FrSky Taranis - user chat

[Peter Christy]

Bear in mind that higher gain is bought at the expense of the antenna being more directional. Antennae are passive devices, and cannot increase the overall signal level. What they can do is beam it more in one direction at the expense of others, giving an apparent increase in signal, but only in that specific direction.

Basically, firing a 5dBi antenna will increase the size of the dead-spot off the tip.

[Pedant mode /on] It will also put the Tx over the legal limit for effective radiated power. All the current transmitters have an output of 60 mW, which when combined with a 2dBi antenna gives 100mW erp. Using a 5dBi antenna will increase this to 200mW in a ring around the antenna. [Pedant mode /off]

Actually, given the much improved efficiency of both Tx and Rx aerials over 35 MHz (also limited to 100mW erp, and where range was never an issue) the standard antenna should give more than adequate range. That is, unless you intend flying it well beyond visual range........!

--

Pete

[Daithi O Buitigh]

Not quite Pete - a co-linear (multi-segment) aerial will give an increase in gain but still be omnidirectional (I've one stuck on my chimney for 2 metre and 70 cm work and, trust me, it's completely non-directional but has 5.2dBi gain at 2 metres and over 7 dBi at 70 cm)

You're thinking of a Yagi beam which is directional

[Brian Lambert]

"a co-linear (multi-segment) aerial will give an increase in gain but still be omnidirectional"

oooh magic, please explain where this extra power comes from, could be useful for a perpetual motion device I am looking into.

Regards Brian

[Daithi O Buitigh]

Before anyone else makes any wise-crack remarks based on zero knowledge, any aerial has an active element. Double the number of active elements and you have 3 dB gain - that's how a co-linear works - it has multiple vertical elements and each element increases gain by 3 dB (allowing for minor losses).

Google 'co-linear' (or the US spelling of 'collinear' and you'll see, among other things, this "A collinear array is usually mounted vertically, in order to increase overall gain and directivity in the horizontal direction. Theoretically, when stacking idealised lossless dipole antennas in such a fashion, doubling their number will, with proper phasing, produce double the gain, with an increase of 3.01 dB. In practice, the gain realised will be below this due to losses.". If it's mounted vertically, there is no directtivity

[Martin Whybrow]

Daithi, you're ignoring the fact that phased arrays are directive and become more so as elements are added. Dipoles, incidentally, are directive and have a gain of ~2dBi.

[Daithi O Buitigh]

Yes - a dipole is directive but a co-linear isn't when it's mounted vertically. I can hit the Dublin repeater (south of me), Isle of Man (east), Coleraine (north) and West Tyrone (west) with the one I have on my chimney pot. If it was directional, I would be working either north/south or east/west - not all compass points. The horizontal component is directional but not the vertical.

btw - elements are added to a Yagi - that has a driven element and parasitic elements to increase gain. In a co-linear all elements are driven

[Brian Lambert]

OK Daithi I will take my zero knowlege somewhere else, but before I go, and i do realise that what you said is almost strictly true, the extra gain is obtained by reducing the signal radiated in all but the horizontal direction. Therfore the signal stength above the horizon will be lower, if the antena is vertical. As most models are flown above the horizon I am not sure the extra gain is worthwhile.

Bye Bye, Brian

[Daithi O Buitigh]

Basically what happens is you add a second (or even a third or a fourth) active element with each giving a 3 dB increase in ERP (Effective Radiated Power) one extra element = double ERP, two doubles again and so on down the line). The aerial is directional in the respect that at its end there is a null point (think of the radiation pattern as a big doughnut with a hole in the middle). That's why it's turned sideways from the casewith the breadside aimed at the model. The trick is either to have two aerials in the model at 90 degrees to each other or, if it's a single aerial, then it has to be in the same plane as the transmitter one (if one is vertical, then the other must be as well)

Oh and for all the FPV guys out there, although the main transmitter ERP is 100 mW, there is a restriction of 25 mW ERP for 5.8 GHz transmitters (5.8 GHz is also used in some medical systems and excessive power output and/or interference on that band is a very bad idea)

[Former Member]

[This posting has been removed]

[Martin McIntosh]

I echo Andrew. This lot is just filling up my new mail. What is wrong with the antenna that came with the tranny anyway?

[Peter Christy]

Posted by Daithi O Buitigh on 31/10/2014 14:45:06:

The aerial is directional in the respect that at its end there is a null point (think of the radiation pattern as a big doughnut with a hole in the middle).

Which was precisely my point - the more signal you push out the sides, the bigger the null point at the top, and the flatter the doughnut!

Antennae are passive and cannot create more power than is put into them. They can, however, re-direct it!

[MartynColes]

How about a Taranis question?
I just bought a Taranis Plus. I tried to be prepared and downloaded the Taranis Quick Start Guide before my set arrived. I have discovered that there are quite a few differences in the menu pages between the two sets. Some screens are similar, but some are new. Also preset names for things are sometimes very different. I thought the best option is to download the equivalent QSG for the "Plus" Does anyone know where it can be found? I've searched everywhere, but it eludes me!

