thUndeadMod v3.4 - openLRS S**T just got real :)

[Cat695]

Sorry to hear that Ian, but deep down I am feeling a little better that I hadn't been doing things wrong (you know how you get when you doubt yourself.

I didn't get a test in today guys because I travelled north to nottingham as I'm on leave now for two weeks.....However I have brought all my gear and seeing as the derbyshire dales are close by I should be able to get a flight in tomorrow.

Awesome that we know the problem!

[Cat695]

shit.. that's not good news for 459 then... Don't think its my code since everybody was getting 3km on 439 mhz...

Going back to previous posts in other threads about openLRS and the 459 freq (and getting some sleep) I think it actually shows itself that its the chip and not your coding mate

[papa_lazerous]

Who'd have thought that I could get more range with my dx7 and a cheap hobbyking Rx over a UHF system lol

[Splashy]

What are the options for OpenLRS in the UK.

I guess they are as follows

1. Modify TX and RX via a hardware mod to give better performance on 459
2. Revert back to 439 and hope
3. Put a booster on the TX with a couple of settings, one of which is 100 mW
4. Abandon OpenLRS in the UK (thankfully got mine from firstpersonview who I am sure have a good RMA procedure)

Obviously 1 is the best option .. the datasheet for the RFM22B states that 459 Mhz is within the spec although is on a different band to 433 (470 as against 433).
It does not say in the spec that the 470 band will have a very poor power output so is there any way to increase the power output on 459?

Is EZUHF totally without problems .. it seems to be the only other option if we cannot get OpenLRS working on 459.

[papa_lazerous]

I am wondering if this is an option...

http://www.hoperf.com/rf_fsk/fsk/22.htm

Its 500mW at 433Mhz so at 459Mhz we will take a hit and lose some power right off the bat. And I am sure it could be toned down a little more. I say this without having a good look at the datasheet.

I am thinking the Rx stays the same as its nice and sensitive, but have one of these in the Tx.... You can't really modify the Tx so I am wondering if it would be possible to do a custom job with an Arduino Pro mini and this module on a breakout board...

All pie in the sky thinking out loud for now

[Coyote]

If the power is low, add an amplification circuit to the output to raise it to 100mw. I think its as simple as that really. That way no heavy modifications to openlrs, just a simple plug n play add-on should have it fixed

[Devonian]

Whoa, hang on a bit chaps.

Let's do more than one test with more than one set of software.

Before I set out on this, HopeRF were contacted and they had tested these modules to 460MHz and said we should be no more than 10mW down on power.  It was Simon @ FirstPersonView who contacted them as he is 'in the trade' and were willing to talk to him.

Let's do some more tests first before writing the kit off, eh?

Nigel.

[Coyote]

Im going back up in the next few days to try the 433 code vs the 459 code, then versions 3.3 vs 3.5 as well side by side. The one thing I cant do is measure the mw output of each system, which would be of great interest

[ghost2212]

Right, so I went out and performed the range test :)

The results, were to say the least, bad, worse than bad, terrible :(

1) This was a ground to ground test
2) TX was at 459MHz UK legal 100mw output power ( Or supposed to be but I seriously doubt it )
3) Tx antenna was a Diamond SRH771 SMA 433MHz
4) Hopping was 5 channels
5) A GoPro was on and recording, but then turned off to see if range came back
6) Gopro was 12" from the OpenLRS Rx
7) My OpenLRS antenna was not fitted as recommended directly to the Rx but on a 24" RG318 tail
8) 5.8ghz vtx was running the whole test with a linear antenna so to cause as much effect on results as possible. It shouldn't, but anything that was gong to be switched on while flying was.

I repeated last times test, the tx was sat at exactly the same place within 12" of last time, the weather was exactly the same as last time and I covered the same route for the test.

Expecting the same results as last time I drove straight to the 2.4km first check point and got out the car, not a thing, RSSI 0.04v no control :( I then just for the purpose of the test continued to the 4.3km point that 433mhz code has passed fine with no glitches no problem. Got out the car, RSSI 0.04 no control :(

Very disappointing

So I started from scratch, I went back to the tx to make sure everything was fine, it was, so I did a much shorter range test.

To my horror my max distance with no glitches was only 300m !

At 470m if I banked the plane to induce dbi loss I lost control at 90 degree bank.

At 870m if I banked the plane anywhere past 10 degrees, total loss of control :(

My conclusion :

1) Cat your not doing something wrong :)

2) I have no doubt Thundeads code is in no way at fault, the pins were moved up one, the RSSI code has nothing to do with the connection

3) I believe, very much, that the 433 chip just can not take the 459mhz, I believe it drops the power that much it renders the system useless. I also don`t believe the output is anywhere near 100mw, not even close. 459  and 433 are that close in frequencies that if they were using the same power, the ranges would match within a few meters of each other. Which suggests the chip is running way short of anything close to 100mw

4) The only way this is going to be improved is by using a different chip

So no one as yet has got a decent distance on 459mhz? This could explain why my Dad and I's DIY system has been getting crap range. We've done all the tests at 459mhz selected thinking that's what other people had done as well.

I'll go repeat my range test in a minute at 433, to help verify this.

Brett

[Splashy]

Yes, that would do it. Of course you won't have telemetry .. but at least it should work.

It should be relatively easy to find a booster that can be neatly integrated. The 7W Flytron amp is a little bit of an overkill but something along those lines with a switch for 100mW and maybe 500mW (or 200) as an emergency switch would be great.

Perhaps we can ask Flytron to come up with such a booster. He does seem to be able to turn around good designs pretty quickly and I am impressed with their delivery costs and speed of delivery.

I rather like this option as I think that OpenLRS works very well and bodging something out of a transceiver chip and a Pro Mini would result in a little too much for me to put my faith into.

[Coyote]

It may not be low on power, but that`s what my money is on.

Flytron I think are looking into releasing a much lower power amplifier, when im not sure

Nigel`s right though, no need to write this off yet, its only one test so far, lots of variables

[Splashy]

Whoa, hang on a bit chaps.

Let's do more than one test with more than one set of software.

Before I set out on this, HopeRF were contacted and they had tested these modules to 460MHz and said we should be no more than 10mW down on power.  It was Simon @ FirstPersonView who contacted them as he is 'in the trade' and were willing to talk to him.

Let's do some more tests first before writing the kit off, eh?

Nigel.

I agree. It is great kit and I would love to see it working.

I just wanted to start the debate on the options available. I agree that the HopeRF datasheet indicates that it should work just fine and whilst 10mW is quite a lot it does not explain the results that may be occurring.

[thundead]

guys be sure to set your fw to 435000 Hz

its more "legal": 435=...  Satellite, to 438=
          435.070 UO-14 sat. FM repeater mode - uplink: 145.975 (University of Surrey, 1990)
          436.625 StenSat FM transponder - uplink: 145.840  (12 cubic inches, 8.2 ounces) launched 26Jan00

[Coyote]

Yes the results are far from expected, all they do though really, is show there is something wrong, it doesn`t show what though conclusively

The basis of my thinking is this :

If the code for the signals and channels were wrong, the range would not matter, it would not work next to the plane.

If the code works next to the plane, the only factors for lack of range would be the transmission of the signals, the reception and antenna tuning ( for max range )

[Splashy]

guys be sure to set your fw to 435000 Hz

its more "legal": 435=...  Satellite, to 438=
          435.070 UO-14 sat. FM repeater mode - uplink: 145.975 (University of Surrey, 1990)
          436.625 StenSat FM transponder - uplink: 145.840  (12 cubic inches, 8.2 ounces) launched 26Jan00

I am not quite sure what you mean by this ..