LQ and RSSI Explained for ExpressLRS and Crossfire

by Oscar

LQ and RSSI can be used to determine how good our radio link is. I will try to explain the differences between LQ and RSSI in popular radio systems such as ExpressLRS and Crossfire, and show you how to set it up in Betaflight OSD and OpenTX to monitor your link quality and signal strength.


Further Reading:

What is RSSI?

RSSI​ (Raw Signal Strength Indicator) is an indicator of how strong, or “loud”, the received signal is.

RSSI is measured in dBm (decibel milliwatts), it’s a logarithmic scale as compared to mW which is a linear scale. RSSI starts from 0 as the highest value, and goes down as signal decreases. -130dBm is the hard limit, however the theoretical lowest RSSI is usually higher than that depending on the update rate and signal frequency.

The reason we use dBm and not mW when talking about signal power is because the receivers can detect signal so weak (e.g. -120dBm is 0.000000000001mW), there’re so many zero’s, it’s probably easier to just say the value in dBm. Here’s a conversion table between dBm and mW.

Power (dBm) Power (mW)
-130dBm 0.0000000000001mW
-110dBm 0.00000000001mW
-90dBm 0.000000001mW
-70dBm 0.0000001mW
-50dBm 0.00001mW
-30dBm 0.001mW
-10dBm 0.1mW
0dBm 1mW
10dBm 10mW
20dBm 100mW
100dBm 10000000000mW

In Betaflight OSD, you have two different options regarding RSSI: RSSI Value (in percentage) and RSSI dBm Value. RSSI in percentage isn’t very meaningful as the failsafe threshold is different across RC systems, even packet rates. RSSI_dBm is the true measurement of signal power, and that’s the one we want to use.

Modern RC systems such as ExpressLRS, Crossfire and Tracer all have RSSI dBm value reporting built-in, you don’t need to do anything, simply enable it in the OSD element and you are good to go. However, some older RC systems such as Frsky and Spektrum only support RSSI in percentage and don’t report RSSI dBm, in which case you have no choice but stick with it.

What is LQ?

LQ (link quality) is the percentage of data that gets through without getting corrupted due to noise or interference.

When displaying LQ in your OSD, you will see something like 3:100. The first number represents RF Mode (“RFMD” in telemetry data) and the second number represents LQ.

RFMD indicates the packet rate of the radio link. For example ExpressLRS’s fastest update rate is 500Hz, the RFMD for this would be 7, and when you display LQ in the OSD, you will see something like 7:100.

RFMD Packet Rate
7 500Hz
6 250Hz
5 200Hz
4 150Hz
3 100Hz
2 50Hz
1 25Hz

In Crossfire, RFMD only goes up to 3 because the fastest packet rate is only 150Hz. At RFMD 3 it’s 150Hz, with RFMD at 2 it’s 50Hz, and with RFMD at 1, it’s 4Hz.

Crossfire has the ability to dynamically adjust packet rate, meaning when LQ drops, it will switch to a slower packet rate in order to maintain a reliable control link (because a slower packet rate has higher sensitivity as mentioned). If you ever see LQ drops below 70% you should turn back immediately!

You can also display a combined RSSI/LQ value in Betaflight OSD, it will always show the worse value between the two (RSSI is in percentage). This can be useful if the used OSD only has one input for radio link statistics.

LQ and RSSI, Which Is More Important?

LQ and RSSI are both useful metrics to determine your range and how good your radio link is, it’s best to have both.

If you can only have one, then LQ is probably slightly more useful in my opinion. Say if you have only 70% LQ you can still fly just fine, but when LQ gets too low, you might get a failsafe (radio link between transmitter and receiver is broken), this could happen even when your RSSI was still high.

To know the range limit based on RSSI, you also need to know the noise floor. Heavy noise level can screw up the RC link all the same regardless how strong the signal is. Noise floor depends on many factors including the environment and the components in your drone.

A good analogy for this is to think of the receiver as the person you are trying to talk to in a noisy restaurant, and you are the transmitter. When you are talking, the volume of your voice is RSSI, the other person can hear you and understand everything you are saying, and LQ would be 100% in this case. What really matters here is not how loudly I speak, but how many words you can hear and understand.