[Peter Christy]

Martyn,

It may just be a case of different software versions rather than the "Plus" being different. The 2.xx series was released a while back, but I'm not sure if the manufacturers are shipping this or still shipping version 1.xx - or maybe the QSG you have is for version 1.xx and the tranny is 2.xx

Do you know what version of software you have?

I have seen a "differences between" guide somewhere, but I'll have to dig around to find where I got it from....

--

Pete

[MartynColes]

Hi Pete,
I've got v2.0.12

[MartynColes]

QSG is dated 3rdDec 2013

[Peter Christy]

The QSG sounds like it is for version 1.xx. There were quite a few changes in version 2.xx. Does this help at all?

http://www.open-tx.org/2014/06/13/difference-2470-20/

[Chris Bott - Moderator]

Martyn have a look at this series of videos. They are new and cover V2.0 and beyond. More to be added too, apparently.

Edited By Chris Bott - Moderator on 01/11/2014 12:39:42

[Phil Green]

...

Edited By Phil Green on 31/10/2014 20:44:37

[Daithi O Buitigh]

Oh I do like it - an amateur who spent his entire working life in electronics

My RADIO LICENSE is 'amateur' - the rest of my paper trail is professional

I have to admit 'QSG' for he guide stumped me for a bit - I wondered what the Quality Street Gang had to do with it

Edited By Daithi O Buitigh on 31/10/2014 20:40:11

[Chris Jones 7]

Posted by Martin McIntosh on 31/10/2014 15:22:23:

I echo Andrew. This lot is just filling up my new mail. What is wrong with the antenna that came with the tranny anyway?

I broke it!

[Phil Green]

Posted by Chris Jones 7 on 30/10/2014 20:00:10:

Guys does anyone know if 2.4ghz antennas are all the same?

As well as gain differences there are connector differences.
If you use OrangeRx or Quanum gear alongside other 2.4g equipment like Frsky, Spektrum, etc remember that where almost everone else uses a male RP-SMA on the module and a female RP-SMA on the aerial, OrangeRx and Quanum use a female SMA on the module and a male SMA on the aerial.
Put simply, the OrangeRx or Quaqnum aerial has a pin in the centre, almost everyone else has a socket. This means its very easy to fit for example a Frsky aerial onto an OrangeRx module - it will apparently fit perfectly, it will screw on nicely, will seat nicely and look perfect. BUT there will be no connection between the module and the aerial - both having the centre socket.

Posted by Andrew Ray on 31/10/2014 15:06:54:

Guys, can I respectfully ask that if you want to discuss the technicalities of a 2.4Ghz antenna you create a thread. This is for the Taranis and this discussion has gone off topic. Thanks.

 Posted by Martin McIntosh on 31/10/2014 15:22:23:

I echo Andrew. This lot is just filling up my new mail. What is wrong with the antenna that came with the tranny anyway?

Steady on chaps, the posts that annoyed you numbered maybe half a dozen out of 670 posts. This is a chat thread and I see nothing wrong in discussing alternatives to the standard Taranis aerial.
You can always switch email alerts off Martin

Cheers
Phil

Edited By Phil Green on 01/11/2014 10:00:11

[MartynColes]

Pete and Chris, thanks I'll take a look over the weekend. Cheers Martyn

[MartynColes]

Hi,

Please can someone explain the difference between Thr and IThr, Ail and IAil, etc ? where I is the reverse-video capital I.

I have found that when mixing in a sticky throttle mix to IThr that I lost all effect of the trim button on servo output. But if I changed to simple Thr then the trim button had an effect on the servo again. This wasn't the case for the three other Ail, Rud, Ele which didn't care if it was IAil, IRud, IEle or the simple version and a mix or no mix. Have I found a bug, or is this deliberate?

I'm using v2.0.12 on a Taranis+

Cheers,

Martyn

[Daithi O Buitigh]

From RC Groups

"I believe iThr is the returned value of the throttle input as defined by the MIXES page. Thr is raw stick input INDEPENDENT of the MIXES page.
So how this works- lets say you are in a flight mode in which the MIXES page limits the THR channel a weight of 30 ( range is +30 / -30). iThr will limit the output of that value to somewhere between -30 to 30. If Thr is used, it will return raw stick position (-100 to +100)."

 

"Ithr etc are the outputs of the Inputs screen, after any weights, cutves, etc are applied. They are normally used as inputs in the Mixes screen. Thr is the raw stick movement. Sometimes one needs to create a mix based on the raw input, that's when these come into play."

Edited By Daithi O Buitigh on 05/11/2014 00:39:39

[Chris Bott - Moderator]

That seems to be two completely different answers doesn't it Daithi?

The programming flow in OpenTx runs from the Inputs (think sticks and switches here) first to the Inputs page, which is the usual place to condition these with travel (weight), rates, expo etc. Next it's passed to the Mixes page, here the inputs (which now have weight rates and expo applied) are mixed or connected to each receiver channel we wish them to affect. We can set how much we want them to affect each channel and add switches if we wish, so they only affect said channels when we want them to. etc etc.

Its at the input to the Mixes page that we choose between plain Ail and [I]Ail. So just as Daithi's second para says - [I]Ail will include any expo and rates, curves or whatever you've done in the Inputs page - but Ail will give you the raw stick movement with no rates, switches, curves or expo.