Hi everyone,
First, sorry if this thread is not under "news & trending" category, as I am relatively new to FPV hobby and to this forum. 

Btw, I am curious if there is existing solution for optimizing VTX power to adapt to RSSI signal strength, and to turns off when its on idle. (I am worried about temperature of my Zeus Nano 350mW VTX when its just sitting on idle and tweaking my Betaflight settings around).

In the CLI in betaflight, enter this:

set vtx_low_power_disarm = on
save

It’ll put your vtx into low power mode whenever it’s unarmed (such as when it’s on the bench). I’d still keep a fan blowing on it though.

(07-Mar-2022, 12:27 AM)Lemonyleprosy Wrote: In the CLI in betaflight, enter this:

set vtx_low_power_disarm = on
save

It’ll put your vtx into low power mode whenever it’s unarmed (such as when it’s on the bench). I’d still keep a fan blowing on it though.

By low power mode do you mean minimum of 25mW, because mine is already set on 25mW and still heating a lot when idling on bench.
Either way, I think that dynamic power based on RSSI signal would be great for long range but racing as well (for interference)

It’ll drop it down to the lowest output power, which is usually 25mw- so yeah, it won’t help you.

This would allow you to turn off the vtx at will:
https://tinysleds.com/products/realpit-vtx-power-switch

Dynamic power would be nifty.

Edit- it looks like there was some discussion of dynamic vtx power in 2018, but it doesn’t look like anything came of it:
https://github.com/betaflight/betaflight/issues/6756

You can implement dynamic VTX power if you run TBS Crossfire / Tracer and you have a TBS Fusion module.

The Fusion module monitors the RSSI of the video signal and then communicates with the Crossfire / Tracer module (via Wifi) and sends VTX power level commands over-the-air via the Crossfire / Tracer RC link that instructs the VTX power to be either increased or decreased as required. I've never tried the feature myself. I just know that it exists.

As long as the quad is moving the vtx will stay cool with the airflow. Even 25mW gets hot on the bench.

I do have pit mode and power levels on a switch but only use that during testing or setup.

99% of the time I just crank it up to full power and fly.

Dynamic VTX power is a great feature but I just don't see many folks using it.

(07-Mar-2022, 01:19 AM)SnowLeopardFPV Wrote: You can implement dynamic VTX power if you run TBS Crossfire / Tracer and you have a TBS Fusion module.

The Fusion module monitors the RSSI of the video signal and then communicates with the Crossfire / Tracer module (via Wifi) and sends VTX power level commands over-the-air via the Crossfire / Tracer RC link that instructs the VTX power to be either increased or decreased as required. I've never tried the feature myself. I just know that it exists.

Glad to hear that!
I use ExpressLRS and Steadyview/RapidMix on my Cobra X V2.
There is ExpressLRS - Dynamic power for TX, and I've heard something about ELRS backpack which does WiFi communication with eg. VRX, but I don't know any details about it, if it supports VTX power control at all and how it works completely.

(07-Mar-2022, 05:10 AM)kafie1980 Wrote: As long as the quad is moving the vtx will stay cool with the airflow. Even 25mW gets hot on the bench.

I do have pit mode and power levels on a switch but only use that during testing or setup.

99% of the time I just crank it up to full power and fly.

Dynamic VTX power is a great feature but I just don't see many folks using it.

I thought it would be nice to:
0mW - disarmed - idle
25mW - armed - strong signal
100mW - medium signal
250+mW - low signal

VTX performance can be easily assigned to a pot or switch. Including complete shutdown thanks to FET switch.
If you have a TX with openTx / edgeTx you can program in logic functions, change based on the strength of the RSSI.
I read somewhere that this operation through smartports overloads the FC CPU and in a critical case can lead to the machine crashing.
It was described by people who fly, for example, in the woods, etc., here the declines in the power of RSSI are common.
Yes, in both open and edge, it can include a time constant in the decision-making process.
Therefore, each pilot will have to agree on his circumstances.

I personally think ELRS backpack or OpenTX/EdgeTX is not going to be able to do what the Fusion/Crossfire ecosystem does in terms of dynamic vtx power.

RC link RSSI is not effectively the same as Video link RSSI.

ELRS backpack is only a wifi based SPI control for the VRX and basically helps switch band/channel similar to manual button pressing. Furthermore none of the VRX’s modules provide RSSI data over any of the module pins.

Yes, thanks to ESP chips for Wifi update, a side benefit has opened up. Just as FC controls VTX (vtx table) via smartport, ELRS controls other devices such as VRX through backpacks. I think it's too young a concept, and we'll see a lot of more features.
Similar to a bluetooth joystick or somewhere I have already seen access directly to betaflight through the wifi module in RX.

I use a small personal desk fan. It keeps everything cool while sitting on the desk. Never had an overheating problem and simply just works.

How will the ELRS backpack enable dynamic power on VRX’s that do not provide access to the RSSI data that the VRX is sensing?

The only published documentation we have where we can get VRX RSSI is for the RapidFire module with details on the SPI programming: https://www.immersionrc.com/?download=5995

I personally became interested in FPV a short time before ELRS was born.
And that is a relatively short time. How far everything has changed in such a short time.
Now there is a backpack with one-way SPI communication to the RTC6715 module.
In my opinion, it's just a matter of time (my personal estimate, in the summer).
Someone will create their own firmware with feedback or create an escape channel for RSSI.It will then send it back.
Yes, at this point the ESP module only blindly sends an SPI command to change the frequency and band.
You know, I'm just a relatively stupid person, but I still managed to understand how it all worked, and I'm pretty sure this modification will be born.
The developers behind this all are miles away with their capabilities. I see only one reason why it couldn't happen, and that is if someone says it's useless.

The one thing that might not make it worthwhile for the ELRS devs to invest any time or effort in dynamic VTX power switching via backpack is because people seem to be moving away from analogue systems to digital, so the demand for such a feature will be diminishing by the day. The reason TBS have done it is because they are also heavily invested in the analogue VTX market with their own products, so it made sense and would have likely been fairly trivial for them to implement something using their own existing analogue hardware with it's WiFi capabilities.

ExpressLRS has nothing to gain IMO by spending time (or wasting time) on dying analogue systems when they would be better off spending that time on other more worthwhile / desirable features for ELRS.