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Remote cctv

Discussion in 'Radio and Communications' started by camerart, May 3, 2012.

  1. camerart

    camerart Active Member

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    Hi,

    For some time I have been making small 'buggies' for photographing wildlife. So far the camera has been triggered by a timer unit, and the buggies move either automatically or by RC.

    I now want to add cctv, so that I can monitor what the the camera is 'seeing' and take photos from a distance. This can be out of line of sight, perhaps behind trees etc. The signal can be poor as long as I can make out what's happening.

    I have seen transmitter receivers for doing this and they can have frequencies os .9ghz, 1.2ghz and 1.3ghz and have typical ranges of 100 to 1000 mw.

    They will be used on private land away from habitation or flying models.

    Does this seem a good solution for me or are there other ways to do this?

    Cheers, Camerart
     
  2. Sceadwian

    Sceadwian Banned

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    Depends on how much money you want to spend. 900mhz is your best bet if you expect a lot of obsticals, the higher the frequency the poor it's ability to penetrate objects. You should be able to find basic 900mhz wireless camera that don't cost too much.
     
  3. camerart

    camerart Active Member

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    Hi Sceadwian,

    I have seen affordable/transmitter receivers. Now I need to know if there any legalities, like are there any power restrictions, here in the UK.

    Thanks, Camerart.
     
  4. dave

    Dave New Member

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  5. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    There are VERY strict regulations in the UK, you must use either approved licence free systems (specific bands and very low power), or obtain a licence to use a specific frequency and power (but this would be pretty well impossible to obtain, and VERY expensive if you could).
     
  6. camerart

    camerart Active Member

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    Hi Nigel,

    I passed the Ham licence exam, but didn't follow it to a licence, this might be one route, I'll dig it out. It's a bit too late for me to chase special licences, for a hobby.

    I did wonder about legal systems in a relay type situation, but this might be too cumbersome and spoil spontaneity.

    Cheers, Camerart.
     
  7. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    I'm not even sure what a ham licence allows in that way, I've not been a practising ham for a number of years, and I never did TV anyway.

    I seriously doubt a licence would be available, even if you were prepared to spend the sums required - we used to have a licence years back at work for radios in the vans, but it got FAR too expensive, and we switched to mobile phones for a fraction of just the licence costs.

    How about a webcam connected via the Internet through a mobile phone?.
     
  8. Sceadwian

    Sceadwian Banned

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    Mobile phone would probably be the simplest sollution, but a ham license should open doors for you as well. You'll have to read up on the specific frequency bands your license allows for extra power or rights to use, finding equipment that will run in those bands might be a little more problematic as most hams roll their own equipment and there would be few to no commercial electronics that would work in the bands you have access to.
     
  9. camerart

    camerart Active Member

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    I'll look into mobile phones, this might be the best, although I think there might be a problem as it they could be 'talking' for hours, with batteries, and charges.

    Also I'll check with hams, as I'm sure they do TV, but as said, this might be a bit too complicated.

    Thanks, Camerart.
     
  10. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    "doing TV" isn't what you're wanting though, and a ham licence probably doesn't cover what you want.
     
  11. camerart

    camerart Active Member

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    Just had a quick look to see if Hams 'do tv' And I found this:

    [Television: Many amateurs can transmit TV pictures to each other, often in colour. Normally the range of these transmissions is tens of miles. However, amateurs have pioneered a system called "slow scan" television (SSTV) which enables amateurs to transmit pictures around the world, albeit at a slow rate.]

    First I'll see if I can get my licence and if it will be worth it.
     
  12. camerart

    camerart Active Member

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    I also will look into Wifi, this might be ok.
     
  13. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Which in no way describes what you're wanting to do.

    SSTV is many decades old, and is rather similar to FAX.
     
  14. camerart

    camerart Active Member

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    Hi Nigel,

    Can you explain why I can't transmit a tv picture from the camera to myself? Or point me to any information please.

    Cheers, Camerart.
     
  15. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    I've no idea what the current ham regulations are (I took my RAE in the 70's), but back then you were only allowed to transmit from your location to other hams - you weren't allowed to transmit from a different location, that would require a licenced ham at that place.

    I see no reason why this would have changed?.

    A mobile phone would seem the best solution?, and uses existing technology and licencing.
     
  16. camerart

    camerart Active Member

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    I just had a quick look and you seem correct, that SSTV isn't very portable or practical. (I took my RAE in 85)

    So I'm down to Mobile phone X2 (to expensive and range in remote areas would be a problem), WIFI and the legal Transmitter/Receivers that are used in Radio control planes.

    Do you know if with a legal Transmitter/receiver with perhaps a range of 100mtrs CLS, what improvement a Yagi or dish aerial on the receiver would bring?

    Thanks, Camerart.
     
  17. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Distance depends on the terrain, and what's inbetween - obviously for an aircraft you have 'line of sight', so distance is as great as possible.

    Assuming you have 'line of sight' then you need roughly ten times the power to double the range, so 10dB gain on the receive aerial will give you double the range in a clear path.
     
  18. camerart

    camerart Active Member

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    Can I assume this applies equally to Transmitter/receivers and Wifi.

    Most of the time the Camera buggy, will be line of sight, but occasionally out of sight. Any assistance from a camera will be good. It's mostly experimental.

    I have made a wifi yagi aerial before. Would a Yagi be better or Dish?

    Camerart.
     
  19. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Dishes are FAR, FAR more difficult to make, it has to be made to a very accurate specification to work properly. Dishes also are much larger.
     
  20. Sceadwian

    Sceadwian Banned

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    Out of site at wifi frequencies is not good, and it's exponentially worse with a high gain antenna.

    Wifi isn't too line of site sensitive with a near isotropic antenna, typical dipoles/whips exhibit near 3db gain because their radiation pattern is in a toroid area around the poles and the poles are nulls, which is fine as you're not attempting to read the signal over the poles only in a plane perpendicular to the antenna axis, reflections make it less line of site dependent.

    High gain antenna's (like a dish or a well made yagi) aren't actually that complicated or difficult to make as Nigel suggests, if you decide to go that route and use frequencies in the wifi range wave guide antennas (cantennas) or bi-quads are quiet practical and very simple to construct, as well as being relatively small, and exhibit 12-15 decibels of gain in their primary radiation zone; but a high gain antenna will only be aim-able at a very narrow cone, there will be fewer reflections and it will require line of site and knowledge of the receivers direction and a physical ability to aim the antenna or you'll lose all the gain the antenna can have, far bellow a simple dipole or whip in an environment that has a lot of blocking objects.

    If you have digital 3G or better cell phone service in the area of operation it's the only practical method that doesn't require a huge amount of design and testing.
     
    Last edited: May 5, 2012
  21. camerart

    camerart Active Member

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    Ok,

    I think for a bit of fun and experience, I will buy a cheap 100Mw Transmitter/receiver set-up, and see what I can do with the information you both have given about aerials etc. This will give me a feeling of how it could work, even if it is used at short range, as practice. I will also check sending wifi signals.

    If I get exiting results, this might prompt me to get the Mobile phone set-up that has been suggested for longer ranges.

    Thanks to you both, Camerart.
     

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