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Hi all, I´m finishing a small 3D electric with 800mm wingspan and would want to mount on it an FPV equipment. I don´t want to go here with 500mW, besides new 500mW lawmate transmitter is very small, but I think plane doesn´t have enough room to separate components as it should be. So I was thinking on something about 100mW, or lower, and with 5V in. For the camera I think that if I want decent quality, and a small one, pretty much is the well known KX-131, but I could consider another altenative.

So you guys whoever uses low power could you advice me in performance of video transmitters?

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I was looking for a similar solution and ordered a uncased KX-131 an a 100mW Lawmate transmitter (http://www.rangevideo.com). Current consumption at 5V should be around 350mA for this combination which is low enough for me to use it on smaller RC planes. Add to that the fact that the combined weight is <50-grams and the option of turning this into a small module that will fit a large number of planes and can be powered off of the ESC BEC through a normal servo cable. Looks like a perfect solution for all your small scale RC plane FPV needs to me.

Cheers,

Sander.

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Yeah, could be a solution but I prefer cased camera, even that weights more, but for sure will last years, and crashes. On transmitters since I´ve tried Airwave, for me they work better than Lawmate, so I was thinking on then rather than Lawmate.Would like to hear opions for Airwave low power users.

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Hi Wavess, I use only the Airwave 10mW and 100mW TX's with the KX-131 and range is good. If you have any worries then go for the 100mW as your receiver set up dossen't have to be so great. With 3D I geuss you will be flying close in anyway ?

Terry

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[Wavess,

On transmitters since I´ve tried Airwave, for me they work better than Lawmate,

Because? That's a bit of odd statement to make when you don't specify what the problem might be. Lawmate (ie. sold by Rangevideo et al) is an off-the-shelf module, you just need to connect power and input, Airwave modules however need to be mounted onto a PCB. Esp. the microstrip needed for the antenne output is not something you will be able to do correctly by chance, you'd need to know what you're doing. So Lawmate certainly has my preference here as it is a foolproof solution, whereas the Airwave modules are not.

Cheers,

Sander.

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Hi Wavess, I use only the Airwave 10mW and 100mW TX's with the KX-131 and range is good. If you have any worries then go for the 100mW as your receiver set up dossen't have to be so great. With 3D I geuss you will be flying close in anyway ?

Terry

Exactly, I don´t pretend going far with this plane, so perhaps a nice airwave 10mW would do the job. How far do u think you can achive with it? (I´m thinking going no further than 500m, for playing with trees etc...

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[Wavess,

Because? That's a bit of odd statement to make when you don't specify what the problem might be. Lawmate (ie. sold by Rangevideo et al) is an off-the-shelf module, you just need to connect power and input, Airwave modules however need to be mounted onto a PCB. Esp. the microstrip needed for the antenne output is not something you will be able to do correctly by chance, you'd need to know what you're doing. So Lawmate certainly has my preference here as it is a foolproof solution, whereas the Airwave modules are not.

Cheers,

Sander.

I don´t have any problem with lawmate, it just a range reason to prefer airwave, since I´ve tried both in similar conditions

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Wavess,

it just a range reason to prefer airwave, since I´ve tried both in similar conditions

Uhm yeah, 'similar conditions', how's that exactly? Without some proper measurements or fieldtests in exactly the same (hence not similar) conditions it is virtually impossible to make these kind of statements. These kind of generalizing comments are not helping anybody I'm afraid. People start buying 1W or even 3W Txs so that they will have 'good reception under any condition', that's just stupid. Rangevideo also sells 10mW Tx modules, just email them and ask. These come factory preassembled, hence need no PCB fitting like the Airwave modules, that, without having proper RF measuring gear, will be your best best.

Cheers,

Sander.

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How far do u think you can achive with it?

It's not that simple, I use 10mW with very few drops up to 400m and some increasing bad drops up to 800m but that is with a stable plane. For you doing 3D I would go for the 100mW unit as it still has reasonable power use and dose not get too hot.

Terry

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Uhm yeah, 'similar conditions', how's that exactly? Without some proper measurements or fieldtests in exactly the same (hence not similar) conditions it is virtually impossible to make these kind of statements.

You don't need measurements to say something like this. If you go out flying regularly with 2 different transmitters and always notice set A has better performance than set B that's enough for me, practical usage experience means much more than any figure.

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Andre,

If you go out flying regularly with 2 different transmitters and always notice set A has better performance than set B that's enough for me, practical usage experience means much more than any figure.

Hence I asked Wavess to specify 'similar conditions', it is rather meaningless without some further info. If you regularly go out flying at the same spot, under the same conditions and see an improvement of set A over set B, then yes, something must be causing that. Could it be the transmitter? Well, yes, but also a number of other things. The transmitter could be transmitting at a frequency that's just a tad off from the frequency the receiver is tuned in to for example, and I can think of a dozen other reasons why you'd see differences that have nothing to do with the actual transmitter, or its output power.