However, if you fly long range, then you should not relying solely on LQ. LQ tends to decrease non-linearly, it can stay high most of the time, then suddenly dip rapidly at the end of your range. RSSI is usually more predictable in that regard, it goes down gradually with range.

You can understand the condition of your radio link a lot better using both LQ and RSSI. For example:

  • high LQ, high RSSI = healthy radio link
  • low LQ, high RSSI = noisy RF environment
  • high LQ, low RSSI = you are very far away and should be cautious, or if the model is very close to the transmitter, that can be an indicator that something is wrong with the antennas
  • low LQ, low RSSI = reaching the end of your range, failsafe is likely to happen

The Ideal LQ and Lowest LQ

In Crossfire, when you are in the RFMD 3, LQ is kind of irrelevant and you can ignore it. Because the system will switch to a lower RFMD if it requires better link quality. You should start paying attention to LQ in when RFMD drops down to 1. If the signal quality continues to deteriorate it will change to the super slow packet rate which only gives you 4Hz update rates. At this rate it’s okay to bring a wing/plane home, but it’s hard to control a multirotor. A healthy long range link (RFMD 1) should stay above 90%. LQ of 70% of lower is considered bad in Crossfire, If you see this you should turn back ASAP! If it’s consistently lower than that then you should check your antenna and frequency setting for potential setup errors.

However ExpressLRS doesn’t dynamically adjust RFMD like Crossfire, so you should pay attention to LQ at all time. You can also configure ELRS to dynamically adjust transmit power according to RSSI and LQ.

When LQ drops to around 70% or 60% you should pay attention to RSSI dBm, and see if you are perhaps reaching the limit of your range. (keep reading for more detail on RSSI)

The Lowest RSSI

The lowest RSSI allowed depends on the packet rate and frequency of the signal, both lower packet rate and lower frequency have a more sensitive signal, i.e. the sensitivity limit is lower which allows you to go further.

For example, according to the ELRS wiki, the lowest theoretical RSSI values for 2.4GHz 500Hz is -105dBm, but for 915MHz 25Hz, that is -123dBm which is better at long range.

DO NOT underestimate a few dBm difference, every 6dBm doubles the range! For example in ExpressLRS, if you drop the packet rate from 500Hz (-105dBm) to 150Hz (-112dBm), you effectively double your range and more!

For ExpressLRS, you can find out what the lowest RSSI dBm is if you go to the ExpressLRS LUA script, it’s next to the packet rate. E.g for 500Hz, it’s -105dBm.

Expresslrs Elrs Lua Script V2 Interface App

Or you can look it up in this table from the ELRS wiki:

Packet Rate Sensitivity Limit
500Hz -105dBm
250Hz -108dBm
200Hz -112dBm
150Hz -112dBm
100Hz -117dBm
50Hz -117dBm
25Hz -123dBm

These are the signal sensitivity hard limits at different packet rates, if the signal goes below the limit, you will definitely get a failsafe.

So what’s the lowest RSSI dBm?

Make sure your RSSI dBm is 10dBm higher than the sensitivity limit (the number you see in your OSD). For example if you are flying ExpressLRS 2.4GHz 500Hz (-105dBm), you should turn back immediately if RSSI drops below -95dBm. Some people push it and use 6dBm as the margin, but if you want to play safe just use 10dBm.

There is one problem though, RSSI dBm doesn’t take into account ambient noise, for example a powerful 2.4GHz WiFi router nearby. If the interference is strong it will reduce your range or even give you a failsafe before your RSSI reaching your sensitivity limit. Most of the time, noise isn’t really strong enough to be a concern at the places we normally fly, but we can still make sure by checking LQ. If RSSI is high, but LQ is low, then noise/interference could be the reason.

Some RF systems reports SNR (signal to noise ratio) such as Crossfire, but ExpreessLRS doesn’t do that yet.

RSSI Alarm

Betaflight OSD will warn you if RSSI dBm drops below certain value.

