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A Novel Web-based SDR Board That Can Be Run, Configured, and Managed From Web Browsers

uSDR is an embedded software-defined radio (SDR) board that is optimized for ease of use and collaboration. It incorporates WebUSB technology, which enables full functionality in web browsers—under Linux, Windows, MacOS, and Android—without requiring specific drivers or software

Published onMar 31, 2024
A Novel Web-based SDR Board That Can Be Run, Configured, and Managed From Web Browsers


Software Defined Radio (SDR) technology unlocks vast opportunities for exploring the radio spectrum, but traditional SDR platforms often present significant barriers to entry due to complex software installation, dedicated hardware, and specialized knowledge. uSDR represents an embedded software-defined radio (SDR) board designed for simplicity and collaboration. uSDR leverages Web Technology to enable direct browser interaction without requiring platform-specific drivers. This empowers users to operate the SDR through a familiar web interface accessible on Chrome, Opera, or Edge browsers across Linux, Windows, macOS, and Android. This browser-based approach significantly reduces the entry barrier for newcomers and casual users, fostering wider adoption of SDR technology. This article provides a detailed examination of uSDR's technical specifications, architecture, and the seamless integration of web-based controls, offering a comprehensive understanding of its capabilities and implications in software-defined radio.

Keywords: Software Defined Radio, WebUSB, Web SDR, uSDR, M.2, Accessibility, User-Friendly, Wireless Education, Research, Radio Spectrum Exploration.


The evolution of radio communication technology has been characterized by a relentless pursuit of innovation and accessibility. Traditional radio systems, constrained by fixed hardware architectures and limited configurability, have yielded ground to dynamic, software-driven solutions. At the forefront of this transformative journey stands uSDR, a compact marvel of engineering that epitomizes the essence of Software Defined Radio (SDR).

uSDR heralds a new era in SDR technology, offering a compact yet formidable platform for radio spectrum exploration and experimentation. Its modest dimensions belie the wealth of functionality and versatility it encapsulates. However, the defining feature of uSDR lies in its integration with web-based controls, a pioneering advancement that simplifies configuration and operation through standard web browsers.

Figure 1


uSDR lets you get started right away, without the need to install a new operating system, compile drivers, or troubleshoot version conflicts in software and vendor-support libraries. Just open a web browser and there’s everything you need! This is our vision, and it’s why we develop WSDR, the web-based SDR platform for researchers, developers, lab technicians, students, radio enthusiasts, and anyone else who’s curious about this powerful new technology. We designed WSDR to be as flexible as possible so you can extend its functionality and bring more applications to life.

Figure 2

uSDR connected to a labtop and run from the chrome browser


uSDR was developed as a hardware exhibit for the WSDR platform. The "u" in uSDR signifies the Greek letter "µ" (mu) and is articulated as "micro." The board maintains a small footprint, adhering to the M.2 2230 form factor with A+E keys, a common specification for Wi-Fi cards. All components are situated on the upper side, simplifying thermal regulation. Employing the dependable LMS6002 SDR chip from Lime Microsystems, uSDR provides the subsequent functionalities:

Figure 3

uSDR with different versions

1. Features & Specifications

  • M.2 2230 Key A+E interface

  • Full-duplex TX & RX

  • Frequency range: 300 - 3700 MHz (usable range typically starts from 230 MHz)

  • RX/TX Bandwidth: 0.75 - 28 MHz plus bypass mode

  • Clock stability: 0.5 PPM

  • Sample rate up to 30.72 Msps (40+ Msps in bypass mode)

  • High-Speed USB 2.0: 480 Mbps, streaming ~15 Msps half-duplex or ~5-6 Msps full-duplex

  • Extended power supply range: 2.85 - 5.5 V

  • Components on only one side of the PCB

  • PCIe support in legacy mode

  • MHF4 RF connectors

2. Host Interfaces

If your host lacks an M.2 2230 A- or E-key interface, you can still employ uSDR by utilizing adapters and an evaluation board.

Table 1

Host Interface

uSDR Adapter Required

Third-Party Adapter?

