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Old Aug 06, 2012, 03:57 PM
More Combat Please!
Wind_of_Change's Avatar
Utah
Joined Dec 2003
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You'll have to explain to me how you guys are using a 600mhz low-pass filter to prevent a DL from interfering with 1.2ghz video. DL is 433mhz, and the video is 1.2ghz. How does a 600mhz filter help anything?

I could see using a 400mhz filter on your video receiver, which would filter out 433mhz interference. http://www.digikey.com/product-detai...360-ND/2270981

Somebody explain to me what you're doing, please.
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Old Aug 06, 2012, 06:05 PM
FPV junkie
m_beeson's Avatar
United States, UT
Joined Jan 2011
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Todd,

The transmitter emitts a lot of noise on a multiple frequency of 433 mhz, which affects the 1.2 band.

By placing the low pass filter inbetween the transmitter, and the antenna, you cut out a lot of that noise.


I don't get much interferance with chainlink on low, but when I kick up the power; I still have to step back from the ground station, even with the low pass filter.

before I put the low pass filter on the transmitter I couldn't be in close aproximity of the ground station.

I think DL only has one power, and it puts out more than Chainlink when it is on low, so you can see where you would run into issues.
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Old Aug 06, 2012, 06:11 PM
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United States, UT
Joined Jan 2011
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I've been thinking about using a high pass filter for the Vtx. "they say" that the 1280 can interfere with the 433 reciever.

It would have to be higher than 400Mhz though.

I just looked on digikey, and didn't find one that would work.
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Old Aug 06, 2012, 06:27 PM
More Combat Please!
Wind_of_Change's Avatar
Utah
Joined Dec 2003
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Quote:
Originally Posted by m_beeson View Post
The transmitter emits a lot of noise on a multiple frequency of 433 mhz, which affects the 1.2 band.
I still don't see how a 600mhz filter is gonna help you, unless the 600mhz filter also filters on multiples of the frequency, in which case it'd filter 1200mhz.

Quote:
Originally Posted by m_beeson View Post
By placing the low pass filter inbetween the transmitter, and the antenna, you cut out a lot of that noise.
Which transmitter are you talking about? Do you put the low pass filter on the video transmitter before the antenna, or on the UHF 433mhz transmitter before the antenna?

Quote:
Originally Posted by m_beeson View Post
I think DL only has one power, and it puts out more than Chainlink when it is on low, so you can see where you would run into issues.
The new DL V2 has a switch for low and high power. The high power setting is what was formerly the ONLY setting, and they've introduced a new "low power" setting, for those who aren't going long range for things like MultiRotors. That extends the life of the TX battery.
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Old Aug 06, 2012, 08:24 PM
FPV junkie
m_beeson's Avatar
United States, UT
Joined Jan 2011
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Quote:
Originally Posted by Wind_of_Change View Post
I still don't see how a 600mhz filter is gonna help you, unless the 600mhz filter also filters on multiples of the frequency, in which case it'd filter 1200mhz.
it goes in front of the UHF antenna.

It is a low pass filter, so it will not allow any rf to get past that is higher than 600Mhz.



Which transmitter are you talking about? Do you put the low pass filter on the video transmitter before the antenna, or on the UHF 433mhz transmitter before the antenna?

The new DL V2 has a switch for low and high power. The high power setting is what was formerly the ONLY setting, and they've introduced a new "low power" setting, for those who aren't going long range for things like MultiRotors. That extends the life of the TX battery.

That's a good improvement.
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Old Aug 07, 2012, 11:55 AM
Mountain? What mount..CRASH!!
cardo's Avatar
United States, UT
Joined Feb 2008
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ya, Low pass=it will pass the lower frequency's through. Same with High-pass, it will pass the high through wile blocking the low. You just have to find ones with the correct specs for your application.
I have had the same problem with my DL totally killing my 1.2ghz video. I finally figured it out when I was getting ready to fly and I was getting no video at all. After checking all the connections on plane/ground station I simply turned off the DL and ta-da, I had video. So I found that I have to make sure the video is working first, then I can turn on my DL. I need to get some filters.
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Old Aug 07, 2012, 12:40 PM
More Combat Please!
Wind_of_Change's Avatar
Utah
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Okay, that makes sense now, thanks for clearing that up for me.

