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Thread: What's going on in Colorado...

  1. #9931
    Young Skywalker Rfriedman's Avatar
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    Quote Originally Posted by Daemon View Post
    Personally I found Crossfire to have sub par performance in our high noise environment along the front range (telemetry signal gave up about 1.5 miles out, forcing the Tx to high power), and none of our 1.3Ghz VRXs play nice with it (They see the Crossfire Tx's high powered 915Mhz signal just like another video signal powered up on the flight line, so video signal gets stepped on pretty hard). Hope it works out for ya.
    So I finally got a new Clearview XLR Receiver. The other one I still had issues after the comparisons we did due to being a prototype. I exchanged it about two weeks ago for a brand new one (which works much better)...

    Since the modules on the other XLR did not have any dramatic improvement with the Crossfire noise, I do not think my new XLR will help much. As helpful as Clearview processing is when out of LOS or indoors, it can't do much if the signal from the modules is consistently crap. The adjacent channel noise rejection works well when the noise is intermittent, such as a quadcopter passing a flight line. Extended periods of bad signal (greater than 5 seconds or so) won't work well.

    I am curious if the working XLR coupled with TBS's filters would end up being similar range to a standard 1.3GHz receiver but better reject the Crossfire noise. Did you ever buy some of those filters from TBS?
    When I move back to Golden in August, we could do some more testing if you are interested. And goblin flying
    Last edited by Rfriedman; 17th July 2017 at 01:34 PM.

  2. #9932
    I was sent some filters Alex made when I first reported the issue, and tried em every which way, one of them passing 1.3Ghz and blocking 915Mhz to be installed on VRX, and another passing 915 and blocking 1.3Ghz to be installed on Crossfire Tx, and it had *zero* positive effect. Many attempts have been made over the years to improve the selectivity of our 0.9-1.3Ghz VRXs and so far they've all failed. One thing to consider, some folks who've used Crossfire with 1.3Ghz video have succeeded only because they could fly Crossfire at much lower power levels. Around here 900Mhz band is full of garbage which is why 100mW telemetry signal is lost so quickly, and means Tx has to run at higher power just to cut through it, which has a greater effect on 1.3Ghz video.

    BTW, if you want to do the ultimate XLR test, go try to fly the cliffs below the saw tooth ridge north of Bierstadt. The multipathing there is off the charts.

  3. #9933
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    I wish I had the balls to fly like you do. The desire is there, but the knees gave up long ago. Once I came to terms with that I also discovered 5.8 is fine for me. My long range desire is to not loose signal past Futaba range now.
    Along with this, I have found my desire to trim down to a more manageable size, thus the Flinch. My mini-Wraith has turned into quite the fun fpv aircraft. Just love a plane with zero field set up.

    Other updates, the Cub is basically done. Just need to throw a receiver in it and she will be ready to maiden.

  4. #9934
    Young Skywalker Rfriedman's Avatar
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    Quote Originally Posted by Daemon View Post
    I was sent some filters Alex made when I first reported the issue, and tried em every which way, one of them passing 1.3Ghz and blocking 915Mhz to be installed on VRX, and another passing 915 and blocking 1.3Ghz to be installed on Crossfire Tx, and it had *zero* positive effect. Many attempts have been made over the years to improve the selectivity of our 0.9-1.3Ghz VRXs and so far they've all failed. One thing to consider, some folks who've used Crossfire with 1.3Ghz video have succeeded only because they could fly Crossfire at much lower power levels. Around here 900Mhz band is full of garbage which is why 100mW telemetry signal is lost so quickly, and means Tx has to run at higher power just to cut through it, which has a greater effect on 1.3Ghz video.

    BTW, if you want to do the ultimate XLR test, go try to fly the cliffs below the saw tooth ridge north of Bierstadt. The multipathing there is off the charts.
    That's unfortunate. At least Iftron is going to release 2.4GHz XLR. That would go well with Crossfire assuming you don't fly with a bunch of quad pilots...

    Reagarding Bierstadt:
    What's the story on flying aircraft there? I tried accessing some maps to check the dispersed camping there, but couldn't find the right map. In the USFS in Boulder, they explicitly permit UAV flights that follow the FAA's 336 guidelines. I am curious if it's the same up there, or if you just launched/landed on the public road. I hiked Bierstadt about 3 weeks ago and there are a large number of suitable launch locations along the way. My goblin easily fits in a backpacking backpack with all the appropriate FPV gear too. Also, do you worry about flying during high fire danger?

  5. #9935
    I've only been up there twice in the last few years and I launch and land from a mostly unused path just south of the main parking lot, which I believe is USFS. However much of the area north and east of there, and Bierstadt itself is inside Mt. Evans Wilderness area so no mechanized vehicles allowed on the ground, and the FAA "requests" (it's not in the FARs as a rule) that pilots fly no less than 2000ft above wilderness areas. Like most places (including your local park) it comes down to noise. I only fly up there later in the afternoon when everyone is down from Bierstadt, and most people have gone home. I launch, fly far away from the normal trail areas to climb, and dive down the mountains with trails on em with the motor off. The sound of the Goblin definitely carries further than the Skyhunter, and the tone is less pleasant. I definitely wouldn't take something like a Zephyr up there. There's no place *everyone* wouldn't be able to hear it.
    Anyway, it's not a place I'd make a habit of flying, which is true of a lot of places in Colorado, for the same reasons. Everything in moderation and be considerate.

  6. #9936
    Quote Originally Posted by Zangetsu57 View Post
    That sounds right. Let me summarize below to make sure I understand:

    - Two video transmitters, each tuned to separate frequencies, each attached to their own VTX and antenna (Yagi)
    - One Rx antenna (Omni) with a 3dB 50 ohm power divider and a separate VRx tuned to the respective VTX frequencies.

    If the above is true, it should work. The only issue you might fight is channel to channel isolation for the receivers since these hobby-grade transmitters don't have the best filtering. Hopefully it just works, but if you observe ghosting or bleed, you might be able to solve the problem with additional external filtering. I'd test it first. If it has issues, PM me and I can help you out.

    Sorry for the late reply, you got it mostly right except there will be 2 vrx one for each channel.
    I got the anaren and the yagi's. the connectors are wrong on the yagis, I think they are bnc for security cams. Im not sure if I should cut BNC and solder on SMA or find an adapter?
    Now I just need some time to put it all together and then test it in town before i send it up with him.

    Thank you for your help!!!

  7. #9937
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    I would keep it simple and just get an adapter.

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