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Chuck

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About Chuck

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    Pittsburgh, PA USA

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  1. Sorry for the delayed response and thanks for the particulars.... I will be using a receiver that has more sensitivity than a TV. Also I will be using a 5 element Yagi which should get me some "front to back" without being too finiky on the pointing (for those who understand antennas, the front lobe is rather wide). Also, [as I recall] doubling the power is 3db of gain. I will be using 500mW for starters (the TX can do 4 watts and I have a brick amp that can do 25 watts), so that 500 mW represents a +6db gain and the Yagi gives me another +6db. But, hay, this is all theoritical math giberish, what I want to see is how it performs in real life. This I will do over the next few weeks with my daughter's help, and I'll let you all know. I managed to get the parts for the TV station/reception part of this along with the GPS portion working in the house. Over the next few weeks I'm going to try some experiments (off the plane) to see how the reception is, and as I've stated, I'll fill you in. To be fare [scientific], I really should do a 2.4 GHz test "side by side" with the 70 cm setup. God save my wallet, but this I would like to do. Any pointers to threads or suggestions on technology in this area would be greatly appreciated (e.g., the most promising technology that I've seen in this area is http://....). I'm basically a scientist at heart, and I would be interested in documenting a comparison of this form. I would also like to know if my "huntches" are correct in these areas. But my primary goal is to "understand" and as such, I would report my findings impartially. As an asside, I also acquired a "Pandora Pan & Tilt Kit". It was clearly well thought out, and I am looking forward to using it on my Telemaster 40. The more I read about this topic, the more that I believe that I should be heading down the autopolot route. There is a great deal of information about this on the boards that I have been trying to sort through over the past few weeks. Again any pointers to specific threads or websites that have been found as interesting would be appreciated. I thank you so much for all of your help!!!! You have all been a great support and have been very helpfull. Manny manny thanks! Very Best Regards Chuck (73 N3BEZ)
  2. I'm not familiar with that antenna... and a google search of "lazy 8 antenna" didn't turn up much usefull, probably because "lazy 8" is used a great deal for other things. Can you point me to a specific reference? Best Regards, Chuck
  3. How true... FM is much more efficient, and as long as the receiver can capture the signal the quality will hold up. AM needs more power, and as the signal degrades the picture will snow. Also, random signals (e.g., atmospheric) below a threshold will not show up in the picture (noise immunity) in FM as it will in AM. The frequencies that we are talking about are different as well; 70cm vs 12cm and 25cm. In the higher frequencies there is more bandwidth available and using FM it is possible to trade bandwidth (modulation index) for noise immunity (a good thing for sure). Also, low noise preamps will help you out. The higher frequencies allow more front to back gain in a smaller physical space but also make the beam narrower requiring a higher degree of tracking (not insurmountable). Higher frequencies have higher free space propagation losses (fspl varies by the square of the distance and the inverse square of the frequency) and shadowing issues. I could add more, as I'm sure that you could as well... If I lived in Arizona on the flat, obstruction free, line of sight desert, it would be a no-brainer; FM, as high frequencies as possible to get as big a bandwidth as possible. But, I live in the rolling hills of WPA with it's peaks, valleys, and lots of trees. It is clear that there are many variables, the pros and cons of which can be debated "till the cows come home." All of this being the case, I'm still interested in the particulars of anyone's experience (band, power, mode, antenna, terrain, observations, and anything else). Best Regards, Chuck
  4. Thanks for the comments.... I wish you would tell me more about the first point; 70 cm band transmitters being less reliable when moving. I would like to understand this better. In your experience was this a reliability issue with the hardware not working, or a difficulty in signal reception as the plane moved? How much power were you using on the TX, what kind of RX were you using, and what kind of setup did you have for antennas? And yes... I havn't own a TV for over 20 years [2% of the US population doesn't own a TV by the way], and I don't intend to change that now... I'll be using a box that converts the 70 cm band signal IN, into video and audio OUT (http://www.hamtv.com/ has a few options). I also intend to use an inverted quarter wave on the TX, and a 5 element yagi on the 70 cm RX. With five elements there is significant front to back, but the pattern out the front is rather broad, and so [like horse shoes] close is good enough. Best Regards, Chuck