In CLI, enter the command:

set osd_rssi_dbm_alarm = -95

Allowed range is -130 to 20, default value is -60

Displaying LQ (The New Way)

Since Betaflight 4.1, displaying LQ or RSSI from Crossfire is made super easy. You no longer need to assign LQ or RSSI to an AUX channel in the receiver (LUA script). It just appears in Betaflight now, all you have to do is:

  • In configuration tab, Disable RSSI_ADC
  • In Receiver tab, RSSI Channel, select Disable
  • In OSD tab, you can now select Link Quality, RSSI in dBm, or RSSI

Previously in older Betaflight versions, LQ would only show a maximum of 99%, but it didn’t show 100-300 range, and so you couldn’t see the fluctuations between 150hz mode and 50hz mode.

Since BF4.2, LQ is displayed in a more complicated way but gives more info, we now have the RFMD value (0-2) followed by the LQ value (0-99).

  • 0: 70-100 (4hz mode, REALLY BAD)
  • 1: 100 (50Hz mode)
  • 2: 100 (150 Hz mode)

As long as your RFMD value is 2 (150Hz latency mode) you don’t even need to worry about the LQ value. Once the RFMD values drops to 1 (50Hz latency mode) you need to start paying attention to the LQ value because anything below 80 while in RFMD 1 is warning territory and 70 is in the critical danger zone (you need to turn back immediately). If you ever see an RFMD value of 0 then your quad is basically already falling from the sky.

Keep in mind that small losses in 150Hz mode are perfectly normal, they should remain within 10% on normal flying.

That’s it!

Note that you need Crossfire firmware version 2.94 or newer for this to work. Otherwise you will get 0 LQ and RSSI.

If you use an older version of Betaflight prior to BF4.1, then you’d have to following the instructions below.

Displaying LQ (The Old Way)

Prior to Betaflight 4.1 you have to use this method. You can also use this if you are using DJI FPV System as LQ doesn’t work.

Assigning Channel to Output LQ

Execute the “Crossfire” LUA script on your Taranis. (How do I do that?)

Scroll down to “Channel Map” and pick a spare Dst. channel and change it to “LQ”, for example channel 8.

crossfire lua script channel lq rssi

Displaying it on OSD

You can display this value on Betaflight OSD.

Go to the “Receiver” tab in Betaflight Configurator, select the Aux channel you are using for LQ. For Ch8, you should pick “AUX 4”. (minus the throttle, yaw, pitch and roll channels)

display lq rssi betaflight aux channel

In the OSD tab, you also need to enable RSSI to display the value on screen and that’s it :)

The value will stay at 99 most of the times, because LQ is ranged between 0 to 300, and RSSI is only designed to display 0-99.

When it drops below 99, it’s already in 50Hz mode, you should be looking at this number closely. And when you see it drops to 70, you should turn back.

Setup Low LQ Warning in OpenTX Radio

LQ in Crossfire can output a wider range than OpenTX can interpret (0-300%). Therefore it’s split into 2 separate values in OpenTX (sensors in the telemetry tab): RLQY and RFMD.

RLQY stands for Received Link Quality. It’s the amount of the transmitted signal received by the receiver in percentage (0% to 100%).

RFMD means the Received Frequency Mode, and there are 3 RF modes:

  • RFMD = 2 , 150Hz Mode,
  • RFMD = 1, 50Hz Mode
  • If RFMD = 0, 4Hz Mode (no telemetry)

Basically RFMD 2 is the Low latency mode for short distance flying and it provides the fastest update rate of 150Hz. Crossfire goes into RFMD 1 when you go for long range. If signal gets really weak, it will go into RFMD 0 and drop the update rate to 4Hz without telemetry.

By the way LQ can drop for a split second when it changes mode.

Here are what the logical switches are doing:

  • L01 – this switch is triggered when we are in RFMD 1 or 0
  • L02 – This is the warning switch. it’s turned on if L01 is on, and LQ is lower than 80%. There is a 0.5 second in case it’s just a glitch when mode is changing
  • L03 – This is the critical warning switch. It’s turned on if L01 is on, and LQ is lower than 70%. There is also a 0.5 second delay for the same reason

taranis opentx logical switch rfmd rqly play warning

Here are the Special Functions that play the audio warnings:

  • SF1 – it plays the sound “Warn1” when L02 is switched on (80% LQ)
  • SF2 – it plays the sound  “Siren” when L03 is on (70% LQ)

You can use function “Play Track” to play any audio files you upload to the radio, here is a tutorial to teach you how.

taranis opentx special functions play low lq rssi warning

!1x at the end of a function means it won’t play when you turn on the radio, and it only plays it once.

