Low Quality FPV Video Problem

Discussion in 'FPV Systems' started by jstrass10_, Feb 3, 2019.

  1. jstrass10_

    jstrass10_ Member

    So I recently finished my first miniquad build and took it for the maiden flight today. Everything worked perfectly except the video coming into my fatshark dominator v3's. I was on the strongest channel but the video feedback was very low quality and was almost too bad to fly with. I'll attach the video below from this flight so you all can see the problem. Any help is appreciated.

    Video:


    Equipment:
    https://www.getfpv.com/lumenier-micro-axii-shorty-sma-5-8ghz-antenna-rhcp.html
    https://www.getfpv.com/vas-ion-v2-5-8ghz-sma-antenna-rhcp.html
    https://www.getfpv.com/immersionrc-tramp-hv-5-8ghz-video-tx-us-version.html
     
  2. Dugdog47

    Dugdog47 Well-Known Member

    That vtx lowest power setting is 1mW make sure it's set higher than that when you fly.

    Make sure your antenna on the vtx is correct, the sma connectors have to be compatible.

    Make sure both antennas on your goggles and vtx have the same twist, either right hand or left hand.

    Make sure you're powering your vtx with a clean power supply at least 9 volts.

    Finally, make sure you have a capacitor soldered in correctly on your power leads.
     
    wafflejock and holtneil like this.
  3. jstrass10_

    jstrass10_ Member

    I did those steps and it works better but still not a great signal. I forgot to mention that I did make the mistake of powering on the vtx without an antenna when I was configuring my quad in betaflight, I touched the vtx after I realized I forgot to put on the antenna and it was only warm not hot. Could this have ruined my tramp? Thanks for helping by the way, I appreciate it.
     
  4. wafflejock

    wafflejock Well-Known Member

    As counterintuitive as it might be would suggest reducing the transmission power on the vtx. Unless you are going more than a football/baseball field away even at 25mW you should have enough signal to not have the kind of break up you're seeing right now. If it is mostly breaking up when you attempt to give it throttle would suggest adding capacitors to all the ESCs (this helped clean out last bits of major noise I would get when hitting the throttle hard). If reducing VTX power helps it could be a couple of things: 1 mutlipath signals (you're interfering with yourself basically bounced signals are hitting the receiver and seen as just as good as the real thing), 2 could be drawing too much power in the VTX and the regulator suppling it amps is at its limit. Would also be curious if you've tried with other antenna at all this is the cheapest thing to swap out I think anyway to start narrowing down components (from the video it looks pretty intermittent which makes me feel like it's just a loose antenna connection, make sure the antenna/pigtail to antenna connection is well soldered onto the VTX (the grounds on the shielding for the antenna can pretty easily come off on some VTX).

    ---

    Also question how are you currently powering the VTX?
     
  5. jstrass10_

    jstrass10_ Member

    065E968B-1535-4E89-B20C-80A7A64ACC8F.jpeg I have it soldered to a 5V pad in the circled section of the flight controller.
    Also do you think I could have ruined it by forgetting to put on the antenna when it was powered up?
     
  6. wafflejock

    wafflejock Well-Known Member

    Yah I would suspect that 5V power supply not supplying enough current for whatever power output (and power bled off as heat in components). Would try powering the VTX directly from 2-6S lipo as they suggest it can handle and see if the video is still really rough otherwise it could just be an issue of the 5V regulator on the FC. There's a chance the VTX got fried when turning on without an antenna but I think that's more of a permanent and complete loss of signal kind of situation (maybe it just partially fried though hard to say I haven't had this happen yet though so can't tell you for sure).
     
  7. Dugdog47

    Dugdog47 Well-Known Member

    Yea that's your problem 5volts isn't enough, solder it to the 9v pad see what happens.
     
  8. wafflejock

    wafflejock Well-Known Member

    Yah I'd say just go straight off the battery then definitely no amperage limiting component in the way, only problem with the main power is it will drain over the course of your flight so voltage won't be consistent but the vtx should have it's own voltage regulator, for the noise the escs put into the lines you can add caps on the escs (Oscar Liang has a long write up on troubleshooting video issues)

    ---

    For esc caps want something high enough voltage to be well a over battery fully charged voltage, I just used some electrolytic caps I had laying around I think 20V 440uF seem to help quite a bit. That said noise I'm eliminating with those is only present when changing throttle.
     
  9. Dugdog47

    Dugdog47 Well-Known Member

    I've found if the flight control board has a 9v hole that's the best place to power the vtx, although powering off the battery is something I've not yet tried.

    Either way 5v is not enough, needs more power lol.
     
  10. wafflejock

    wafflejock Well-Known Member

    Well thing is it says it should work off 5V supply too but it doesn't specify how many amps it will draw. Power is combined Amps times Volts, so at 9V it will take less amps to deliver the same Watts, say we have 45W to deliver (to make the math easy) at 9V it's 5A, but at 5V it's 9A, the higher amperage means more energy lost as heat in components I^2*R and also at some point you'll be drawing more amps than the regulator is designed to supply (it will overheat itself and maybe shut down or maybe just slow roast). If one goes straight off the battery you're only limited by how many amps the battery can deliver and whatever internal regulator the VTX has (which ought to be sufficient otherwise it would never work). Down side is the main power is "dirty" from the ESCs making voltage spikes, but the capacitors can effectively smooth those out.
     
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