Just because it is simpler to state that one has better performance than the other based on practical experience and then disregard that Tx doesn't mean you shouldn't investigate why that is. Or at least that's how I approach things, and that usually gets you farther than the trial-and-error method of replacing stuff until you've found a combination that works.

Cheers,

Sander.

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Wavess,

Uhm yeah, 'similar conditions', how's that exactly? Without some proper measurements or fieldtests in exactly the same (hence not similar) conditions it is virtually impossible to make these kind of statements. These kind of generalizing comments are not helping anybody I'm afraid. People start buying 1W or even 3W Txs so that they will have 'good reception under any condition', that's just stupid. Rangevideo also sells 10mW Tx modules, just email them and ask. These come factory preassembled, hence need no PCB fitting like the Airwave modules, that, without having proper RF measuring gear, will be your best best.

Cheers,

Sander.

Heyyy, take it easy or next time you´ll get no response from me with those kind of quotings.

Similar condition is tried both on different days, at my same local club with the same plane.

Exactly same conditions is tried both in the same day (with 30 min delay on each :lol: ) and same field, and same plane. (also i´ve done this test)

I always flight at my local club, have only flown twice in more than a year at different location, so I really know what I´m saying and how my enviroment behaves. Hope it gets clear now.

Edited by Wavess

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so I really know what I´m saying and how my enviroment behaves.

Same here. I have more than 50h of flight using the same configuration at the same location, in all kinds of conditions. So I know exactly what to expect when. If I test a new setup and see different performance, I'll repeat the test in the "exactly same" conditions as described by wavess (fly system A, land, change, fly system B with the same patterns).

Usually systems A and B are kept as similar as possible (for example only change TX, or TX/RX set if needed but keeping the same antennas) to have the minimal of sources for the difference.

This way I've ditched the 200mW Lawmate that was repeatedly giving me worse range than my usual 10mW TX, in 3 completely different locations and conditions, while significantly increasing R/C glitches even 60cm away from my RX. There the only difference between A and B was the TX, the RX was not even moved. I did try using the Lawmate RX "just in case" it would be matched to the TX better, but it didn't help. I also tried 3 different TX modules in case one was weak.

I don't know what more is needed. Maybe a spectrum analyzer could tell the "why", but not only I don't have one but I don't really care, the goal is to have a unit that works well... not really to know why it doesn't. I wouldn't start spending dozens of hours trying to improve it anyway.

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I'll repeat the test in the "exactly same" conditions as described by wavess (fly system A, land, change, fly system B with the same patterns).

Usually systems A and B are kept as similar as possible (for example only change TX, or TX/RX set if needed but keeping the same antennas) to have the minimal of sources for the difference.

Fair enough, I guess we're dealing with a smarter crowd here than those that frequent the other forums. I'm just trying to point out that the above indeed is the right way of approaching this, many people just don't have a clue though and just change parts and configurations at random and then declare certain parts don't work as advertised.

Cheers,

Sander.

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Ps. I just ordered a 200mW Lawmate from Hobbywireless last week, I'll let you know how it fares, I could be in for a dissapointment as per your comments :blink:

Cheers,

Sander.

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Maybe a receiver issue? Not all modulation schemes are identical it seems. I've ordered a receiver from the same vendor, so I'm guessing this should be allright?

Cheers,

Sander.

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Hi Wavess, I use only the Airwave 10mW and 100mW TX's with the KX-131 and range is good. If you have any worries then go for the 100mW as your receiver set up dossen't have to be so great. With 3D I geuss you will be flying close in anyway ?

Terry

Thanks Terry, I´ll go with the 10mW solution,do u get them from active robots in the UK?

Something similar as related by Kilrah is happening to me know. Since I changed my crashed easy´s fuse and change BEC¨S position (this last position has the wires shorter from motor to BEC, and is has more distance from rc receiver) I hardly get 1 km range from my r/c system, before I usually got 2 km more or less.

Tried with different TX modules, and last day something weird happened. I tried a Wfly TX module, manufacter states that they have <=700mW rf power. Also measured with a home made probe the original futaba module and this one ending up to the conclusion that this one is very close to what Wfly says (700mW) my origianl futaba module has got about 20mW. Well, both modules where tried at the exact same conditions, changed the same cristal between both, and notice that my futaba was acting like everyday (got hardly 1 km) but with Wfly module I have lot more glitches while flying, and I suspect that when oracle changed to the 2.4ghz receiver antena closer to me, there were some kind of noise in the video that 5 minutes before there weren´t so this module is not only working better in distance, that also puts some noise in the video, this is always my personal experience :D

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Thanks Terry, I´ll go with the 10mW solution,do u get them from active robots in the UK?

Yes I got my last modules from them but I would order a 100mW unit as well just in case, they are cheap :D

Terry

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