Comment by rm30
1 month ago
The project is interesting, the concept too, the idea of indipendent communication tools also.
I'll tell you a story.
Usain Bolt, the world 100/200m recordman, is not faster than cheeta. He needs a motorbike or a car to be beat a cheeta. But even with a car or motorbike is unlikely is going to overtak a cheeta on the ground of savannah.
This to tell you are thinking about optimizations of a system while you need to choose the right system for the environment.
A 433 MHz based link and a strong modulation is much suitable solution than a BT class 2 device included in the phone.
And here the real hack, most of phones has an integrated FM receiver, higher sensibility than BT, a simple FM transmitter (88-108 MHz) and problem solved.
but for that to work, you need to attach an antenna, no? and where do i get such an FM transmitter? AND android does not support it in the software level, and there's no protocol for the waves?
To have an FM receiver work on a phone, you do need an antenna, the wired headphones serve that purpose perfectly. An FM transmitter is easy to find; you can use the simple 'Jack-to-FM' adapters designed for car radios, or much better, a USB SDR (which can range from a few kHz to GHz).
Regarding the 'protocol for the waves,' you'll need to play with modulation. That’s the fun part. In technical literature, there are many well-defined modulations (like AFSK or FSK) with clear suggested applications for low-SNR environments.
As for Android support, I have no idea. I understand that in this thread, 'free' sounds like 'freedom,' but freedom has a cost. The freedom of communication requires investment: in hardware, software, and the time to learn the physics of the environment.
hm, than i think it's better to use the LORA stuff, no? if i need an external device with my device anyway, i can use one of them.
because the fun thing is cool, but people want some usable...
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