True diversity on the tx end, what would it take?

As the title says, what would it take to setup a diversity setup on a Devo tx? We have multiple point diversity receivers (my current OrangeRX system has 4 antenna, 2 in the vertical and 2 in the horizontal plain- 2 on the main RX and 2 on the sat), I get good reception most of the time but I notice a pretty substantial drop in range when I go strapping on my metal camera bracket (and camera it's self) and all that crap. I think having 2 antennas on the txt would be pretty beneficial. Can I just hook up a second CRF module to the same pins and have it transmit the same signal at the same time as the internal one? Is there some sort of [logic based, I know a actual Y splitter won't work] RF splitter so I can use only the one module with a device between it and the antenna(s)?

I'm a RF noob (but am very interested in learning). I want to stick with omnidirectional linear antennas but would like to get my tx upgraded to real diversity. How can I do this?

Obviously price is a concern but just to get the convo started let's pretend for a sec it's not...

It is a bit difficult to state "true" diversity.

They way most receivers are implemented is that the same signal from Tx is received by different rx antennas, the best antenna is then selected, but only one rx chip. How this selection is done and what algorithm hyseteresys to switch i do not know.

A better way would be multiple different rx chips both with it's own antenna, then the output between dffferent receivers is compared and best is selected.
like with DSMX spectrum sattelites. The big risk is still if there is big interference in 2.4ghz band, all rx antennas are affected.


On tx side, you could radiate with better circular polraized antenna, however you can't use multiple antenna on the same signal to get diversity, at leasdt wont give benefit. (only more gain/directivity) So diversity on tx you could use two different tx modules, or two same modules but with different bind code. Bsst would be to use two differetn modules, 35mhz and 2.4ghz or uhf and 2.4ghz and use 2 independant rx.

It would be certainly a killer feature if we could activate 2 Tx modules active at the same time in deviation.... But I belive most users here use devation for cheap toy models.

You might want to look through Bruce's rcmodelreviews channel on Youtube. Before he fell into the FPV miniquad tarpit, he did some videos on diversity setups. IIRC, he even did one showing how to build a DYI module for it.

Without telemetry or any sort of Rx feedback Tx can never know which antenna to switch to.........am I right???

Block137 wrote: Without telemetry or any sort of Rx feedback Tx can never know which antenna to switch to.........am I right???

Right, the tx doesn't need to choose which one it uses, it needs to use both of them all the time, then the FC / diversity controller on the model chooses which signal is best.

I wasn't thinking about the multiple bind code situation, is it possible to bind one receiver to two TX's at the same time? (I know you can easily bind two RX's to one TX by entering bind mode at the same time). If so this shouldn't be to hard, just run both tx modules from the same processor so they receive and transmit the same data, the model's FC / diversity controller will take care of the switching on that end...

Fernandez wrote:
On tx side, you could radiate with better circular polraized antenna, however you can't use multiple antenna on the same signal to get diversity, at leasdt wont give benefit. (only more gain/directivity) So diversity on tx you could use two different tx modules, or two same modules but with different bind code. Bsst would be to use two differetn modules, 35mhz and 2.4ghz or uhf and 2.4ghz and use 2 independant rx.

Like controlling 1 model with DSM2 and FrSky protocol at the same time?
And let the RX choose which is best then discard the other?


When I start thinking about it... that sounds like Spread-Spectrum in a nutshell

IMO people will start comparing and end up picking the one Rx switches to more often (probably only 1 protocol remains stable at a range).

Yup indeed thats what I mean two independant tx modules acive (different frequncy, system or bind code) , two independant Rx active in the model then a diversity switch to select.