Hi there guys

Im looking into building my first fpv aircraft and looking to get a good transmitter and receiver for sending video and audio(opt)

Can anyone out there who has done some fpv flying please share their experience and also the equipment that they use(i know there are many other formus out there for fpv but want to know from guys living here), it would be much appreciated. What im trying to figure out here is to know on what freq the TX and RX is that has minimal interferance .Since im currently using a 2.4ghz system for flight control there's only 900mhz, 1.2ghz and 5.8ghz to choose from.
Will there be interferance on the 900mhz from cell towers , I know the 5.8ghz band is license exempt since allot of newer wifi networks cards "n" use the 5.8band and what about 1.2ghz, does anyone have experience with any of these Tx Rx combos, and is the 1.2ghz band used for other comms and is the band available(seems like a good choice)?

From what i read on the internet the lower the freq is the more the wave is likley to bend and the better range you get for the given output, again allot of guys say rather run on the higher 2.4 or 5.8 systems , but these become quite bigger as they start to go above 500mW output, well really most of them do.

Guys im really no expert here so please if im saying things wrong please tell me lol

See my goal here is to go beyond visual range and also to build my own transmitter for flight control(full tranceiver, send and receive) that will run on the 433mhz band, getting data modules on the 433 band that can go the distance(about 5 km) is fairly easy(abit pricey though). I'll be stripping and old tx appart and by using a micro controller read the values of the sticks and buttons to send as serial data over rf. Allot of guys on the other formums seems to get good results using their own made setups and there's this one guy i saw that build a setup that plugs into a JR 9x(very cool)
I know there are 433 systems for long range flight out there but personally i think its just too dam expencive.
Im currently building my own receiver that has about 4 servo output(more can be added later)
that reads serial data(Rs232) for setting the pos for each servo(using pic16f628A @ 4mhz chip), the programming is almost complete and will be starting on the Tx side soon(not sure which chip maybe pic16f877).
As soon as i have this setup complete i want to start doing flight tests and from there add other sensors like GPS, gyro's, video and osd(on screen display)...im thinking of attempting to build the OSd myself but will see later(custom display for gps data seems better)
So my idea is to get a smaller tx rx for video probably around 100mW for testing and move on to bigger outputs as other tests for flight and systems are complete(just not sure about the freq yet).

Has anyone here atempted anything like this yet , if so any help will be usefull

As for the Fpv side , I live on a small plot and want to make sure that my plane comes back so after all testing is done and flight test are good there has to be a way for the plane to come back if video signal is lost or out of range(going to build my own antenna's, very good forums on RC greoups), therefore an autopilot will be needed with a gps (I will be working on that as soon as the fligt system is fully working with decent range , for flight leveling(taknig pictures) and navigating back home)

Also is anyone out there using video goggles and whats the verditc on these?They seem abit pricy but resolution for 640 * 480 seems to be the min if using osd?

Thanks

Hey Arnoldt

Firstly, you are not going to like very much what I have to say to you. Not meant maliciously, but you HAVE to be aware of this.

Firstly, you have to be very careful about flying out of visual range. According to air law, you are not allowed to fly out of visual range with a radio controlled aircraft. The only people allowed to do so are the airforce or any military operations. So be VERY careful about that. Civil aviation dictates that we are only allowed to fly at a radius of 2nm (about 1.5km to each side of where you stand) and at a maximum height of 400ft. And operations not to be conducted closer than 5nm from an airfield. That is for SAMAA registered fields. On non registered fields it drops down to about the size of a rugby field. and, if I remember correctly, 150ft.

More than that, everybody (industry as well as hobby) is limited to the amount of output power used on telemetry transmissions. ICASA set that rule. If I remember correctly, we are limited to about 100mW on the lower frequencies, 400mW on 2.4GHz (telemetry only 100mW for hobby) and 1W in the 5.4/5.8GHz range.

Right, the warnings and red tape aside...... Let's look at the practical issues.

Firstly. Yes, you will get more range with the 433Mhz system. BUT!!! be careful. If you are going to transmit an analog signal, which it sounds like, I would not do it. Mostly all garage door openers and some alarm systems operate on 433MHz. There are also some license free radios that operate on that frequency. So, unless your signal is digital in nature, and I am not talking about the serial data but the transmission modulation, you are in for trouble. 1.2GHz is out because Telkom uses it for their Routel system. They transmit up to 50W at times, so if you fly far out, chances are you are going to be shot down by their signal. And not to mention if they catch you.... Cell towers normally operate from 933MHz and up but I am not to sure the exact frequency. If you want I can fire up my spectrum analyzer and check for you. Let me know. If it is clear, it should work fine.
2.4G should work provided you use the correct antennas and provided you use a digital modulated transmission signal (like DSSS). Since ICASA monitors the 2.4G band closely, you will have to stay in your power output range. bearing in mind I have used a 200mW transmitter to set up a 30Km link once.
The 5.8G range is out. It is too prone to interference from things like trees, water, metal rooves and the like.
So the only option I would look at is either the 433 band with a digital modulated transmission system or the 900M band but only once checked if clear.

Just on a side note, look at the PIC18F range. They are a lot better designed. Some of them can run up to 40MHz.

