LQ and RSSI Explained for ExpressLRS and Crossfire Radio Links

by Oscar
Lq Rssi Fpv Drone Expresslrs Crossfire Link Quality Signal Strength

LQ and RSSI are both important metrics for ensuring a reliable radio link in FPV drones using ExpressLRS or Crossfire. While both provide valuable information, they measure different aspects of the connection. Understanding the differences between LQ and RSSI can help pilots monitor the signal quality during flights, determine maximum range and make adjustments to their equipment or flying style as needed.

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Further Reading:

What is RSSI?

RSSI (Raw Signal Strength Indicator) measures the strength of a received signal and is crucial in determining how much range is left during a flight. RSSI is measured in dBm (decibel milliwatts), a logarithmic scale, as opposed to mW (milli-watt) 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 in reality the lowest RSSI is usually not that low as it depends on the update rate and signal frequency.

Using dBm is preferred over mW because receivers can detect incredibly weak signals that are difficult to express in mW. For example, we can express 0.000000000001mW as -120dBm. It’s just so much easier to use dB when there are so many zero’s in mW. As you can see in this conversion table between dBm and mW, it perfectly demonstrates the benefits of using dB over 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 RSSI options RSSI Value (in percentage) and RSSI dBm Value. RSSI dBm is the recommended option as it provides a true measurement of signal strength. In Betaflight OSD,  Modern RC systems like ExpressLRS, Crossfire, and Tracer support RSSI dBm reporting, but older systems like Frsky and Spektrum may only support RSSI in percentage.

What is LQ?

LQ, or link quality, measures the percentage of uncorrupted data that passes through the receiver. LQ is displayed in a format such as 9:100, where the first number represents “RFMD” (or RF mode), and the second number represents the actual link quality value (it’s in percentage between 0 and 100).

For ExpressLRS, you can look up the RFMD and the corresponding modes and packet rates in the following table. For 9:100, the packet rate would be 500Hz.

RFMD Modes Packet Rates Sensitivity Limits
13 F1000 1000Hz -104dBm
12 F500 500Hz -104dBm
11 D500 500Hz -104dBm
10 D250 250Hz -104dBm
9 500Hz 500Hz -105dBm
8 333Hz Full 333Hz -105dBm
7 250Hz 250Hz -108dBm
6 200Hz 200Hz -112dBm
5 150Hz 150Hz -112dBm
4 100Hz Full 100Hz -112dBm
3 100Hz 100Hz -117dBm
2 50Hz 50Hz -120dBm (900Mhz)
-115dBm (2.4Ghz)
1 25Hz 25Hz -123dBm

For Crossfire, RFMD only goes up to 3, with the fastest packet rate being at 150Hz. When RFMD=3, it’s 150Hz; When RFMD=2, it’s 50Hz, and when RFMD=1, it’s 4Hz. Crossfire can dynamically adjust packet rates to maintain a stable control link. However Betaflight advises against using Dynamic packet rate as it may interfere with RC smoothing as explained here.

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 have to choose between LQ and RSSI, LQ might be slightly more important because it’s a more direct indicator of how reliable the radio link is. However it doesn’t tell you how much range is left in your link solely based on LQ, and you will also need RSSI for that, so RSSI is a very useful supplemental information.

To determine range limit based on RSSI, you need to consider the noise floor as well. Heavy noise level can screw up RC link all the same regardless how strong the signal might be. 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, with you being 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, in this case LQ would be 100%. What really matters here is not how loudly you speak, but how many words the other person can hear and understand. If the restaurant is too noisy, your voice might be heard, but not a single word is understood, then in this case you have high RSSI but 0% LQ.

LQ tends to suddenly drop off at the end of range, while RSSI tends to decrease gradually in a more predictable fashion. It’s best to use both LQ and RSSI to understand the condition of the radio link.

  • High LQ, high RSSI = healthy radio link
  • Low LQ, high RSSI = noisy RF environment
  • High LQ, low RSSI = If you are very far away, caution is needed as you are approaching the end of range; If the receiver is very close to the transmitter, that can be an indicator of antenna problem
  • Low LQ, low RSSI = the end of range, you should turn back as failsafe is likely to happen

The Lowest LQ

LQ should ideally be 100%, but it’s normal for it to be below this value. For instance, an LQ of 50% means that only half of the packets are getting through. Even so, you can probably still fly with this. For example, at 500Hz, there are still 250 commands per second getting through, which is way faster than an older protocol like SBUS with 50Hz update rate.

