Hi all, 

I ran some tests on LORA modulation schemes to get the best results I could on a 100mW TX power budget. 

I nearly ran out of gas during this latest test, and unfortunately I managed to screw up my data logging, so I don't have RSSI or SNR data, but this map contains all the places I stopped and got a two way signal on my jet ski.

The transmitter was in my hand, the receiver was at pier 50, SF. 

DIY half wave dipoles were used, with a center freq of 900MHz with a +/- 100MHz 3db roll off. 

https://www.google.com/maps/d/u/0/edit?mid=1dE2QZS9cgX_oHLWyzmUNAYrjlbX0wJpE&ll=37.75708554224248%2C-122.33675183183021&z=13

I found that quarter wave antennas are no good (see the red markers). The blue markers are today's test, using RFM95's from HopeRF.

To get the very long range, I used the following modulation scheme using the RadioHead library.

RH_RF95::ModemConfig modem_config =

{

/*Reg 0x1D: BW=125kHz, Coding=4/8, Header=explicit*/

(7 << 4) | (4 << 1) | (0),

/*Reg 0x1E: Spread=4096chips/symbol, CRC=enable*/

(12 << 4) | (1 << 2),

/*Reg 0x26: LowDataRate=On, Agc=On*/

(1 << 3) | (1 << 2)

};

RF95.setModemRegisters(&modem_config);

In other news, you can still jet ski if your core body temp is 88F. Little unpleasant though.

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