Hard to choose frequency.

[bcavett18]

I read somewhere that 900mhz is better for penetrating objects, and may be more reliable?

It seems like a lot of people are selling video equipment more for 2.4ghz.

It sounds like getting a diversity receiver is the way to go.


I think I want to go with 2.4ghz radio, like futaba. Not too sure which remote yet.


Anyone have any different pros and cons on using the different frequencies?

[camship]

I read somewhere that 900mhz is better for penetrating objects, and may be more reliable?

It seems like a lot of people are selling video equipment more for 2.4ghz.

It sounds like getting a diversity receiver is the way to go.


I think I want to go with 2.4ghz radio, like futaba. Not too sure which remote yet.


Anyone have any different pros and cons on using the different frequencies?


2.4GHz. RC TX/RX=RUN AWAY! (10 years practical field experience with high power microwave communications using 100+ watt transmitters is why I say this. I'm one of the guys you used to see building those microwave towers)

[bcavett18]

microwave towers?

What frequency do you use for you Radio, and video Tx

[camship]

Just good old 72.mhz. FM RC TX and data on 900MHz. + video on 2.4GHz. At least when you get interferance with an "analog" system SOMETHING happens part of the time when you move the sticks even when things get real dicey. No lock-out reboot nonsense.

I use Futaba TX's but do not use Futaba receivers or PCM for anything.

Camship

[typicalaimster]

Here's the thing. A 2.4ghz video TX will overload a 2.4ghz RC RX within close proximity. There are reports of people flying with a 2.4ghz video tx and RC RC in the same plane but I don't trust it. I've tried a few of my own experiments and almost lost a plane in the process.

A few of us are switching back to 900mhz video feeds with a 2.4ghz RC system. The 900mhz system will not interfere with the 2.4ghz setup and vice versa. Many people are switching over to the 2.4ghz RC systems since they are 'glitch free'.

Then there is the whole thing about frequency usage. The 900mhz frequency can be used in the U.S. However the regulations are different in other countries. Check your local listings for that ;)

I've ran RC on 72mhz, Data on 900mhz, and video on 2.4ghz.. They all interact very well with each other..

[Mr.Pibb]

I found out (unfortunately) that even a 900MHz video TX can overload a 2.4GHz RC RX given the right conditions.
See: http://www.rcgroups.com/forums/showthread.php?t=682562
and, more specifically, I was able to re-create the problem on the bench:
http://www.rcgroups.com/forums/showpost.php?p=7414013&postcount=13

Given another chance to buy stuff, I'd probably back off on the power of the video TX (100mW instead of 500mW?)

[Kilrah]

2.4GHz video and 40MHz R/C (equivalent of US's 72MHz, and to be replaced by 35MHz here soon, with an equipment change in the process :mad: )

[bcavett18]

so I should probably just stick with the old 72mhz radio.

Futaba claims there shouldn't be any interference with there radios


What do you mean by data on 900 and video on 2.4?

[typicalaimster]

Given another chance to buy stuff, I'd probably back off on the power of the video TX (100mW instead of 500mW?)

Hmm, interesting. Like someone said, I try to keep everything at least 6-12 inches apart. I've ran data back down to the ground on 900mhz and that link was only 100mw. I never had a problem losing link and it seemed to keep up right along with the 2.4ghz camera. Usually I put the 900mhz data modem up front.. Then put my 72mhz RX inside my wing on one side, then the 2.4ghz TX inside the wing on the other side.

[Kilrah]

Futaba claims there shouldn't be any interference with there radios

I see people every day mentioning makers of 2.4GHz radios advertise "no interference" and think it's time to clarify one point.

Don't forget they DON'T take FPV flying into account, that's if they actually do know about it in the first place. We have many more sources of problems than conventional fliers, the main one being blasting RF energy next to the receiver. The second one is that this RF energy is emitted continuously, not in random bursts like it would be the case with digital transmitters. Feel free to complete the list with a second video TX (I've ran up to 4 on the same plane), data modems,... that can all add up.

The "no interference" primarily means there won't be any problem at a field full of people flying their planes at the same time with 2.4GHz radios, who by the way now don't even need to keep a frequency table anymore to know who flies what channel and avoid frequency collisions.
That's just about all that matters to a conventional flier. If he gets his fast response and can fly at his field without worries he's happy.

These radios are good, just like the "old" ones, and with the few improvements, but just like them they still are not made to be used in these circumstances / at distances we reach in no time.

[bcavett18]

So I guess it really doesn't matter then, as long as I use a different frequency for each type.

In which case I'd probably go with the 2.4 radio and the 900 video.

Probably need at least a 500mw transmitter then, with diversity receiver. Do they have diversity receivers with 900mhz frequency? The only ones I've seen are 2.4.


I thought futaba's 2.4 Rx and Tx have a very good range? Or do you just have to put a better antenna on there?

[Mr.Pibb]

The only "diversity" setup that works with 900MHz I've seen is RC-Cams VIDEO diversity setup, which is currently in Beta testing (I'm testing one).
Read up on it here:
http://www.rc-cam.com/forum/index.php?act=ST&f=6&t=1324

[Kilrah]

I thought futaba's 2.4 Rx and Tx have a very good range? Or do you just have to put a better antenna on there?
I think it's only a few days since they've started arriving to the customers, a bit short to have reliable practical experience data.

[bcavett18]

oh


What do you guys mean buy 72mhz r/c, 900mhz data, and 2.4ghz video.

I know what you mean buy the r/c and the video, but what is the data for?

[Kilrah]

Telemetry downlink

[typicalaimster]

GPS and sensor downlink

[bcavett18]

oh, wow, I forgot about that.

crap, I wasn't even thinking about gps yet. So I probably will have to go with a 72, 900 and 2.4 then.

[typicalaimster]

Well that's just if you want to send that info back down to the ground. You can use something called a OSD or On Screen Display. I mostly use the data for an moving map back on my laptop. I was gearing more toward UAV before settling for FPV.

[Mark Harris]

You can use a audio line on your video/audio tx to transmit your GPS data...
http://www.rc-cam.com/forum/index.php?showtopic=1691

Last page has information on the commercialisation of the project.

[deh6]

I read somewhere that 900mhz is better for penetrating objects About 10 yrs ago I was into the amateur satellite communication. Even 440 MHz gets blocked by tree leaves, so 900MHz would be worse and 2.4GHz "more worse". When the satellite was in position behind some tall trees by the house the signal for a 440 downlink went to zilch. If the downlink was 2m it still was OK. This was, of course, very weak signal stuff, so flying a model close-in one might not lose the signal when the model goes behind a tree, but near the max range it is strictly line-of-sight (or hopefully some fortuitous reflection off some tall building).