The short story is that I have a FrSky Horus X10S and I want to use it.

The longer story is that I have too many darn transmitters that I need to use some of them sometimes.

The problem is that I use ExpressLRS almost exclusively now and the Horus X10S does not like to play nice. Yes it works but........

The situation is that the baud rate between the transmitter and the external ExpressLRS module can only set at 115K baud.

At 115K baud I cannot set my ExpressLRS packet rate to more than 150 Hz.

So here is the question.

1) Is the packet rate only impact the telemetry data and has nothing to do with control data going from the transmitter to the receiver?
2) All my multi copter flight controller seems to recommend a 250 Hz packet rate. Will running at 150 Hz mess/impact with the flight controller?
3) Any latency issue with a lower packet rate?

I did test fly LOS and I cannot really feel any difference on a 65mm quad.

1) Packet rate is the rate your transmitter sends signals to your quad. ELRS also adjusts your telemetry rate with this, but it is technically a different, adjustable, rate.
2) 150hz vs 250hz is not a huge difference, and the quad/FC won't notice or care.
3) If you're super sensitive to latency, then maybe, but realistically, it won't make a difference unless youre a top end racing pilot.

I have a QX7 i modified to be able to use the higher baud rate, and i can't tell the difference in the packet rate for even my most aggressive flying.

(17-May-2024, 04:42 AM)matt0725 Wrote: 1) Packet rate is the rate your transmitter sends signals to your quad. ELRS also adjusts your telemetry rate with this, but it is technically a different, adjustable, rate.
2) 150hz vs 250hz is not a huge difference, and the quad/FC won't notice or care.
3) If you're super sensitive to latency, then maybe, but realistically, it won't make a difference unless youre a top end racing pilot.

I have a QX7 i modified to be able to use the higher baud rate, and i can't tell the difference in the packet rate for even my most aggressive flying.

Thank you. I looked at the modification needed with the different inverter and couldn't decide if it is worth while. So I decided to leave it. 

I only plan to use this to cruise around inside the house so no big deal even if there is more latency. I won't notice. 

I just didn't want some compatibility issues with the flight controller besides the data rate being a bit slower.

(17-May-2024, 06:56 AM)SeismicCWave Wrote: Thank you. I looked at the modification needed with the different inverter and couldn't decide if it is worth while. So I decided to leave it. 

I only plan to use this to cruise around inside the house so no big deal even if there is more latency. I won't notice. 

I just didn't want some compatibility issues with the flight controller besides the data rate being a bit slower.

Nope it will work just fine. If you flew frsky before ELRS, youll still have way lower latency than before anyway.

I modded my QX7 with sheer willpower. I thought the little chip i'd have to solder in was going to be way larger, but its literally tiny. If you have long nails you could maybe pick it up, otherwise its tweezers only. For indoor flying/not racing, i wouldn't bother dealing with it and ruining your radio potentially.

(17-May-2024, 04:42 PM)matt0725 Wrote: Nope it will work just fine. If you flew frsky before ELRS, youll still have way lower latency than before anyway.

I modded my QX7 with sheer willpower. I thought the little chip i'd have to solder in was going to be way larger, but its literally tiny. If you have long nails you could maybe pick it up, otherwise its tweezers only. For indoor flying/not racing, i wouldn't bother dealing with it and ruining your radio potentially.

Thanks, yes I flew FrSky the longest. Then again I flew so many radio before FrSky and never worries about latency. Especially back in the days when the debate was raging between 512 PCM and 1024 PCM. Then before that I started with Galloping Ghost.

No, one look at those itty bitty little components and the gigantic wires that needed to solder onto them made me cringe. So the radio will stay as is.

The reason why I like the Horus X10S so much is because it has some of the most incredible feeling sticks.

I did fly more in the house and no issue. I couldn't tell the difference between that and 250 Hz packet rate.

Out of interest with the baud rate set to 115k, how long does the ExpressLRS LUA script take to load? When I inadvertently had the baud rate set to 15k on my X9D+ that script took forever to load. After I changed the baud rate to 400k the script loaded instantly. Maybe not an issue if you never need to look at or change any ELRS settings in the field but it would be interesting to know if the slow baud rate also affects the ExpressLRS LUA script on a Horus X10S.

(17-May-2024, 07:04 PM)SnowLeopardFPV Wrote: Out of interest with the baud rate set to 115k, how long does the ExpressLRS LUA script take to load? When I inadvertently had the baud rate set to 15k on my X9D+ that script took forever to load. After I changed the baud rate to 400k the script loaded instantly. Maybe not an issue if you never need to look at or change any ELRS settings in the field but it would be interesting to know if the slow baud rate also affects the ExpressLRS LUA script on a Horus X10S.

I have not paid any attention except when the LUA script hangs on some of my older Taranis X9D+. The LUA script always took a little while to populate but nothing too long. I will pay a bit more attention next time I click on that between two different baud rate.

Ok that got my curiosity. So the first transmitter is a Taranis X9D+ 2019 at 400K baud rate. I started the stop watch when I press the LUA script. 2.91 seconds when the status bar disappeared.

