[sudo-discuss] diaster.radio modulation scheme tests

[Marc Juul]

Wow very nice!

Were the quarter and half wave antennas both DIY?

On Wed, Apr 25, 2018 at 9:38 PM, Adam <me at adammunich.com> wrote:

> 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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>
> I seek to understand, and aim to create.
> Weblog: http://adammunich.com
>
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