I’m having a very interesting conversation with you and gave me some good ints.
Well the GSM/GPRS module seems to be only way, it offers everything I need and doesn’t require big RF skills to work.
The option that I like most is the one proposed by xaxaxa, it combines a chip with all the dirty stuff inside but doesn’t remove all the fun and magic behind playing with RF, I was searching a chip like the ax5043 for quite a long time, thank you very much!
The LoRa module is also a good competitor, but like the other solutions (except the GSM/GPRS one) “isn’t legal” on long range.
I know that I need big antennas at this low frequency but the bigger problem is what is the best frequency? For me higher is better because everything becomes smaller, but how higher frequency signals behave during the transmission and the enviroment attenuation doesn’t increase with frequency?
I’m quite sad that the GSM module is the best competitor because I really like stuff like PLLs and similar and making a wireless system out of these less integrated components should be amazing, unfortunately my knowledge is to limitated (at least for now, I hope to learn a lot from school) and this type of things is too far from me; chips like the ax5043 seems to be a good trade off between fun and not too complex design (I’m really curious to see the schematics about this IC).
Another interesting solution is the one offered by the rfPIC12F675 that combines the PIC MCU and UHF transmitter, the only problem is that includes only the transmission module but not the receiver one
Thanks to everyone, I appreciate your accuracy while sharing with me your experiences!