Amateur TV, 70cm video systems.

While researching video systems for a recent project, I stumbled across something I had completely forgotten about Amateur TV systems.

Amateur TV is limited to those who hold a Technician Class or higher amateur radio license.  If you don't have a license yet, I highly recommend getting one.  ATV comes in several different frequencies; 70cm(420-450 MHz), 33cm (902-928 MHz), 23cm (1240-1300 MHz), and 13cm (2390-2450 MHz).  This gives you a wide range of frequencies to choose from to avoid RF interference.

I used the 434 ATV transmitter from www.hamtv.com, which runs about 99$.  This can be received on any TV that can receive analog cable signals via channel 59.  My receiving system consisted of a 5-element Yagi antenna tuned to 434Mhz connected to an old VCR outputting to a small LCD monitor (the older VCR had better reception than a newer hybrid TV).  I tried to use a USB TV Tuner at first, but I could not get a signal unless the transmitter was very close (they have very weak pre-amplifiers) and there was a buffering delay of about 2-3 seconds.  Not good for FPV.

My range for the 100mW system ended up to be approximately 2500 feet.  Next time I will get the 5 Watt version for another $100 that will give me much more range and will allow me to drop the VCR from the setup and just use a cheap portable LCD TV.  Maybe if I am really ambitious, I will even pump the power to 20 watts with an amp.

Overall I was pleased with the system I had slapped together on a tight budget.  The transmitter module was easy to use and, thanks to the circuitry being potted, even survived a 70 mph crash into the desert floor.

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Replies

  • Is there an HD version of this?
  • Wonder if anyone has hardware and/or software up and running and/or would just like to share ideas?

    My RC up link is 72 MHz …current model
    Pitch and yaw on right stick…current model
    Throttle on CH6 knob…current model
    Pan & tilt on left stick… prior model

    CH5 three position switch Adrupilot 2.6 mode control…on test bed, GPS lock and all servos move in correct direction.

    Video TX is Z70A (HAMTV.com)…not powered up yet
    ATMega328 Ground station…kit built, not powered up yet
    74HC4046 Telemetry modem…Up and running at 9600 baud but probably way to fast for the Z70A audio channel.

    Wayne,
    I am new to this forum and so glad I found your thread and certainly don’t want to step on toes or hijack a thread and don’t know if this is the place to share a couple free ‘two-thumbs-up’ test equipment downloads. One, a soundcard oscilloscope / spectrum analyzer / signal generator, the other a USB stand alone dot-exe file (no dills) smart terminal with RX, TX, file storage, baud rates out the kazoo, more…Plays real nice with ArduPilot.

    John
    Ham TV - Amateur Television
    ATV, Amateur Television
  • WOW!

    Glad I found you guys.
    I am tooling up to run a 440 tlm/video downlink.
    Do you think I can push at least 2400 baud through a TV sub-carrier?

    John
  • Moderator
    Is aeronautical mobile permitted on ATV??

    Guess it is looking at this

    http://www.eham.net/articles/10144
  • Lately, I've been interested in using 802.11 (WiFi) for command and telemetry links. When we flew at the AUVSI competition, our XBee link faded on us. While this was primarily an antenna problem (the ground station was looking at the end of the XBee's 1/4 wave whip), the restrictions on ISM band devices make these kinds of problems really hard to fix. I think Ham WiFi link would be more reliable and easier to deal with.
  • Excellent information and advice Wayne..an inexpensive optimal solution.

    Is it legal to attach digital telemetry data into some of the horizontal scan lines?
    If not....
    Is there an equivalent ham setup that can handle long range telemetry in a similar way?
  • For folks in the US, the Ham bands are the way to go!

    -- Mike (KB9RMK)
  • As N8TV, ham radio is the way to go.
    Earl
  • Moderator
    Wayne,

    Timing is everything! I am studying for my Technician class now, I hope to take the test in late July, or sometime in August. I would echo your advice about obtaining a Ham license, to anyone interested in transmitting video from their aircraft, FPV or otherwise. The test should not be a challenge for anyone here. I would recommend the ARRL publication, "Ham Radio License Manual", available here form the ARRL web store. Be sure to get the 2nd edition, the question pool changed July 1, 2010 and is good through June 31, 2014. You can also download a copy of the question pool (good to 2014) here. The entire test is only 35 questions and a passing grade is 26. There isn't a code requirement any more, so nothing to be intimidated by. Many of the questions can probably be answered by most people here without any additional studying.

    In short what are you waiting for ATV is the way to go!

    2010%20HRLM%20Cover%203D%20copy.jpg


    Nathaniel (no call sign yet.....coming soon)
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