Edit History

  • Apr 2018 – article created
  • Jan 2020 – added tldr section, added instructions to display LQ for Betaflight 4.1
  • Jan 2021 – updated for BF 4.2 – changed how LQ is displayed in OSD
  • Mar 2022 – updated URL, re-written for ExpressLRS

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Volodymyr 10th April 2022 - 8:29 am

i was not able to get RSSI working automatically on 4 quads. i have had to do update Output to RSSI/LQ (not just RSSI) in nano XF settings and then use AUX4 as RSSI channel in Receiver . BF4.3, BF 4.2.11. only this way its working.

Kristjan 25th January 2022 - 4:13 pm

There seems to be conflicting information in this article about using LQ as RSSI:

“A Crossfire LQ between 300 and 200 means it’s in 150 Hz Mode, between 200 and 100 it‘s 50 Hz Mode and then it switches to 4 Hz Mode below 100 LQ”


“The value will stay at 99 most of the times, because LQ is ranged between 0 to 300, and RSSI is only designed to display 0-99. When it drops below 99, it’s already in 50Hz mode”

If the RSSI only shows from 0 to 100 it means it only shows up in 4 Hz mode, unless there is some scaling going on with RSSI in Betaflight?

Jacob 23rd January 2022 - 12:40 pm

Great info Oscar. Thanks for that. I have one question though. Dose thus work the same for my happy model 2.4ghz elrs?

Dmitriy 6th August 2021 - 1:35 pm

Hello Oscar! Thanks for this guide. I would be grateful if you answer the question.
My Taranis QX7 does not have a TBS converter installed – does this mean that the LQ display will not be correct, without a converter telemetry is not transmitted at maximum speed? Or in the latest revisions of QX7 this problem is solved and the converter is not needed?

rey reyna 20th July 2021 - 10:35 am

new build here and i cant seem to get lq to show in osd. i know i have lq since i setup a telemerty screen on my taranis x9 light and shows full bars. rssi is working also in my osd. i set up betaflight for aux 8 and for the receiver on ch12 rssi/lq also changed it to just lq. dont know what else to check or do, can you steer me in the right direction

Oscar 20th July 2021 - 11:36 am

Is Betaflight updated to 4.2? Only then it will work properly.
You no longer need to pass LQ and RSSI through a channel, latest version of Betaflight will just pick it up from the RX.

Krotow 22nd November 2021 - 3:36 pm

Can confirm that. Now LQ and RSSI in Betaflight OSD appear correctly without sending from radio in separate channel. Works even as Betaflight RSSI in DJI googles. Tested in Betaflight 4.2.9+ and Betaflight 4.3 development preview.

elDava 18th January 2022 - 9:15 am

hi, i have the same problem on the new tango2 v3, everithing is updated bf and tango but i still cannot see any lq in the osd!! just the rssi…
can you halp me?

Ruslan 13th March 2022 - 11:26 am

i have the same problem

Mark Turkel 21st June 2021 - 9:56 pm

Hi and thanks for your great blogs! I just got the latest TBS Micro starter set… I think I followed all your directions correctly, but for some reason, it is showing RFMD = 1 on my RadioMaster TX16s, and not 2. I can’t seem to figure out what I’m doing wrong. Any help would be greatly appreciated!

Oscar 22nd June 2021 - 11:16 pm

ON your radio, can you go to System settings, Tools, Crossfire Configuration, Crossfire RX, and check if RF profile is set to Dynamic or 150Hz? Maybe it’s set to 50Hz.

