Jump to content

Attention: RC-CAM.com will be closing down August 2021.

The RC-Cam.com forum was the very first online community dedicated to the advancement of wireless video cameras on radio controlled (R/C) models. This is now called "FPV" (First Person View). We are proud of the contributions that our members have made to the FPV hobby.

We've seen significant changes over the last twenty years. Initially there were a lot of eager R/C hobbyist that built their own video systems. Allowing these creative individuals to share their work was the purpose of this site. Now the FPV market is flooded with low cost systems; Sadly DiY FPV video projects are now rarely discussed.

RC-CAM.com (main site and forum) will be closing down August 2021. This is being announced now (March 2021) so that everyone has time to download any information that is important to them. After the site is shutdown the information will no longer be available here.

We appreciate every member's involvement with advancing the FPV hobby. It is indeed sad to say goodbye to all our online friends. Be safe and stay healthy.

Old Man Mike

Trusted Member
  • Content Count

  • Joined

  • Last visited

Community Reputation

0 Neutral

About Old Man Mike

  • Rank

Recent Profile Visitors

The recent visitors block is disabled and is not being shown to other users.

  1. I'm quite suprised that you would have a test layout like that. The amount of leakage would be so bad that any test results would be suspect. While I don't doubt the possibility that the new SAW filter's 50 ohms vs 280 circuit design would provide a poor result, you really can't base it on that test. Using the TX as the signal source for evaluation of RX sensitivity would require that it be mounted in a completely shieded box with filtering on power and video lines. The first attenuator would also have to be mounted within that box. I've done quite a bit of testing to prove this as has b
  2. I happen to capture that video entirely by chance. After determining the location of the plane, I eventually made contact with the flyer. The details are contained in a few pages of this thread starting here: http://www.rcgroups.com/forums/showthread.php?t=1147430&page=31 (this was recorded with my earlier CPOD antennas. The new stacked PinWheels measured about 2dB better than my year old stacked CPODs probably due to sunlight degrading the PCB material.) I did some specific real world tests for video signal quality improvement using low noise preamps. Here is a summary o
  3. Believe me, EME is much harder to get results that match the calculations. Here's video from a plane 12 Km away recorded with my omni system: I would say that is a fair amount of "moving and twisting". Except for a brief instant during the flip there is at least 6 dB of margin. The plane was running half the power I use on the quadcopter and an antenna that is 2 dB poorer. Since I don't do any flips, I think this also supports my claim that 32 Km should be possible. Of course if you do not believe math then .... I will admit that my triple diversity system is unique with the ex
  4. I'll put the 30 dB on the RX if you wish and will post the video. How about you do the recommended test with the 50 ohm dummy on your 15 mw with 26 dB attenuator and tell us if you receive a video signal at 200 meters? I think Thomas proved the math was correct with this post of a video picture from 51 Km using 18 dB antenna & 500mw at 2.4 Ghz: http://www.rcgroups.com/forums/showpost.php?p=10526535&postcount=11 My independant 32 Km calculation seems to be remarkably close to the results scaled from his system: His 2.4 Ghz frequency compared to my 1.28 Ghz frequency is
  5. Terry, The attenuator is working perfectly. I verfied the 1mw level with my spectrum analyzer. The bigger concern is any leakage from the transmitter getting into the power and video leads which can radiate like an antenna. As mention in my post, I also measure this leakage to make sure it was well below the radiation from the 1 mw to the antenna. As for your test, you probably have a large amount of signal leakage. Leave the attenuators attached but replace the antenna with a 50 ohm dummy load. You should have no detectable signal at 200 meters. Be sure and rotate the system 360
  6. Well things have improved since I originally did the 1.2 Km with 10 mw post over a year ago. The new standard is 1 Km with 1 mw Power. I have replaced the omni stacked CPOD antennas with omni stacked PinWheel antennas. There is now a Stack of two PinWheel antennas on the SW, N and SE sides of the tower. As a test, I inserted a 30 dB attenuator on the output of the 1 watt Lawmate video TX and was able to get good video at 1 Km using just 1 mw of power from the quad: Here is the video at 1 Km, first in the West direction and then in the North direction. I also rotated the quad thru 1
  7. Thanks for the detail response, especially the jello prevention approach. I would have thought just the opposite with less jello from more light rather than less light. What makes your video remarkable is that you posted nearly the entire flight. It is easy to get super smooth video when the quad is slowly ascending which is why that is the type of quad video so often posted. I've done hundreds of hours of quad FPV flying and I can tell you that you've got something to be proud of with that nice portable system. After a bit of reading I also came to the conclusion that the stock configu
  8. I'm even more amazed after seeing the photos. Maybe the smoothness comes from such a light weight system for HD video. And although light, the GoPro cameras are quite sensitive to vibration and will often produce a jello effect in the video. But certainly not noticable in your system. Also, those props look similar to the old Draganflyer props. Plus they look like the tips have been cut off. Did you do that or did they come that way? I like to carry extra items on the quad for my long distance flights so I wonder how well the system scales to a larger payload capacity. Guess I'll hav
  9. Wow! Since vimeo does such a poor job on these types of videos, I downloaded the file and played it back in Quicktime. As a multiple MK quad owner, I'll say that your video so impressed me that I'm considering buying the X3D-BL. Could you post a picture of your quad and how the camera is mounted? Again, VERY impressive! OMM
  10. For the last week I've been trying to define a PinWheel antenna in 4Nec2 with variables that allow it to be optimized by the program. It was certainly one of the most difficult antennas to model but it is finally done. Here is a little video showing how the program converges toward an optimization balancing SWR, Gain (at zero elevation) and axial ratio (best multipath performance): Note that this is for a 1280 Mhz antenna and that the optimized result was: Leg Length = 67.14 mm Arc Angle = 81.8 degrees Arc Length = 121.5 mm Pitch = 47.1 degrees (this was for a 0.6 mm di
  11. After observing some interference to GPS and FASST from my 1280 Mhz Video TX, I decided to try designing a microstrip PCB to eliminate the interference. I soon found that low pass filters were not effective since 1280 Mhz and 1575 Mhz are so close together. Instead, I ended up using notch filters. Here is the initial analysis for the filter (red is attenuation and blue is Ref Coeff which is like SWR) as designed in the Agilent Genesys program: Rusty used his CNC milling machine to fabricate the boards. We had to iterate the design a few times to compensate for the variables in the P
  12. Hi Nigel, And sorry I got your 5.8 Ghz build post confused with RCC. I've corrected my post and also gave you credit in the other 3 mile omni system thread. Yes, I made it around 100 degrees but did not try too hard for an exact angle. I tried compressing and moving the elements around a bit and it did not change the minimum SWR frequency much. The frequency is pretty well controlled by the full wavelength loop. Because of that, I can see a real big advantage for 2.4 and 5.8 Ghz since it is so difficult to get things accurate at those frequencies with soldered quarter wavelen
  13. Nice work, Devonian. I'm most interested in hearing how much rejection you get between RHCP and LHCP. Given that the weather is so nice for a couple of days, I also decided to build and test a 1280 Mhz version before doing the 4nec2x modeling. I built mine in a LHCP configuration on a male SMA connector using gold plated memory wire and a small PWB used for the solder points: The resulting antenna weighs 0.2 oz (6 grams) and even with the small diameter (.025 inch) memory wire is very solid once every thing is soldered. Here it is mounted on a PWB microstrip filter which is connne
  • Create New...