  5. Electric. Yes, one of these should do the trick... Thanks! There is also a Real Flight model for the larger one that I could adapt.... http://www.knifeedge.com/forums/downloads....ile&id=1293 I'll play with it on the simulator and see how it files with the extra weght! Yes, the 2.5 ghz equipment is lighter and cheaper. However, the propagation is better on the 70-cm band (for equivalent power) and a ham can legally use more power. You just have to ID after 1W (call sign painted on the fuselage in view of the camera), and not "step on anyone". The TX and RX are synthesized so I can change frequencies if necessary. Also, since I'm going to use a low light level B/W camera, I almost need to have auto iris, so there will be "a few extra ounces to reckon with" anyway. Again Thank You. Best Wishes Old Man, Chuck
  6. I've settled on a transmitter.... http://www.transmitvideo.com/pdf/VM-70X_Manual.pdf http://www.hamtv.com/pdffiles/VM-70XwHS.pdf I was going to use a B/W camera on this. They are less expensive (about $30US) and can see better in low light conditions. Later I'll experiment adding GPS data to the audio of the transmitter. For an antenna on the transmitter I was going to use a 1/4 wave (electrical; physically shortened stubby duck) vertical pointing down mounted on the belly. That is the ground plane will be above the radiating element, so the radiant energy will be omni directional and pointing down. This will let me see when the plane is turning, it will also help decrease interference with the on board 50 MHz receiver since it's antenna will be horizontal. I'll start out with 1/2 watt on the transmitter, and test to see if I need to shield the receiver. RealFlight simulations have shown that the plane that I have now (BLT) wont' hold the projected weight (it doesn't climb much and is not stable like it is without the weight). I'm going to play around with shifting the weight and center of mass on the simulation, but just in case can anyone please suggest a kit plane (balsa frame, high wing, stable flier) that is known to hold 6-8 ounces? Thanks in advance!
  7. Are you talking about something like this?? http://www.hamtv.com/pdffiles/R-C.pdf http://www.hamtv.com/pdffiles/TXA5RCbinfo.pdf Charles
  8. Thomas, I appreciate your feedback. I'm going to hold off on the video decisions for awhile till I sort this out. I am going with VHF (6 meters) RC though. No problems here in the US... The only "probllem" seems to be that the equipment is not going to be available in the future. It seems that the major brands are selling off their remaining stock, and that's it. My guess is that some time ago when the US FCC "gutted" the ham exams that the RC manufacturers assumed that there would be people with Tech licenses coming out of the woodwork. But that didn't happen. Given the lack of used [ham RC] equipment that I see on EBAY and the small sales fugures at retail, it's no wonder that the manufacturers are getting out of that band. There's no market for it. For VHF RC I found an interesting article, and plan on "voiding my warranty" just as soon as I'm sure that the TX works... http://mysite.verizon.net/res7yvp2/w4dh22/id3.html I would think though that the gain on the UHF video antennas would need to be much higher to be effective, and therefore have a narrower focus (as you are aware I'm sure in antenna design there is no "free lunch"). This being the case it would make more sense to mount the RC antenna with the Video antenna and move them as a unit. Strangely enough I hadn't considered the ham UHF frequencies for video. It makes sense. I believe that having a GPS is important if for no other reason than getting an idea as to where to start looking for any remaining pieces. Thank you for the food for thought... I'll keep building my plane, flying the simulator (with the camera perspective in the cockpit), reading the boards, and will post here before picking a direction. Best Regards Old Man, Chuck
  9. Thanks for the feedback.... Yes, I had thought of adding GPS... It occurred to me (from my experiences in a time long ago) that it would make sense to use a modem on the audio portion of the downlink of the video camera.... You could add the GPS data as well as other information there. Even at 1200 baud, it should be sufficient. I think that there are some folks doing that... Once you have the data link you could add a PIC that monitors the voltage on the plane battery and send down that information as well (it would be nice to know how much power you have left in the battery before going ever on...). Likely this is being done as well. But you are talking about interference from the 900MHz Tx and the 1200-1500 Rx on the GPS. Interesting, just considering the harmonics it would seem that the 2.4GHz would be more of a problem, but I haven't actually done it... Thanks for the information/observation. Is this a complete "no go?" My thoughts are that the 900MHz would have a better range, and so don't want to abandon it lightly. Chuckle... I started out this thread completely sold on the concept that a 2.4GHz spread spectrum rc control system is what I should use... After much discussion (here) and throught, I've decided to use the regular old fixed frequencies, on the Ham 6 meter bands. In theory, the range on VHF should be better in my world (the rolling hills of SW PA, in fact the VHF repeaters that I have used in the past had a better range than the UHF ones), and my monitoring of the frequencies associated with those rc channels (at my home) shows some of them to be quite dead. But again it only takes one problem to crash the plane... I don't believe that there are any [specific] legal frequency prohibitions in my area. I'm far enough away from Greenbank WVA. Possibly I didn't understand the point about "legal in my area", can you explain further? Again, thanks for the thoughts and feedback. Charles
