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jonesyboi
27th April 2017, 02:17 PM
hi I'm quite new to fpv in general. i will tell you where i am at the moment and also, my choices i want to make. please feel free to comment but id like to note only ground/surface fpv only.

so far.

vehicle: traxxas summit & traxxas xmaxx

radio control: traxxas tqi 2.4ghz also i have a better radio gear once i reach distances/penatration limits on video.

display: fat shark dom v3 googles.

vtx: fat shark 1.3ghz 250mw
antenna: I'm using a standard 1.3 ghz (omni dipole) linear 3dbi

vrx: fat shark 1.3ghz version 3 receiver module
antenna: I'm using a standard ( omni dipole ) linear 3dbi

I also have circular polarised blubeam ultra antenna set. which i found not to be as strong a signal, not much testing done yet. my understanding is linear would be a better way to go due to liners qualities being at one altitude, and that the car is not tilting much, size of the antenna ad less interference at 1.3ghz rf.

estimated range I've found is maybe 200yards though thick bush, at this point my video gets very poor and nearly un-viewable. radio gear is nearly at its limits.

at around 700/900yards los standing on a hill, until the radio gear goes out of range. the los for the video is still very good and i haven't been able to see the full range of testing.

where i plan to ride will have many natural objects maybe even a few structures and walls. i have in mind. upgrading my antennas to increase gain before upgrading the power.

the choice i have came to would be:-

-standard 1.3ghz linear whip for the vtx on the truck.
8dbi optimised patch antenna for the vrx on a tripod.

or

-madmushroom/standard linear whip for vtx on the truck.
pepperbox/cross hair vas antenna for the vrx on a tripod.

thanks for reading through my thread and any advice is more than welcome.

Roboforcer X2000
2nd May 2017, 04:56 PM
I agree that linear would be better, but 2.4 for radio and 1.3 for video doesn't work together well. You need filters and separation but still, won't get that much extra. The rule of thumb is your video frequency has to be higher han radio. With 1.3 video the way to go is 433mhz LRS systems.

jonesyboi
3rd May 2017, 03:41 PM
i also have ezuhf 433mhz and taranais radio gear which I'm currently setting up. kind of hard to set up how i want for the traxxas summit. but ill get there eventually.

anyways I've gone and bought a 6dbi 1.2ghz linear rubber ducky antenna for the vtx.

back to antennas.

for the receiver side of the video, I'm looking at getting the patch antenna. it is optimised 8dbi patch for 1.2ghz and gives a 65degree field of range from rmrc. is this the best option for ground pounder, or should i look at a different choice?

i have a tripod to mount the antenna too.

parajared
3rd May 2017, 05:01 PM
I like the idea of a directional receiver antenna on a ground-pounder. Maybe a magnetometer + an Arduino to keep the direction it's pointing consistent and the pan servo wires routed to a channel on your radio receiver to deviate the angle off what the Arduino is seeing.

In any case most people just use a 433 whip antenna on these vehicles but on airplanes I have known dipoles to outperform monopoles. If you have the room for it go full dipole, if you don't have room go coil-loaded dipole.

76812

Also check out what gimbals can do for your ground-pounder. Ground FPV videos are usually really jarring but I am amazed at how smooth some of these gimbal videos are coming out. Here's one with a 3-axis gimbal.


https://www.youtube.com/watch?v=5CHCHCiSBT0

jonesyboi
6th May 2017, 05:27 PM
ok so I've added ezuhf to my set up. and i have a dipole antenna on the radio transmitter and a sanders antenna on a 8 channel lite mounted to the car, the receiver is mounted quite low. standing on quite flat ground with some bumps etc. longer grass just above the car roof. antenna was tucked under the body for the car. notch filter on tx

i have found that i do indeed get a longer range with 433mhz but its not what i expected. i found maybe an extra 300yards with frsky taranis with immersion rc jr module uhf 433mhz radio. should i be using a better antenna say the diamond aerial? and a longer if they even exist antenna on the truck? I'm sure i heard or thought that these uhf radios would be more than sufficient to go round a field out in the sticks! video was nearly as bad aswell but at around 1100yards i had no radio range..... kind of disappointed.

