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modelman

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About modelman

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    RC-Cam Visitor

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    http://www.we-aeromodellers.8m.com
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    RC Aeromodelling, Electronics and computers.
  1. modelman

    2.4Ghz TX/RX

    Just a quick question...Why 5 miles? To obtain such a distance you will need a transmitter that puts out Watts rather than MW's. The TX will be fairly large and a very good quality battery will also be needed to power it. This makes this setup only practical for larger models (80" upwards) because of the weight and size.
  2. Hi Robe_uk The aerial on my TX was not as good as yours. It was just a piece of wire. I simply calculated the correct length for the TX frequency which was 1.106ghz. Tested on a field strength meter and power meter. My TX has a pot on it for video signal adjustment. The signal from the camera was overloading the input and making the picture contrast too strong. I simply reduced it for the best picture quality. For best performance in range build the GP Patch you won’t regret it. As Randall rightly said a frequency counter is useful as there are many channels allocated in the 1.1/1.2ghz bands. The GP Patch needs to be built accurately for best results as it only has a 3% bandwidth I have got both a standalone and build in TX setup. Both are in the 1.1ghz band but classed as 1.2ghz, typical of Hong Kong Cams. Simple test : plug a camcorder into your TV and note picture quality Now plug TX into camcorder and transmit signal to your TV via RX. Compare the difference. After slight tweak my TX and RX picture was almost identical to the direct link.
  3. Hi I bought a similar 800mw setup. The true power output is around 200mw. I rematched the Tx aerial and tweaked the video input and the quality is now superb.(as good as any 2.4ghz setup in this price range) It also has sound as well. I know the RX tuning can be an issue, however run the TX on a 1000ma AR or AAA 9.6volt pack and you wont have any more problems. It also puts out a bit more power. The 9volt transistor radio batteries are a no no as you will be constantly re-tuning. I have also found that 1.2ghz setups have slightly better range especially in more built up area's.
  4. Thanks guys for your comments. I have already done a little research. Below is the link for a USB2 device that claims real time viewing on a pc at DVD quality resolutions. It sells for around £40. Maybe someone has already tried it!! http://www.trust.com/products/product.htm?...nr=13991&show=1 And another by Maplin costing around £60 http://www.maplin.co.uk/Module.aspx?Module...ldID=&doy=11m10 Regards...Mark
  5. After using a 7” DVD player screen for viewing my wireless cams images I suddenly thought why not use my 14" laptop for viewing and recording. This has presented a few issues in linking the RX's video to the computer. I wish to display my video wireless camera’s images on the laptops screen during flying in real time (30 fps). I also want to record images at this frame rate on to the laptops hard drive in my chosen format. My 1.2 GHz laptop only has USB 1.1 so I will have to fit either a USB2 or firewire card using the expansion slots. My questions are: 1) Which card is the best to use? Firewire is probably best as it is more geared towards photo applications. However I have heard there are more devices available in USB2 format. 2) What is the cheapest option of getting composite video into my laptop at 30fps and 640x480 resolution? I believe that there are small adapters available. 3) Where can I get these devices from? 4) Which is the best software to use? i.e.- Pinnacle Studio Any comments or advice appreciated. Regards…Mark
  6. Hi Engineman, Try to run the RX from your model boxes 12 volt supply. Use a good quality 8.4 volt rechargeable battery on the TX. This should give you around 2 hour’s continuous running on a Hong Kong 200mw cam setup. You may still not get the desired results in terms of range so I strongly recommend constructing a patch antenna. As Terry rightly confirmed try to keep all dimensions as accurate as possible and you should obtain a 3 to 5x increase in range. A quick question were did you get your Laptop VIDEO to USB converter from and roughly how much did it cost? Ragards...Mark
  7. UPDATE TO MY 1.2ghz PATCH ANTENNA TEST Myself and 10 other modelers finally got round to doing some detailed in air testing with my rescaled 1.2ghz patch. The results were almost unbelievable compared to the original supplied whip antenna. 1) Range was increased from 200ft to as far up as we could see the 60" model to control it. (800/1000ft) 2) Coverage was around 180 degrees arc with 90% unbroken images throughout. 3) Antenna even worked when flying behind it. Very strange but not such strong signals. 4) With 45 degree elevation and flying in front of antenna no repositioning was needed at any time. CONCLUSION This antenna exceeded all our expectations. We hoped for a small increase in performance but not to this degree. If constructed correctly this design will improve any systems receiver and in our case by around 500%. Simple to make with very good results why not give it a try! A note on construction. Pay particular attention to accuracy when building a patch and try to obtain your TX's exact frequency. All my element dimensions were within 0.5mm and spacers 0.2mm A patch only has around 3% bandwidth so to achieve the 8 or 9db's of gain matching and size is critical. Spend a bit of time on your dimensions and you will be well rewarded. Regards...Mark
