Replies to This Discussion

Permalink Reply by Chris Huitema on June 4, 2012 at 6:58pm

Does it make any difference if the motors are running? could it be electrical noise from the esc's. try taking the camera and tx with a lipo for a walk down the street without the rest of the quad.

maybe also try taking the reciever out of the car and into a clear area. cars normally have alot of metal to block the signal (mines mostly plastic so im fine!) 5.8ghz is really only good for line of sight even trees will effect the signal.

I plan on doing a antenna tracker pan and tilt setup with a panel antenna, using the ardustaion. just waiting for my 5.8ghz panel to arrive. 900mhz panel for the xbee's is here and ready and the ardustaion is pretty much ready to go. just need to find a good way to actuate it all

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Permalink Reply by Alex on June 7, 2012 at 3:11am

Righto. Wasn't as much rain around... so got out again today and took the receiver with me this time.

Seems much clearer until it gets about 50m or so up and then the interference starts again (at about 4.30 mins). Is it better to have the antenna facing downwards or sidewise for flying above?

Probably should add that I'm in the middle of a city (Sydney)... so there is also likely a lot of other noise in the air also. Off to the country on the weekend, so looking forward to trying out the gear there.

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Permalink Reply by Eddie Furey on August 7, 2012 at 4:23pm

Hi Alex,

I'm also in Sydney so perhaps we can catch up and compare notes some time. Admittedly my APM2 is in a plane, but it doesn't look like ESC interference in your video, so I'd bet that it's your antennas.

Here's a video I made in a park near Manly. This is more what you should expect with CP antennas.

BEVRC PV700 flight recorder + PZ0420 D-WDR CCD camera test

 

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Permalink Reply by Crasher on June 7, 2012 at 3:21am

I've had some pretty good (solid to about 3KM) results on 5.8Ghz, here's what I've found to work:

1. Circularly polarised antennas. Forget all that sticky up stuff, you need something like these:

http://www.firstpersonview.co.uk/antennas/5.8ghz

You need them on the TX and RX side.

2. Take your RX out of the Faraday cage which is your car. The roof will make a far better base, and you can run your wires through the sunroof if you want to.

3. I've recently switched from BEVRC gear to ImmersionRC, and, although it shouldn't make any difference, I seem to be getting better results on my 200mw BEV gear than my 600Mw ImmersionRC gear. It's early days, and I know this shouldn't be the case so maybe it's just bad luck until now..

4. Circularly Polrised patch antennas are also a good idea for anything long range, less likely with a copter, more for fixed wing. Once again, the patch needs to be CP too.

Regardless of comments, you CAN get good results on 5.8Ghz. I have. Good luck

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Permalink Reply by Alex on June 7, 2012 at 3:29am

I'll stick some CP's on the wish list.

Thanks for the advice!

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Permalink Reply by Eddie Furey on August 6, 2012 at 5:20am

As previously mentioned, make, or buy, a pair of circularly polarized antennas. They will reduce your multipathing down to almost nothing. Also get your receiver antenna up high, 1m high or more is ok, 2 is better.

Have a quick read about the Fresnel zone. I'll attach a Freznel zone spreadsheet I made so you can quickly get an idea of it's size. make sure the zone is clear of objects, especially metal ones like your car. :)

Attachments:

• Freznel Zone Calculator.xlsx, 11 KB

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Permalink Reply by Neill McOran-Campbell on February 26, 2013 at 4:37pm

This, absolutely this.

I am very certain that your problem is multipath or polarization loss which can be easily corrected by making a good set of circularly polarized antennas. 

I actually am thinking about making some videos on building them, it is very easy stuff.

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