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robyr1

Live video from a powerboat?

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Hi to all!!

i would like to send a live video from a bullet camera fitted on a powerboat. I can use an helicopter has a "bridge", so here are what i would like to do:

POWERBOAT:

12v lead acid battery 7A+ bullet camera CCD 1/3" and a 2,4 ghz 8 channel 2W TX with a simple 2db circular omni antenna.

HELICOPTER:

2 omni patch antennas, 1 oracle diversity, 2 receivers.

So i can give the video signal to the broadcast digital transmitter fitted on the helicopter, wich is used to send the live video from the cameraman (sure, once at time!) and i can see a clear image on the ground.

What do you think??? The helicopter will follow the boat, and the maximum distance (boat-helicopter) will be around 150meters maximum.

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Why use a helicopter? At 150m range the boat is well withing range of a ground receiving station. 10mw video Tx would be strong enough for the Tx-Rx link unless your boat will be out of sight when operating. 2 watts Tx may be illegal for unlicensed operation. At any rate, at these distances, it's overkill for the purpose.

As for the helicopter, I assume the diversity Rx would be used for heli control so you would need an additional Rx for the reception of the signal from the boat and another Tx to rebroadcast it. If using 2.4ghz for the video links, you would need to use different frequencies for control of the boat & heli. 72mhz if you're in the US.

In addition, using 2 - 2.4ghz video Tx, you probably would have interference between the two signals even if they were operating on different frequencies/channels at opposite ends of the band.

Using a chopper, or anything for a relay link within 150m sounds like it would be a good exercise in frustration.

EDIT: Just noticed 150m would be distance between boat - heli. What is the max range from the heli to the ground station?

Edited by W3FJW-Ron

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I think it's safe to assume that the boat would be that far away as well, so it begs the question, At 3 to 4km, how are you going to control your boat?

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Ron you missed the point, he's talking of full size boat races that he's equipping for TV broadcasting, not models/FPV ;)

I assume the heli (full size too) is there anyway for TV aerial images.

Sounds good. You just need to check that you don't have interference from the digital TX on the analog receivers.

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Ron you missed the point, he's talking of full size boat races that he's equipping for TV broadcasting, not models/FPV ;)

I assume the heli (full size too) is there anyway for TV aerial images.

Sounds good. You just need to check that you don't have interference from the digital TX on the analog receivers.

yes!!

it's a real offshore powerboat, with pilots inside!! and we have also an helicopter. We need to send 3 different live videos..HOW TO? i found this website:

www.rf-links.com

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Ah! Well! OK...Different story then. I just assumed when someone asks a ? like that that the powerboat would be a Mr Darby perhaps? I do have to admit that from a hobbiest point of view I was a bit perplexed and didn't even think it would be about a real world situation.

Do gotta say it makes it a lot easier now. Just an uplink and a downlink. I'd go up at 2.4ghz and down at 900mhz or vice versa as the 2.4 is 2 watt. But a 2w Tx isn't legal????? is it???

Where are the 3 live feeds originating? 3 boats? Will the heli be receiving and retransmitting all three?

Perhaps a video multiplexer & demux would work for the three live feeds if that's the case.

BTW, thanks for that RF site link..

Edited by W3FJW-Ron

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yes, we have to send the live video from 3 different boats. but we can choose wich one of that to send to ground. I think to use a 2,4ghz with a common 2db antenna from the boat, and to send the video from the heli to ground with a 900mhz TX. My customers are: www.class-1.com

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Boy, I have no idea how much 3 2.4ghz systems would interfere with each other on different channels. Hopefully someone else here has some idea.

The 3 video outputs from the Rx would need to be fed into a video switch with probably a small video amp to overcome any switching loss and the output of the switch to the 900mhz Tx. Not too hard to do.

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We need to send 3 different live videos..HOW TO?

Hmm, now that will get more tricky. From my experience, having 3 2.4GHz transmitting simultaneously even on different channels can indeed cause serious interference depending on the TX power, relative distances involved, and equipment brand. Easily, there's no way to know how well a particular equipment brand will work or not before you buy and try, the sellers usually haven't tried that so asking them is often of no help.

and to send the video from the heli to ground with a 900mhz TX.

Didn't you say you were using a broadcast transmitter for that?

