| > charge at least 5-10x more for wildly different hardware, use hundreds of times more power, etc So I think what's super interesting is that it not necessarily need to be 5-10x more, nor needs hundreds of times more power. I'll start with the power argument first. WSPR (pronounced "whisper") often uses 100mW transmissions and can be heard across the globe in the HF spectrum. The techniques for reception can pull the signal out of the noise. It's common for weather balloons to send telemetry this way. People use it to monitor band conditions as well. The trick is that WSPR puts all the power into one signal approximately 6hz wide. That's why it's so efficient, and one reason why it can be heard across the globe with such low power. Now you're probably not going to get that distance in the 900Mhz ISM band, but you will be heard further if you so choose (or need to be). As per cost? 100mW assuming a 75ohm antenna (dipole) is 36mA of current. For 1W (which is roughly the ISM limit) it's 115mA of current, so the components won't need to be high power, probably jelly bean parts. The RTLSDR is $25 bucks with 2.4Mhz bandwidth which is way overkill for this. Lots of microcontrollers are cheap. There's engineering cost and time, sure, but Meshtastic did show that a need for reliable mesh low power messaging exists even if it's not the final form. |