Panoramic sensors transmit measurements to a nearby Bridge wirelessly. For those transmissions to be received and interpreted by the Bridge, the signal received by the Bridge needs to be strong enough to overcome the electromagnetic noise.

RSSI: received signal strength indicator (RSSI) is a measurement of the signal power present at the measured frequency between the nearest Bridge and the sensors.

Panoramic Power sensors transmit modulated signal to the Bridge which demodulate the received signal to interpret the measurement data it contains. The RSSI level should be between -30dBm and -75dBm. However, to ensure successful demodulation of the signal the reception level should also meet a minimum Signal to Noise Ratio (SNR). 

For Panoramic Power sensors, the received SNR should be between 30-40dBm, considering that the signal level may decrease, and that Noise Floor level may increase from time to time due to the dynamic environment.

SNR is the difference between the received signal strength indicator (RSSI) and the Noise Floor.

Noise floor Is the sum of all the electromagnetic noise sources and unwanted signals at the relevant frequencies, where noise is defined as any signal other than the one being monitored. This would impact the data delivery between the sensors and the Bridges because similar frequencies mean interference. A way to bring this value down or to N/A is to move the Bridge closer to the sensors or away from the source of the noise (systems working on similar frequencies, etc.)

Where to view Noise Floor

On the platform, you can find the Noise Floor for each Bridge on the Bridges & Loggers table.

Where to view RSSI

Each sensor’s RSSI level can be found in either:

1. The Deployment Tool where you can see real-time (and few last minutes levels), that is helpful during installation. Note that there is a need for the monitored load to consume power, so the device is operating.

1. In Time View, when the phase level is selected you can overlay RSSI levels. This allows you see reception levels over time.

We can see that the RSSI is within the range ( -44dBm is between -30 and -75dBm) and the SNR is about 36dBm (-44dBm RSSI and -80dbm Noise Floor), which means the environment is not impacting the reception between the sensors and Bridges negatively.

What affects the RSSI and Noise Floor?

When it comes to electromagnetic signals, many things can affect the reception levels, among which are:

• Distance between the transmitter and receiver – The further the Bridge is from the sensor, the lower the reception level is.
• The medium/obstacles between the transmitter and receiver - The more the medium is conductive (metal plates for example) and the more obstacles there are, the lower the reception level. Reflections of the signal from conducting materials can also affect.
• The position and angle of the sensor and Bridges' antenna – Even the slightest change in the location or angle can affect reception levels as it.

Noise Floor is affected by other electromagnetic transmitters, those could be other wireless communication devices, but also electronic devices emit electromagnetic noise.

When reception levels are low try to place the Bridge closer to the panel or even within the panel but note that placing it too close to the sensor may result in Receiver Compression (RSSI levels above -30dBm).

Placing the sensor in a different location on the wire or even slightly changing its position may also help.