The lowest LQ you should react to is subjective and depends on how much risk you are willing to take. You definitely don’t want to wait until it’s too low, the drone becomes uncontrollable. But in the above example, 50% at 500Hz might be acceptable. The point is, when your LQ drops, it’s a sign of warning: there could be interference corrupting the radio data, or you are approaching the end of range, or some other issues.

If your LQ drops to around 50-70%, you should pay attention to RSSI. If RSSI is also low (within 10dB margin to the sensitivity limit of the packet rate), it would be a good idea to turn back. If RSSI remains high, keep monitoring LQ and see if it improves. If not, you should turn back because there might be interference and it could get worse if you keep flying. Definitely turn back when LQ drops below 20%, as increased latency will make control difficult.

The Lowest RSSI

The lowest RSSI allowed depends on the packet rate and frequency of the signal. Lower packet rates and lower frequencies have a more sensitive signal. For example, the lowest theoretical RSSI value for 2.4GHz 500Hz is -105dBm, but for 915MHz 25Hz, it’s -123dBm, which is better for long-range flying.

It’s important not to underestimate a few dBm difference, as every 6dBm doubles the range. For example, in ExpressLRS, dropping the packet rate from 500Hz (-105dBm) to 150Hz (-112dBm) effectively doubles the range and more. I have a tutorial explaining how to use dB to estimate range in FPV.

Here’s a table of the lowest RSSI (sensitivity limit) values for each RF mode (packet rates) from the ExpressLRS WiKi. If RSSI goes below these limits, you will get a failsafe.

Modes Sensitivity Limit
D250/D500/F500/F1000 -104dBm
500Hz/333Hz Full -105dBm
250Hz -108dBm
150Hz/200Hz/100Hz Full -112dBm
100Hz -117dBm
50Hz -117dBm
25Hz -123dBm

You can also find out the sensitivity limit in the LUA script when picking a packet rate:

Expresslrs Elrs Lua Script V2 Interface App

So what’s the lowest RSSI we can go to avoid failsafe?

Your RSSI should be 10dBm higher than the sensitivity limit. For example, if you’re flying ExpressLRS 2.4GHz 500Hz, you should turn back if RSSI drops below -95dBm. Some experienced pilots might push it and use 6dBm as the margin, but if you want to play safe, use the 10dBm margin.

However, RSSI dBm doesn’t take into account ambient noise, so it’s important to also check LQ. If RSSI is high but LQ is low, noise/interference could be the reason. Some RF systems reports SNR (signal to noise ratio) such as Crossfire, but ExpressLRS doesn’t do that yet.

Display LQ in OSD

On the Receiver Tab in Betaflight, set both RSSI Channel and RSSI_ADC to Disabled.

Betaflight Configurator Setup Expresslrs Receiver Link Quality Rssi 2024

On the OSD tab, enable “Link Quality” and “RSSI dBm value” elements (not “RSSI Value”).

Betaflight Configurator Setup Expresslrs Receiver Link Quality Rssi Dbm Osd 2024

The Link Quality element gives you the RFMD value (0-13) followed by the LQ value (0-100). RFMD indicates which packet rates you are using as mentioned previously in the RFMD table.

I recommend having both Link Quality and RSSI in dBm in your OSD.

Lq Rssi Fpv Drone Expresslrs Crossfire Link Quality Signal Strength

RSSI Alarm in OSD

You could enable the RSSI dBm warning. As discussed, it’s important to have a link margin of 10dB higher than the sensitivity shown in the ExpressLRS LUA script for the packet rate (e.g. for 250Hz, -108dBm, so -98 for the alarm).

Betaflight OSD will warn you if RSSI dBm drops below this user defined value.

In CLI, enter the command:

set osd_rssi_dbm_alarm = -98
save

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

Likewise, you could set an alarm for LQ using the CLI command set osd_link_quality_alarm = x with x as your LQ Alarm level. 60 is a good value to start with.

Setup Low LQ Warning in EdgeTX

In your radio, go to model setup, press the “PAGE” button to scroll to the Telemetry page. Set “Low alarm” to 50, and “Critical alarm” to 20. Make sure “Disable alarms” is unchecked.

That’s it.

You should get a voice warning when LQ drops below these values.

Edgetx Rssi Lq Telemetry Critical Warning Low Alarm

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
  • Mar 2023 – updated RFMD for ExpressLRS 3.0

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82 comments

Kurt Kenyon 27th November 2024 - 1:30 pm

Oscar, thank you for the amazing information, on all the subjects you discuss. you have helped me solve many issues.

Reply
John Markadakis 18th November 2024 - 12:13 am

Hi Oscar,

I’m having a small hiccup when setting the RSSI warning. I input -95 for example, and when I click save, the number changes to 161.

