This thread is privately moderated by IBCrazy, who may elect to delete unwanted replies.
 Jan 17, 2013, 10:53 AM Playing with AutoCAD! United States, ME Joined Oct 2008 2,656 Posts This is an interesting conversation. If the power of the TX is known, along with the sensitivity of the RX, is it possible to calculate the rough range (assuming there is no outside noise, ect.)? I'd like to compare the Berg 7P (sensitivity 1.2uV) and the Corona synthesized RX (sensitivity 2uV). Maybe it's only practical to compare the range relative to one another (i.e. Corona will get approximately twice the range of the Berg).
Jan 17, 2013, 11:12 AM
Rocket Programmer
United States, AZ, Mesa
Joined Jul 2007
25,946 Posts
Quote:
 Originally Posted by IBCrazy ^You'd think so, but in reality the RX is far more important. Remember that in order to double your range you need 4X more power. Generally our radio systems are confined to a very small range of power outputs and therefore the difference in power has little effect on the ultimate range. Just an example of what a good RX can do: I once made a 4000 foot flight on 125uW (yes 0.000125W) transmit power. Video was great the whole way. I even ducked behind a row of trees (video wasn't so great when I did that). -Alex
Ah yes... The darn inverse square law...
Jan 17, 2013, 01:19 PM
Engineer for Christ
Amherst, VA
Joined Jun 2006
11,092 Posts
Quote:
 Originally Posted by PiperCub49 This is an interesting conversation. If the power of the TX is known, along with the sensitivity of the RX, is it possible to calculate the rough range (assuming there is no outside noise, ect.)? I'd like to compare the Berg 7P (sensitivity 1.2uV) and the Corona synthesized RX (sensitivity 2uV). Maybe it's only practical to compare the range relative to one another (i.e. Corona will get approximately twice the range of the Berg).
There are environmental effects that will attenuate the signal such as humidity, but short and simple and relatively accurate answer is "yes".

-Alex
Jan 17, 2013, 01:21 PM
Engineer for Christ
Amherst, VA
Joined Jun 2006
11,092 Posts
Quote:
 Originally Posted by williamjames Here's a question regarding the LC filter: (a) Does it matter if I wrap my power wire and ground wire around the same toroid or two different ones? Will any yield better filtering? (b) If I put two torroids together and wrap my wires around it as to treat it like it is one torroid, would that in any way help or hinder the the performance of the LC filter? Thanks
a. Two toroids is better as there will be no mutual coupling between them. However, with enough wraps, it is really irrelevant.

b. Technically yes, but why bother?
Jan 17, 2013, 03:37 PM
Wallop!
Bussum, Netherlands
Joined Oct 2009
922 Posts
Quote:
 Originally Posted by PiperCub49 This is an interesting conversation. If the power of the TX is known, along with the sensitivity of the RX, is it possible to calculate the rough range (assuming there is no outside noise, ect.)? I'd like to compare the Berg 7P (sensitivity 1.2uV) and the Corona synthesized RX (sensitivity 2uV). Maybe it's only practical to compare the range relative to one another (i.e. Corona will get approximately twice the range of the Berg).
You could have a look here, it gives you a theoretical upper bound:

http://en.wikipedia.org/wiki/Friis_t...ssion_equation

Martin
Jan 17, 2013, 04:41 PM
United States, ME
Joined Oct 2008
2,656 Posts
Quote:
 Originally Posted by Martin. You could have a look here, it gives you a theoretical upper bound: http://en.wikipedia.org/wiki/Friis_t...ssion_equation See also the online calculators at the bottom. Martin
Thanks. I wish I had the means of finding the quantities of these variables. I might be able to calculate the approximate gain of each antenna, but I can't find the power of my 9C.
Jan 17, 2013, 06:33 PM
Firepower
North Brisbane, Australia
Joined Mar 2010
3,754 Posts
I have several flying wings and used to put the two antennas for my Futaba 9C (FrSky Module) on the bottom of the wings at right angles.

I am FPVing the wings and thought more range could be obtained if I put one antenna vertical and the other one near the winglet at right angles. I buy the longer antennas to get them near the winglet.

The antennas now come with a balun near the end so harder to mount in a tube. Someone has said the balun gives almost twice the range.

The vertical one in the photo is in the pink tube without the balun.

So not sure if the vertical antenna makes any difference but I think it would?

