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FrSky V8R4 receiver range?

PostPosted: Mon Aug 15, 2011 2:39 am
by kaptain_zero
Bruce, I see you installed the V8R4 receiver in your AXN according to what I saw in your video on the AXN. I'm just curious what kind of range you are getting out of this little 4 channel receiver.... You, and anyone else of course.

My AXN is arriving tomorrow and I have a spare V8R4 as well as 7 channel and 8 channel FrSky receivers which both have the dual antennas and I'm wondering if I should just use the little 4 channel for now..... Granted, my eyesight isn't what it used to be so I probably won't be flying all THAT far off in the distance.... but I'm kinda curious about the V8R4, which up until now, I've only used in small foamies.

Regards

Christian

Re: FrSky V8R4 receiver range?

PostPosted: Mon Aug 15, 2011 4:06 am
by Sid Sideslip
Hah! I just ordered an axn arf this morning. :D

I ordered an 8 channel V8Fr (HV) for it, as the price and weight difference isn't worth bothering about. What I did notice on the FrSky website though was a larger 5dB antenna. I wonder if they are worth getting, especially for long distance FPV?

Regular 2dB
Image
5dB antenna
Image

Re: FrSky V8R4 receiver range?

PostPosted: Mon Aug 15, 2011 4:21 am
by RCModelReviews
To answer the questions:

The 4-channel receiver gives me "out of sight" range with the AXN and with my DLG too. In fact, on the weekend I was flying the AXN very high and far-away when I lost sight of it for several nerve-wracking seconds until I finally spotted a glint of white.

Never lost control though.

As for the 5dBi antenna -- not worth it.

They are more directional than the 2dBi and that means that although they radiate a slightly more powerful signal perpendicular to the antenna, there's a much bigger null-spot near the end of it. If you inadvertently point the 5dBi antenna at the model (especially when the model is further away) then you *increase* the chances of losing contact.

Using the standard 2dBi antennas, I've flown the FrSky 2.4GHz system out to ranges of 2.5Kms (1.5 miles) with no issues at all and, since even a model as large as the HK EPP FPV plane effectively becomes too small to see properly at about 700m, I think three times that range is more than enough anyway.

Re: FrSky V8R4 receiver range?

PostPosted: Mon Aug 15, 2011 5:07 am
by kaptain_zero
Thanks for the quick comeback on the V8R4 receiver, I suspected as much, but wanted some confirmation.

As a ham, I knew that the high gain antenna had to compromise the radiation pattern in order to get the additional gain, so if you can keep your head clear and not point the tip of the antenna against where your model is supposed to be, you should be fine.... Me, I'll stick with the 2db version.

So, my spare V8R4 receiver is going into my new AXN tomorrow as the tracking number indicates it is in the city tonight.... or course, this assumes that the box it's in, hasn't been mangled on it's way over here.... I trust my mail lady though... she works at the desk next to mine! <grin>

Now.... if my AXN looses contact with my transmitter... I shall hold Bruce accountable and will start walking directly towards NZ from where I am in Canada. When I get there............. wet and all...... ooooh..... Bruce had better watch out! :mrgreen:

Otherwise I had a particularly good day out at the Gimli Model Fest today, great weather and NO standing water, unlike the past couple of years.

Plenty of interesting models and NONE were of the type I'm planning to build this winter... perhaps ONCE, I'll have something nobody else has done better.... <grumble>.

Regards

Christian

Re: FrSky V8R4 receiver range?

PostPosted: Mon Aug 15, 2011 5:30 am
by Sid Sideslip
Thanks for the info Bruce.

Btw, how's the weather atm? I hear you guys have had quite a storm...snowed in are you?

kaptain_zero wrote:
Otherwise I had a particularly good day out at the Gimli Model Fest today, great weather and NO standing water, unlike the past couple of years.


Ooh, would that be the same Gimli where the "Gimli Glider" jetliner landed after running out of fuel?

http://en.wikipedia.org/wiki/Gimli_glider

Whatever, looks like a good festival. :D

Re: FrSky V8R4 receiver range?

PostPosted: Mon Aug 15, 2011 6:00 am
by kaptain_zero
Sid Sideslip wrote:T
kaptain_zero wrote:
Otherwise I had a particularly good day out at the Gimli Model Fest today, great weather and NO standing water, unlike the past couple of years.


Ooh, would that be the same Gimli where the "Gimli Glider" jetliner landed after running out of fuel?

http://en.wikipedia.org/wiki/Gimli_glider

Whatever, looks like a good festival. :D


Indeed... the very same!

The Airforce Cadets were flying their gliders all afternoon as well. We had to put up with the constant drone of the tow aircraft....<sigh>.

The conversion from Imperial gallons to liters is very much like my confusion with electrics.... Let's see now..... I connect + to - and run everything else to ground, right? :mrgreen:


Regards

Kaptain "BZZZST..... ouch..... " Zero

Re: FrSky V8R4 receiver range?

PostPosted: Mon Aug 15, 2011 6:51 am
by RCModelReviews
kaptain_zero wrote:Now.... if my AXN looses contact with my transmitter... I shall hold Bruce accountable and will start walking directly towards NZ from where I am in Canada. When I get there............. wet and all...... ooooh..... Bruce had better watch out! :mrgreen:

Just remember to set your failsafe to cut the throttle (and I normally add a bit of up and a bit of turn) so you'll be sweet :-)

Oh, and don't forget the range check ;-)

Re: FrSky V8R4 receiver range?

PostPosted: Mon Aug 15, 2011 6:52 am
by RCModelReviews
Sid Sideslip wrote:Btw, how's the weather atm? I hear you guys have had quite a storm...snowed in are you?

Yep, woke to a light snowfall this morning and there's probably going to be another tomorrow.

My cold has turned into a horrible permanent headache at the moment so I'm hoping that'll be gone by the time the weather clears.

Re: FrSky V8R4 receiver range?

PostPosted: Fri Aug 19, 2011 12:36 pm
by disco stu
I thought I read somewhere that the antennae is slightly wrong length on a lot of them. If its trimmed to 31mm the range is meant to get increase. I'm yet to go to the trouble of calculating the wavelength of 2.4ghz (can't even remember the speed of light :oops: ), but apparantly.......................

Re: FrSky V8R4 receiver range?

PostPosted: Fri Aug 19, 2011 9:13 pm
by kaptain_zero
The short answer is that 2.4GHz has a wavelength of 0.125m, which is 12.5cm or 125mm. The antenna on these receivers is most likely 1/4 wave or 31.25mm.... but... and there is always a *but*, this length depends on the *actual* frequency being used.... as in, it's not exactly 2.400000000GHz and being spread spectrum, it never uses just one frequency but hops all over. So I would think it's almost impossible to *tune* such a short antenna to be resonant for this purpose.... a 1/4 wave antenna is pretty forgiving, even if you are slightly off on the length, and it receives pretty well from most directions.... a bit of a kink in the middle probably doesn't hurt either! :-)

About the only way I can think of to broaden the band width is to go for a thicker shorter wire.... but again, at this small size, it's not very practical compared to say the 20m band where you can pump up the diameter to gain some bandwidth.

Regards

Christian

PS: Bruce, hope you shake that cold soon.....