Do you have any ideas on why I can’t set this right?

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Oscar 18th November 2024 - 4:08 pm

I guess what you meant to change is RSSI_dbm? But you are changing RSSI, which is a % setting.
RSSI and RSSI_dbm are two different things in OSD.

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Simon 1st September 2024 - 5:58 pm

Hey Oscar, i think there is a typo ?
For Crossfire, you say “When RFMD=3, it’s 150Hz; When RFMD=2, it’s 50Hz, and when RFMD=1, it’s 4Hz”.
On the documentation (team-blacksheep.com/media/files/tbs-crossfire-manual.pdf), they indicates : “RFMD Uplink – update rate, 0 = 4Hz, 1 = 50Hz, 2 = 150Hz”.

Thanks,

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Dieter 1st September 2024 - 6:06 am

Great explanation of the concept of uplink link quality. But I have seen almost no discourse regarding the downlink link quality. Given the fact that there is an order of magnitude less power for the downward link in Crossfire, there is a good chance it will drop before the uplink. OSD aside, you controller will go into alarm on a poor dowlink quality or total dropout, while you uplink is still great. Maybe that would be a good subject for another day.

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Badmonk 14th August 2024 - 5:05 pm

Great article thank you and also for all the amazing advice!
I don’t have to worry about LQ in my OSD if I am using DJI 03 right? I can see my RC3 and Googles 3 connection is full bars but the LQ says 0.
This doesn’t apply to drones with DJI O3 right?

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Oscar 19th August 2024 - 4:35 pm

Correct – if you are using DJI remote controller, then you just have to monitor bitrate in the goggles. LQ and RSSI are only for separate radio links like ExpressLRS and Crossfire.

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Dario 3rd February 2024 - 6:44 pm

I noticed my RSSI was sitting around 35% at a distance of 2.2 clicks, but back at the home point, it’s cruising at a solid 59%. (By the way, I’m switching to using dBm for RSSI going forward.) But man, why’s it so weak out there? And hey, I was checking out those tables and it says the Packet Rates for 900 MHz radios should be 50 Hz, but mine was running at 200 Hz… Think that could be the culprit? I went ahead and tweaked it to 50 Hz, but not sure if that was the right call…
P.S. I’d like to mention that I’m rocking the Commando 8 ELRS V2, 900 MHz and Chimera 7 Pro V2

Reply
Oscar 5th February 2024 - 4:21 pm

You will get more range with lower packet rate, so going from 200hz to 50hz will give you more range.

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Tom 6th January 2024 - 3:12 am

This has to be one of the best article on the internet explaining LQ and RSSI I’ve seen. Very detailed and easy to understand. Thanks so much!

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Sergei 16th May 2023 - 5:54 pm

What are the units in EdgeTX telemetry alarms? It doesn’t make sense for dBm

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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.

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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”

and

“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?

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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?

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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?

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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

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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.

Reply
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.

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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?

Reply
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!

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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.

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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

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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.

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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

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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.

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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.

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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.

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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.

Reply
jeremy 28th August 2020 - 7:21 am

Hi,

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

Reply
Dominik 26th August 2020 - 4:24 pm

Hi Oscar.
Is this normal ?
https://youtu.be/8rzm6xe4sZ4
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.

Reply
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.

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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

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Oscar 31st July 2020 - 3:53 pm

Update BF to latest version.

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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??

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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 :)

Reply
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.

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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%

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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.

Reply
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

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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

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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

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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.

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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.

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Nathan 18th March 2019 - 3:18 pm

Hi,

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)…

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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

thoughts?

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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.

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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)

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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).

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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

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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

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Oscar 10th February 2019 - 6:36 pm

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

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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?

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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.

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Oscar 10th January 2019 - 3:15 pm

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

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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

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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

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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

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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)

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Oscar 25th February 2019 - 4:55 pm

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

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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” ?

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Papayou 15th September 2018 - 4:52 am

Pour l’afficher dans l’OSD de βf

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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?

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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”

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Oscar 28th August 2018 - 4:42 pm

old firmware?

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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.

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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 ?

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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?

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Oscar 9th May 2018 - 11:57 am

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

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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.

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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

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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 :)

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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?

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Oscar 17th April 2018 - 8:43 pm

Sorry I am not a KISS user.

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Mads Bergdal 9th April 2018 - 6:33 pm

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

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Marty Keilloh 9th April 2018 - 6:54 am

thank you Oscar

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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%?

Thanks

Mike

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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 …

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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?

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Thomas Houser 8th April 2018 - 5:04 am

Oscar..
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??

Tom

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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.

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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.

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