# Images

 Jan 18, 2013, 04:27 AM Registered User United States, FL, Miami Joined Jun 2011 767 Posts Hey guys, which push rod and clevis do you guys recommend from hobbyking? I'd like something sturdy with not too much flex in the push rod.
Jan 18, 2013, 08:26 AM
Engineer for Christ
Amherst, VA
Joined Jun 2006
11,092 Posts
Quote:
 Originally Posted by Firepower I have several flying wings and used to put the two antennas for my Futaba 9C (FrSky Module) on the bottom of the wings at right angles. I am FPVing the wings and thought more range could be obtained if I put one antenna vertical and the other one near the winglet at right angles. I buy the longer antennas to get them near the winglet. The antennas now come with a balun near the end so harder to mount in a tube. Someone has said the balun gives almost twice the range. The vertical one in the photo is in the pink tube without the balun. So not sure if the vertical antenna makes any difference but I think it would?
Yes, keep it vertical.
Jan 18, 2013, 08:28 AM
Engineer for Christ
Amherst, VA
Joined Jun 2006
11,092 Posts
Quote:
 Originally Posted by williamjames Hey guys, which push rod and clevis do you guys recommend from hobbyking? I'd like something sturdy with not too much flex in the push rod.
I buy 2-56 fully threaded rod from Tower Hobbies and the Great Planes or Du-Bro clevises. These are stiff, cheap, and easy to make and adjust.

-Alex
Jan 18, 2013, 08:48 AM
Team PeasantCopter... kind of.
United States, FL, DeLand
Joined Sep 2012
2,245 Posts
Quote:
 Originally Posted by IBCrazy I buy 2-56 fully threaded rod from Tower Hobbies and the Great Planes or Du-Bro clevises. These are stiff, cheap, and easy to make and adjust. -Alex
Ditto on the Du-Bro. I use some of their stuff on a 100cc yak.
Jan 18, 2013, 01:12 PM
Wallop!
Bussum, Netherlands
Joined Oct 2009
922 Posts
Quote:
 Originally Posted by PiperCub49 Thanks. I wish I had the means of finding the quantities of these variables. I might be able to calculate the approximate gain of each antenna, but I can't find the power of my 9C.
The Friis equation gives you a too optimistic number. But comparing your receivers shouldn't be too hard. Let me try it:
Berg 7P: 1.2μV => power@50Ω input = 1.2E-6 * 1.2E-6 / 50 = 28.8fW = -105dBm
Corona: 2μV => power@50Ω input = 2E-6 * 2E-6 / 50 = 80fW = -101dBm

The Berg is 4dBs better so that's about 50% more range.

Martin
Jan 18, 2013, 01:53 PM
Registered User
Joined Jun 2010
2,733 Posts
Well.. i will try a new aproach to my random glitches issue..

Until now i was using "3-switch mode" in IkarusOSD , that mode uses a 3-way switch , the center is the neutral position, you flip it and back to neutral in one way and it will switch between the 4 diferent HUDs, you flip it into the other position and will change destionation for the autopilot between HOME and HOLD (hold position will make the autopilot fly straight.. HOME will obviously return home, there is also the option of follow waypoints, wich i dont use yet). And you let the switch in any one of the 2 outter positions and will enable autopilot.

My problem is that randomly (well, seemed to be located in some points in space) i get my screens switched and autopilot modes switched too without input of my part.. it was at the same time as i could observ light jitter (sometimes heavy jitter) in the PAN servo..

as you can see here:

 FPV Escuela test 4 Glitches y 950m Ikarus OSD (8 min 55 sec)

so it was something that affected all radio chanels, seemed something too quick wich wouldnt affect the controls much, but enought to make an input in the OSD... apart from the anoyment of having your HUD changed there was a small risk of waypoint selection and autopilot activation..

The option i will try is to use the "basic 3-switch mode" , it uses a 3-way switch too but diferently.. you can use only one screen and cant select the autopilot destination (it will allways return home or if you wish follow route IF there is one programmed) the 3 way switch only manages the autopilot, position 1 is manual (you have full control) , pos 2 is STAB mode, (OSD stabilizes the plane and you still have control, like an asisted mode) and pos 3 is full autopilot.

The advantage here is that the switch must be in the exact position to work.. to have the autopilot it must be constantly in position 3, to be in stab mode it must be in 2.. and so .. so quick glitches will never engage the autopilot... not more than half second anyway, since the radio is broadcasting, if it has link it will obey the radio , save for those glitches, and if it looses link it will go into FAILSAFE mode and enable RTH..

Will see how that works out
Jan 18, 2013, 05:43 PM