Horus X10S at 115K baud rate. 5.45 seconds it took from the click to disappearing status bar. So considerably slower there.

I intentionally set my packet rate to 150hz. Most pilots would not notice any difference in latency between 150 and 500hz and I suspect many racers would not either, but of course I don't race or fly fast. However with the lower packet rate, you gain significant sensitivity in signal reception and add huge amount of robustness to your link. Before when I ran 250hz, I would get a few rare failsafes in bad enough situations (bad antenna placement coupled with blocked/noisy location), but since going to 150hz, never had any failsafes yet.

Sensitivity limit at 250hz is -104dbm vs -112dbm at 150hz (or 200hz) - as dbm is logarithmic, that is more than 6x increase in sensitivity!


https://www.expresslrs.org/info/signal-health/

(17-May-2024, 08:20 PM)mstc Wrote: I intentionally set my packet rate to 150hz. Most pilots would not notice any difference in latency between 150 and 500hz and I suspect many racers would not either, but of course I don't race or fly fast. However with the lower packet rate, you gain significant sensitivity in signal reception and add huge amount of robustness to your link. Before when I ran 250hz, I would get a few rare failsafes in bad enough situations (bad antenna placement coupled with blocked/noisy location), but since going to 150hz, never had any failsafes yet.

Sensitivity limit at 250hz is -104dbm vs -112dbm at 150hz (or 200hz) - as dbm is logarithmic, that is more than 6x increase in sensitivity!


https://www.expresslrs.org/info/signal-health/

Gosh, why on earth am I worrying about the packet rate........duh.

Before I started flying FPV in February I was flying fixed wing. Mostly electric gliders from my backyard because I get a lot of thermals. All my transmitters were set to 100Hz Full. I never paid attention until when I started playing with these quad flight controllers and started to read about using 250 Hz and not 100 Hz Full.

Now three months down the line and I am worrying about the lower packet rate messing the control link. 

That's because I have no idea what all these means.   I am just a user swaying by what I read.

You're saying there was a "100Hz Full" transmission protocol back in the day? I'm not sure that would be an apples-to-apples comparison to packet rate.

This table is courtesy of ChatGPT so while it may not be completely accurate, it will give a good ball park comparison

But who knows, beyond the placebo affect, maybe there are some super sensitive humans who can notice a few milliseconds difference.

(17-May-2024, 09:01 PM)mstc Wrote: You're saying there was a "100Hz Full" transmission protocol back in the day? I'm not sure that would be an apples-to-apples comparison to packet rate.

This table is courtesy of ChatGPT so while it may not be completely accurate, it will give a good ball park comparison

Code:

| Protocol            | Frequency Band | Typical Latency (ms) | Packet Rate     | Range                |
|---------------------|----------------|----------------------|-----------------|----------------------|
| **ExpressLRS (ELRS) | 2.4GHz, 900MHz | 4-9                  | Up to 500Hz     | Long Range (>10km)   |
| **TBS Crossfire**   | 900MHz         | 15-25                | 150Hz           | Very Long Range (>50km)
| **ImmersionRC Ghost | 2.4GHz         | 4                    | Up to 500Hz     | Long Range (up to 40km)
| **TBS Tracer**      | 2.4GHz         | 3                    | Up to 250Hz     | Medium Range         |
| **FrSky ACCST**     | 2.4GHz         | 18-22                | 50Hz            | Medium Range         |
| **FrSky FPort**     | 2.4GHz         | 8-18                 | 100Hz           | Medium Range         |
| **Spektrum DSM2**   | 2.4GHz         | 16.5-22              | 11ms (Air), 22ms (Surface) | Medium Range
| **Spektrum DSMX**   | 2.4GHz         | 11-22                | 11ms (Air), 22ms (Surface) | Medium Range
| **Spektrum DSMR**   | 2.4GHz         | 5.5-16.5             | 5.5ms           | Medium Range         |
| **FlySky**          | 2.4GHz         | 20-30                | 50Hz            | Short Range          |

But who knows, beyond the placebo affect, maybe there are some super sensitive humans who can notice a few milliseconds difference.

I meant this:



So between the 100 Hz Full, 250 Hz and 150 Hz I couldn't feel any difference. Even though the 100 Hz Full was controlling servos and now I am controlling speed controllers for motors.

Ok didn't realize you meant ELRS 100hz full. Yeah thats about a 6-9 ms difference and if you involve micro servos I believe most of those respond in 100ms range. But even for a drone, those few ms are not likely noticable by 99.9999999999+%, but the increase in link sensitivity most definitely is.

(17-May-2024, 10:11 PM)mstc Wrote: Ok didn't realize you meant ELRS 100hz full. Yeah thats about a 6-9 ms difference and if you involve micro servos I believe most of those respond in 100ms range. But even for a drone, those few ms are not likely noticable by 99.9999999999+%, but the increase in link sensitivity most definitely is.

Yeah I don't think I can feel any difference in either the response or link sensitivity from a quad. I was flying my electric glider over 400 meters away which is still considered very close range compare to some of these FPV guys fly.

and yes I was talking about the packet rate within the ExpressLRS Tx module and the receiver.