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About Hartwig

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    RC-Cam Regular

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    Model aircrafts, Video, Electronics, Programming
  1. Hartwig

    EVG920 goggles repair

    Hi, just in case you're still in trouble with those goggles, I've seen this on other goggles as well. As far as I found out, it's a connection problem inside the Kopin module itself. The actual LCD screen connection to the flat ribbon cable gets bad with time. Though all seems well when the module is cold, as it heats up, the connection gets loose and the electrical levels on the LCD start fluctuating. This results in a huge brightness shift, and contrast reduction, which ends up in a white screen. So far I have not found an easy way to fix it. You might be successful in opening the module and find out if you can locate the exact location of the loose connection by pressing and bending specific spots. Only do this at your own risk, and if the warranty period is over! Good luck, Hartwig
  2. Indeed. I got led bargraph displays on my reciever and it's very useful as long as the video TX still transmits, and as long as there are no other TXs on similar frequencies near. In my area, they are The last 2 crashes I had got the front half of the plane crushed into pieces, and nothing survived. The lipo was squezzed and I found the videoTX 5meters apart from the plane. What you really want is a reliable beacon that stilltrasmits when everything else doesn't work anymore. It has to be "crash-proof", needs it's own battery, and has to be totally independent. The second thing you will love is a simple Lost Model Alarm beeper for the "close range approach". From my experience , I can only recommend this!
  3. Hartwig

    Help with the ESC/BEC/LiPo in a FPV Easyglider

    Well, you might like to solder a T-style-adapter made of a male and a female Deans plug, and a cable with a JST connector on the other end to which you will connect your BEC. The ESC is plugged into the Deans connector as usual. Alternatively you can just solder the cable with the JST connector directly to the battery connector of your ESC and forget about the 2 extra Deans plugs. On the output side make sure that there is NO electrical connection between the 5V out of the BEC and the 5V out of the ESC! Otherwise you will fry one of them or both. You can supply, for example, elevator and rudder Servos and the receiver from the ESC, and ailerons and pan/tilt from the BEC. Just make sure that the signal wires from the servo connectors is plugged into the proper sockets of the receiver. The servos will get their power and GND via the BEC (and the others via the ESC).
  4. You probably found out about this already, but anyway, here's the link: http://www.rangevideo.com/index.php?main_p...3d651abb6dbac99 Choose one of the systems that suits your area. You might like to try a 500mW TX to make sure it still works in noisy environments. (Oh, yes... Be aware that you might need a license for this amount of power. 10mW is ok without a license in all places I've heard of.) Rangevideo offers TX and RX seperately so you can buy one TX and as many RXs as you need. Enjoy! :-)
  5. Hartwig

    Audio track as modem data NMEA

    Hello Jan, I tried this and it works fine. The only thing is that you have to limit the NMEA output of your GPS receiver to the sentences which you definitely need, and at a reasonable rate. The circuit needs some "recovery pause", as Thomas mentioned before. I limited it to RMC and GGA, both at 1Hz which seems to be fine. Jeff (jparisse) offered the kit a while ago. Maybe he still does. You might like to send him a pm and ask. Cheers, Hartwig
  6. Yeah, good point! I haven't used them, yet. Do you have a link to a good information source on this that you can give me? I guess 2490MHz should be within legal limits. I was looking for good information pages on it but all I found was the information that 2.4-2.5GHz ISM is usable for video transmission. Is that correct? The highest WLAN center freq (chnl14) is at 2483.5MHz, so 2490 should have the least interference problems of all channels in the 2.4-2.5GHz range. -AT-Terry: I was talking about the systems from rangevideo, channels 5-8. I'm currently using airwave systems at 2410MHz which works very nice, but I "share" the freq with lots of others. So, after all, a tracking antenna seems to me a good solution in terms of "filtering" what's in the air because it "listens" into the right direction. It only needs a reliable repositioning control. I would consider a GPS downlink via a seperate TX on 433MHz or whatever, and a GPS at the ground station to calculate azimuth and elevation.
  7. Terry, I'd love to see you continuing your project :-) I have the same problems with WiFi noise and others. Maybe selecting the frequency to a channel that doesn't interfere too much, could help. Especially RSSI is sensitive to everything on the same channel. This is a channel table of WiFi frequs: http://www.moonblinkwifi.com/2point4freq.cfm So running the video link on 2370, 2390, 2490, 2510 MHz should be worth a try. I didn't have a chance yet to test it, but as soon as I have some results I will post them.
  8. I'm currently using an old Hi8 camera with an external video input jack. This seems to me a very reliable solution as it doesn't blank the screen or drop frames if the signal gets bad. I tried several DV recorders and it was just a matter of "signal disaster" until they stopped accepting signal and recorded a black or a blue screen instead. Anyway I guess most of us are using DV recorders successfully. Regarding the recording I just like to be able to record snow for minutes as long as there's a chance to get one usable frame, in case the plane gets out of range and might disappear or get lost. Just for that reason.
  9. I got 2 questions: 1) Is there a big temperature difference between your indoor test and outdoor test? Meaning that there might be some detuning for some reason. Sorry, I know it sounds strange, it's just an idea. 2) Is there another RF source (WiFi or whatever) that might desensitize your video receiver? cheers, Hartwig PS: Any chance using a groundplane antenna under(!) the eagle?
  10. AFAIK in Germany you are limited to 10mW EIRP for analog data, and to 100mW EIRP for digital data, at 2.4GHz. That means including the TX antenna Gain. Thus feel free to use a high gain antenna on the RX side, and a highly directional antenna on the TX side while "wasting" some power with (unnecessary...sigh...) long antenna cables to avoid breaking the 10mW limit. I know that really sucks, but that's what's legal. This calculator might be helpful: http://www.compex.com.sg/home/WDC.asp
  11. Hartwig

