Lopy restricted to 14dBm in europe

[Cortez]

I'm planning to transfer data from my small hydropower plant to my house through Lora modules and I'm in search for the right hardware.
The distance to bridge is 1km Non line of sight ,so maybe I will fall short of power with the 14dBm restriction.
Is there an easy way to get the full 20dBm out of Lopy @ 868MHz ?

[mfalkvidd]

@Cortez are you asking for advice on how to override the legal limit?

[Cortez]

@mfalkvidd No,never-I'm only interested!

[Cortez]

@mfalkvidd till this day I'm using a 500mW ISM radiomodem and I want to get rid of it-too expensive and runs out of production.

[robert-hh]

@Cortez TTN uses 869.525Mhz/SF9 in the RX2 window for replies with higher energy, 500mW = 27dB, 10% DC (see https://github.com/TheThingsNetwork/ttn/issues/155). That is permitted. Otherwise use good antennas. 1km is not that far away.

[Cortez]

@robert-hh Thank you.Do you know if I can tweak the settings of the Lopy module to get full 20dBm transmit power?
I'm new to pycom hard and software-with adafruit RFM95 it is possible.

[robert-hh]

@Cortez You cantry to set in the lora instantiation tx_power=20. The Lora module just checks, whether the setting is between 2 and 20. But I could not tell from the code whether that sets the modem to 20dB power. I might have to check.

[Cortez]

@robert-hh It would be interesting if the module unlocks the power if set to 20dBm?As an example ,in the description of the adafruit RFM 95 there is clearly declared you can choose 20dBm - Maybe someone from Pycom can tell ....

[rskoniec]

@Cortez According to the Docs:

tx_power is the transmit power in dBm. It accepts between 2 and 14 for the 868 band, and between 5 and 20 in the 915 band

so you have to check if it would be possible to pass values greater that 14 for EU868.

[robert-hh]

@Cortez Setting tx_power=20 increases the transmitted signal. I have no power meter. I just can see a change to about twice the amplitude (4 times the power) in my 'guessing' tool compared to tx_power=14.
I'm using v1.20.0.rc11.2, Lopy4
P.S.: Between changes of the settings I have to push the reset button to make the change effective. Ctrl-D or power-on is not sufficient.

[robert-hh]

@Cortez I should add that I made a receive test with a Lopy to a few gateways around, one of them in my place. it is a city/village area with quite a few buildings, but not many closed blocks. To my home antenna, Aurel GP, which is a simple 3dB ground plane antenna placed outside, distances up to 2.5 km were possible. Another gateway with a very good high positioned antennas (loking like a Taoglas barracuda) picked up the signal in up to 8.6 km distance. A third with an Aurel GP antenna received it at 5 km distance. That place is on the top of a hill with free sight to the area.
So the best you can do is attach a good outdoor antenna to your gateway.

[thinginnovations]

Have you actually tried to see if you can transfer data at this range?
You may need to try alternative spreading factors to be sure but 1km is readily achievable without having to resort to breaking regulations on plower limits.

Andrew