On the FPV side, as you say it :), I would rather look at something like an autopilot. I am going to using AVITUS but you can look at cheaper options like the Ardupilot and the like (DIYdrones.com). Reason is if you loos signal, it is going to come down for sure, or dissapeer in the cool blue yonder. The Autopilot will bring the plane "home" if the signal is lost.

Video goggles are so cool, BUT, get yourself a decent pair. Yes, it is expensive, but the cheaper ones just don't have the resolution. Oh, and get a buddy to fly with you when using goggles. One tend to loose the plane when coming in to land just after you take the goggles off.

Once more. Be careful not to break airlaw and ICASA rules. Those guys don't play with you if the get hold of you.

my 2c worth is this. FPV is great fun. it can be dangerous cos you lose orientation VERY quickly. and i almost fell over when trying it as you lose youre balance. weird but true
I used a 2.4ghz system with a 35mghz radio about 3 years back and it worked ok. not fantastically. but then again i cobbled it together from junk i bought off ebay.
Lood knows his stuff about RF(he is a RF engineer)
SAMAA has also been rather quiet on the issue of FPV, its a bit of a grey area.

incidently hobbyking has many lovely FPV products, if you need any let us know and we can get them for you.

Im flying FPV in South Africa and enjoying it very much. I have done everything to do it legally. I am even busy my HAM licence. just waiting to write my exam.

Just remeber flying fpv does not mean flying far distances away. Its just a new exciting way of flying your plane. And it is a really great feeling.

The 433mhz links that are out there like dragon link and thomas scherrer are extremely secure. regardless of all the other things operationg on that band. The signals are infact digitally encoded and they frequency hopping. However, I dont think 433mhz has been approved for RC control in SA. Im trying to get more info on this.

I would say get a frsky 2.4ghz module which goes 1.5km. Its all you need and its legal. they are available at hobbyking. nudge nugde wink wink Wifly! =)

For video link: 900mhz is illegal whether you have your ham licence or not. there is an amature band at 1280-1300mhz. there is also one at the 2.4ghz and 5.8ghz. Iv gone for 5.8ghz at 200mw and Iv never out of range. Just make sure you chose the right channel on the transmitter that is in a legal range.

Hi Brett

Yep, you hit the nail on the head with your comment. Except. The entire 1.2GHz Spectrum has been annexed by Telkom. It is an ISM band overseas, but here good old Telkom took over that spectrum for their ROUTEL system. I know this because we set up a bunch video links not too long ago and we ware shut down by Telkom. Had to move the entire system to 2.4GHz.

Also as far as I know 900Mhz has been set aside for Cell phone operations.

ok i understand the legalities of all this. but what is the impact if someone uses a short range fpv system on 900 or 1.2 surely icasa couldnt give a rats bum if its out in the open not near any major installations? or are they the men in black who will hunt you down and arrest you? while murderers roam free?

brettb said:

Im flying FPV in South Africa and enjoying it very much. I have done everything to do it legally. I am even busy my HAM licence. just waiting to write my exam.

Just remeber flying fpv does not mean flying far distances away. Its just a new exciting way of flying your plane. And it is a really great feeling.

The 433mhz links that are out there like dragon link and thomas scherrer are extremely secure. regardless of all the other things operationg on that band. The signals are infact digitally encoded and they frequency hopping. However, I dont think 433mhz has been approved for RC control in SA. Im trying to get more info on this.

I would say get a frsky 2.4ghz module which goes 1.5km. Its all you need and its legal. they are available at hobbyking. nudge nugde wink wink Wifly! =)

For video link: 900mhz is illegal whether you have your ham licence or not. there is an amature band at 1280-1300mhz. there is also one at the 2.4ghz and 5.8ghz. Iv gone for 5.8ghz at 200mw and Iv never out of range. Just make sure you chose the right channel on the transmitter that is in a legal range.

Hi Brett

I want to take aerial photographs (South Africa) but need to put a fpv system on aswell to track the camera so that I can see what I need to photograph. I dont need a to big range and was thinking of useing the 5.8 ghz 500mW. Do you know if there will be any legal problems or can I use 5.8. I am using a Futaba fast 2.4ghz radio

loodbirk@pages4africa.co.za said:

1.2GHz is out because Telkom uses it for their Routel system. They transmit up to 50W at times, so if you fly far out, chances are you are going to be shot down by their signal. And not to mention if they catch you....

Hi Lood
Regarding Telkom using 1.2GHz: I looked up the frequency allocations on ICASA's site and they don't list the 1.2GHz range as being allocated to anyone. The closest I can find is from 1350MHz and upwards, where Telkom is allocated a portion as well.
I'm not saying that 1.2GHz is in fact free to use, but I can't find any documentation that says it is allocated to anyone. Can you perhaps help with more info? The video transmitters use these frequencies: 1080, 1120, 1160, 1200, 1240, 1280, 1320, 1360 MHz.
The 1320 and 1360 are probably not usable as the one is close and the other falls in the 1350MHz and up allocated range. How about the others though?

Johan

I am also interested in FPV and I am also wanting to go for the 1.2 to 1.3 range but I can't find any information about this Telkom Router system. I might opt for 5.8Ghz to begin with to be safe.