Bad RSSI

[DussanR]

When sending in a room no more than 2 meters apart, i get a RSSI of around 70. In the backyard through a couple of walls and 20 meters tops a RSSI of 105.

I wanted to make this better, but i don't quite understand how to use the setTxPower. If someone could help me i would really appreciate it!

[dontsovcmc]

I use https://www.ebay.com/itm/LoRa32u4-II-Lora-LiPo-Atmega32u4-SX1276-HPD13-868MHZ-EU-Antenna/282623601184 with external antennas 20cm.
I see very strange RSSI -115 when distance is 1 meter 👍 (
LoRa.setTxPower(17);
LoRa.setSignalBandwidth(31.25E3); /
LoRa.setSpreadingFactor(7);
LoRa.setCodingRate4(5);

Is it normal?

[sandeepmistry]

@DussanR what hardware are you using?

Do you have the correct antenna's for the frequency you are using?

https://github.com/sandeepmistry/arduino-LoRa/blob/master/API.md#tx-power

For AI thinker modules RFO is used for power instead of PA boost. so you could try:

LoRa.setTxPower(14, PA_OUTPUT_RFO_PIN);

[DussanR]

I am using a dragino shield on an arduino uno. I have the antenna the shield came with.

Would it be something like ... ?

LoRa.setTxPower(17, PA_OUTPUT_PA_BOOST_PIN);

Thanks!

[dontsovcmc]

For my problem: I can't find the reason ( Sometimes RSSI is -70, sometimes -20 (normal) for 30cm.

[sandeepmistry]

@DussanR LoRa.setTxPower(17)l or LoRa.setTxPower(17, PA_OUTPUT_PA_BOOST_PIN); is fine.

Do you have a photo of the shield? Are you passing in the correct frequency into begin that the board and antenna are designed for?

[DussanR]

This is the shield:

http://wiki.dragino.com/index.php?title=File:Lora_Shield_v1.4.jpg

With the second parameter do i have to declare a new pin?

And yes, i have the shield/antenna for 915 and using the LoRa.begin(915E3)!

[sandeepmistry]

With the second parameter do i have to declare a new pin?
Nope.

I have the same shield here, and am getting reasonable RSSI.

What board are you connecting the shield too?

[DussanR]

To an original arduino. Odd, what could be the problem?

[sandeepmistry]

Could be the 3.3V doesn't have enough current or power source generating noise?

I've been using and Uno with the shield.

[DussanR]

I’ll try using the second parameter, cause i’ve used different arduino unos with the same problem.

Thanks!

[boonkerz]

i have the same issue.
Only when i place both near by i can transmit and receive messages. (2cm)
Arduino UNO with DRF1278F

[Sukuri]

Hi, I'm using arduino uno with RFM95 915MHz (arduino uno shield), can I use LoRa.setTxPower(17, PA_OUTPUT_PA_BOOST_PIN); as well?
Is it really limited to 17 because from datasheet maximum is +20dbm,
and the pin called PA_BOOST, or just use PA_OUTPUT_PA_BOOST_PIN?

I use the example code with SF11 and distance 0.5m, but RSSI -79

[dontsovcmc]

I see RSSI -20 with SX1276 ~0.5m.
I think LoRa.setTxPower(17, PA_OUTPUT_PA_BOOST_PIN); is not needed, cause it has been already called somewhere (check LoRa.begin())

[Sukuri]

@dontsovcmc thanks. But I've still no idea about my RSSI, I only can get -20 for a few centimeters.
What SF you are using?

[dontsovcmc]

check https://www.elecrow.com/wiki/index.php?title=Lora_RFM95_Shield-_915MHZ
(use another RadioHead library example)
or check RSSI with:
setTxPower(14, PA_OUTPUT_RFO_PIN) for both modules & check RSSI
setTxPower(14) for both modules & check RSSI