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WiFi Troubleshooting

Understanding WiFi signal strength and how a WiFi signal is broadcasting is the first step in the WiFi Troubleshooting arsenal, in this guide I will show you some of the fundamentals behind your WiFi signal and how to go about troubleshooting intermittent or low signal issues plaguing your devices. At the bottom of the page, I have included a link to changing your WiFi Router settings.

Visualizing WiFi

A big help understanding how WiFi broadcasts from your Wireless Router, is visualizing the radio waves as they emanate from the broadcast source. A mathematician used an algorithm to predict his own WiFi signals in his house, I have provided some pictures to help you visualize your own WiFi inside the house. As well as a short video clip of WiFi broadcasting from the Wireless Router.

Signal Strength & WiFi Troubleshooting

To begin it helps to understand WiFi signal operates on a lower frequency, as a result, the most accurate measurement is in milliwatts (mW), but you end up with tons of decimal places due to WiFi’s super-low transmit power, which can make it very difficult to understand. For example, -40 dBm is 0.0001 mW, and the zeros just get more intense the more the signal strength drops.

So the easiest way to represent this in signal strength is with dBm, which stands for decibels relative to a milliwatt. Every vendor of WiFi devices deals with this representation differently, so it is usually converted to dBm to make it readable.

  • mW – milliwatts (0.0001 mW = -40 dBm)
  • RSSI – Received Signal Strength Indicator (usually 0-60 or 0-255)
  • dBm – Decibels in relation to a milliwatt (usually -30 to -100)

How to read dBm

Firstly you will require the use of some form of software such as a WiFi analyzer, these can widely be found on all platforms but I highly recommend use on a smartphone as it is far easier to carry with you from room to room. Many are free and available from Google Play store or Apple App Store. Next, we are going to look at our SSID broadcast frequency in dBm, dBm is always registered in negatives, -30 is a higher signal than -80, because -80 is a much lower number.

Next, it’s important to know that dBm does not scale in a linear fashion like just about everyone would expect, instead, it is logarithmic. That means that signal strength changes aren’t smooth and gradual. A good way to understand it is the Rule of 3s and 10s which showcases the logarithmic nature of dBm:

3 dB of loss -3 dB Halves signal strength
3 dB of gain +3 dB Doubles signal strength
10 dB of gain +10 dB 10 times more signal strength
10 dB of loss -10 dB 10 times less signal strength

What is the best signal strength

So what signal strength should you be shooting for? For tasks like sending emails, browsing the web, or scanning barcodes, -70 dBm is a good enough signal strength, as these low bandwidth related tasks don’t require much more. For more demanding applications like VoIP or streaming video, -67 dBm is better, and some network engineers recommend -65 dBm if you plan to support mobile devices like iPhones and Android tablets.

Note: The numbers in this chart are suggestions only. The desired signal strengths will vary, based on the requirements of the network.

Signal Strength Required for
-30 dBm Max achievable signal strength. The client can only be a few feet from the AP to achieve this. Not typical or desirable in the real world. N/A
-67 dBm Minimum signal strength for applications that require very reliable, timely packet delivery. VoIP/VoWiFi, streaming video
-70 dBm Minimum signal strength for reliable packet delivery. Email, web
-80 dBm Minimum signal strength for basic connectivity. Packet delivery may be unreliable. N/A
-90 dBm Approaching or drowning in the noise floor. Any functionality is highly unlikely. N/A

 

Tracking Your Signal Strength

You can now track your signal strength using your smartphone by selecting your network and walking the area inside your house. If you see your signal strength falling below the dotted line you have a Deadzone. You can try and adjust the signal strength in your Wireless router using your mobile app or relocate it to another position/orientation from its current location and check coverage again. I have provided a GIF to better help you visualize the effect of moving and re-orientating your Wireless Router. These are the most effective means of providing coverage in the desired areas of your home and eliminating potential dead zones.

 

 

 

 

 

 

Sources of Interference

Eliminating potential sources of interference can be a massive help in extending range and reducing intermittency, there are many types of devices that operate at similar frequencies or higher powered frequencies that can obliterate your WiFi signal. To that end, I will attempt to break down some of the biggest sources of interference so you can identify any that may be causing your intermittent WiFi connections.

  • 2.4 GHz Cordless Phones – The base units that charge your handheld operate on the same frequency make sure these units are far away from your Wireless Router
  • Baby Monitors – Most baby monitors operate on the 2.4Ghz spectrum and cause a lot of disconnections as WiFi enable device struggles to obtain a signal
  • Fluorescent Lighting – Operates between 60-120Mhz and will almost certainly interfere with your Wireless signal
  • Metals – Most metals refract or reflect WiFi signals one of the worst offenders is copper piping as this was a standard used for plumbing in older structures – avoid metal desks
  • Microwave Ovens – Microwave ovens will certainly affect anything operating on WiFi channel
  • Power Sources – Breaker boxes or poorly shielded cables are another main source of interference the electrical energy can cause disruptions

These are not the only sources of interference however they are the most likely and should be considered in the first step if WiFI Troubleshooting, below I have provided a scale of materials that will inhibit the transmission of wireless signals. For a guide on how to change your WiFi signal to operate or perform better follow the guide, I have provided here.

Type of Barrier Interference Potential
Wood Low
Synthetic material Low
Glass Low
Water Medium
Bricks Medium
Marble Medium
Plaster High
Concrete High
Bulletproof glass High
Metal Very high
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