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I was thiking of installing a video system on my airplanes and heli for some years now and reading this forum I decided it's time to go ahead and do it.

I spend most of the day reading product descriptions and I have a really hard time deciding which frequency band I should use. At www.rcdon.com website I read that after a lot of testing he concluded that 900Mhz does the job better (his long range-high altitute video footage shows no glitches at all!), supercircuits also state that 900Mhz have a better range and "handle better the various obstractions".

Also from my experience (with long range wi-fi links) the 2.4Ghz band has a lot of noise the last few years (mainly due to the recent popularity of the Wi-fi systems, DECT phones). Still most of you here, as far as I can tell, are using the 2.4 band, which is something I would also like to do since I already have a lot of hardware (amps, commercial patch, yagi, rubber duck antennas, etc).

My ultimate goal is to fly the aircrafts through the camera and not just around myself at 100m distance, so link reliability is a priority. I am also concerned with the 900Mhz since here in europe we have the GSM phones in an adjacent frequency. My father that flies with me is a licenced amateur radio operator so law is not a problem.

What are your experiences, thoughts, suggestions?

Thank you,

Dimitris, Greece

PS: Also will the Seagull telemetry system from Eagle Tree cause interfearance to a 900mhz video system? - it transmits at 900 too.

Thank you in advance

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Come on guys. Some feedback on these bands (interference close to residencial areas etc) would be very helpful. I need to order my wireless system!

Dimitris

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Well the reason I did not reply is because I have no idea what the conditions are like in grease. If you were in the UK I would say go 2.4Ghz at 10mW if you want to be legal and 200mW if you want good range the easy way. 900Mhz is no go here.

Terry

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Terry,

why is 900Mhz is a no go in the UK? Is it a legal reason or interference make it useless?

The situation in Greece right now is that everybody is buying Wi-fi devices and noise in 2.4Ghz skyrocketed the last years (I see 10X more noise all over the band than 5 years ago when I first got involved in the wireless networks). With my laptop's internal low gain antenna I can receive at least 40 wireless access points sitting on my desk! Not to mention those long range links on the roof tops... they crank up the wattage of cheap access points through firmware upgrades, install a high gain omni and "leak" RF pretty much everywhere.

Back to video transmission: My only experience is at home with three different 2.4Ghz TX/RX sets that I bought in order to watch my PCs video in the livingroom is that none of them are practicaly working at 20m distance! They work perfectly in my summer home which is in the middle of nowhere though. Of course these are cheap chinese transmitters/receivers but the results make me reluctant to believe that 2.4 is a reliable band for this application now days in urban/suburban areas.

I think also Mr.RC-Cam mentioned somewhere here that 2.4 at his local flying field is not working like it used to.

Somebody with 900 experience?

Dimitris

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900MHz is a band used by cellular phones throughout all Europe, Greece must then be part of that.

That means that 1) you won't be allowed to fiddle in there, and 2) you have cellphone towers everywhere that can blast up to 200 Watts, plus numerous phones that send 2W each...

So I don't have experience... and I won't try.

Edited by Kilrah

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GSM phone transmissions may cause serious interference... Did anybody use his cell phone next to a 900 system (in Europe)?

Dimitris

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As Kilrah said cell phone use is the reason its no go here. 1 it would invite interference and 2 you would get jumped on as you would get reported for sure by the phone service providers. On 2.4Ghz here if you are away from a built up area you can get away with using a bit more power as nobody will even notice.

Terry

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I went to the local electronics shop and they had a lot of 2.4Ghz systems but all of them were complete with cases, RCA connectors, power supplies etc.

The only bare (tuna can) TX modules they had in stock were in 1.2Ghz @ 400mW. Do you think 1.2 Ghz are any good in Europe? Does anybody know any sourses of serious interference in this band?

Dimitris

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No idea about interference sources, but what I know is that they are illegal. Dealers here who had 1.2GHz stuff don't exist anymore...

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For those interested:

In Europe the 900Mhz GSM cellular telephony band has channels numbered 1-124, ranging in frequency from 890.2 to 914.8Mhz (in 0.2Mhz increments).

The 1800Mhz GSM band has channels 512-885, from 1710.2 to 1784.8Mhz, in 0.2Mhz increments.

Regards,

Dimitris

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In Greece you may have an option of 868 Mhz, because it does match european bands assignements. Here in Russia we have only a 2.4 Ghz for amateur use in fact 900 Mhz is cellular, and 868 is a legacy government frequency :P

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Hi all. I'm new here as of today. Although the only model I have is a leccy heli and not in the same league as what I'm seeing in here ;-)

My reason for joining this forum was from parallel interest in 2.4GHz video.

I design devices that use this band. I recently purchased a TX/RX combo that may well be of interest here.

The TX size is 30.6mm x 28mm x 3.70mm so would appear to be good for flying.

Power supply is 5V -AT-55mA nominal. 10mW standard output power.

The matched RX is also small.

It is possible to add the various external components directly to the TX module directly ( 2x caps video in & antenna out) this keeps weight down to the minimum.

The picture quality is excellant.

Heres a direct link to the products>> 2.4GHz AWM630TX/RX

I hope this is of useful interest.

Steve

edit: Added TX PDF below

AWM630TX_SPEC_Ver_A2.pdf

Edited by Stevie

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I saw those modules a while back as LPRS send me emails about once a month. I was put off as they are stereo and all my other gear is mono. I would like to see any pictures of your gear if you can post thm here though. I may give them a go...

Terry

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Sure no problem.. Not sure why theres a problem with stereo? I'm assuming you would be using the TX/RX as a pair, not all 2.4GHz channels are not the same from different manufacturers ;-)

Channel Freq's: 2414, 2432, 2450, 2468MHz

Note: for an idea of scale.. the TX wire antenna is 31mm.

The PCB for the TX is same size as module, all smd. Wiring was a quick latch-up just for testing

The RX was made using a Conventional & Smd component mix, no problems of space for the RX.

The small camera is a low-light B/W Russian job, (0.01 lux) nice size, unfortunately no longer produced :-(

Steve

post-5-1146735241_thumb.jpg

Edited by Stevie

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Just for info: Here's the module side view pic >>

post-5-1146735737_thumb.jpg

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Stevie, the problem for me is I dont use them as a pair as I have lots of TX and RX set ups that I mix and match depending on the plane and application. I have some RX modules built on to the back of the aerials so it would be hard to swap them all now.

Terry

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Terry It maybe fine as it is. Just check if your channel freqs match the above ones of the AWM630TX which I believe are pretty standard.

Stevie

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The video is fine, the problem is the audio sub carrier frequency.

Terry

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