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About ssassen

  • Birthday 06/27/1974

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  • Location
    Purmerend, The Netherlands
  • Interests
    Bits and bytes in no particular order

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RC-Cam Regular

RC-Cam Regular (3/4)



  1. I can confirm that the pre/deemphasis doesn't really pay off. I couldn't see any increase in sensitivity or noise levels that would stand out from the margin of error in the test configuration. The SAW filter upgrade however did pay off nicely. I've seen a nice 4 tot 5dB sensitivity increase with a sampling of two receivers modified (BSS479 type). I did however do away with the whole baseband video decoding and reworked that entire part of the circuitry after some extensive modelling in LTspice. I now have video quality that's indistinguishable from the best 2.4GHz receivers I have here. The audio portion is next, but that requires a little more effort. Ps. getting the SAW filter out was a piece of cake in my experience. Use solder wick to remove solder on the input/output pins and make sure they can move freely inside the hole. Use a soldering iron >50W for the ground pin with a broad/flat tip. Heat the ground pin and with a small screwdriver (slightly larger than the pin) just push the pin down after a few seconds of heating the pin. That'll pop the SAW filter right out without any effort! Cheers, Sander.
  2. Great minds think alike? I was just about to solder in these pre/deemphasis networks and do some further measurements. Unfortunately I'm still waiting for my SAW filters to arrive, but once they do I'll be doing the same measurements both of you have done. I've flown out to >4km with a 500mW 1.2GHz (1180MHz) Tx (http://www.vimeo.com/8715397), which shows plenty of link budget left at that distance (RSSI values noted are for the EzUHF RC control link, but video is crystal clear). Since then I've plotted the RSSI curve and verified the signal levels actually reflect a useable image and am confident that with an omni (0dBi) on the Tx and a 8dBi flat patch on the Rx I should be seeing >10km of range, if these SAW filter and pre/deemphasis mods work out that should about double. Cheers, Sander.
  3. I think you need to be a little more specific. 1. In an environment with little or no causes for interference (i.e. the receiver on the ground) shielding isn't that important. 2. In an environment with multiple causes for interference (i.e. the tightly packed cable mess inside a plane's fuselage) shielding is important. Cable impedance only factors in when you look at the attenuation per length of wire. Hence for composite video you need not worry as the frequency is low enough, you can use long runs of cable without significantly attenuating the signal. What you will see in cables of significant length is reflections due to an impedance mismatch, i.e. a double image. Cheers, Sander.
  4. It is not the length of wire that will cause for issues, it is the fact that unshielded wire with sources of interference nearby (ESC, switched BEC, transmitter, etc.) will couple directly into an unschielded cable and cause for lines, noise, etc. Cheers, Sander.
  5. James, You're most welcome! Been there, done that, never doing it again, too much hassle Yes and vertically. Cheers, Sander.
  6. Jalves, That BEC might the cause for the interference, have you tried a linear regulator just to see if that fares any better? Cheers, Sander.
  7. Nah, they just don't want to lose out to McD again and open a chain of Chinese take out food places before the US steps in. Cheers, Sander.
  8. http://www.pcbcart.com - PCBcart, PCB manufacturer from China I rarely do home-built PCBs for prototyping anymore as these guys are cheap and deliver worldwide in about 8-days. Cheers, Sander
  9. Gary, I wouldn't worry much about the material, however as per the picture you posted I'd be concerned about stripping the servo, or taking the whole servo horn off. The weight of the camera, combined with the long aluminum bracket and the vibrations in flight will not be an ideal combination. Cheers, Sander.
  10. Ivan, That is what I have on my EasyStar which works just fine, the dual gyro solution will not work better as they are never 100% identical and hence will be fighting each other. Esp. if you're using two aileron servo's on different channels using a single gyro is simple, just plug it in between one of the servo cables. Cheers, Sander.
  11. Fine writeup, but I'd like to note that with any Rx that uses an AGC approach the water gets rather muddy. When a weak signal is received it'll increase the gain, hence you gain in signal strength, but the noise also goes up, so it is up to the subsequent circuitry to dissect the signal from the noise, so you could end up trading one disadvantage for another. Cheers, Sander.
  12. I'm using a gyro on the ailerons, but this is on an EZ which is pretty sensitive to gusts anyway, it helps, but it is all relative of course. One thing that did help significantly is to weigh it down, making it too light will just make it more jumpy in windy conditions, so I fly with large packs so the extra weight is actually put to good use. I quess a good approach for a steady plane with good tracking would be to have an airfoil and wing that is optimized for slow speeds and has slanted ends so it is more stable. Cheers, Sander.
  13. Well, if the camera and Tx are 5V parts then that definitely is *NOT* okay, you risk setting things on fire and hurting, or killing, your eagle in the process. Cheers, Sander.
  14. Now there's a nifty RC plane, it has even got feathers and comes with a built in auto pilot that homes in on a piece of meat, where can I buy one? Cheers, Sander.
  15. Obviously this topic is worthless without pics or video! Cheers, Sander.
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