  10. From reading the boards, it appears that people are using and having success with the following packaged solution... Aerial Video System 900MHz 500mW KX171 http://rangevideo.com/index.php?main_page=...;products_id=98 If starting again from this system, are there any specific "lessons learned" tips that anyone would be willing to pass along? Thanks, Chuck
  11. Based on what I have been able to read [at least] the 9C Super Tx is modular, so when I decide what band I want to use I just get the Tx module, Xtal sets, and the appropriate Rxs. I'm going to set my old Drake R8 receiver scanning on the 6 meter RC frequencies, and just listen for what's happening. Given that 6 meters is less "line of sight" I don't believe that I have to worry that the antenna is on the ground or [as in a plane relatively] near the ground. Also, I'm thinking that the 9C has been around for a while and so is more likely to be found used. I decided to stick with Futaba since I have been using RealFlight for the past year or so. I build a BLT with a larger brushless outrunner motor for the excess weight I hope it to carry. I want to change the stock BLT simulator definitions to include changes for this motor and the extra drag and weight associated with a camera etc, and play with it before I try to wreck the real plane! I decided on the BLT because there's not much there but wings, and I can attach things without worrying about destroying a fuselage. Don't really know if this makes any sense, cause I havn't done it before... Any feedback from you who have would be welcome. 73, N3BEZ
  12. Thanks for sticking with me on this... I've done some more reading on the boards. At this point I am looking to purchase an R/C radio system. Given the bandwidth requirements of video, it makes sense to stick with the high frequencies on this. I want to avoid interference, and being an extra class ham in the USA, it would seem that one of the 50MHz rigs would be a good option (Futaba 9C?). Also, with the 50 MHz system, I could more easily find a commercial Yagi to increase the directional gain and thus (if I am lucky e.g. source of interference is away from the plane) reduce possible causes of interference. At this point I would like to make a decision on an R/C radio system that would "minimally hinder" experiments with video systems on a plane. Specific suggestions as to manufacturers and models would be welcome. Charles
  13. Added my location to the profile... Thanks... Well.. Range should be no problem with the VHF radios, but what about intefrerence with others on the same frequency?! Or is this [in fact] an "oberblown" issue. If you are flying in an area where there is [likely] no other R/C activity you should be OK so long as the receiver doesn't get to high in the air. My experience with the ham VHF bands is that the signal can carry, especially near the peak of an 11 year sunspot cycle. Though with a VHF R/C and a UHF camera you will loose the picture before control of the airplane. However, if you can't see what you are doing that's not much help. So, from what you are telling me, and from my knowledge that UHF tends to be "line of sight", if I keep the plane "in sight", the x10 camera should work just fine, especially if I add some vertical separation between the DSS transmitter, and the x10 receiver?? Again thanks, Chuck
  14. PA USA. I'll need to read the boards more carefully. I got the impression from scanning several posts that the major interference was to the video signal, and not the Digital Spread Spectrum receiver. If that's the case, then that's good. I've been involved with a number of ham repeaters over the years. Given the weight restrictions on a plane and lack of space there would not be much that could be done on same band interference. However, vertical antenna separation (of verticals) is very effective, especially given the 2.4 GHz short wavelengths. Are you aware of anyone who has tried this with the x10 cams and a DSS radio? Best Regards, Charles
  15. Please excuse me if my topic is trodden ground... However, as most on this forum, I am interested in controlling an R/C aircraft with a video down link. Most of the commercial solutions would appear to be problematic. The new spread spectrum R/C control tx/rx setups are great w.r.t. lack of iterferance (both directions), but the higher frequencies are mostly line of sight. They also tend (from my ham experience) to loose in the winter time when every twig on every tree ends up looking like a quarter wave vertical and thus eats the power. Couple that with the fact that the spread spectrum solutions use the same frequency range (or harmonics of) the off the shelf video cameras, and you have a bit of a mess. I was wondering if anyone has modified any of the commercial equipment to work on the ham frequencies available for R/C, and if so your success. I was also wondering if anyone has had any luck with the Futaba FAAST systems. They "claim" to "jump around on more frequencies", this would (in theory) spread the interferance on the video over a greater space and (in theory) make it less noticable. Comments, pointers, and even rebukes for my niavety... Best, Chuck
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