Personally, to do it "safely", I think I'd use an R/C TX, with an RX on each boat that controls a power switch to remotely turn the video transmitters on/off. Then, you turn them on/off from the heli as needed, so that there's always only one transmitting. You are then sure you don't have any interference, and you can even set them all on the same channel, so that you only need one receiver in the heli, and don't have any switching to do there.

Edited by Kilrah

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Good hit Kilrah. Didn't even think of switching Txs. With cheap Rx such as This being available, and a cheap 4 channel Tx, or about $8 more ea for synthesized Rx, the whole thing would cost very little to do. Should be able to find a $25 to $35 4ch Tx fairly easily. Perhaps on RCG (where I got all my present gear when the switch to 2.4ghz began) could even find a good used one for $10.

Edited by W3FJW-Ron

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With cheap Rx such as This being available, and a cheap 4 channel Tx, or about $8 more ea for synthesized Rx, the whole thing would cost very little to do.

Erm, personally for professional broadcast applications where you usually have a budget in the range of several thousand $, and where you'd get fried if something doesn't work... I'd go for a brand name high quality set, not some cheap Chinese stuff. And especially NOT the 4-ch GWS RX, which is well known for going awry already at short distances (<20m in some cases) even without any particular interference sources...

I don't know about his budget and audience, but in all cases I'd get a good quality PCM set. The idea above with one video RX and all transmitters on the same channel is the "budget" idea, as there are many failure points. The R/C link MUST work, or you risk having multiple TXs transmitting simultaneously on the same channel, or none transmitting at all. If the (single) video RX fails, you're screwed too.

To maximise all chances and offer some redundancy, if the budget allows it, I'd prefer going with the following:

3 TXs but with less power (500mW), set on different channels, 3 video receivers in the plane on the corresponding channels. A 3-channel R/C controlled video switch between the 3 receivers and the uplink, with compatible plugs so that if needed you can directly physically connect the RXs with the uplink should the switcher fail.

On the boats, retain the power switch idea, with PCM receivers with failsafe. Set TX mixings so that you can switch each TX on while switching the others off, and have the R/C video switch automatically select the good receiver. So 4 R/C receivers altogether. Set the failsafes to switch the TXs on should an R/C link failure happen.

In summary:

When everything works, you have just one switch/stick on the R/C TX that you can use to easily switch between video 1, 2 and 3. This switches the corresponding video TX on, turns the others off, and selects the correct video receiver to send to the uplink.

If the R/C link fails on one boat unit, its video TXs starts transmitting. You risk some interference as you'll have multiple units transmitting, but at least you have something. If the video switch fails, you can directly connect the video RXs to the uplink. If one boat unit or a video RX fails, you can just ignore it and use another one.

That way you have high redundancy, and can be nearly sure to always be able to provide at least an image in any case, at least until the heli. Record the output feed you send to the uplink in the heli on tape or whatever, in case of an uplink failure you'll always have the recording to provide for "offline" shows.

On that type of jobs usually the budget isn't much of a constraint, the only real constraint is that you have to do all you can to provide something. Customers who pay you several thousands to organise that kind of thing won't be very happy if something goes wrong and you can't provide anything. An event only happens once, so you don't get a second chance.

I'm typically reluctant to use our usual analog hobby level RF gear for such things, or if the customer really has a low budget and can't call a company that is equipped with digital broadcast level equipment, I make sure to make him understand that I do NOT guarantee clean and perfect images at all times. Behind the scenes I'll still do a setup in the scale of what I said above to put all the chances on my side though.

Edited by Kilrah

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Yeah, I missed the commercial aspect of this project. Couldn't open the link of that class-1 site due to a local problem with my inet connection last night. Anyway, I always try to think of solutions as a hobbiest with hobby dollars. Been almost 40 years since I've done any commercial work, but I like your solution if the money is there although I'm not averse to using analog gear.

As an aside, I have 4 4ch GWS Rx for over a year now (72mhz) and have never had any problems with them out to 300+ meters. Haven't flown any further out. Eyesight not that good.

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I'm not averse to using analog gear.

The problem is that with that analog gear in the "trash" ISM bands, all it takes is one guy/organisation in the vicinity with some gear working in the same band to ruin all your efforts, and there's nothing you can do to prevent that. The customer needs to know it beforehand, so that in case this happens he can't blame you for not warning him.