I'm hoping that with higher antenna id get a lot better range. if so then diamond for transmitter and some type of long whip antenna for rx if they are around? if so please point me in the right direction

thanks very much

RonSII
6th May 2017, 06:30 PM
You will find elevation is key to range, you say the 'antenna was tucked under the body for the car' you mean for the ezuhf?

jonesyboi
7th May 2017, 07:37 AM
Yes the antenna for the ezuhf receiver on the car was underneath the car body, I really think if I find a long antenna for the Rc car that I'll get better range. But I can't find one for the life of me.

a antenna for 433mhz receiver which is as long as possible which is bendable. Ie whip style so if I do roll over I don't damage it. And I can get through bushy areas to a certain exstent without damaging it

Slowpoke in Dublin
7th May 2017, 09:25 AM
I have a coil loaded diapole attached to the rear bumper of my XMax. I use EZUHF with a Diamond antenna on my FlySky pistol grip radio. I can get about 1/3 mile on the low power setting thru my mobile home park.

For video, I'm using a RMRC 2.5 watt vtx with a liner polarized rubber ducky on the XMax, and 2 Yagi antennas in diversity mounted on a 20 foot mast. (1.3ghz)

I've done a lot of experimenting with antennas, and for me, liner polarization works slightly better. At the 1/3 mile mark at the far edge of my mobile home park, I have just enough video to tell where I am, but it's not very good. A quarter of a mile is about the limit for good video. I have a 5.8 repeater on the mast sending the signal to my Fatsharks.

jonesyboi
7th May 2017, 10:08 AM
Ok great well I think range wise that'll be good for me! I'm going to get the diamond and a coil loaded dipole then. I'm thinking to get the rmrc fpv kit, I was looking to get the 800(600mw) true power transmitter from them but maybe I should go up in power? It's going on a traxxas summit as I have tried the maxx and summit and prefer the summit. Thanks for the quick reply I've had this on my mind for awhile now so I'm glad to have heard your results. I've got a tripod for vtx antenna and only using a single antenna. I'm thinking to go for the patch antenna on a tripod. But did think about the yagi. Also have a notch filter on my ez transmitter but found one of the solders have become disconnected. I'll probely resolver it on but wondered if the actually help a lot? Suggestions on vtx power output for 1.3ghz? Bigger the better? I was thinking 800mw but if say the 1.5w would do better I'd go for that

Slowpoke in Dublin
7th May 2017, 10:44 AM
for ground use, the power requirements are steeper. I started with the 800mw vtx, and it would only give me video to the end of my street. I tried the 1.5 watt next, and could get the next street over. Going with the 2.5 watt gave me another 50 yards or so.

Getting the antenna high in the air really helped.

jonesyboi
7th May 2017, 11:52 AM
Agh ok. I haven't bought yet so was thinking 800 would be better than the fat shark 250mw I have at the moment. Do you think
1.5watt rmrc would be best then? I only usually fpv in woods and quarries. The size of the 800 is actually quite small so maybe the 1.5watt would be a good idea. More gain on the antenna would achieve better results than more power?

jonesyboi
7th May 2017, 11:59 AM
Agh ok. I haven't bought yet so was thinking 800 would be better than the fat shark 250mw I have at the moment. Do you think
1.5watt rmrc would be best then? I only usually fpv in woods and quarries. The size of the 800 is actually quite small so maybe the 1.5watt would be a good idea. More gain on the antenna would achieve better results than more power?

jonesyboi
7th May 2017, 08:04 PM
have just been checking out antenna for the uhf receiver and seen the coiled dipole suggested. while i was looking i seen the vas bazooka antenna. i can't find any information on this antenna but would this be a better choice? for ezuhf receiver mounted vertically?

sparkyincali
8th May 2017, 08:57 PM
The stock ezuhf sanders style antenna is not very good for range.For the RX you will be better off with any type of dipole.If you want to fabricate some kind of whip you can get a Dragonlink Dipole with a long cable so you can get it a foot or 2 in the air. You could also use a moxon on the tx which is directional and should double your range ,the beam width is 150 deg so quite wide.I also like the pepperbox for the vrx for the same reason that it is 13dbi and 145 degrees.All this ground pounder talk is making me want to work on my summit.

jonesyboi
9th May 2017, 04:31 AM
Some good information there! I ended up getting Diamond SHR77CA receive antenna for my rx, its 15" long, I'm pretty sure from reading the forum that it'll work and gets me off the floor a lot more than this sanders one does. The problem I have is that the rx won't be very high off the truck i.e it'll be inside for protection and connections. I also have a diamond srh771 tx antenna so both antenna for ez should be good. Hopefully anyways. I need to set my ezuhf transmitter onto uk frequency with the firmware next and once I get antenna should beable to give it a test. If anyone hs already changed firmware will this limit my power considerably ? I'm just glad I can make it legal and still have uhf