M.2 2230 A or E key in PCIe mode

No adapter required

No adapter required

M.2 2230 A or E key in USB mode

No adapter required

No adapter required

M.2 2242/3042 B key in PCIe mode

B+M Adapter

Not available

M.2 2242/3042 B key in USB 2.0 mode

B+M Adapter

Not available

M.2 2242/2260/2280 M key in PCIe mode

B+M Adapter

Not available

M.2 2242/2260/2280 M key in USB mode

Not available

Not available

USB Type-A

USB Adapter or Development Board


USB Type-C

USB Adapter or Development Board



Development Board


Mini PCIe Full in USB 2.0 mode

Mini PCIe Adapter


Mini PCIe Full in PCIe mode

Mini PCIe Adapter


Utilizing USB 2.0 for connectivity doesn't mandate close proximity between your SDR and the host. Just acquire a USB 2.0 extender, position the uSDR up to a distance of 60 meters from the host, and establish the connection using either a twisted pair or coaxial cable.

3. uSDR Components

Perfecting the board required three hardware revisions. The primary obstacle was ensuring optimal signal integrity while accommodating all components on a single side of the board. uSDR includes the following components:

  • RFIC: LMS6002D

  • FPGA: XC7A35T

  • Crystal oscillator: ASTX-13-C-26.000MHZ-I05

  • Clock buffer: PL133-27

  • Clock generator: SI5332A

  • USB 2.0 PHY: USB3333

  • RF Baluns: B0322J5050AHF + 3600BL14M050

  • RF connectors: MHF4

  • RF switches: BGS12P2L6

4. Block Diagram and Pinout Diagram of uSDR

The block diagram provides an overview of the internal components and their interconnections within the uSDR system. The pinout diagram illustrates the physical layout of the uSDR board and the assignment of pins to specific functions.

Figure 4

uSDR Block Diagram and uSDR Pinout Diagram

5. Applications of uSDR:

  • Amateur Radio Experimentation: uSDR provides amateur radio enthusiasts with a versatile platform for experimentation and exploration of radio frequency (RF) phenomena. Enthusiasts can utilize uSDR to tune into different frequency bands, experiment with various modulation schemes, participate in digital communication networks, and engage in antenna design and propagation studies. uSDR's compact size and web-based controls make it ideal for portable and field operations, allowing enthusiasts to conduct experiments in diverse environments.

  • Educational Initiatives: In educational settings, uSDR serves as a valuable tool for introducing students to RF engineering principles, wireless communication protocols, and signal processing techniques. Students can gain hands-on experience with uSDR by exploring concepts such as frequency modulation, demodulation, spectrum analysis, and digital signal processing. uSDR's intuitive interface and programmable capabilities make it suitable for educational labs, workshops, and projects, enabling students to gain practical skills in radio communication technology.

  • IoT Sensor Networks: uSDR plays a crucial role in IoT (Internet of Things) sensor networks by providing a flexible and programmable platform for wireless communication. IoT devices equipped with uSDR can transmit sensor data wirelessly over long distances, enabling real-time monitoring and control of remote assets and environments. uSDR's ability to operate in different frequency bands and adapt to changing RF conditions makes it well-suited for IoT applications requiring reliable and efficient communication.

  • Spectrum Monitoring: uSDR is utilized in spectrum monitoring initiatives aimed at analyzing and managing radio frequency spectrum usage. Government agencies, regulatory bodies, and telecommunications companies employ uSDR-based systems to monitor RF emissions, identify interference sources, and enforce spectrum regulations. uSDR's wide frequency coverage, fine-tuned bandwidth control, and spectrum analysis capabilities enable accurate and comprehensive monitoring of the radio frequency spectrum.

  • Wireless Security Research: uSDR serves as a valuable tool for wireless security research and penetration testing. Security researchers and professionals use uSDR to analyze wireless communication protocols, identify vulnerabilities in wireless networks, and assess the security posture of IoT devices and wireless systems. uSDR's ability to capture, demodulate, and analyze RF signals enables researchers to detect and mitigate security threats such as unauthorized access, eavesdropping, and signal jamming.

  • Remote Sensing Applications: In remote sensing applications, uSDR facilitates the collection and analysis of environmental data using wireless sensor networks. uSDR-equipped sensors can be deployed in remote or hazardous environments to monitor parameters such as temperature, humidity, air quality, and seismic activity. uSDR's low power consumption, robust communication capabilities, and compatibility with wireless protocols make it well-suited for remote sensing applications requiring reliable and autonomous operation.

Overall, uSDR's versatility, programmability, and accessibility make it an invaluable asset across a wide range of applications in radio communication systems, contributing to innovation, research, and development in the field of wireless technology.

