2.4 or 5.8?

To discuss all things relating to flying models via remote video

Re: 2.4 or 5.8?

Postby RCModelReviews » Wed Feb 02, 2011 7:39 pm

Your idea of a "hi gain antenna" and mine are a little different :-)

At 5.8GHz, a 24dBi gain antenna will have quite a narrow radiation pattern (just a few degrees).

Yes, it is possible to use the video system to deliver telemetry but there is little headroom to cope with "uh-oh" moments and besides, there are now plenty of RC systems that offer telemetry -- which can make it simpler and cheaper than using the video system as your telemetry downlink.

As we've seen with the huge variety of RC and FPV systems, there are many ways to skin a cat -- it's just a matter of choosing the way that gives you the required levels of performance, functionality and comfort.
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Re: 2.4 or 5.8?

Postby Kamu » Thu Feb 03, 2011 12:46 pm

Why wouldn't you send the vital information on a longer range frequency? Trusting it to the video tx is a bit risky.
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Re: 2.4 or 5.8?

Postby Allan Warner » Thu Feb 03, 2011 6:19 pm

Further to my other post re the use of the VTx for use in aerial tracking. From my reading of many posts on various forums this seems to be the way its done. But, I admit, this is generally with the lower frequency video links(better range than 5.8gHz). Your system, Bruce, is already returning the required info via the AP117 OSD although I'm not aware of any dedicated P&P unit to drive the antena tilt and track unit at the ground station, I could well be wrong. Plus, if you do loose video you can activate the RTH/RTL function on the FY21AP unit(the plane then becomes an autonomous UAV) until video is restored. From what I've read the other useful info that can be feed down the video link is the RC Rx RSSI indicating the state of the RC link. With your current setup, looking at the failure modes: 1/ You loose video. Action, activate RTH/RTL from RC Tx until video is restored. 2/ You loose RC link. RC Rx failsafe setting activates RTH/RTL and you can watch the in flight movie until RC link is restored. Granted that your range will always be limited by the range of your video link but thats the name of the game. FPV - flying the plane as if you are in it by using a video link.
If you use the RC telemetry link for tracking are you going to build an interface unit to go between the FY21AP/AP117 units and the 2.4gHz RC reciever or use another GPS unit. At the other end of the RC link(RC Tx) how are you going to get the required telemetry info to the ground station tracking unit, a lead/RF link. A duplicate RC Tx modul is not an option as it would have a different GUID (unless you use FrSky-joke). To me it seems a duplication/over complication and a divergance from the KISS principle. IMO the facility is already available via existing units and the main con is negated by the RTH/RTL of the FY21AP/AP117. I'm just seeking the rational for using telemetry when all the bases seem to covered already.
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Re: 2.4 or 5.8?

Postby Coyote » Thu Feb 03, 2011 7:14 pm

RCModelReviews wrote:Your idea of a "hi gain antenna" and mine are a little different :-)

At 5.8GHz, a 24dBi gain antenna will have quite a narrow radiation pattern (just a few degrees).


Yes indeed, i dont use 5.8ghz, never will. Its so limiting with narrow radiation patterns, multipath problems, over twice the power to get as far as 2.4 and over expensive equipment. For me theres much better solutions. 2.4ghz has the upper hand by far. All the long distance records have been done using 2.4ghz. All the manufactorers have developed the technology more being the main stream wifi band. Its much better catered for and practical.

Yes, it is possible to use the video system to deliver telemetry but there is little headroom to cope with "uh-oh" moments and besides, there are now plenty of RC systems that offer telemetry -- which can make it simpler and cheaper than using the video system as your telemetry downlink.


True, but if your looking at covering the distances we are to find the need for telemetry then an OSD would always be used. The telemetry comes as part of the OSD and is transmitter by the video transmitter already on board so cost really doesnt go up, its just a case of using what you already have. I use a UHF system for RC control thats about as impressive as it gets, but ive completely lost bind on a few occasions even on that. What i was left with was video but no control. So its 6 and two 3`s both systems could fail at some point and you loose the data link.

As we've seen with the huge variety of RC and FPV systems, there are many ways to skin a cat -- it's just a matter of choosing the way that gives you the required levels of performance, functionality and comfort.


Agreed, theres plenty of wrong systems and bad choices, but plenty of good ones that vary in all ways and if used correctly give unparallelled performance
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Re: 2.4 or 5.8?

Postby Sampey » Sat Jun 18, 2011 1:20 pm

Hi Bruce i'm new here, i'd like to say thanks first off, that debacle some years back with the DIY cruise missile, was a huge inspiration to me as a designer and hobbyist, and i've been following your work online since.
Currently i'm working on a more simple non-autonomous, no payload, FPV plane concept, with around 1.5km range on the telemetry, and the same for R/C (2.4Ghz), so the system you mentioned here:
RCModelReviews wrote:Right now I'm using a 200mW 5.8GHz system that I've tested out to over 1KM (1100 yards)and it looks as if I'll probably get to about 1.5Kms (nearly a mile) before the signal degrades too much.