Digital broadcast gear is a lot more tolerant, and offers more flexibility to save the day in case it still causes problems.

Talking of reliability and redundancy... definitely needed when you're doing things on contract. 2 days ago we were hired by an organisation to do an FPV flight demo/dual control setup so that people could try. I had 4 video-equipped planes to use.

On the actual day:

- One was ruled out because of excessive wind (it's very rare in that region, but of course on that day we had 30+ km/h winds all day long).

- One had an electrical failure on location - unuseable.

- One had a 10mW camera on CH1, apparently there was some interference source in the vicinity that created interference lines on the picture as soon as the distance exceeded ~200m. We asked people to turn their phones / BT / Wifi off, the organisation went to switch their Wifi off. No change, so that must have been something beyond our control. Useable but not satisfactory.

Only the 4th one, with a 200mW TX on CH2 gave satisfactory performance.

So.. there are always things that can, and will, go wrong. Always need to think about what can fail, and have backup gear that is different enough so that the same problem is very unlikely to happen on more than une unit... :)

Edited by Kilrah

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Thanks guys!! thanks for your special suggest..

I think i will try to fit 3 tx's of 2W each, has 8 channel so i can choose to set: 1- 4-8

I will use 3 receivers on the heli, with 1-4-8 channels set, all the output connected to a QUAD, and the video out of the quad connected to the TX to ground.

So now, i have to choose the TX for the video to send to ground, and also what kind of antennas to use: on the boats, on the heli for receivers, on the heli for the TX, and on the ground for receiver.

I have also an oracle diversity, but as i understand i will use on ground only. or not? because the heli is always near to the boat, we can follow it everywhere..

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Hi guys!! i have another question from my customer!

the day before the race, they want to put a wireless camera and send a live video for a 1km of high speed only. What do you think if i use a 2w tx on the boat on channel 1, a receiver on the heli connected to another 2w tx on channel 8, and i will receive at ground with my 2 receivers connected to my oracle diversity. what do you think?

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Since this is a commercial issue, I think I'll bow out of the conversation. My experience with Video equipment dates back to the 70s and I have no idea what's up these days with what equipment. Will keep up with the thread though as I'll probably learn something (if I can remember it for more than a month is the problem I face).

Edited by W3FJW-Ron

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What do you think if i use a 2w tx on the boat on channel 1, a receiver on the heli connected to another 2w tx on channel 8, and i will receive at ground with my 2 receivers connected to my oracle diversity. what do you think?

It can work. BUT, it can also cause problems, as in the heli you will have a 2W TX very close to the receiver that gets the signal from the boat. Even if one is on CH1 and the other on CH8, you can have image ghosting or loss of sensitivity/range on the RX. That's what I was saying above, no way to know until you buy, and try to replicate the setup on your own before the event. I'd use different bands for both. Anyway, be sure to have the TX and RX as far as possible.

Also, don't forget the "preparative work" before choosing a solution. Do the boats, heli, other things in the vicinity have telemetry, sensitive devices, or other equipment that could cause you trouble on the frequencies you intend to work, or even worse, be disturbed by your equipment?

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thanks Kilrah,

yes, i have to test it.

For this i bought also a 5W 1,2ghz transmitter also, so i will try with send with a 2w 2,4ghz from the boat, and send with a 2w 2,4ghz or 5w 1,2ghz trasnsmitter from the heli.

But now, i need 2 good antennas of 1,2ghz, where can i buy it??

another question:

what kind of antennas i should to use there for the tx of the boat, the receiver on the heli, the tx on the heli and the rx at ground?

here what i have: common stilo 2db omni, patch, parabolic and directionals (but all 2,4ghz)

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I'd put standard whips everywhere except on the ground receiver(s), with higher gain and more directional antennas.Something that has a beamwidth that covers the horizontal span the heli will move in. Shouldn't be much if as you say the race is a couple of km out in the sea.

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One other thought worth mentioning is to keep the Tx antennas on the boats, mounted high on the boat with a clear 360 degree field of view.

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One other thought worth mentioning is to keep the Tx antennas on the boats, mounted high on the boat with a clear 360 degree field of view.

yes! thanks, this is the first thing wich i'll do it there!

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