Walkie-talkies are well-known devices that allow communication without any network support or phone charges, providing great convenience in our lives. The typical walkie-talkie consists of an antenna, host unit, battery, and charger. Walkie-talkies can be divided into three main categories: analog, digital, and IP walkie-talkies. So, how can we make a digital walkie-talkie?
Ebyte's newly launched EWM201 series modules offer a quick and easy solution. By simply connecting a microphone (MIC), audio amplifier, speaker, antenna, and power supply, you can DIY your very own walkie-talkie with a 5-kilometer communication range.
Preparation
To complete this DIY project, you should have some basic knowledge of electronic circuits and be well-prepared.
Materials: Ebyte EWM201-470A30S module, microphone (MIC), speaker, passive components (resistors, capacitors), etc.
Tools: Soldering iron, solder wire, tweezers, etc.
Documentation: User manual for the EWM201-470A30S module, recommended circuit diagram.
Software: EDA (Electronic Design Automation) software.
Designing the Circuit Diagram
Based on the pin functions of the EWM201-470A30S module, design the surrounding circuits, including the microphone amplification circuit, speaker driving circuit, power supply circuit, control button circuit, antenna output, etc. You can refer to the recommended circuit diagrams provided on Ebyte's official website for guidance.
For the microphone section, the audio signal captured by the microphone must be amplified before being fed into the audio input pin of the EWM201-470A30S module.
The speaker section involves using an audio power amplifier chip to amplify the audio signal output from the EWM201-470A30S module to drive the speaker, producing sufficiently loud sound. The volume and sound quality are somewhat dependent on the quality of the speaker you choose.
Ensure to determine the parameters of the components, such as the values of capacitors, resistors, and inductors. You can refer to the datasheets of the relevant chips and previous design experiences for these values.
PCB Fabrication and Soldering
Once the circuit diagram is designed, use specialized PCB design software (such as KICAD or Lichuang EDA) to create the PCB layout and complete the soldering process.
Debugging and Usage
After ensuring the circuit's safety, power it on and use instruments like oscilloscopes to observe the signal waveforms at key nodes, such as power supply voltage, audio input/output signals, etc., to verify that they meet the design requirements.
Test the microphone and speaker functionality by speaking and listening to check if the audio signal is correctly captured and played back. If the sound is too quiet or there is noise, check if the audio amplification circuit and related components' parameters are correct and verify there are no soldering issues.
At this point, you can start using your DIY walkie-talkie.
Optimizing Performance
If you want to achieve the best working condition for your DIY walkie-talkie, you may need to use instruments like a spectrum analyzer to check the transmission and reception frequencies, transmission power, and reception sensitivity of the EWM201-470A30S module. If there is a significant frequency deviation, adjust the relevant components such as inductors and capacitors to achieve optimal performance.
Testing Kits for Easy Setup
We also provide the EWT201-470A20S/30S testing kits, which are easy-to-use digital walkie-talkies. These kits correspond to modules with transmission power of 20dBm and 30dBm, respectively, enabling users to perform voice communication tests over 3.5 km or 5 km.
Using the EWT201-470A20S/30S testing kits, simply connect the antenna, power it via a power bank, press the PTT (Push-to-Talk) button, and switch both transceivers to their respective transmission/reception modes. Communication is then possible. You can also add an external case for a more aesthetically pleasing design.
Communication Modes and Features
The DIY walkie-talkie based on the EWM201-470A30S module supports three communication modes: unicast, multicast, and broadcast. To configure these modes:
Frequency Configuration: First, communication isolation can be achieved by setting different communication frequencies. Walkie-talkies with the same frequency can communicate, but to group them, you need to configure the PANID (Personal Area Network ID). Walkie-talkies with the same PANID can communicate within the same group.
Unicast Communication: To enable unicast, set the DESTID (Destination ID) to a non-zero value to specify a particular walkie-talkie.
In addition to these three transmission modes, the walkie-talkie also supports half-duplex and full-duplex communication.
Half-Duplex Mode: Only one walkie-talkie can speak at any given time in the same network.
Full-Duplex Mode: In full-duplex mode, there must be one host unit (main unit) and one terminal unit (subunit). These two units can send audio simultaneously.
With these features, your DIY walkie-talkie can be used in a wide range of scenarios beyond traditional walkie-talkie communication. It can be adapted to build intercom systems where precise communication with specific individuals is needed, or even used as a wireless audio broadcasting system. The possibilities are endless!