IRIS upgrade project

In order to satisfy my bloodlust for the Inspire 1, at least temporarily, I've decided to try and maximize the performance of my IRIS+ w/ Tarot 2D and GoPro, especially for video and photo. I have the following upgrades to make and thought it might be useful to post the process and results here as I go.

  • GPS/Compass: install a Ublox GPS + Compass Module with mast as a new primary GPS, retaining the existing internal GPS as a secondary source. I'll have a very similar mount to this. My current model is the + upgrade kit on the original IRIS, with the original covers and configuration.
  • GoPro lens filters: I'll test all three of the filters here. I have high hopes for these, although I might need to make some adjustments for the filters to fit all the way on the lens despite the blue Tarot bracket. I'm especially excited to see if I can get some decent nighttime shots with my basic GoPro.
  • FPV: The hit-or-miss aspect of flying photos and video without FPV and trying to frame shots at a distance with little depth perception is a fun and useful learning experience, but at this point I'd like more reliable outcomes. There's a very reasonable looking kit from Helipal here. With a splitter I'll power it off the gimbal power source exactly like the LiveView system does.
  • Gimbal Dampers: I've read that the Tarot rubber dampers on the 2D gimbal are not ideal, so I'll try a couple stiffer replacements, especially with the added filter weight and FPV cables.

The idea is to get the low-hanging fruit first, so I'm sticking with my existing GoPro Hero 3 White and the Tarot 2D for now to see what I can get out of it before I consider a camera upgrade or 3D gimbal. If you have any experience with these modifications, I'd love to hear about your results.

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  • Wow, I tried out the antenna mount this AM and got a HUGE improvement in Tx range! 1000'+ out, 160' up, and just one little peep at the maximum distance. This more than doubles my previous range with the antenna just kinda taped up to the bottom of the shell from 3DR. What a relief. $4 mod.

  • Oh buddy..just flew my new inspire! My Iris and x8 are feeling very neglected! One hell of a ship. this may replace my iris. tbs discoveries and my kraken octo!!!!

  • A couple of notes:

    - If you install a secondary GPS/compass, don't leave the original compass in the I2C splitter along with the new one. It's clearly stated that Pixhawk will probably work OK with a secondary GPS, but can't use two compasses. I somehow missed that disconnection and it caused all kinds of problems.

    - If you'd like to use the GoPro as an FPV camera with the Tarot 2D gimbal, you'll need a very low-profile video-out plug for the camera to clear the gimbal arms and motor mounts. I'd recommend this one at XProHeli,

    - I just installed a Rx antenna bracket to try and get some improvement on my poor range. I should be able to find some room under the cover for a permanent mount if it works.3702027577?profile=original

    • Once I get my Iris+ returned from 3DR, I will be changing the GPS. How do you like your set up? Did it make big changes to hdop? What unit did you have before and what did you upgrade to? Also, did you try or consider just upgrading the GPS in place (no ext antenna)?


    • I did the IRIS+ upgrade, so I have the original GPS/compass mounted to the underside of the top shell with the adhesive shielding patch provided in the upgrade kit. The external is the standard Ublox GPS+Compass from 3DR, although it looks like there's a new unit available now.

      HDOP is consistently lower with the new unit, frequently at 1.5-1.7, with a lock within 10 seconds. This is in contrast to the original setup, where HDOP was normally 1.9-2.1 and could take up to 2 minutes for lock. LTR is improved. I believe the compass performance is better as well now that it's up and away, as the yaw-seeking issue is much less noticeable in video. I didn't try upgrading the original unit in place as I was anticipating some improvement by getting it out of the shell.

  • 3702017664?profile=originalGeez, I don't know...200mW or 500mW? I know there's now a 600mW at nearly the same size as the 200mW above. I'll put the monstrous 500mW in my Noob Mistake drawer and maybe use it on an RC car.

  • Some more test footage, with and without filters.

  • I'm waiting for some parts to arrive for Phase II, especially a frame mount for the GoPro. I guess my 500mW FPV Tx is probably overkill and pretty heavy to boot, but for testing's sake I'm going to ditch the gimbal and rig the GoPro FPV off the static front mount and ziptie the Tx as close to COG as possible using the air vents on the belly. Meantime I'm having some persistent issues with what I think is a bad accel error that popped up out of nowhere, but I can't seem to pin it down and duplicate it.

    Now I'm thinking about range, both RC and FPV, and antennae are the first place to start. I have a great spot picked out for some range testing, should give me at least a km to play with.

    • FPV: I gather that the 5.8MHz video signal will be increased substantially with a circular polarized antenna on either or both ends, so I've ordered a cheap set of those as well. Not going for the patch antenna just yet. I assume my RC range will be way less than the FPV range, especially if the CP works.
    • RC: This seems like a tricky subject and quite a bit over my head, but what I've read about the stock antennae is that they're not well suited to my 915MHz IRIS. I get little RSSI warning blips as close as 150m with a clear LOS with stock parameters, which seems pretty poor and at the low end of normal IRIS+ performance. So I wonder what would happen if I used a better whip antenna on the controller and this Tri-Band PCB Antenna...

    • I would also be interested in eliminating the occasional ~1s warning blips from the (2.4) FrSky RC Tx. They are usually of no consequence, but have also triggered an RTL from about 150m. (I now know a quick flip of the flight mode switch will return control to me). It seems like the stock antennae on both ends could be improved.

      Just to be clear, I'm talking about dropouts with the 2.4GHz RC Tx reception using the FrSky module in the upper right of the picture that causes the RTL. I also have dropouts with the 915 MHz 3dr radio that mounts in the nose and attaches to the external rubber ducky antenna. But that hasn't caused me any real problems.


    • Assuming the FrSky Rx has the stock whip antennas, there is room for improvement by using the sleeved dipoles. I buy them from Aloft Hobbies (would link but I'm on my phone). With the stock Tx antenna I've gone to 1km with no beeps (same platform as the RCTimer VTx). The issue with putting a higher gain antenna on the transmitter is that your doughnut-shaped radiation pattern becomes flatter, at which point you have to pay much more attention to the orientation of the antenna with respect to the quad.

      I don't know where the stock antennas are located in the Iris, but relocating them may improve reception.

      I've got mixed results with the 3dr radios and stock antennas. On my laptop, I've had them work for up to a kilometer. On my phone I frequently get sketchy reception within 300m.
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