Pre-Installation Planning

Site Survey

  When planning the setup of The Water Window, it is a best practice to review the area around the tank to try and determine the best placement of the unit and estimate the Wi-Fi signal strength at that location.

Mounting

	The meter should be place 30cm to 50cm (12” to 18”) above the ground with the front face of the meter pointed towards the Wi-Fi Access Point to be connected to. Choose a location near the tank where the path between the meter and Access Point has the least number of objects such as walls, bushes, etc. in the way as every object will reduce the Wi-Fi signal.
Choose a suitable object to mount the meter to. A wooden stake, vent pipe on tank lid etc. Do not mount to a metal object as this will distort and interfere with the Wi-Fi signal.

 

Wi-Fi Signal Strength

Once a location is selected, the Wi-Fi signal can be measure to help determine if there is adequate signal at the location for a stable Wi-Fi connection. This can easily be done with a smart phone, tablet or similar device.

The signal strength, sometimes called RSSI, is a value calculated by Wi-Fi devices and used to indicate the quality of the communications between the device and the Access Point. The value is a negative number typically falling in the range of -40dBm to -120dBm. Being negative means the smaller the number the larger the signal and vise versa. Different devices measure and calculate the signal slightly different and may give slightly different readings at the same location. For this reason and several other factors that can affect Wi-Fi connection quality, these readings should only be used as a reference to indicate if a good connection between the meter and the Access Point is possible or if changes to the network are needed to increase the Wi-Fi signal at the installation point. 

The following values are what have been observed in the past at typical locations. Locations that have higher levels of noise will have more problems even with a good signal strength and locations with low noise levels can allow for good connections even with a low signal strength. There is no easy way to test for noise with these apps, but this test will give an indication of what to expect. But again, this does not guarantee a good or bad Wi-Fi connection and the final determination will be made once the meter is installed.

Usually a value in the range of -40dBm to -75dBm will give a good stable connection. If the range is between -75dBm to -90dBm a connection probably can still be made, but increased page loading times and frequent network disconnects may occur causing difficulty viewing data and  missed alerts. In this case you may want to look at ways to improve the signal.

Measuring Signal with Android Devices

There are many Android apps that will scan for Access Points and display the signal strength as a raw dBm value. Here we will use an app called Wi-Fi Analytics Tool. 

1. From the Play Store search for and download Wi-Fi Analytics.
   
2. Open the app and tap the Auto Scan button to start the scanning process. As the app finds the wireless networks in the area, it will add them to the list. Look for the signal strength along the right side next to the wireless network you want to use. In this example it shows -84dBm.
   

Measuring Signal with Apple Devices

To view the raw signal on an Apple device, the  Airport Utility app is used.

1. From the app store download the Airport utility app.
   
2. Once installed you have to enable the Wi-Fi scan functions in the settings screen. Open the settings menu on the phone and scroll down to the app section and open Airport Utilities app.
   
3. Enable the Wi-Fi Scanner option.
   
4. Exit out of the settings and open the Airport Utility app.
   
5. Tap the Wi-Fi Scan link at the top and you will be taken to the scan screen. Tap the Scan link at the top to start scanning.
   
6. The app will now scan for Wi-Fi networks and display them in a list. The RSSI value is the signal strength indicator.
   
   

Improving Signal

If the signal at the installation location is weak, you can look at moving the Access Point you are trying to connect to a new location that is either closer to the meter or to an area that has fewer obstacles in the signal path. Another option is to add another Access Point to your network that is closer to the meter. The Wi-Fi hardware in the Water Window meter is a basic 2.4Ghz wireless g/n network adapter with no specialized or high end features. As such only a basic 2.4Ghz Access Point or extender is required and actually interfaces better with the meter than higher end Access point.

The easiest device to add would be a dedicated Wi-Fi extender. Another option would be to add another Access Point to the network, however it would need to be properly configured so as not to interfere with the main access point. 

An extender we have had great success with is the TP-Link TL-WA850RE.