaves cause more problems with 2.4 GHz than 5 GHz.

Cordless phones can be hard on both WiFi bands. It's further complicated by the fact that when you shop for cordless phones they may not mention anywhere on the packaging that it uses 2.4 GHz or 5 GHz frequencies. But when you start using it, the interference may be devastating to both bands. Cordless phones may seem passé to you, but if they are still an option in your home or business, be sure to purchase units that are clearly labeled as based on DECT 6.0 technology. DECT 6.0 works at 1.9 GHz, and couldn't interfere with WiFi if you wanted it too.

Pull those plugs

"Wall-wart" power supplies are those cheapie AC adapters that either power or charge an endless range of devices, including many discussed in this article. Amateur radio operators and RF engineers know well the interference damage that these mass-produced, low-quality disposable power supplies can wreak. They can be brutal to diagnose and easy to look right past. It helps to have a spectrum analyzer that can show you signals in the air. But when a cheap power supply is radiating wideband noise, an easy test is to simply unplug it and see if your WiFi problem goes away.