Yes! LISNR’s ultrasonic SDK Radius® does not require an Internet connect to transmit or receive tones.

The Radius® ultrasonic SDK can transmit and receive tones while offline if it has been less than 24 hours since the last online connection.

The Radius® SDK only requires an online connection once every 24 hours to sync.

While the Radius® 3.1 SDK file size is very small, the actual size varies by platform. Our customer success team can help you quickly determine the file size.

An ultrasonic SDK implementation process typically follows this process:

1. Establish data flow

• Customer is introduced to Radius® concepts in order to understand the expected data flow and where the Radius® SDK will fit into their application(s).

2. Get access to LISNR® Portal

• This is where LISNR® customers can download the Radius® SDK, create SDK and API tokens, read documentation in the knowledge base, access testing tools, and download Radius® Sample applications for all supported platforms.

3. Environment setup

• Customer developers create SDK Token(s) using their respective Android app ID and/or iOS Bundle ID (if applicable) and put the Radius® SDK into their application

4. Integration

• Customer developers create a Radius® object, Transmitter and Receiver objects (if unidirectional) or Transceiver objects (if bidirectional).
• Transmitter side – Add logic and UI/UX elements for broadcasting payload data (Tones).
• Receiver side – Add logic and UI/UX elements for receiving and validating incoming payload data (Tones).
• Testing

Radius® 3.1 ultrasonic SDK offers multiple ways for companies to secure their payloads:

• ToneLock is a LISNR® created tone security protocol that ensures only the intended device is able to receive the payload. 
• AES256 Encryption is an industry standard for securing data. LISNR® offers encryption to be applied to all transmitted/demodulated payloads within a customers LISNR® portal account. 

Companies can also choose their own security protocols and transmit/demodulate them through the Radius® SDK.  

LISNR’s Radius® product is a software development kit or SDK that can be used to build applications/software.  

While the SDK isn’t an application itself, if you’re looking to demonstrate the capabilities of the SDK or need to test the SDK features, the LISNR® team has also developed two separate in-house applications:

1. Radius® Experience Application – For demonstrating UI/UX elements within specific industry use cases.
2. Radius® Sample Application – For testing nearly all features of the SDK. Users can input custom payloads.

While the ultrasonic SDK isn’t a platform, it can function within a wide variety of platforms including Android, iOs, Linux, RPi, and Windows.

The Radius® ultrasonic SDK is available for the following platforms:

• native Android
• native iOS
• Linux (x64 and ARM64)
• RPi
• Windows

The LISNR® Experience Application is available for the following platforms:

• Android
• iOS

The LISNR® Sample Application and source code are available for the following platforms:

• Android
• iOS
• Desktop (Windows/Linux/RPi)

*Note: In some instances, (Beta) Radius® SDK for Web may be available by request.

Your customer success representative will guide you through the requirements gathering and implementation process. Here is an example of a typical technical requirements checklist for an ultrasonic SDK implementation:

• Data Flow

• • What is the size of the data that will be broadcasted with the Radius® SDK in bytes?
  • What is the expected transmission distance between speaker and microphone when using the Radius® SDK?
  • Does the data transmitted by the Radius® SDK get sent from one device to one device (1 to 1)? Or from one device to many listening devices (1 to many)?
  • Does the data transmitted by the Radius® SDK only get sent from one device to one/many (unidirectional)? Or will the other device need to respond using the Radius® SDK (bidirectional) or network (unidirectional with network validation)?
  • Does the data transmitted by the Radius® SDK need to be secure? Are the security methods provided in the payload or is ToneLock needed?

• Hardware

• • Broadcasting application/devices have a speaker?
  • Listening application/devices have a microphone?

• Software

• • Broadcasting Application platform is Android/iOS/Desktop?

• • • Broadcasting Application platform will use LISNR® Tone Service API?

• • Listening Application platform is Android/iOS/Desktop?

For more information, contact a LISNR® representative or visit our integrations requirements page.

Implementing LISNR’s Radius® ultrasonic SDK for proximity marketing—on-prem and digitally—is a very common use case.

Here’s an example of how an on-prem proximity marketing use case could function:

• A loyalty customer store enters a physical space (such as a grocery store, restaurant, pharmacy, hotel, or venue) that is broadcasting a unique identifier using the Radius® SDK.
• When the consumer opens the retail company application (which would be using the Radius® SDK), the app detects the broadcasting tone.
• Once the tone is detected, a targeted, in-person advertisement can be broadcast to the consumer on their mobile device, which the consumer can then utilize.

Radius collects zero personal data. LISNR collects high-level analytics data to ensure the experience is secure and reliable. 

• Secure Storage: Analytics data is sent through highly secure, “bank-grade” encrypted channels (HTTPS) to our private servers.
• What We Capture: We collect technical details such as your device type (e.g., iPhone or Android) and whether your microphone is enabled.

To provide the most secure and reliable experience, LISNR features are recommended to be used when the app is open and active (in the foreground). This ensures that the speaker and microphone performance is as intended, allowing the end user of the application to be in control of when the Radius action occurs. 

• App Open (Active): When consumers have the app open in the Radius instance, the Radius SDK is ready to “hear” the secure tone to complete the Radius action.
• App in Background: Background listening and transmitting features are controlled by the application that the Radius SDK is built into; this can provide an inconsistent experience when implemented in the background because the Radius SDK cannot guarantee continuous speaker or microphone access.

Radius requires microphone permissions to detect ultrasonic tones and process incoming data. When the Radius SDK lives within an application performing receiving functionality, it must request permissions so the user knows it is using their microphone.  

• The Goal of Education: We want to address any confusion early on. When you understand how a feature like the microphone improves the app, you’re more likely to feel empowered to use it.
• Better Experience: Granting access enables simple, hassle-free digital wallet payments or check-in at your favorite store or transit gate.

No. LISNR transmits and processes data in real-time, not through audio recordings. Moreover, Radius applies bandpass filters to audio picked up by the microphone, only processing our frequencies of interest (16kHz-20kHz), which are too high for most audible speech.

• Privacy-First Design: No audio is recorded or saved to your device or our servers. 
• User Control: Both Android and iOS require applications to request microphone permissions. We recommend a “primer screen” to explain exactly when and why the app will use these features.

A common misconception is that physical sound perception at high frequencies implies physiological strain. For pets and all animals alike, LISNR Tones are in a safe audio frequency range. High-frequency sounds aren’t inherently dangerous on their own; hearing damage is caused by sounds that are too loud, regardless of frequency.

Several government agencies and research organizations provide recommendations on acceptable sound levels for near-ultrasound. Generally, the standards assume a constant long exposure such as an 8-hour work day with the most conservative limit being 75dB. For just a few seconds or momentary exposure, which applies to most LISNR use cases, the minimum limit increases.