Our Nokia 3310/3330 replacement board with 70cm band FM/FSK/M17 support can now be purchased through PCBWay. All of the sales commission goes to the M17 Foundation.
Sample firmware for the MCU provides M17 messaging support with T9 text entry method. The device can be powered with original Nokia lithium-ion batteries or their replacements and is able to charge them through the USB-C port. A UART USB interface is available, allowing the device to work as an RF modem.
The device is a minimalistic PMOD RF shield featuring the Semtech SX1255 IQ transceiver. The device supports virtually any amateur radio mode, including TETRA, and covers 400-510MHz range. The baseband interface is I2S compatible (full duplex).
I performed a quick test to check the harmonic content of the RF signal generated by a CC1200 hotspot. Here’s the spectrum plot for a +14dBm M17 signal at 433.475MHz:
The CC1200 hotspot shield for Raspberry Pi can now be ordered through PCBWay. This shield offers frequency mod/demod capabilities, and can be used for analog FM, M17, and APRS. DMR support was not tested.
The SX1255 RF hotspot shield for Raspberry Pi can now be ordered through PCBWay. The sales commission goes to M17 Foundation. Follow the link below to learn more.
When introducing my fellow Austrian hams to M17, I kept hearing the same question: “How does it sound?” This coincided with my desire to experiment with Rust and WebAssembly, creating the perfect opportunity to build a tool that would answer this question while expanding my programming skills.
How it works
m17web consists of three main components connecting to mrefd and working together to bring M17 digital voice to your browser. The system listens to UDP traffic from M17 reflectors, routes it through a proxy server, decodes the audio in the browser using WebAssembly, and presents it through a clean web interface—all without requiring any special hardware or software installation.
You can’t have your cake and eat it, a well-known proverb says. The state of this proverbial cake is strictly determined – it exists in exactly one of two possible states. This is very similar to the rules of Boolean logic – there are two (bi-nary) significantly different values for a logic sentence – true or false, or 1 and 0.
Real-world problems, including measurements, might not always have a strictly defined logical value. Imagine a blue square. The statement “the square is blue” is obviously true, whereas “the square is green” is undeniably false. But what if the square was turquoise, having a shade that’s a mix of both colors? What the logical value of “the square is blue” would be then? False? Or maybe something in between? This is exactly where Boolean logic fails, but soft logic offers a solution.
TYT MD-380 was one of the first platforms to receive M17 support through OpenRTX open-source firmware. A small modification was found out to be required to make it work with our protocol (its stream mode for digital voice). Many MD-380 users performed the required surgery.
Fast forward to Jan 2025: Rick KD0OSS provided a piece of code making it possible to receive and transmit M17 packets – text messages!
