Jump to content

secretspy711

Members+
  • Content Count

    22
  • Joined

  • Last visited

Posts posted by secretspy711

  1. I test-flew the Pyle @ max setup this evening.  It was a much more punishing 5 miles than my earlier tests due to flying low over many rock formations that would've been in the fresnel zone.  The sync instability is much reduced, and was about on par with my friend's Uno as before, with a few bounces here and there, but overall it's much better and I'm pretty happy with it now.  The picture also seems clearer at range compared to the RMRC receiver.  The few bounces I saw were almost like a "pre-warning" that starts before the fuzziness you get when you start to fly a behind something, out of LOS.

    Haven't had a chance to swap out the resistor yet, there's only so many hours in the day and frankly soldering small things like that intimidates me a little bit.  I don't want to screw it up before the annual FPV meet next weekend.

  2. I have an assortment of metal film resistors but not any 100 ohms.  I could get close by using a couple of them in parallel but I decided to just order a few of the correct ones for a "cleaner hack".  These are what I got: http://www.mouser.com/Search/ProductDetail.aspx?R=ERJ-T06J101Vvirtualkey66720000virtualkey667-ERJ-T06J101V

    I wanted to clarify something you said earlier.  You said the entire waveform from the Uno was poor/disappointing with reduced bandwidth.  What exactly are you looking at when you say this?  Is the RMRC receiver better or worse in this regard?

  3. I rigged up the Pyle (quick and dirty with long cables I had lying around).  Here's a shot with it adjusted to 1Vpp.  I am still able to produce some bouncing using my ground test procedure:

    Uno to Pyle adjusted single line.jpg

     

    And here is a shot with it adjusted to its maximum.  I am NOT able to produce bouncing at this setting :)  Overall level is high compared to the standard, but image looks ok in the goggles, at least indoors.  I need to clean up the wiring to the Pyle and perform a flight in this configuration, but that will have to wait, maybe tomorrow.

    Uno to Pyle at MAX single line.jpg

  4. Full-size shots of the Uno PCB:

    https://drive.google.com/folderview?id=0BxRugM4Cs1qIaUd0U1M4ZTBPRGs&usp=sharing

    I'll let you study that while I work on wiring up the Pyle amp and see if that helps the levels.  If it works then maybe we don't have to mess with the Uno's guts, but I'm curious if you are able to spot anything obvious that might help.

  5. Ok I'm just back from flying, typing on my phone at the field while it's still fresh in my mind.

     

    1st flight, using my own Uno, started getting a lot of bouncing at 3.5 miles.  Came back and landed.

    2nd flight, using friend's Uno.  Saw one or two bounces on the way out at about 3.5 miles, but nothing to complain about.  Pushed on to 5 miles without any more bounces on the outbound leg.  Turned around, again saw one or two bounces on the way back, but in general was clear.

    Just to be sure, I made a 3rd flight with my own Uno again.  Bounces started at about 4 miles, pushed on to 5 miles anyway with bouncing the whole way.  Turned around at 5, bouncing remained until I was inside of about 3.5 miles.  In general it seemed like the overall video quality was not quite as good compared to my friend's Uno.

    I will post pictures of the PCB when I get home.  I would love to be able to coax a higher signal out of it.

  6. Yes, I did that the other day, here is that image (with the Vector bypassed).

    Cam only with bypassed Vector using IRC 2.4vtx as load.png

    I haven't tried the Pyle amp yet.  I was about to go fly 2 back-to-back flights to 4-5 miles, one with my Uno, one with my friend's, and see if there is any difference in stability in a real-world test.

    BTW, I'm not sure if you picked up on this from the other thread, but when the Uno's first boot up, the waveform is significantly taller, around 1.2-1.3 vpp (and thus so is the sync.)  After it beeps 3 times to indicate the # of cells it's connected to, it drops.  Depending on which of my 4 vtx's I'm using it's slightly different, but in general mine goes to ~840-860 mV while my friend's goes to 920-930 mV.  So maybe there is a chance I can send my Uno back to immersion and have them tune it to put out slightly higher levels.  If my back-to-back flights show improvement with my friend's Uno, I will probably pursue that.

