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Thread: TBS CROSSFIRE with 1.2GHz Video

  1. #91
    Spearheading an Aliance BravoGolf's Avatar
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    Rule #78 - When upgrading or changing set ups, never sell your old gear until you determine the new gear performs as intended/expected, serves its intended purpose and meets your needs.

    A lot of very bright minds in this hobby/industry. I'm certain a solution, probably better designed VTX's, is right around the corner. And of course cheaper knockoffs not too long after that!

    I would however like to see something noted in the product description that the system may not be compatible with 1.2. I intended to use the crossfire with 1.2 but will have to adapt for now and use 2.4 gear I have on hand. I'm perfectly ok with that and look forward to a day in the not too distant future when we have a solution for this.





    Quote Originally Posted by zlutyslamak View Post
    Hi Chris,

    thanks for your reply. Should we understand that the Crossfire is for now in combination with 1.2G gear useless for long range - meant for higer power levels ?

    Please do not understand me wrong, I do not want to blame anybody. Its just a question - it seems to be that all 1.2G FPVers which had bought the Crossfire had just overseen the proximity of signal carriers. But thats just law of physics and we all have to count with them.

    The real world testing of notch filters did not (till yet) shown significant improvement. Daemon,Killerbean... both had same results - interference still present + hardly reduced range on 1.2G videogear.

    Therefore I would propose to TBS to be fair and put your answer to product page of Crossfire - just not to get customers to my situation that shortly before start of thermalling season is the glider grounded with gear for almost 400USD which does not work as was planned - of course old proven gear in euphoria from Crossfire already sold :-(
    I know that part of the story should be on my side - should study more about proximity of frequencies... nevertheless with warning that the Crossfire does not work with 1.2G gear, would not come to situation of lost of one thermalling season :-(

    Cheers Jan
    Last edited by BravoGolf; 7th April 2016 at 12:06 PM.
    ~BG

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  2. #92
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    Quote Originally Posted by Killerbean View Post

    On another forum I got a pm from somebody using a iftron receiver (449usd).
    He said that he didn’t have any problems bench testing with the iftron at 0,5 meters from the crossfire at 500mw setting. I asked him to put on attenuators and test again, I hope he can do this.
    I'm the somebody you are referring to. Been busy lately (bought a house) and am finishing up my wood-kit built 3m plane (Bearospace Gemini). I will perform some more tests this weekend hopefully if nothing comes up.

    But yes, I can confirm I did this test about a few months ago: I had a VAS Mad Mushroom connected to my Iftron and a Moxon to my Crossfire (should be 2x the power then at regular 500mw output, right?!). Held the Moxon 1m away and no issues, not even a line or static. Held 0.5m away still no issues at all. At something like 10cm I started to get significant static, but again, this was super close (probably even dangerous to the internals of the Iftron).

    Since I don't have any attenuators I must figure out another way to do this test in my NYC basement (read: lots of noise). Probably will keep the Iftron antenna and Crossfire on one side of the basement and 1W Iftron vTX along with the Crossfire RX to the other side. There are a few cement walls in between. Will note the Crossfire signal strength to try to mimic real life levels from many kilometers away and will make note of video image. I will toggle Crossfire on/off to see if it has any adverse effect on video quality. I think the Iftron spectrum analyzer (although its quite basic) can still analyze the entire ~900mhz to ~1300mhz range and will take note of any numbers that show up. Following this, I will move my vTX outside to my backyard (now 4 layer brick wall + 10 inch cement layer + 10ft height difference + 20ft distance difference) and repeat test. I know from previous Crossfire tests that one cement wall in the way will bring signal down a good 25db from 5 ft away. So I think if I can get 3 cement walls in the way I can count on a ~50 to ~75db loss from the vTX side. I don't think this will be the best test (because of city noise, but being in a brick basement will probably help) but it will be worth a shot and provide some clues.
    Last edited by daBKLYNdoorman; 7th April 2016 at 10:40 PM.

  3. #93
    Shedding light over FPV HugeOne's Avatar
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    Quote Originally Posted by Killerbean View Post
    Thanks for this honesty. Now i know what to do.