So the frequency on a filter is not to filter a specific frequency, it's to filter all frequencies above or below the filter value. Got it.

I didn't realize that you put them on the UHF antenna, I thought that they went on the plane.

So I bought a 2.4Ghz High Pass Filter for reducing interference to GPS and RC Receivers. I put it between my VTX and video antenna. That allows 2.4ghz and above frequencies, while blocking everything below it, right?
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Old Aug 07, 2012, 12:47 PM
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United States, OR, Portland
Joined Sep 2011
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Yep, that's correct. High Pass means it passes from that frequency and above, everything below is atenuated. There's also BAND pass filters which filter frequencies above AND below which is similar to what you were thinking before, they only let frequencies around that target band to pass .
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Old Aug 07, 2012, 12:58 PM
More Combat Please!
Wind_of_Change's Avatar
Utah
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Is it just me, or does it seem like vendors should automatically include a band filter on any products they sell that are targeted to a specific frequency?

Should be law that all UHF and RC gear have a band filter internal to the gear so it only broadcasts on the specific frequency.
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Old Aug 07, 2012, 01:15 PM
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Well, the problem is that these are all passive filters, meaning there's no amplification or active component. No passive filter is ideal so the resulting signal output has always less amplitude than it's input, i.e. some attenuation. My guess is that manufacturers don't include a filter because of this and cost and because not everybody needs it. An active filter would need to be powered and will cost more.
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Old Aug 07, 2012, 03:59 PM
More Combat Please!
Wind_of_Change's Avatar
Utah
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Ah, makes sense. Pfff. So many issues with every aspect of FPV.

So here's a question for you guys.

Backstory: I tossed a prop on my X650 quad during take-off, and it flipped over onto it's head on the asphalt. Broke all 4 props and got a little sandy grit in the motors.

After that it just won't fly. Replaced props and cleaned out motors, but when I lift off, it shakes randomly, has little spasms. It's not oscillations like you get when your gains are off in the controller, but just random twitches. Dips a side suddenly and then straightens back up.

I thought maybe I'd damaged one of the motors, so I swapped each one out with a good one until they were all new motors. Still acts the same.

I'm thinking maybe one of the ESC's got messed up when the motors kept spinning after flipping it. The resistance could have caused one to go weird. But it seems like it wouldn't fly at all if that were the case.

Could the Naza controller, maybe the gyros, have been damaged? If so, seems like it wouldn't fly at all.

It'll lift off and hover, it just twitches like it has a nervous tick.

Any thoughts as to why?
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Old Aug 07, 2012, 04:16 PM
wheeeeee!
elCapitan's Avatar
United States, UT, Provo
Joined Oct 2011
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...because it's a quad. Talk about finicky! Dang, these things.
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Old Aug 07, 2012, 04:24 PM
More Combat Please!
Wind_of_Change's Avatar
Utah
Joined Dec 2003
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Yeah, but the thing flew rock solid before the crash. So I know it's not the frame. The frame is fine. I was getting some incredible control & stability out of it. I'm sure a hex is more stable, but a hex also has 50% more things that can go wrong with it.

EDIT:

I just swapped the NAZA controller, and it does the same thing. Must be a bad ESC or a bad wire connection in one of the arms. Ugh, didn't buy a spare ESC in this brand. I'm kicking myself.
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Old Aug 07, 2012, 05:35 PM
wheeeeee!
elCapitan's Avatar
United States, UT, Provo
Joined Oct 2011
916 Posts
No, I wasn't talking about the frame. I just meant multi-rotors in general have approx. 1.3 billion things that might go wrong. You warned me, and I've confirmed it. So why is it giving you problem? Because it hates you, Todd. They hate me too.

Good luck, man. Hopefully some more successful multi-rotor flyers can help you out.
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Old Aug 07, 2012, 07:20 PM
3d NOOBular
3DNater's Avatar
USA, UT, St George
Joined Aug 2010
8,021 Posts
replace all the motors esc's and the control board and I bet it works perfect
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