    My Uno at startup:

    brian uno startup.jpg

     

    My Uno after the 3 beeps:

    brian uno.jpg

    Friend's Uno at startup:

    randy uno startup.jpg

     

    Friend's Uno after 3 beeps:

    randy uno.jpg

  7. What video amplitude can you achieve with the stock PowerBox's video gain set higher?

    Using the Immersion vtx, not high enough.  Setting the power box on its highest setting results in just slightly lower levels than what I get straight out of the Uno, so it's like the power box is only meant for bringing down signals that are too high, not too low.  I do have a Pyle amplifier/splitter I could try, from an old ground station build.  Just seems odd to have to go to all this trouble to get in-brand components to work together, when the reason I went with Immersion is because I thought it would just work.

    The Chinese vtx has a pot yes, and it's overall level is a bit high while the sync is low. The Immersion does not have any adjustment.  Ideally I would like to come up with a solution that uses he Immersion transmitter due to owning 4 of them already (with a 5th sunk in a lake) and because the Chinese one gets quite hot if uncased (I've heard they burn up easily) and is quite heavy and bulky with the case on.  I'd also like to think the Immersion is more reliable, but who knows.  I'm getting frustrated with them now, after all this scope testing with the levels still being low.

  8. Thank you Thomas.  You have been a huge help and I've learned more than I could have hoped for.

    It does seem as though the RMRC transmitter with the Uno receiver produces the best sync level (though still short of the 280mV ideal) out of any combination I've tried.

    Alternatively, I wonder if I could replace the pot in the powerbox with a different one, to make it "go to 11" ? (spinal tap reference).  The goal would be to make the entire signal, including the sync, taller, and may get me above the threshold needed to maintain stable video.  The Vpp out of my Uno, when measured correctly as you pointed out, seems to be about 840mV.  My friend's Uno is about 920mV, which means the sync portion on his is also slightly taller.  Just an unfortunate luck of the draw I guess, but as you said, not the entire cause of my problems, most of which seems to be the transmitter.

  9. For some reason it won't let me upload pictures to this thread.  Even though the 2 images I want to post are about 170kb each, it says "you are only allowed to upload 501.76kb."  In that case I have posted 2 shots of the TV field from both the Uno and RMRC receivers (both without using the powerbox) using the RMRC transmitter.  I apologize for all the linking away from your forum.

    When you say the sync level is still low, you are referring to the difference between: the middle of the lowest flat part (where your horizontal blue line is drawn) to the middle of the color burst, correct?

     

  10. I bypassed the Vector once more, using the original setup with the Uno and Immersion 25mW repeater.  With attenuators and putting my hand on the antenna I was still able to produce some bouncing.  For sanity's sake I wired my goggles to the Uno, did the same thing, and the picture was much more stable.  Then I tried using a boscam 200mW transmitter as the repeater, and the bouncing was back.  Routing it through the powerbox again did not help.

    I found an old 2.4 700mW RMRC transmitter I had laying around and put it on the plane.  Receiving on the Uno (mixing brands), the waveform was much stronger looking (actually quite high at about 1.5 vpp, and the difference between the sync "bucket" and the color burst was much more well-defined.).  Saw the same thing when receiving on the RMRC receiver.

    Routing these through the powerbox and adjusting the pot to approximately the middle of it's range, the vpp went from 1.5 to ~1v.  But now the difference between the sync bucket and the color burst was lower, but maybe good enough?

    pictures here

    The only problem with this one is that it gets quite hot without the bulky blue anodized case, though some are having success with it.  One of my flying buddies uses one of these and drilled 4 holes in the interior (silver) case for airflow.  Not sure if that's a good idea or not... I tried removing the lid of the interior case on a 1.2GHz transmitter recently, and it cause the video to be very distorted.  I think some heatsink fins would be better.

  11. Quote

    Do you use the 5V output on the 2.4Ghz vTx? If so, what is on it?

    No.  I've used it in the past on other aircraft but am not currently using it here.