    Last question.....
    Please point us all to a good 2.4ghz antenna to mount on a tracker.
    An antenna to have at least 50km of video range, preferably low alt.

    Your long range video was also done on 2.4ghz with 24dbi grid antenna at aprox 400m alt.
    These grid's are too big and heavy on the tracker.

    i have a custom made 2.4 yagi 13 element from the same guy that tbs gets their yagi's from, but it is not sufficiŽnt.
    More gain than the 13 elements yagi, much easier to handle.

    http://www.truerc.ca/shop/antennas/2-4ghz/gatling-2-4

    -Hugo

  4. #94
    Young Skywalker Rfriedman's Avatar
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    Quote Originally Posted by daBKLYNdoorman View Post
    I'm the somebody you are referring to. Been busy lately (bought a house) and am finishing up my wood-kit built 3m plane (Bearospace Gemini). I will perform some more tests this weekend hopefully if nothing comes up.

    But yes, I can confirm I did this test about a few months ago: I had a VAS Mad Mushroom connected to my Iftron and a Moxon to my Crossfire (should be 2x the power then at regular 500mw output, right?!). Held the Moxon 1m away and no issues, not even a line or static. Held 0.5m away still no issues at all. At something like 10cm I started to get significant static, but again, this was super close (probably even dangerous to the internals of the Iftron).

    Since I don't have any attenuators I must figure out another way to do this test in my NYC basement (read: lots of noise). Probably will keep the Iftron antenna and Crossfire on one side of the basement and 1W Iftron vTX along with the Crossfire RX to the other side. There are a few cement walls in between. Will note the Crossfire signal strength to try to mimic real life levels from many kilometers away and will make note of video image. I will toggle Crossfire on/off to see if it has any adverse effect on video quality. I think the Iftron spectrum analyzer (although its quite basic) can still analyze the entire ~900mhz to ~1300mhz range and will take note of any numbers that show up. Following this, I will move my vTX outside to my backyard (now 4 layer brick wall + 10 inch cement layer + 10ft height difference + 20ft distance difference) and repeat test. I know from previous Crossfire tests that one cement wall in the way will bring signal down a good 25db from 5 ft away. So I think if I can get 3 cement walls in the way I can count on a ~50 to ~75db loss from the vTX side. I don't think this will be the best test (because of city noise, but being in a brick basement will probably help) but it will be worth a shot and provide some clues.
    Just a tip. There are two modes on the iftron spectrum analyzer. Try both of them. Also it does take a few seconds to scan the band, so make sure you give it time to settle.

    Good luck on the gemini build. Post on the gemini thread when you are finished as I'm curious how the solar works out. I'm gonna try to get funding for our school to build one

  5. #95
    Navigator Beachflyer's Avatar
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    Shameless plug^ lol

  6. #96
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    Hi guys,

    I am not RF specialist but what about such a filter style on VRx ?

    https://en.wikipedia.org/wiki/Distri...element_filter

  7. #97
    Navigator Killerbean's Avatar
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    Quote Originally Posted by HugeOne View Post
    More gain than the 13 elements yagi, much easier to handle.

    http://www.truerc.ca/shop/antennas/2-4ghz/gatling-2-4

    -Hugo
    Hi hugo,

    Yes we had some email contact last year about this antenna. But I cannot find any one flying far and low with this antenna. Therefore I don't want to buy for 250 usd and hope that it's good enough for me.
    It's too much money for that.

    I was hoping for tbs to recommend an antenna.
    But I think it is just like one of my friends said, tbs is 2.4g all the way. Every other frequency does not matter to them. That is a pity

  8. #98
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    As I said before:

    A new transmitting protocol with sophisticated, penetrating behaviours OFCOURSE will interfear with your current vrx when it's within a few feet or stuck inside your goggles (the smaller the equipment, the more prone it is to interferance). TBS Crossfire is working fine as long as you are okay to adept to some basic rules of this new protocol that has been modified to actively change it's own powersetting.
    First rule is to keep space between your Crossfire tx and your tripod with vrx. Second rule: Don't place these two sources in eachother's operating direction. Third rule: In a nuclear plant you wear protection. Treat your setup as if it needs to be prepared for a visit to the plant Honestly.