ronald kennedy 2nd May 2021 - 1:54 pm

Hi Mr Liang: My setup’s all 28 of them Use Pixhawk’s BF and iNav will not work with Pixhawks i got the TBS Bundle system for Long Range and FPV I have yet to find a diagram or better yet a video to show me how to set this up using a minim osd micro so could you point me in a youtube video or suggest a help site for a Old 71yrs young to help me out Thanks. R.K

george 26th April 2021 - 9:08 am

I’ve got an issue with Crossfire telemetry on Taranis x9d. In the radio’s telemetry screen, it’s giving me weird values for RFMD like -4 or 8, instead of 0,1, or 2. RQly also shows low %, even though the link is good. OSD values for link quality and RSSI are working fine. I just updated to OpenTX 2.3.11, renewed the SD card contents, and added the BF toolset. Anybody seen this type of thing before? Really bugs me, because I can’t set good audio warnings for LQ/RSSI.

azri 21st April 2021 - 7:14 am

hello oscar liang, thx for the article, i have question about my setup
i have bad rssi value in OSD, i have warning in the osd that says RSSI LOW, the rssi value around 40-50. but the lq always 2;100 or 1;100
i play it in open area such as rice fields

Junni 8th February 2021 - 4:32 am

Pretty sure it won’t go into mode 0 aka 4hz mode unless you’ve got op. mode set to force telemetry. That’s how they explain it in the manual. Mode 0 won’t kick in for normal flying even at the end of range. It’s for ardupilot type flyers and it allocates more signal for telemetry not less. I’m guessing it uses a slower data rate from receiver down to transmitter to increase telemetry range. Normal mode is 150hz then 50hz then signal lost. Force telemetry mode is 50hz then 4hz then signal lost.

Justin Hawkins 11th December 2020 - 3:47 am

I set up the aural alarms on my TX16S, hope they work. Couldn’t figure out how to simulate it.

Additionally, I’m running DJI video and tried configuring CH8 to LQ, and set up BF as described in the “old way” section. My goggles do display a value, usually between 85 and 60. However, on my radio, I have RQly and RFMD. In flight, they’re always 100 and 2 (150hz) respectively. Strange that my OSD isn’t showing 99 all this time.

Trying to work this out, as I’ve had intermittent “glitches” with my quad that cause crashes, trying to trace it to a RX signal issue.

terry zelk 7th December 2020 - 7:41 pm

Hey great article, but I have a strange result.
I have BF 4.2.5 and what I get in OSD is rssi 64, rssi dbm 45, LQ 2.
This is 10 to 20 feet distance.
I don’t get the 0 to 300 reading and LQ at 2 it shouldn’t fly but I flew it a short distance. the rssi fluctuates up and down a bit and the rssi dbm moves a bit but the LQ stays at 2.

Rob Hafey 2nd November 2020 - 12:55 am

I had to get a new replacement receiver from TBS. After setup everything worked except I had the stuck at 49 problem (all settings in BF and in the Tango 2 were the same). My issue was that the receiver Dst Channel 8 wasn’t set to LQ (see above). This cause my LQ to be stuck at 49. Thanks Oscar for the great articles.

jeremy 28th August 2020 - 7:21 am


I’m currently trying to setup the LQ and RSSi signal on my betaflight 4.1.6 but nothing happen. I tried the old and the new method but no result could you help me :) ?

Thanks and keep going your website is perfect

Dominik 26th August 2020 - 4:24 pm

Hi Oscar.
Is this normal ?
Bad RSSI and averange LQ.
I change antenna (i have oryginal and fake and is similar),
I fly in Europe (868 MHz).
Thx for help.

Oscar 4th September 2020 - 3:59 pm

Just focus on LQ, as long as it’s above 70 you’re fine.
low RSSI might suggest you have problematic antennas.

Jeremy Holt 30th July 2020 - 8:27 pm

Hey I tried doing these steps and I have the rssi showing up on osd but my link quality just has one digit. It has a 9 and it never changes even though rssi drops as expected. I am running bf 4.0.4

Oscar 31st July 2020 - 3:53 pm

Update BF to latest version.