    Quote

     Can you swap the 2.4GHz vTx with your 5.8GHz vTx (easy/simple connector access) and check the waveforms? 

    I can...  but I'm not quite sure I completely understand what you would like me to do.  If I put a 5.8 vtx on the plane, I can measure the waveform between the camera and the vtx.  Measuring at the groundstation as before would require an Uno5800 which I don't own.  I can attempt to measure it directly on the goggles through the AV-in/out jack, terminated with a 75 ohm resistor, or I could probably rig up a way to connect the goggle module with jumpers instead of directly plugging it in, in order to access vid and gnd between the module and the goggles (the goggles would be the termination load).  Something of note, several weeks ago I measured the goggle's module sockets with a multimeter and found the goggle video input to be 43.6 ohms.  A far cry from the 75 I expected.  But I'm not smart enough to know if that's a valid measurement or not, or if anything can be done about it if that is the problem.

     

  12. When I was attempting to get the field to show, inside the "Trigger" menu, I found a submenu called "Shortcuts", and inside that was an item called "...a TV or video signal."  In the dialog box that popped up, it had several picks for different video standards.  One of them was "NTSC 525/60."  I picked it but the waveform would constantly scroll to the left.  Another option was "User defined" so I picked it, at which point the waveform stayed put and this is what I used to generate the images, which I see now is probably not correct.  I selected "all lines" in a drop down menu, and I zoomed out to see if the vert sync pulses were at 16.6mS as you said they should be, and they were, and then I took a screengrab.  Notice the shot of mine shown above has a scale of 2 mS/div.  I see that yours remains at 10 uS/div, so apparently I need to stay zoomed in to 10uS/division to get the shots you are looking for?  I think I was almost there, I just need to put it back on NTSC 525/60, figure out how to get the waveform to stop scrolling, and zoom back in to 10uS/div.

    I used a servo Y harness to go directly from the camera to the vtx and bypass the vector, while providing power to both using a 3S battery.  I was focused on making oscilloscope measurements and I didn't actually try to replicate the bouncing in this condition by simulating flying at range (installing attenuators, placing my groundstation across the room, and putting my hand on the receiver antenna).  Of course the real test would be flying at 4 miles or so, but there are only so many hours in the day.

  13. I have an SDR dongle and have successfully used a 1998MHz downconverter to view a 2.4GHz signal in SDR#.  Something I didn't realize when I first bought it, was that you also also need a bias tee (and corresponding male to male F type adapter) to power the downconverter through the coax port.  Then it's just a matter of entering the correct offset, in this case 1,998,000,000 Hz into the SDR software.  As Thomas said, this is not very elegant, but does work.  The bandwidth of the dongle is very low for such use (about 2MHz), so to see the entire analog video signal in realtime is impossible.  About the best you can do is stitch together several screenshots.

    • Like 2
  14. Very helpful!  A high color burst makes some sense, I have the color gain in the camera turned all the way up. 

    I'll work on bypassing the Vector tonight and see if that changes anything.

    I only know enough to be dangerous...which is a shame because I do realize what a powerful piece of equipment I've got here.   Regarding setting up the TV sync profile, I am not quite sure what to look for on the scope.  Is this a triggering thing?  What should it do differently when it's set up correctly?  From the little bit of reading I've done, it sounds like the higher-end scopes rarely have a dedicated TV sync feature because of the more versatile triggering options available.

    I will pick up a 2nd probe from the hackerspace today.

  15. Well I hauled it to my house anyway...

    I should make it clear that the bouncing I am seeing is distinct from what I would call "tearing."  The problem I originally set out to solve is the entire image shifting left by about 1/10 of the image width and going back, over and over again.  Tearing, to me, is when part of the image distorts and produces some waviness at the edges.

