459MHz UHF legal Tx and Rx - Arduino based programability.

[Dennis Frie]

This is what I use, please ignore the ekstra GPS implementation etc.

[Splashy]

Hi, please find attached a zip of the 1_11 version of the code modified for the Spectrum analyzer.

The code is only to be used for the Spectrum Analyzer ..

That's the old code - please don't use that.

oops, it worked for me!

[Dennis Frie]

Hi, please find attached a zip of the 1_11 version of the code modified for the Spectrum analyzer.

The code is only to be used for the Spectrum Analyzer ..

That's the old code - please don't use that.

oops, it worked for me!

Well, the new GUI is almost backwards compatible - but the code for the receiver have been rewritten and now supports 1 MHz interval at start/stop instead of 10 MHz. If you set the start-frequency to say 458 MHz with the old code and the new GUI it shouldn't work very well  ;)

[zitron]

My guess is something like 186 RSSI value compared to 192 around 435 mhz. The difference is 6 rssi value ~= 3 dB. That should be about 50% of the power available at 435 mhz.

OK that is pretty damn significant. I will now move to 458MHz instead of 459.5MHz so it's a little bit closer to 435MHz. Would be interesting to see what that means in real-world performance.

Also first post!

[Devonian]

I'll test later.
Once again, thanks to Dennis for this Spectrum Analyser tool, we would probably still be unaware that we were not actually on 459MHz without it.

Have a virtual beer on me, in fact, everyone can have one  :laugh:

Attached is Dennis' latest (v05) spectrum analyzer software.

Nigel.

[Devonian]

OK, tested my modified/re-tuned Tx for 459MHz.
Rx is still standard and best around 435MHz.
Both Tx and Rx are using homebrewed 1/4 wave antennas cut for 459MHz.
Tx was 5 metres away on 100mW output and running thUndeads v3.4 code.
Spectrum Analyzer software is v05.

I also have a wireless weather station in my home running on 433MHz...which is exactly why we should run on 459MHz for UHF model control.




If anyone else is crazy enough to want to modify their RF board, I attach AN435.pdf for your info.
I used the values for 470MHz.
Be warned, you may ruin your board if you are not extremely careful - just take a look at those grains of sand on the board, that is what you have to remove and replace with components of the correct value - never again!!  ;D

Shame HopeRF stopped making the board for 470MHz....

Nigel.

[BigMouse]

thanks for the tests Nigel.

For people that want to forfeit telemetry for range, it will be much easier if we can find a lower power version of the 7W booster, and use it to control output to the full 100mw for general transmission (hence regaining any losses due to freq change) and have the facility to switch to higher power level to get out of trouble.

Also I might experiment with a mildly directional tx aerial mounted on a tracker complete with the rf board, instead of the board being mounted on the tx itself, just ideas for now though, too many projects on the go as it is, and with the summer season approaching fast...

[Coyote]

This is making me wonder now, while I was flying 1.3km out on 50mw yesterday, was i actually on 50mw ? or 25 ?

[papa_lazerous]

This is making me wonder now, while I was flying 1.3km out on 50mw yesterday, was i actually on 50mw ? or 25 ?

What do you mean Ian?  If you had the booster option set as one in the Tx FW then you where running at 50mW why would it be 25mW?

[Coyote]

If the power output on 459 is half that of 433, I assumed I was on 50mw, I might have been, but just wondering if it was in fact lower

[zitron]

If the power output on 459 is half that of 433, I assumed I was on 50mw, I might have been, but just wondering if it was in fact lower

If the loss is 3dB maybe 1.5dB of the power is lost on the tx, and a further 1.5dB lost on the rx? So maybe you were sending like 40mW, but more like 25mW once it gets through the rx front end. Really need more tests...

[phibin]

really exited today...

got olrs fitted to the gaui 330xs flashed with v3.4 on 459mhz and...

it was glitching bad! very noticeable as it turned the osd on and off everytime :/
i was only getting 20ft or so before it started doing it :((

[Coyote]

That sounds like a voltage drop more than a Open fault ?

[Splashy]

This speculation about the power output and range from OpenLRS on 459 Mhz is very disconcerting.

Surely someone has a power output meter that they can use to determine the power output on 459MHz. Does Flytron not have the ability to give us a figure in mW.

I have purchased one of the 0.3-3Ghz RF Signal Sensors which returns a voltage value for the output power but without some idea of how voltage translates to power I cannot use this to give a definitive answer.

If the power output of OpenLRS at 459Mhz is as low as has been suggested then it would be foolhardy to use it for anything other than short range use.

I think that OpenLRS is a great product but we need to know whether a modified version of the TX unit is required for 459 Mhz or another alternative is required such as using a version of the booster which will give the option of raising the power output.

[Coyote]

Im going to repeat my 100mw range check I did the other day when I got to 4km + and still had loads to go, I`ll document my findings, to see if it at least matches it

I will also take my laptop and record the spectrum analysis at the same points so someone that can understand it more than myself can draw conclusions comparing against close range ( in house ) analysis