Brandon 18th June 2020 - 3:20 pm

Crossfire nano connected to FC via sbus 3 wires. Using dst channel 8 for LQ on nano rx. Plug in, Rssi in osd is 99 for the whole flight, 97 on occasion. Take that same quad, plug in, go in the nano, change LQ to off, then back to LQ. Rssi in the OSD is now 99 when close and drops fairly quick as I fly away, and reads all over. Any ideas?? 3.23, opentx 2.2.4, bf 4.2??

genivos 17th June 2020 - 6:53 pm

When I set this up for use with the DJI FPV system, it works but only shows RSSI selected on the OSD screen in Betaflight. I know that it’s the case cause the goggles doesn’t show LQ yet. But .. the number of RSSI is 60-70 while flying. I also read that’s normal and you can scale it (set rssi_scale). But here comes my question, what’s the best to set in this case while using a digital system like DJI FPV? Can’t really find anything about that how to precisely configure it.

I’m running Betaflight 4.1.7 and 4.2 so I’d rather use the new way of configuring to free a channel :)

Oscar 22nd June 2020 - 1:13 pm

RSSI is not as useful as LQ for Crossfire to be honest. Setup audio warning on your radio perhaps? I have a tutorial here. But really your radio link will almost always out-range your video since the frequency is so much lower.

Ciprian Silvasan 31st March 2020 - 6:54 am

Got an answer to my question.
So in the googles you will see LQ on three stage. 2=150Hz, 1=50Hz and 0=4Hz from 0 to 300%. On Taranis you will get from the telemetry 100% all the time in stages 1 and 2. If LQ goes in stage 0, it will show the LQ from 0% to 100%

Christopher F 28th March 2020 - 1:38 am

I just wish XF would make this easier to understand about all the RSSI and LQ readings.
I use both R9M and XF full size version and find myself using my R9 more because one it’s way easier to setup especially in INAV for LR wings.
I have yet to figure out how to properly setup XF on any of my planes or wings and actually stopped buying XF receivers and will most likely just install R9 slims. Rssi from 0-100% is way easier to understand it I’ve never had any issues with it.
Plus I can use Bluetooth on my R9 with Telemetry viewer app and XF Bluetooth doesn’t work with anything but Ardupilot. That’s a huge let down for me. I’ve tried asking for help in groups with all this rssi setup with XF but get no response.
I’ve set my XF up on one quad and at 300m out I get warnings of low LQ and even critical Low LQ from My Tx but in osd my LQ reads 198 or 199!! This is set up exactly how you showed above.
That’s what’s confusing to a lot of us especially LR wing pilots that real rely on LQ and Proper rssi.

Ciprian Silvasan 12th March 2020 - 7:23 pm

Hello, thank you very much for the article!
One question. In the goggles I can see LQ around 300%. But on the telemetry on Taranis I can see on RQly only 100%.
Why I cannot see 300 instead 100?
If I set the alarm to trigger on 70% will it be 70% out of 100% or 70% out of 300% ?
Thank you,
Ciprian Silvasan

Jason Slater 15th March 2020 - 12:04 am

In my goggles I see 0 for rssi and 0 for LQ. on my jumper t16 it reads 100 for RQly.. driving me mad trying to work it out

Bobii 28th January 2020 - 10:46 am

Hello and thank you for your tutorial
I just bought crossfire and I followed your tutorial with BF 4.1 but the problem is that I have a LQ of 300% but a very low RSSI, at 3m from the quad I am only 80 while in FRSKY RXSR I am 99
In the next room I go to 70
And in corridor 50 of RSSI with always a good LQ?
Does my Crossfire have a problem?
My two drones have identical values,
With Frsky RXSR the RSSI was much higher I don’t understand

Oscar 2nd February 2020 - 4:00 pm

use LQ as your signal indicator, it’s much more accurate representation of how good your signal is.

Airmaxx23 30th July 2019 - 2:41 pm

What does the “Warn1” sound like? I can’t find the sound file anywhere to hear it so I know what to listen for.

Nathan 18th March 2019 - 3:18 pm


Do you know if it’s possible to have a numerical value of rqly from a PDB steele/ kiss FC v2 ?
I just have the reception symbol for the moment but I prefer having the value on the osd (like in betaflight)…

gino carpio 11th March 2019 - 12:00 am

i have crossfire running with a TBS tango. my rssi for some reason is reading 25. never see it at 100. ch 8 is on LQ and rssi is on ch 4. but the scaling is way off. i plug it and immidiately its on 22-24rssi


Dikto Vally 24th February 2019 - 1:28 am

Hi Oscar, thanks for tutorial, its really help me with my crossfire, just one to know if we can set failsafe in special function when L03 is active? And how to set it ? Apreciate your reply.