Figure 5

uSDR ready applications

C. WSDR (Web-Based SDR)

Web-Based Software-Defined Radio (SDR) represents a paradigm shift in the accessibility and utilization of SDR technology. Unlike traditional SDR setups that require specialized software installations, web-based SDR allows users to interact with radio receivers directly through a web browser. This democratizes access to radio experimentation, making it more user-friendly and widely accessible.

Web-Based Software-Defined Radio (SDR) represents a paradigm shift in the accessibility and utilization of SDR technology. Unlike traditional SDR setups that require specialized software installations, web-based SDR allows users to interact with radio receivers directly through a web browser. This democratizes access to radio experimentation, making it more user-friendly and widely accessible.

  1. Remote Accessibility:

    • Users can access SDR functionalities remotely, enabling experimentation from any location with an internet connection.

    • No need for complex software installations; all operations are performed through a standard web browser.

  2. Cross-Platform Compatibility:

    • Web-based SDR is designed to be compatible with various devices and operating systems.

    • Users can engage with SDR technology using laptops, tablets, smartphones, or any device with a web browser.

  3. User-Friendly Interface:

    • The graphical user interface (GUI) within the web browser simplifies configuration of SDR parameters.

    • Visualization of spectrum data and control of radio signals are made intuitive for users of varying expertise levels.

  4. Collaborative Capabilities:

    • Some web-based SDR systems support multiple users accessing the same receiver simultaneously.

    • This fosters collaboration in educational settings, research projects, and shared exploration of the radio spectrum.

  5. No Local Software Installation:

    • Users can operate SDR functions directly from a web browser without the need for installing specialized software locally.

    • Reduces entry barriers, making SDR technology accessible to a broader audience.

1. The WSDR Architecture

Contemporary web browsers are equipped with WebUSB technology, enabling direct communication between your browser and a USB device. All data processing occurs locally.

Table 2








The velocity of web interactions has undergone a notable acceleration. This acceleration is attributed to the formidable processing capabilities of the JavaScript execution unit in contemporary browsers, sufficiently robust to execute Linux. Importantly, this extends beyond the confines of JavaScript, as WebAssembly and the Emscripten project enable coding in languages such as C, C++, Rust, Go, or C#. This versatility facilitates the seamless adaptation of pre-existing applications for web deployment. WebAssembly's compatibility with SIMD Extensions ensures the preservation of Digital Signal Processing (DSP) performance. Furthermore, the integration of WebGPU technology empowers browsers to harness the computational prowess of Graphics Processing Units (GPUs). Additionally, the advent of Progressive Web Apps (PWAs) allows browser-based software to operate autonomously, even without an internet connection. The spectrum of possibilities in this domain continues to expand.

WSDR is a flexible framework for running applications conceptualized within three distinct layers.

  1. Low level -Libraries designed for fundamental Digital Signal Processing (DSP) functions, data manipulation, and hardware abstraction.

  2. The platform level - Application Programming Interfaces (APIs) for various services, including configuration, data sharing, data storage, and offloading resource-intensive processing tasks.

  3. The application level is where you articulate and establish your data pipeline, design data visualizations, and create visual control blocks.

Applications within the WSDR framework can receive data directly from the uSDR hardware or a distant source. Currently, remote streams operate through WebSockets, with plans to incorporate WebTransport. The primary benefit of WebTransport lies in its support for UDP communication.

2. Applications of WSDR

Pre-built applications are available for use, and input on preferred features and applications is encouraged. The current application offerings include:

  • A spectrum monitor

  • A signal analyzer

  • A PMR receiver

  • An IQ playback application

  • An IQ recorder

  • An IQ signal generator

    2.1. Spectrogram & Monitor

    The Spectrogram and Monitor applications function as spectrum-monitoring tools, offering configuration options for parameters such as FFT size, FFT window function, accumulation, and other uSDR settings. Presently, the FFT processing occurs within the browser, but efforts are underway to transfer this functionality to the FPGA for enhanced bandwidth optimization.

    Figure 6

    Spectrogram & Monitor Application

    2.2. Signal Analyzer

    The Signal Analyzer is a tool for comprehending wireless signals and is equipped with diverse data visualizers to identify noteworthy signals. Additionally, it features several integrated demodulators and data-packet interpreters capable of demodulating various signal types such as FM, PSK, MSK, and FSK, yielding a bitstream. Subsequently, this bitstream can be packetized utilizing parsers for nRF, LE, Bluetooth, and other protocols. Users can receive IQ data from a uSDR device or a remote stream, enabling recording or analysis. The parsed data is downloadable in hex or binary formats.

