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.
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!
I recently came into possession of a C22 handheld transceiver from Retevis.
The C22 is an alternative version of the C62, which is believed to be the same (or a very similar) radio, just with different firmware (with its interface using cyrillic script)1. Both C22 and C62 are advertised as analog FM handhelds with some super-duper fancy AI noise cancelling technology. A fellow ham, Ferdy EB5DQ, recently shared a video on YouTube2 showing the C62 with a cryptic “Digital” mode enabled. The mode is undocumented and can only be enabled through the CPS.
