Hi, I have just started out with FPV and guess I did all wrong from the start regarding the placement of my antennas. I got about 50meters of range with my googles and breaks in the image when facing somewhere other than straight ahead. I have now realized the placement is crucial together with keeping some space between different hardware onboard. Just wanted your opinion on my modifications. Will hopefully go out try it tomorrow.
The specifications are one 3DR telemetry module at 433mhz on the right arm (left on the picture) and one VTX from fatshark at 5,8ghz. The radio RX is on the back of the frame hanging straight down, now separated from power lines.
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my 5c
Rx near an ESC (especially if it is of the 433mhz kind) is a bad idea, all ESCs emit RF noise on the 400mhz band which atmel/silabs chipset clock speed. vTx is fine as long as it is as far from the Rx and GPS as possible. I would put your Rx near the center and use a dipole for it, as well as move ESCs under the motors between the landing gears. make sure you twist their power cables though to decrease mag interference.
Good point. A lot of care needs to be taken using 433 primarily on Tx/Rx selection. There are some high dollar systems on the market that tend to be "RF dirty." I've heard stories of said systems spoiling up motors because of what was just said. I luckily have a group of guys helping on the RF side that have been long distance FPVing for years on 433 MHz control, and have tested almost every 433 system on the market.
433 control is moot since you are using 433 for telemetry. A set of good antennas will help with your range issue, plus what Artem mentioned. Another thing that is critical is your VRx placement. It needs to be away from metal objects, such as a car. Putting the Vrx near the ground helps in some cases to reduce bounce.
Also need to look at the video wire going from the cam to the Vtx and the power supply wire. Adding a ferite ring near the Vtx on the video feed wire may help. Your power supply to the Vtx also needs to be filtered. Here is one such filter http://www.getfpv.com/lc-common-mode-power-filter.html.
Hope this helps
If you only get 50m then it is not the antennas but the channel. My guess is that you have almost the correct channel on the receiver but not quite. Check your channels and if using Boscam stuff do not trust the manual.
An antenna upgrade is however still also recommended.
I've got more after placing the antennas differently but have not tried it yet. Did trie though the equipment on an airplane and got at least a few 200-300 meters with good video. Bought new antennas (pictures above) but for some reason the one on the googles did not fit. Ordered another pair I hope will work.
Oh.. ESC's also create problems. Should have thought of that.
You mean moving the ESC's even further out on the arms? I have been reading about doing the opposite to prevent high DC currents which cause compass interference. There the idea is to have ESC's as close as possible the power line and extend the cables to the motors instead as they switch polarity and don't interfere the same way. Seems like fixing one problem creates another. Will think about that. 400 and 433mhz as you say don't sound smart together.
Cables under flight controller (in frame) twisted!.. maybe should twist them out on the arms also..
if you twist the power cables it will largely diminish magnetic interference, also, routing the cables inside the CF tubes will help a bit with RF noise as well (not the mag interference though, as it goes right through alum/CF tubes, but twisting the cables will largely take care of that).
I have a 6s tricopter with 370mm arms and the ESCs are located right under the motors, so far my compass mot shows about 4% interference. (external compass). this is negligible, as AC code can cope with 10x more interference.
edit: if you can stuff al the ESCs under the frame, than you can put your Rx further out and not worry about mag interference. space on a tricopter is at premium,...
Philip-
Things I would say to consider are...
1. Are you going to fly high or low? If you plan to fly high up above yourself then the current positioning should provide the best results. If you fly very low or close to the ground then positioning them pointing upwards may provide a tiny improvement in signal.
2. The strength of the Vtx. With a 200mw vtx the range with standard dipole antennas will be very small. Any change of orientation or obstruction due to frame will hurt or cut-out signal. So what you can do is purchase better circular polarized antennas or a stronger transmitter to increase range/quality. And then in the future choose directional antennas like helical ones to further increase range.
And I would generally recommend placing the Vtx in front to make sure you have signal when flying back towards yourself and nothing blocked out by the frame.. But just a suggestion from my own experience.
Hope this helps! Let me know if you have any more questions
Thank you Jordan for your answer. Regarding your questions I don't have the answers today.
1. This would be an outcome from experience. I am not so experienced flying but thought FPV would make things easier. Now after a first try I realize its not all the truth. What ways I'm gonna use it will have to develop together with my flying abilities starting of on big fields with plain sight with quite a lot of hight. Started last time getting the copter into a stable loiter before I put on the glasses. It felt much better for me to start that way.
With time I might feel the will to try FPV where there is not a clear line of sight. Then I guess I'll have to abandon 5.8ghz.
2. The transmitter I have today is a 250mW. And now thanks to you I know placing them in the front was a good idea. My previous placement was on top of the platform obstructed by the flight controller and close to RX as on picture below.
The Telemetry kitt and the FPV antennas where mounted on each side the same way. Only telemetry on the photo.
I actually bought other antennas but they don't seem to fit and I don't know why. Maybe you could help me out there.
This are the antennas I have.
And here is a picture of when I try to connect what I believe is the receiver antenna (has one more blob) to my goggles. The thread does not go in more than max two laps. The one on the TX fits perfectly.
Another question.. I guess these are also best placed horizontally. Is there any degrading on the link bending the cables 90 degrees? Would have to do this on both TX and RX.
You are likely not going to be happy with those antennas; they look like ones I got from HiModel and they didn't work too well.Try out these http://www.getfpv.com/ibcrazy-5-8-ghz-bluebeam-ultra-antenna-set.html. They are pricey, but there is no comparison. Your placement looks good. Think of the clover leaf antennas like a donut. The very top is a hole and signal will be weak, which means you want that to be pointing straight down. Since you have some carbon fiber (not RF invisible) you need to place below the main plate of the copter to minimize bounce. You may want to review your VTx as well. Quality is everything.
I was in the same spot as you a few months back and couldn't get good range out of my 5.8 video, 2.4 control, and 915 telemetry. I've switched to 433 MHz control using the Hawkeye/DTF UHF and a custom pigtail dipole antenna, 1.3 GHz video with bluebeam ultras, and 915 MHz telemetry with a custom dipole. I pushed this setup on my quad out to two miles last week. I am switching to 2.4 GHz video using the DJI lightbridge and some antennas that will be hitting the market in the coming months.
Those antenna's need to be bent so that they are vertical, either straight up or straight down. I have my VTX horizontal on top of my Discovery with the antenna bent down at a smooth'ish 90degree so it's pointing straight down under the frame.
With regards to the fitting on your goggles, have you checked the gold sma connector? one side should have a central pin and the other should have a hole for the pin.
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