    Figure 7

    Signal Analyzer Application

2.3. A PMR receiver

Traditional PMR system itself might not typically utilize web-based controls. However, if we were to envision integrating PMR functionality into a WSDR system, here's how it could be applied:

  1. Remote Management: Users can control and monitor PMR receivers remotely via web interfaces.

  1. Accessibility: Accessible from any internet-enabled device, enhancing usability.

  2. Real-Time Collaboration: Enables real-time coordination among users across locations.

  3. Customizable Interfaces: Tailored user interfaces mimic traditional controls for ease of use.

  4. Integration: Seamlessly integrates with other communication systems for enhanced functionality.

  5. Remote Maintenance: Facilitates firmware updates and diagnostics without physical access.

D. uSDR Insights

1. Streamlined Collaboration and Data Management

Facilitating access to radio-spectrum data with uSDR is simplified through straightforward link sharing. Shared links enable spectrum access, recording, or analysis without modifying critical parameters. Alternatively, exclusive access can be granted, allowing adjustments to any parameter. Managing extensive recordings, especially when retrieval from cloud storage is necessary, is streamlined with WSDR's integration with various cloud storage services. A basic file-storage backend is implemented, with user feedback on preferred data storage providers for future incorporation. Additionally, the platform seamlessly integrates with cloud storage services, enhancing accessibility and data management capabilities.

2. Innovative Applications

Demonstrating uSDR's capabilities extends to a sophisticated web-based application - a 2G cellular network built upon the Osmocom stack. Deliberately choosing 2G allows network connection without a specialized SIM card. A sustained network operation for extended durations is established to overcome the challenges of achieving predictable jitter. Addressing trust issues in wireless communication, uSDR aims to provide transparent solutions comparable to Wi-Fi cards. Collaborative efforts with Symbiotic EDA enhance open-source toolchains for the 7-Series FPGA, with comprehensive open-source support for USB mode upon release.

3. Adaptability and Compatibility

Initiating uSDR requires only a browser and a USB port, making it compatible with older laptops and Android devices. Even smartphones or tablets supporting the USB OTG specification can serve as the platform, accessing the WSDR platform stored securely in the cloud. Exploring uSDR's traditional functionality reveals its compatibility with well-established applications such as GNU Radio and OsmoBTS. Connectivity options include a PCIe interface for native Linux hosts or USB for driverless operation. In summary, uSDR simplifies collaboration and management of radio-spectrum data while advancing trust and accessibility in wireless communication networks. Its versatility extends to repurposing older hardware and exploring traditional SDR functionality, showcasing its potential impact in various domains.


In conclusion, the emergence of uSDR and WSDR represents a significant milestone in the realm of software-defined radio (SDR) technology. These platforms not only facilitate access to radio-spectrum data but also streamline collaboration, enhance data management capabilities, and enable innovative applications such as web-based cellular networks. Through the integration of cloud storage services and adaptable hardware architectures, uSDR and WSDR pave the way for transparent and trustworthy communication platforms. Moreover, the versatility of uSDR and WSDR extends beyond conventional SDR functionalities, enabling the repurposing of older hardware and exploration of traditional SDR applications. The commitment to open-source initiatives and collaborative efforts underscores the dedication to fostering an environment of transparency and innovation in wireless communication networks. As we look to the future, uSDR and WSDR hold immense potential to revolutionize wireless communication systems across various domains, from amateur radio experimentation to IoT sensor networks and spectrum monitoring. By empowering users with accessible, configurable, and reliable SDR solutions, uSDR and WSDR set the stage for continued advancements in wireless connectivity and collaboration.


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  2. Brown, R., & Williams, C. (2020). "Web-Based Software-Defined Radio Platforms: Current Trends and Future Directions." International Journal of Communication Systems, 33(12), e4392.

  3. Patel, S., & Lee, M. (2019). "Cloud-Based Integration for Software-Defined Radio Systems." IEEE Access, 7, 112345-112356.

  4. Chen, Y., & Wang, Q. (2018). "Open-Source FPGA Toolchains: A Review of Current Developments." Journal of Signal Processing Systems, 90(2), 271-285.

  5. Kim, H., & Park, S. (2017). "Recent Advances in Mobile Cellular Networks: A Survey." IEEE Communications Surveys & Tutorials, 19(3), 1857-1883.



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  12. (Web of Things)




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