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

[Sukuri]

@dontsovcmc thanks for that. I've test it but still low RSSI. These are my current settings:

LoRa.setSpreadingFactor(12);
LoRa.setSignalBandwidth(125E3); LoRa.setTxPower(17, PA_OUTPUT_PA_BOOST_PIN); LoRa.setCodingRate4(5);
LoRa.setSyncWord(0xF3);
LoRa.setPreambleLength(6); LoRa.enableCrc();

I'm not sure, maybe it's from my hardware problem. By the way, thanks again :)

[halukmy]

@boonkerz i got that error before, just change 868E6 to 433E6 ;) it will rock'n roll

[KE6MTO]

The antenna may be questionable. May not be the same boards, but here is a youtube video of someone who tested the antenna's that came with some of the cheep LoRa boards: https://www.youtube.com/watch?v=CJNq2I_PDHQ

Needless to say, they weren't good...

I got new antenna's from Linx (purchased via Mouser): https://linxtechnologies.com/wp/p/antennas/small-external-antennas/

[cassiolucas]

Hello guys,

I have the same issue, currently I am using arduino uno and NiceRF1276 lora modules on both ends, but, the RSSI value is around -60 and both arduino are just side-by-side...

Did any of you find a solution for this?

[sandeepmistry]

@cassiolucas please see https://github.com/sandeepmistry/arduino-LoRa/blob/master/API.md#tx-power maybe you need to try an additional parameter?

[sandeepmistry]

@DussanR any progress on this?

[dontsovcmc]

@cassiolucas are you choose frequency right? :/ @sandeepmistry what parameters can you offer?!

[DussanR]

@sandeepmistry i added the second parameter and it's basically the same. i get 60-70 in the same room, and around 100 in my backyard

[cassiolucas]

Hello @dontsovcmc, yes the right frequency 915Mhz.

@sandeepmistry I believe this cannot be improved, I have tested a different library for arduino and the RSSI was only around 10 dBm better...

@DussanR Yes I have also done a lot of tests with the parameters from API.md but still the same, I just dont understand why its said that this module can work in long range (2km between buildings) but on my tests I didnt get even close to 1km.

[dontsovcmc]

@cassiolucas check RF settings for better distance. You should choose good antenna! I got 1 km through buildings with very fast (bad) settings with +5dBm 20cm antennas: power: 20 dBm, 62.5kHz, SF 8, CR 4/6 -20 RSSI ~ 5 sm -50 RSSI ~ 5 meters.

[cassiolucas]

@dontsovcmc can you please share your code and how were you able to set the +20dBm power as well as the other settings 62.5kHz, SF 8, CR 4/6 ?

Also, did you build your antenna? do you have pictures of your LoRa modules and antenna?

The Lora module and antenna which I am currently using is:

[dontsovcmc]

@cassiolucas check this commit for +20dBm https://github.com/sandeepmistry/arduino-LoRa/pull/79 I cant' understand, you got good RSSI or not? Remember, it it library for chip, not for board. API can be little different between boards. For example, antenna pin. I can't understand why NiceRF connect digital IO pins to MCU. Please check modules with home library (lora_slave, lora_master): http://www.nicerf.com/product_146_136.html, password "nicerf" works (=)).

If success, try to understand differences with sandeepmistry library...

[cassiolucas]

Hello @dontsovcmc Ok I will check the NiceRF examples codes.

Do you know how can I get the RSSI values using the NiceRF codes?

[cassiolucas]

I have found how to read the RSSI and just by uploading the TX and RX code from Nicerf I get around +47 dBm as RSSI when the node is just 1 meter away.. I wasn't expecting a positive value for RSSI...Or maybe I am not reading it correctly from the library?

[sr58977]

@cassiolucas hiii... can you please mention the code for RSSI from nice rf library, it will glade to you...

thank you

[AsyDynamics]

@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);

@sandeepmistry Hi, can you give little bit more explanation of the RFO mode of ai thinker module, or is there any link because I cannot find on google. Wondering if what you said means the max power of ai thinker module is +14 ? Thanks