  8. Most of the so called 1.2GHZ systems are actually on 1.1GHZ so a frequency counter test is a must!!!
  9. Sounds like this cheap setup could be a winner with the ccd cam. I bought a similar setup from Hong Kong as did Mr rc cam however the TX is the real let down at only 42mw output. I noticed in your picture that the TX is stand alone. Mine is built in the cam which I realise now to be a disadvantage. Is your setup 1.2 or 2.4ghz ? Have emailed you for links. Regards...Mark
  10. I'm glad our test results matched. We must be doing something right!! I will have to get round to trying the cone and see what extra gain can be grabbed. Some other sites suggested that a correctly assembled patch had a 65 degree horizontal and 75 degree virtical angle, forming in fact an oval shaped radiation pattern. I'm not quite sure why this is but maybe something like ground effect makes the angles different. I'm no patch expert yet but I'm learning. Regards...Mark
  11. There is no need to answer the questions I asked on patch antenna gain thanks. If anyone is interested on how a patch works and produces 8db of gain then all is reviled here. http://www.orbanmicrowave.com/antenna_appl...ation_notes.htm Regards...Mark
  12. Hi everyone, In answer to your question Terry I conducted some tests today. By adding a ¼ wave reflector to the original whip I found a medium increase in performance. The results were about ½ the range of the patch design. Using the half wave dipole as ref to 0db I would expect a 3db increase in signal strength using a rear reflector. This should equate to around 1 ½ to 2x range which is roughly what I found during testing. I don’t know if this matches your results but I consider my findings to be only approximate. This brings me on to my question of how does a patch antenna receive up to 8db’s of gain? The rear reflector should give us an instant 3db increase, however how is the remaining 5db achieved without use of directors? Any comments from patch experts appreciated. Regards…Mark
  13. Hi everyone, some interesting comments on the so called all British made cam. I have now constructed a Patch antenna for my Hong Kong Cam setup. First a point for people intending to purchase one of these setups. The seller assured me 100% the cam was 1.2 GHz but that was rubbish. A freq counter proved that 1.106 was the exact frequency. So most of these cams on EBay should be sold as 1.1 GHz models. For those of you that have a 1.1 GHz setup here's the re-scaled patch dimensions. LARGE PLATE = 232mm SMALL PLATE = 123mm SPACERS = 10.85mm 11mm should be ok Try to keep the material as thin as possible as this is a fairly large antenna to support on a single connector (over 2 xs larger than 2.4 GHz ver) Everything else is as per the design on this web site. I used a redundant fishing tripod stand to fit the receiver on. TESTING Although in flight testing has not been possible yet I have conducted a number of ground tests. Initial line of sight tests showed an increase in range of about 3x (1000-1200ft) over the standard supplied wip. Picture quality was also improved with far less broken images on a moving target. Even built up area testing was greatly improved. This aerial would probably work well in a large warehouse environment were the standard wip would not have enough gain. Conclusion - Very pleasing results and well worth constructing. My Sardine Can has been promoted to Tuna Can. Next time I'll go to work on the TX and see what can be done to improve 1.1 GHz transmissions. From Tuna Can to Salmon Can -we will have to wait and see!!! Any questions fill free. Regards...Mark
  14. Thanks everyone for your comments and info. Has anyone tried using the below setup from this company? http://www.rc-cam.co.uk/Products.htm Anyway about to construct a re-scaled patch antenna for my 1.106ghz Hong Kong Phoey setup. Will publish my results here in the near future. The weather in the UK is not looking too good for the next 4 days so in flight testing might be put on hold for a while. Regards...Mark
  15. Thanks for the info Terry, I must admit I never intended to use this equipment as my main system. It was more of a experimental project and at £20 it doesn't matter if I damage it through modding. I have currently only seen one uk company selling a complete setup at about £165. I would be grateful of any info or prices of other current 2.4ghz equipement available. If company names and price's cannot be displayed here please mail to :-clubmail-AT-tiscali.co.uk which is our club address.(west Essex Aeromodellers) Myself and others would be interested to know which 2.4ghz equipment and aerial combinations you and your colleagues have had best results with at 10mw. (yagi / patch ) Kind regards, Mark.
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