Oscar 25th February 2019 - 5:16 pm

You can probably trigger failsafe in Betaflight with an AUX channel.
You can make this AUX channel from L03 in the Taranis? (Mixer page)

Tim Eckel 22nd January 2019 - 6:58 pm

Talking with the TBS Crossfire engineer, you should be using the RSNR sensor for RSSI, not as discussed on this page.

The formula should be: RSSI = (max(RSNR, 40) + 4) * 2.25

Scale will be 0 to 99 with a warning at a RSNR of 0dB (or 9 using the above RSSI formula).

CaptainPilou 28th January 2019 - 7:21 pm

Hi Tim,
I applied this formula to data I collected from my logs and am a bit confused. My values of RSNR goes from 0 to 60. When RSNR=50 for example, according to the formula, my RSSI would be (60+4)*2.25=144, which is out of the range 0-99. Am I misunderstanding the formula? Thank you

CaptainPilou 4th February 2019 - 4:02 pm

It looks like the formula should be rather using MIN. As a result, it seems much more relevant to have RSSI=(MIN(RSNR,40)+4)*2.25. @Tim Eckel, could you please confirm with the Crossfire engineer you’ve been in touch with? Thx a lot

Oscar 10th February 2019 - 6:36 pm

Can you ask your TBS Crossfire Engineer to make a public announcement and clear things up?

I. V. 6th January 2019 - 9:00 am

I saved all my moneys to get me a crossfire micro bundle and I saved all my moneys again to build a catalyst machineworks merica with a f405 Mamba flight controller. I have bound the receiver with the tx and I am transmitting between the two. I can arm and fly but I have rssi issues. I set my LQ on channel 12 which is aux 8 in my flysky nirvana, and I can see that aux 8 is at 2000 on the receiver tab of betaflight, so I know that its working. also in my sensors txlq and rxlq are both 100. I have rssi checked in the configuration tab, as well as telemetry, but still my rssi value never increases more than 40 or 50. I have never seen 99 on this quad. My antenna placement is not bad either, my receiver is not blocked by a lot of carbon, and I am just lost as I don’t know what to do at this point. I even tried another receiver.any ideas?

John 7th January 2019 - 6:25 pm

I am having this same issue… I have crossfire nano receivers in multiple quads / wings and only one quad is behaving this way. I updated my full sized crossfire module to the latest firmware and rebound the nano on the trouble quad and no change. Any help would be appreciated.

Oscar 10th January 2019 - 3:15 pm

Are you using the correct frequency? I.e. EU 868MHz and Rest of the world 915MHz.

Jackonesia fpv 16th January 2019 - 4:22 pm

Hello sorry for the translation I also have the flysky nv14 I think the trouble comes from a place in input the weight option only goes to 100 while on the taranis it goes much further then on the flysky the value is just divided by 2 I think the problem will be fixed in a future update

Andre 20th December 2018 - 3:52 am

Does anyone know how I could get Link Quality to show on my OSD (Betaflight) using HeliNation Talon F7 FC and Crossfire Nano.It is connected to UART4

James Oldfield 27th October 2018 - 12:31 pm

Hi Oscar, I’m trying to set up the logical switches section on the taranis but don’t have the option for rmfd or rqly. I have the crossfire working fine in my quads I just need rssi for my wing that doesn’t have a fc and no osd. Is there any reason these options aren’t there? Cheers James

Jacob 19th February 2019 - 2:11 pm

I have this same issue – but the rmfd and rqly aren’t showing up for my quad. Using the flightone revolt v3 FC. (If you know how to get it to work for my quad)

Oscar 25th February 2019 - 4:55 pm

Try to delete all telemetry sensor, and discover sensors again.

Toper 5th September 2018 - 8:52 pm

Hi Oscar,
i just write a tuto on the “We are FPV” blog here wearefpv.fr/tuto-crossfire-taranis-qx7-20180726/, and i have a question: why do you set a spare channel to “Lq” ?

