SOCORAD32, a.k.a. the ESP32 Software Controlled Radio, is a professional-quality, hackable walkie-talkie for amateur-radio exploration, voice communication, and data transfer using simple AT commands. Just add a speaker, connect a battery, and you’ll have a fully functional walkie talkie radio. With its dedicated push-to-talk (PTT) button, SOCORAD32 can be used straight out of the box without touching a single line of code!

Unlike complicated SDRs, SOCORAD32 is tailored to amateur-radio applications and optimized for simplicity. Using basic AT commands, you can configure audio volume, tone squelching, CTCSS, CDSS codes, etc. SOCORAD32’s frequency range covers the license-free bands for most countries.

SOCORAD32 also features all of the operations of a standard walkie-talkie. It employs a proprietary RF design featuring the RDA1846 IC. This same IC is used in commercial walkie talkies such as Baofeng, Motorola, and Hytera. Because of this, SOCORAD32 can communicate with commercial walkie talkies when configured to do so. So how is SOCORAD32 different from such a commercial walkie talkie? It includes built-in functions, features, and high-level configurability that make it perfect for exploration.

SOCORAD32 prototype. Final product assembled by PCBWay

SOCORAD32 can send and receive data, which means you can use it to exchange texts or to explore the amateur-radio frequencies set aside for IoT applications. Received text can be read via the onboard OLED screen or on a bluetooth-connected mobile device. Best of all, it’s fully open source and hackable. If you want to explore the intricacies amateur radio, build a portable transceiver, or poke around with long-distance audio- and data-communication protocols similar to LoRa, this device not only allows you to do so, it makes doing so easy and fun! Its frequency range covers the license-free bands in most countries, we’ve added an 18650 battery holder and a charger to the design, and we’ll be publishing design files for an enclosure soon!

Designed for Exploration

Thanks to the ESP32 module’s Bluetooth functionality, you can configure all settings through a connected mobile device—via the serial Bluetooth app of your choice—rather than using the dedicated buttons. And the ESP32’s onboard memory allows you to store as many channels as you could possibly need. Advanced users can even tinker with the RF module and optimize the power amplifier, the antenna, the filter, the matching circuit, etc.

SOCORAD32 prototype. Final product assembled by PCBWay

Features & Specifications

• Frequency Range: 400 - 470 MHz (covers most countries allocated license-free Walkie Talkie bands internationally)
• Frequency Step: 5 K / 6.25 K / 12.5 K / 25 K
• RF Output Power: 2 W / 0.5 W (+5 KM @ 2 W) set to what the local law permits, see video below
• RF Input Sensitivity: -122 dBm (see video below)
• Voice Scrambling: Support for eight different methods
• Voice Compression & Expansion
• SMS Exchange: Send and receive SMS (or, for IoT, send and receive data)
• CTCSS (38 group) + CDCSS (83 group)
• Automatic Tail Elimination: Eliminates the squelch burst often heard at the end of a transmission as the PTT is released
• Volume: Adjustable speaker output (1-8)
• Sample AT Commands to Configure Settings:
  • To turn on voice-operated exchange (VOX), use AT+DMOVOX=X, where X is the sensitivity level (1-8).
  • To control speaker volume, use AT+DMOVOL=X, where X is the loudness level (1-8).
  • To change communication parameters, use AT+DMOGRP=RFV, TFV, RXCT, TXCT, Flag, Flag1, where RFV = receive frequency, TFV = transmit frequency, RXCT = CTCSS/CDCSS coding, TXCT = CTCSS/CDCSS transmit coding, Flag = busy locking/band setting (narrow or wide), and Flag1 = transmit power settings high (2 W) or low (0.5 W).
    • Example: AT+DMOGRP=450.02500, 450.02500, 7006, 7006, 0, 0

Comparisons

TX Power at 2 W

Receive-Sensitivity Test at -120 dBm

SMS Demo

The following images shows the simplicity of sending texts

Step 1

SOCORAD32 TX data transfer

Step 2

SOCORAD32 TX data transfer

Step 3

SOCORAD32 RX data transfer

Versatile & Extensible

SOCORAD32 is appropriate for a wide range of project, including:

• Walkie-talkie applications
• Intercom applications
• Pager applications
• IoT applications via the data-transmission module
• Voice-activated audio-monitor applications
• Amateur-radio experimentation

Support & Documentation

All documentation and project files are available in our GitHub repository. To maintain cohesion and organization, we will be using this repo for all things SOCORAD, including forum discussions, questions, support, collaboration, etc.