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Attention: RC-CAM.com will be closing down August 2021.

The RC-Cam.com forum was the very first online community dedicated to the advancement of wireless video cameras on radio controlled (R/C) models. This is now called "FPV" (First Person View). We are proud of the contributions that our members have made to the FPV hobby.

We've seen significant changes over the last twenty years. Initially there were a lot of eager R/C hobbyist that built their own video systems. Allowing these creative individuals to share their work was the purpose of this site. Now the FPV market is flooded with low cost systems; Sadly DiY FPV video projects are now rarely discussed.

RC-CAM.com (main site and forum) will be closing down August 2021. This was announced several months ago (March 2021) to allow our members ample time to download any information that is important to them. After the site is shutdown the information will no longer be available here.

We appreciate every member's involvement with advancing the FPV hobby. It is indeed sad to say goodbye to all our online friends. Be safe and stay healthy.



Yea, its that new guy again....


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So,

After flying for a few days and being absolutely addicted, and having limited idea on how this RF stuff really works, I've come to the conclusion that most of my problems are multipathing interference.

So,

I started doing some google searches, and stumbled upon this antenna design, the choke ring antenna.

http://www.trimble.com/infrastructure/gnss...x?dtID=overview

http://www.javad.com/jns/index.html?/jns/t...oke%20Ring.html

So,

Has anyone tried one? It looks easy enough to fabricate. Well, easy if I had dimensions to start scaling one to my 910mhz stuff. :)

BTW, when describing multipathing, most images make it look like a game of billiards. How accurate is that depiction for my frequency? Would a chain link fence be a source of reflections in my frequency band? Moving away from these reflectors should rapidly improve performance, yea?

Also, while I'm going to try this, does lowering the output power of my "500mw" transmitter make sense with regards to reducing multipathing problems? According to the 'documentation' if I reduce DC input power, the Tx will reduce output power. I'm currently running off a 3s lipo, and could easily use a 2s setup.

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Would a chain link fence be a source of reflections in my frequency band?

Absolutely, it's a multipathing nightmare. Multipathing will also occur from cars, buildings, hard earth, etc.

According to the 'documentation' if I reduce DC input power, the Tx will reduce output power.

I recall seeing a popular FPV vendor advertise that the 900Mhz 500mW system would reduce RF power with lower voltage. But it's not an accurate claim (it applies to the 200mW, but not the 500mW). There's a 7808 8V Vreg inside that powers everything, including the RF circuitry. It ensure that RF power remains the same as the 12V battery discharges. Once you get below about 9V, the video quality begins to degrade, then goes away completely on voltages a bit lower than that. So, by the time you've lowered the voltage enough to substantially reduce the RF power, the video image will be toast.

If you are experiencing too much multipathing on your 900Mhz system then you need to move to another flying site. It needs to be wide open area, away from everything. Flying in a field with metal fences, cars, man made structures, and other RF reflective surfaces will just cause grief.

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