Papayou 15th September 2018 - 4:52 am

Pour l’afficher dans l’OSD de βf

Mark Pfeifer 30th August 2018 - 5:24 pm

I’ve been getting intermittent haptic warnings on my Taranis even though I was well within range with 99% LQ showing in the OSD. Do you think it is just the system switching between the two modes? Does your set up method above eliminate the warnings when switching modes or is this just something we need to get used to and understand?

Jesse 24th August 2018 - 4:02 am

In the x7 menu in the ay track section I can only get it to show “!-” instead of the “! 1x”

Oscar 28th August 2018 - 4:42 pm

old firmware?

Josh 30th August 2018 - 6:34 pm

I’m seeing the same as Jesse. on OpenTX 2.2.2 with all updates done (as far as I know) to crossfire lua, crossfire tx and nano rx, if it matters. I see one “!-” and then just numbers.. no option for “!” and a subsequent number value.

Jan 21st June 2018 - 4:00 pm

Oscar, so I have my crossfire set to LQ/RSSI on channel 8, not running teranis. Using osd, would it be better to just run LQ only through the osd ?

William Jarvis 30th April 2018 - 6:29 pm

Great post, really helpful. Am I right in thinking that it’s best to use 8 channels max with crossfire? I accidentally put LQ on channel 12, would this cause a more latent output?

Oscar 9th May 2018 - 11:57 am

i don’t think so, all 12 channels are sent regardless there is useful value or not.

James (not a robot) 21st April 2018 - 10:54 am

Thanks Oscar. You are the first I have come across who explains the “!” before the x1 in the special functions warnings.

Many thanks.

schim 16th April 2018 - 2:44 pm

Oscar! This is really good info! I only use TBS crossfire a few weeks now (activly after the winter).
It’s great to get this telemetry – confidence with good set up alarms. Now I have my RSSI monitored and I get notification if I fly out to far (I use the smaller crossfire TX).
thanks, RCSchim

Oscar 17th April 2018 - 9:24 pm

Thank you Mario :)
It’s indeed important to understand how to read the values and set this up correctly for long range :)

Jason 11th April 2018 - 5:30 pm

Any chance of a how to article on the setup of LQ for Kiss OSD/Mr Steele PDB OSD?

Oscar 17th April 2018 - 8:43 pm

Sorry I am not a KISS user.

Mads Bergdal 9th April 2018 - 6:33 pm

On my Taranis QX7 I can’t find the “!1x”. Is this the same as “!-“?

Marty Keilloh 9th April 2018 - 6:54 am

thank you Oscar

Mike 22nd December 2018 - 11:56 am

Hi, if the LQ is 0-300%, and Betaflight shows 0-99% in the OSD does it scale the 0 to 300 into 0 to 99? I.e. 50 would represent 150% LQ? Or does it show 99% into the LQ drops below 99%?



titanium 8th April 2018 - 6:09 am

Great explanation gathered in one place :D Thx !
These drops when changing mode are sometimes annoying as we are not able to display the TX transmit power on the OSD.
I sometime dream we have a second field in betaflight to display it as we have the value in the taranis …

Juanma 9th April 2018 - 1:02 pm

I would second that, a way to display custom telemetry values like the RFMD in the Betaflight OSD. Is there any Github task to do that? Maybe it’s worth to take a look and create one?

Thomas Houser 8th April 2018 - 5:04 am

I recently setup my Taranis and BF OSD for CF LQ. I am using the TBS Fullsize Crossfire TX and the Nano receiver. I selected Ch12 on the Nano for LQ and Aux 8 in BF configurator. The problem I’m having is it appears “Stuck” at 49 in the BF OSD and Configurator when checked. I am using the Brain FPV Radix which uses it’s own “Special Sauce OSD”. So.. really don’t know where to look to resolve the issue. Is it a Crossfire issue or a Radix OSD issue??


Oscar 17th April 2018 - 6:42 pm

What does RSSI say in Confirgurator Setup page? You can also confirm in OpenTX.
In the Configuration tab of BF, check the RSSI_ADC option is NOT checked on.

David M Butz Jr. 4th July 2018 - 4:49 am

Tom, I had the same issue. I found that if I turned off RSSI_ADC in the configuration tab of betaflight that it would read 99 intead of 49.