    Vp-p directly from the camera is a little high, about 1.1 to 1.2V.  Levels out of the Uno were around 950mV, a little low.  When I put a PowerBox in the system, I had to turn up the pot all the way to even get close, at about 900mV, and saw significant tearing.  Turning it down made things worse until the image went black and white, and as expected, Vp-p went down with it.    Levels out of the RMRC receiver were 990mV to 1.1V (this is my go-to receiver right now, it seems to produce the best image when flying at range) but the waveform was not nearly as clean looking.  I have some pictures here.  I played with the settings in the camera a bit, but it seemed to want to stay a little high no matter the settings.  Something else interesting is that when I had the powerbox in the system, I cranked up the brightness in the camera which caused the tearing to stop, but then the bouncing started and levels were at about 870mV.  Mind you, this is without any attenuators, as before... this is full power of the vtx about 20 feet from the receiver.

    I didn't try physically bypassing the Vector since it's sorta buried in the plane and a pain to do, but I did toggle the switch to turn off the OSD text.  That didn't seem to make a noticeable difference in the levels, and didn't make a difference to the bouncing when using attenuators to simulate flying at distance with the Uno.  I played with the vector settings a bit, and the only setting that seemed to change things noticeably was setting the black level to 0 which produced some horizontal white bands in the image.  Everything else didn't seem to do much, but it's getting late and I need to play with all these settings more deliberately in order to say that conclusively.

    So, lesson learned tonight is that the camera is a little high, the Uno is a little low, the PowerBox makes things worse, and the RMRC receiver has good levels but the waveform is dirty (go figure).

  16. The man himself!  Thank you for the reply Thomas.  I will see if I can find one with TV sync.  But to answer your questions...

    Quote

    Is the UNO2400 being used with a Immersion 2.4GHz vTx?

    Yes, the vtx is Immersion's 700mW 2.4 unit and has been tested recently with my Immersion PowerMeter, and is outputting very close to 700mW.  I typically make my own antennas for the aircraft side, and I have been using a RHCP airblade that I made which is measuring 1.2 SWR at the frequency I am using.  Looks like this, though that's not the exact one.  I'm using a VAS pepperbox on the ground.

    Quote

    Is the 5.8GHz relay vTx and the vRx module in the Dominators both FatShark brand?

    The relay vtx is an Immersion 25mW 5.8 transmitter with a VAS airscrew on it.  I own 2 different modules and have tried both in the goggles:  an original Fatshark 5.8 module as well as an Immersion raceband module.  Both behave the same.  I'm using a VAS mad mushroom on the goggles.

    So as you can see, I have tried to stay with Immersion and Fatshark as much as possible, since they both use NexWave modules, which should theoretically present the best chance for compatibility.  The only components in the link that are not, is the PZ0420H camera and the Vector OSD.  So I would be most interested in hooking up the O-scope to the camera first to see if that's the culprit.  I suspect that some configurations at the groundstation just tend to mask the problem better.

    Sander recently suggested adding a PowerBox to the groundstation which has an adjustment pot and apparently a sync restore circuit to clean up distorted pulses, but as they say, "garbage in, garbage out" so I would rather find the source and fix it there.

    -Brian

  17. Hello,

    I've been having a problem with my FPV video where, when flying at range (4 or 5 miles), the picture in my goggles looks like it's being smacked by a gremlin on the right side of the screen, and "bounces" left.  When I return and fly closer, the bouncing stops.  This only happens when using my Immersion Uno 2400 receiver, wired to a 5.8GHz relay to my Dominator v2 goggles.  If instead I use a different receiver, or hardwire my goggles, or use my old v1 goggles, the problem seems to go away but I do not consider any of those to be "solutions."  Using the other receiver causes the audio to be terrible (probably due to sideband modulation differences), and I do not like being tethered to my groundstation, and I prefer the image quality of the DomV2 goggles.

    I can replicate the problem at home using attenuators on the transmitter and unscrewing or placing my hand on the receiver antenna. The UHF radio (Rangelink) is OFF for these tests at home so it's not external interference.

    I am considering buying an oscilloscope to help me diagnose the problem, as I suspect the root of the problem is due to improper video levels or impedance mismatch somewhere.  According to Mr. RC-Cam's page here, I need one that can measure at least 10MHz:  http://www.rc-cam.com/lawmate.htm

    Is the SainSmart DSO203 an acceptable tool for this job?  I have some concerns with it based on this video:

     

×
×
  • Create New...