    @Killerbean: I watched several interference tests you did with your setup on Youtube. If you want to find the solution to the interference problem, you need to put the interfering signals to work in a natural environment, under the same circumstances. Several times you held the tip of your Crossfire tx next to your plane. In what circumstances in the field are you holding the tip of your antenna close to your plane? Ofcourse you will manipulate interference that way, but not the kind you're looking for to solve.

    But don't worry, somebody else made the same mistake:

    @Perna: In your search to discover the same kind of interference Killerbean was reporting about, you thought it would be the ultimate idea to have the same test done in a professional lab packed with the most expensive measuring equipment money can buy. But is that the right way to imitate the situation in which your customers discover the mentioned problems? Does testing in a pro-lab meet the conditions of a test in a 'natural environment, under the same circumstances'? Do Crossfire customers use expensive professional measuring equipment to receive their analog videosignals with? No they don't. They use cheap videoreceivers from Asia. So in that case, a test in a professional lab will -ofcourse!- show different results.

    Nevertheless, it's a shame that the TBS crew denies the fact that the Crossfire interfears on the 1.2ghz band when set into higher output modes and says that 'tests with cheap spectrum analyzers show bad results which don't match values that expensive lab equipment show'.

    But this small info might clear up ssome of the confusement related to the long range system: The LoRa broadcasting technique wasn't developed for operating at more than 100mW whatsoever. Moreover, development kits which manufacturer Semtech sells have an output of 25mW only, so the key thing of the issue is that we are dealing with an overpowered transmitter module. Compare it to a nice equipped small car full of the latest technology onboard....and a V16 engine in the trunk; that won't work either.

    The LoRa 1272 chipset is TBS modified by adding some step up regulator UHF booster in the module and we all know what problems boosters usually give... Anyway the specific 1272 chipset has the official designation of 'end of life' so manufacturers are called upon not to use it in their current products anymore.

    Which means we'll get a Crossfire V2 end of summer gentlemen!

  9. #99
    Navigator Killerbean's Avatar
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    Fpvlad,

    You are correct with most of your post.

    sometimes, the ground testing seems to look good, as is the same with the notch filter.
    But then the real world test is a bummer.

    This is what i experienced the last weeks. Winter is over, so i need to get ready for flying season.
    Please note, that crossfire IS a very VERY !! good system. on 10mw setting flights of 20 and 25km are possible.
    But in my own tests, everything above 100mw setting will destroy the video feed in real flight.
    This is due to the video signal getting weaker and the vrx has to listen better.
    As i mentioned before, Lineair has more problems with it then circular.

    Since the crossfire tx antenna is omni, its only important that you do not get in front of your VRX antenna.
    I had the best successes when i hold the hole of the donut, the point where the tx signal is the most little, to the receiver. Usually that ment to hold the crossfire tx antenna horizontal since the antenna on my plane is verycal, Resulting in crossfire automatically upgrading power.
    So its a circle :-)

    For now, i ordered dragonlink v3. I am not mad at tbs. I dont sell my crossfire UHF. TBS has been very good to me in terms of support. It is just another flavor.
    I will preform a ground test with both the DL and the TBS at the same time and make a movie of this.
    It is pretty interesting to see.

    433 is lower freq so would go further.
    But DL is 433 800mw max.
    And TBS is 868 2000mw max.

    I think both systems will get pretty much same range.
    So maybe i have to incluse the rf explorer to sweep the band and look how busy it is.

    When i am done testing, i'll post here too.
    for now i just have to wait a few weeks for the package to arrive.
    And then i have to learn the DL system before i can use it.

  10. #100
    Navigator Killerbean's Avatar
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    P.s. what do you guys think of this antenna:

    http://www.elboxrf.com/EN/p102/Tetra...9_20_RSLL.html

    Lineair, not expensive, 19dbi and from a good company. Normally used in the Wifi/PC prof business.

    A friend of mine got out 51km at 500m alt using a 16 element 16dbi yagi on 1280mhz.
    I think with the 19dbi 2.4 panel antenna the same should be possible(?)

    Just an idea.... i have one now but no time for testing.

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