Interesting  discussion  going on in RCG  relating to  FPV .

The  range  achieved with Corona  and conventional receivers is interesting , so I thought I will link it here for benefit of all :

http://www.rcgroups.com/forums/showthread.php?t=1214302#post14668409

I was told the same thing by Singa Hobbies  when I asked their frank opinion  3 kms line of sight without  obstruction  ie gain altitude  so that the aircraft is far above  obstructions  and Tx antenna is pointed towards Rx antenna   

Sai

About a year before Sai and me tested the corona receiver's range (on ground). I was pretty much amazed by the range acheived. To be honest, we could not make the receiver to glitch even at ~1000 meters range. In fact, I returned back as it was way too far for a receiver range check. Impressive!

-Ismail

Does it support a "reduced power" range test mode? And you got 1000meters with or without such reduction ?

Normally this question does not make sense, but with Corona receivers having said to have ranges up to 5km , it may not be a stupid question !

This is the "receiver" and I don't think there is a reduced power mode available. However, it is worth mentioning that the test was done using a standard futaba transmitter with its antenna pulled in. Note that we could not find the maximum range. The receiver kept on working without a glitch and we gave up. Truely, incredible receiver perfomance!

Yep, that is what I meant to ask, with the antenna pulled in the case of FM.  Too much 2.4Ghz in my head

In any case, your response removes the ambiguity; and it does confirm that these provide great range.

Ismail ,
that time I knew it was good  but I never imagined  the range these guys are achieving  .
Mind you this range is  got a catch " CLEAR LINE OF SIGHT ".

I went 1.28 km on the easy glider and not a glitch 

One may be stupid question " why is  range better at higher altitude "  eg when my Easy glider pro went up to 400 m I could not see the plane but  the Video transmission and Image  quality  improved  drastically  not a line on the screen  but a 50 m there was some disturbance.

sai

Sai,

The disturbance is caused due to ground effect. There would be some reflection and absorbtion of the RF energy by the earth and this would result in loss/distortion of the received signals.

When you are at a higher altitude there is more chance of a direct wave from the transmitter reaching the receiver but at lower altitude there would be more reflected waves reaching the receiver. Further, the direct wave would be also degraded. These reflections are NOT easy to measure or reproduce.  That is why the range is quoted in line of sight.

For a technical explainiation:
http://en.wikipedia.org/wiki/Antenna_%28radio%29#Effect_of_ground

Now, you are learning radio communications the practical way!

-Ismail

Hey Sai, I just found something 'Very long range' 2.4G system (100KM!!)

http://www.rcgroups.com/forums/showthread.php?t=905915&highlight=futaba+receiver+antenna+modification

http://www.webx.dk/rc/uhf-link3/uhf-link3.htm

http://www.webx.dk/rc/uhf-link3/pa7w.htm

Hope it helps!

Looking fwd for your plane takeoff form Chennai and land in Bangalore

Hi Ujjwal ,
Thanks I  am most likely going for this one :
http://www.terranova.net/~winger/RCVideoStore/DragonLink/DragonLink.htm

Thomas's  system is also good .

Thanks again

Sai

Hi guys I'm new in the forum and wanted to know how much range would i get with Tx-JR XF631 and Rx-R700 at 35mhz
I heard you could 1.5 km on standard 35mhz system, and is this frequency legal in india (I plan to build a fpv plane)

Questions like is this frequency legal are easily solved in searches !

http://www.rcindia.org/search2?search=legal+frequency

Why are people not searching before asking !

oh sorry didn't search it, will do for in future
thanks for the link by the way