Sounds perfect for my application (its just for fun hence the low range), could you post some information on where you got it, for how much etc, and if theres a supplier here in NZ?
I've looked at a few types online, but with little understanding of Mw ratings and effects on range its been hard, so the info here was most helpful.
There was a 500Mw 5.8Ghz system i looked at, is there a simple bit of math to figure out the likely range from that?
I noted your points on receiver antennae, but the antenna/signal tracking required makes this too complex for my liking, ideally i'd like a video range of about 2km line of sight, so that my video range is greater than the control range, and i thought if your system does 1-1.5km at 200Mw then a 500Mw might just make it to 2 Km......?
That FY21AP system looks really cool despite the price, my plane uses a parachute recovery system, which also doubles as a failsafe (it deploys automaticly as part of programmed failsafe in the event of control signal loss).
To keep the system simple as far as FPV, im not using OSD, instead i'm using the eagle tree seagull system to display info on a seperate screen.
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Re: 2.4 or 5.8?

Postby pwy » Sun Jun 19, 2011 10:00 am

Sampey wrote:Hi Bruce i'm new here, i'd like to say thanks first off, that debacle some years back with the DIY cruise missile, was a huge inspiration to me as a designer and hobbyist, and i've been following your work online since.
Currently i'm working on a more simple non-autonomous, no payload, FPV plane concept, with around 1.5km range on the telemetry, and the same for R/C (2.4Ghz), so the system you mentioned here:
RCModelReviews wrote:Right now I'm using a 200mW 5.8GHz system that I've tested out to over 1KM (1100 yards)and it looks as if I'll probably get to about 1.5Kms (nearly a mile) before the signal degrades too much.

Sounds perfect for my application (its just for fun hence the low range), could you post some information on where you got it, for how much etc, and if theres a supplier here in NZ?
I've looked at a few types online, but with little understanding of Mw ratings and effects on range its been hard, so the info here was most helpful.
There was a 500Mw 5.8Ghz system i looked at, is there a simple bit of math to figure out the likely range from that?
I noted your points on receiver antennae, but the antenna/signal tracking required makes this too complex for my liking, ideally i'd like a video range of about 2km line of sight, so that my video range is greater than the control range, and i thought if your system does 1-1.5km at 200Mw then a 500Mw might just make it to 2 Km......?
That FY21AP system looks really cool despite the price, my plane uses a parachute recovery system, which also doubles as a failsafe (it deploys automaticly as part of programmed failsafe in the event of control signal loss).
To keep the system simple as far as FPV, im not using OSD, instead i'm using the eagle tree seagull system to display info on a seperate screen.


I'm not Bruce but maybe I can give you some information anyway :)

Range is closely related to antenna. There are many people flying >5km on 200mw 5.8Ghz and it's possible to stretch that to over 10km. So 2km can easily be done on 200mw. If you don't want to mess around with antenna trackers you can simply get or make some of the fancy circular polarised antennas. With the BlueBeam set here http://videoaerialsystems.com/products/blubeam-antenna-systems/ you can reach 2km. If you don't want to buy anything you can find the instructions on how to make them in the FPV forum on RcGroups.
I have flown out more than 1.5km with similar antennas and 200mw and only had to turn back because I ran out of battery power.
That's the set to buy http://www.bevrc.com/bev-58g-200mw-pulg-and-play-system-specially-designed-for-fpv-p-18.html. The same place sells the 500mw version but be aware that the 500mw version is just the same 200mw component but overdriven and fitted with a fan for cooling!
Standard antennas will get you no more than 500m (a bit more if you follow Bruce's tips) so most important advice is to ditch the standard antenna and get something better. Happy flying.
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Re: 2.4 or 5.8?

Postby Sampey » Mon Jun 20, 2011 11:30 am

Cheers pwy that was most useful, the second link was down for maintenance, i'll check later but the first looks most intresting, never seen antenna like that, arent they nifty!
Can they be mounted inside the airframe (balsa, carbon fibre rod, plastic, the usual materials) ? or do they need to go in some sort of housing on the outside?
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Re: 2.4 or 5.8?

Postby pwy » Mon Jun 20, 2011 12:04 pm

Yep, bevrc is down. Mr HobbyKing sells them now as well http://www.hobbyking.com/hobbyking/stor ... duct=15295

You can mount the antenna inside but keep them away from carbon. Also motor and LiPo will block the signal if the antenna is too close and you fly in a way that the motor/LiPo sits between the tx/rx. They work best on the underside of the plane or high up on the tail with free sight down to your receiver. These antennas are tiny (5.8Ghz version is about 2.5cm diameter) and weight almost nothing so they are easy to fit anywhere.

Here the build instructions for the Cloverleaf which goes on your transmitter http://www.rcgroups.com/forums/showthread.php?t=1388264
and the Skew-Planar Wheel for your receiver http://www.rcgroups.com/forums/showthread.php?t=1352583

Simple construction but very fiddly work and measurements are important. I did build my own and it took about 2.5h for my first one ;)
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