    Diversity or not?

    Very nice! For the RC it might also be possible to use a part of a conventional RC Receiver which gets the PPM data from the handheld radio and does the decoding part, including Failsave and so on. Just an idea, but it will probably be a lot more fun do that programming yourself
  12. Hartwig

    Diversity or not?

    You're welcome! As I see you discovered a lot of nice alternatives already I was very much impressed when I read about your EOS1 a couple of months ago. I'm curious on the performance of the antenna tracking system. How will you send the APRS data down to the ground station? Will you use the audio channel of the videoTX or an extra TX? Will you add tracking equipment to your plane as well, as an emergency backup if the link gets interrupted?
  13. Hartwig

    Diversity or not?

    I have great results with this one (vertical polarization): http://www.lechner-cctv.de/artikel_einzeln...q7bc8t1plavdjm4 ...and this one (circular polarization): http://www.lechner-cctv.de/artikel_einzeln...q7bc8t1plavdjm4 I can help with translation, in case you need.
  14. Hartwig

    Diversity or not?

    Hi jonpet, That's right. Just don't forget about dropouts due to reflections, wherever they may come from. I strongly recommend to go for a diversity solution. Interference occurs easily and when I watch the leds on my diversity system, it sometimes switches so fast between the two antennas because the wavelength at 2.4GHz is just about 13cm and dropouts are easily produced. I recommend a combination of a high gain vertically polarized antenna (14-15dB Patch or a 17dB Yagi which matches exactly the frequency of your videoTX because of their narrow bandwidth), and an 8dBi Patch or even an omnidirectional rubber duck for the near field. I had excellent results with this combination, even in urban environments with LOTS of other RF sources around, as there were very strong wireless room to room video transmission systems in the nearby houses, WLAN, Bluetooth, GSM,... Make sure you're the only one on "YOUR" channel, and you'll be happy with this setup I'm very interested in your antenna tracking solution and I would love to see how you proceed and to see the results. I was thinking of exactly the same setup with the TinyTrak and so on. Just one little difference, I considered a seperate TX for the APRS to make sure it ALWAYS gets to you, regardless the video link. That's because you need the GPS data to control Az/El of the antenna for the video link, so you must not loose the audio link. Cheers, Hartwig
  15. Mark, you're absolutely right! I recently lost a fully equipped plane because I did FPV at low temperatures and suddenly the motor stopped and 2 minutes after that the video screen just got black Usually when I fly at low temperatures I heat up the lipo's a little in those cases the Pizza Delivery Services use and it works great. But that time I didn't , and also didn't have an osd to monitor the power status, so I had to pay an expensive lesson... But those Pizza cases are great for that! :-) Last winter I had 40 minutes flight time at temperatures below 0°C with a 2200mAh on my Easystar.