🐞 [Bug]: nodes UIs always shows “signal good” when RSSI value is unknown (indicated by 0)

[powersjcb]

Firmware Version

2.5.*

What did you do?

View nodes list page

Expected Behavior

It should show unknown or some other indicator if the data is missing. Ideally hiding the value when zero.

Current Behavior

UI shows 0 and “good” signal when only SNR is present.

Participation

• I am willing to submit a pull request for this issue.

Additional comments

I don’t have a lot of context on this could use help defining more clear behavior when data is missing.

[garthvh]

Rssi is included in the snr and only tells us if there is noise, not sure what this would do

[powersjcb]

I think something might still be wrong in how we display this. I'm pretty sure our code assumes RSSI is always present, but a value of 0 represents. ("not available") Using RSSI of 0 would be extremely an strong signal.

This RSSI of 0 (actually null) seems to be getting plugged into some calculation for how we display link quality. ("good" "bad" "fair") I haven't dug into the source for this, but it looks like we are using something like SINR.

See these two nodes:

node 1: {
  rssi: 0 // actually an unknown value
  snr: -15
  display: "good"
node 2:
  rssi: -121
  snr: -10.75 // better signal to noise ratio than node 1
  display: "bad"

The node 2 has better SNR, but it's still showing up as a worse link than node 1.

[powersjcb]

Yup, it looks like our code assumes that RSSI will always be available. (which isn't the case)

func getLoRaSignalStrength(snr: Float, rssi: Int32, preset: ModemPresets) -> LoRaSignalStrength {
	if rssi > -115 && snr > (preset.snrLimit()) {
		return .good
	} else if rssi < -126 && snr < (preset.snrLimit() - 7.5) {
		return .none
	} else if rssi <= -120 || snr <= (preset.snrLimit() - 5.5) {
		return .bad
	} else { return .fair }
}

I'm going to update this logic to ignore rssi when it's value is 0.

[powersjcb]

Per the discord #firmware channel

RSSI is not stored in NodeInfo, only SNR. So, if you haven't received any data from a node after connecting, you'll only see the SNR.