When the Radius SDK demodulates/receives an incoming tone, the following values are available from the Tone object:
Signal-to-Noise Ratio (SNR): Indicates in decibels (dB) the amount of interfering noise relative to the received strength of the Tone.
Header and Payload Error Vector Magnitude (EVM): Gives an indication in decibels (dB) of how challenging it was for the Tone to be received by the LISNR Radius SDK.
Header EVM: EVM value indicating the quality of the Header.
Payload EVM: EVM value indicating the quality of the Payload.
These values are only available when receiving Point1000 or Point2000 tones. Zone66 tones will not have a header/payload EVM value.
Below is a relative scale to indicate how SNR and EVM (db) values can be associated used to measure how easy/challenging it was to receive a tone.
Note:
Default values for an unknown signalToNoiseRatio will give the default value of -60.0
Developers using the Radius SDK can use the SNR and EVM values to provide UI/UX indicators or messaging to their end users. If you are experiencing either poor SNR or EVM values, the following actions are recommended:
Transmit at a higher volume.
Reduce the distance between the transmitting speaker and the receiving microphone.
Angle the transmitting speaker and receiving microphone towards each other and ensure there is nothing obstructing the line of sight.