Originally Posted by msev

Hope you return and finalize this tracker stuff coz i'm incapable:-)...i've already found the code for rssi tracker, but I'm a bit worried about its performance at the edge of antenna performance (5.8ghz helix + a cp omni)...so what are your new projects after your second most popular project - spectrum analyzer (first is of course diy osd).

If you make antenna-tracker based on RSSI you need 2 directional antennas - and it should be the same antenna.

The spectrum analyzer was just a quick "hey, we need that tool" . But it turned out pretty well.

I just finished a Maxi Swift with 10.000 mah batteries (maiden yesterday), have been looking a bit at OpenLRS and have a bunch of electronic laying around waiting



Should also have a 150 gram quad ready soon.


- and ofc I also fly a bit

Originally Posted by LKJ

Don't forget, a tracker based on RSSI will always follow the strongest signal, when you are a long way out and your signal become week, it is not necessarily yours signal anymore, its been done by more then one person, here on RCG but was never really reliable.

Lars.

I wouldn't use it for long-range, but as a quick tracker for something like 360 degrees covering with 8-14 dBi antenna or something like that, it should be fine.

As long as you have a descent picture/video-signal, it's fine to use RSSI. If your video-signal is lost due to the noise-floor, RSSI will be useless - but then your video-signal will already be gone.

The videos that i see with circular polarization show that the video signal fades pretty slowly..so maybe it could be still enough signal left when I return home...one antenna stationary and pointed in the general direction of flight and the other one on servos..
Although an interesting thought regarding olrs, quix is getting telemetry from rfm22b at 15km using the moxon as a ground antenna...

Originally Posted by Dennis Frie

Arduino/Atmega can handle both decoding and encoding - servo-control on ground, battery-monitor and whatever. I don't really see any need for an extra IC.

Dennis, the Arduino Might be able to handle the job on both end but what about Noise rejection? Ham operators use DTMF all the time.

Originally Posted by rimshotcopter

Dennis, the Arduino Might be able to handle the job on both end but what about Noise rejection? Ham operators use DTMF all the time.

Gotta admit I have no further knowledge about DTMF technology (and noise rejection)
But please keep us updated if you try it out. Would be interesting to see how it performs in comparison.

Originally Posted by Dennis Frie

Looks very good
I have pretty much stopped developing, as the OSD does all I need for new - and I have started a few other projects. But I'm still around and don't mind to help you guys. But personally I would just use the audio-channel as it should be a lot easier to read again, and as far as I know, more stable.

The idea was to emulate the protocol used by the eagle tree OSD and let the FPV station handle the decoding, but of course you need to know the details about the protocol and I guess Eagletree won't give us that info for free.. It's probably more trouble than it's worth with this approach, it was just a thought I had.

Btw, that Maxi Swift looks nice! How long flight times do you get with it? What FPV cam do you use?

Originally Posted by andreas77

Btw, that Maxi Swift looks nice! How long flight times do you get with it? What FPV cam do you use?

I haven't really tested flight-time yet, but with 2 x 2200 mah I can get 30-45 min flight time if I fly nice
I would expect 1 hour with 2 x 5000 mah.

I use RCV922 as fpv cam. Probably not the best cam, but it's pretty cheap, okay image quality and runs at 5 volt.

Just checked my recording from today. Got 33 min and only used 2000 mah. Found some great thermal

Ok, nice! I'm thinking about building something similar but we'll see when that happends..

Originally Posted by andreas77

Ok, nice! I'm thinking about building something similar but we'll see when that happends..

Well, it's a great plane
Here is a bit of ground-recording with the OSD in action

First bit is just some thermal soaring with the Maxi Swift
http://vimeo.com/39784833

Awesome Job Dennis and the place where you fly is just beautiful! Really would love to see more.

Dennis

No filtering at all? After the clamping and the opamp, was there any more circuitry?

Originally Posted by pia32

Dennis

No filtering at all? After the clamping and the opamp, was there any more circuitry?

It's just ideas, I haven't tested much myself.
Try to measure the audio-output and see what's necessary to get a good and stable signal. You can add a little filter if you want, no problem. Just be aware how it affects the signal.

Filtering is where the performance is at. You can get data through even with a SNR of -5db if you have awesome filters (DSP)

Look at the graph on page 3
http://www.urel.feec.vutbr.cz/ra2007/archive/ra2002/pdf/39.pdf

Originally Posted by pia32

Filtering is where the performance is at. You can get data through even with a SNR of -5db if you have awesome filters (DSP)

Look at the graph on page 3
http://www.urel.feec.vutbr.cz/ra2007/archive/ra2002/pdf/39.pdf

Sure, filters will help removing noise etc. but will also change the signal quite a bit, as it's close to square-waves.

Testing filters etc. is not a bad idea, but I would just start with a simple circuit. Just my opinion. The Atmega328 offers a little digital filtering on the external interrupt-pin.

Another solution could be analog-input and digital filters? Simpler hardware, but more sophisticated software. It's all up to you