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Old Jan 02, 2010, 12:08 AM
Technician Steve
Stylish187's Avatar
Rochester
Joined Jan 2010
98 Posts
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FPV RC Car Driving:

Hi All.

I wanted to start a thread relating specifically to First Person View RC car driving as I think FPV flying is hogging to much of the scene, he he, not to take anything away from the equally brilliant airborne sport.

I have recently finished my first FPV build, a nitro powered Schumacher Havoc.



I have built a pan and tilt camera mount using a spare Roll Cage from the havoc.
The Pan and Tilt camera head (MSR-H01-PTH) is from (Micromagic Systems Robotics).

The camera i've used is actually a revering camera, but good quality, and importantly for me, water proof. CMOS i think??

Im have also somehow managed to accumulate three AV transmitters and receivers.
One is a 2.4Ghz with a 200mw transmitter. (cheap)
One is a 1.2Ghz with a 800mw transmitter. (cheap)
The other I extracted from an RC spy car with a small LCD screen in the controller, you've undoubtedly seen these. (presumably worked well for its original purpose)
I believe this one is also 1.2Ghz. Also the transmitter is of a much smaller size:



Unfortunately no matter what combination of transmitter or receiver I use, I am getting a very broken signal.
Although the picture is of a very good quality, the signal is intermittently lost whenever the transmitter is moved, i.e. when on the car, or when more then 20 feet away.

STANDARD HAVOC:



MORE PICS:
Schumacher Havoc FPV MK1:





I have tried all manor of batteries and voltages, including 6v 9v and 12v.
(lead acid)
I have tried to remove all potential interference I can think of, including taking the car to a remote location, and switching off all other radio gear, controllers etc.

I haven't tried doing much with regards to modification of the antennas however I didn't think that would be necessary as the small distances and speeds I an experimenting with?

Any ideas where i'm going wrong?

I thought I would ask as I would have thought that even the cheap equipment I am using would have given me better results than I am currently getting, leading me to believe that the error is probably on my part.

I would really appreciate any help or advice you can offer.


UPDATE;
I have some better equipment on order from:
http://www.firstpersonview.co.uk/
Will Post soon


Many thanks

Steve, UK
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Old Jan 02, 2010, 08:27 AM
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Elmhurst, NY (Queens in NYC)
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Maybe you can hook up with an FPV flyer in the UK who might be able to help you check your gear. Awfully hard to diagnose a problem when everything looks good in the pictures.

Pete
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Old Jan 02, 2010, 08:35 AM
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I have found that if the VTX antenna is to low to the ground it's range is drastically reduced, try getting the antenna as high as possible.
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Old Jan 02, 2010, 10:10 AM
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FIRST OFF, Congrats on your nice rig.
SECONDLY, DITCH the nitro, and go electric for fpv, seriously


I cant really diagnose your exact problem, but in general, if you want decent video, and decent video range, you may need to consider going to 1.2g ~ 1.3g for Video. ( A great unit from HK is only about $40usd for Vtx and Vrx, and out of the box, it will give you fantastic results.

rule of thumb, from my experience playing with different setups in cars/trucks.

The Video Transmitter antenna, needs to be the HIGHEST thing on your truck, and pointing straight up.

With 2.4g video, on ground based vehicle, you will get a lot of interfence and video breakup, and you will not be able to drive your truck behind anything either. thats why i reccomend you go to 1.3g for video if you can.

on 1.3g video.......
100mw is fine for carparks, and you can use a DX7 or similar for RC.
400mw is fine for larger parks and ovals, and if carefull, can still use a DX7 for RC as long as you maintain los.
800mw is great for long range, this will give you range greater than most RC links are capable of.

If you want beter long range RC, you will need to go to 35Mhz !
(you're in the UK, so im taking a guess that the UK is 35mhz for RC ?)



I have some FPV driving setups in my RCGroups blog, or click my username, its all there.
You will see ive gone further than anyone imagined possible, and thats using my simple setup.

I wont post my videos in your thread, i think you should have the honor of posting your own video in your thread, first.

good luck, i can tell you its a blast, way more fun than i ever imagined.

BEST BIT IS...........since getting into fpv driving, I'm not as obsessed with the wind and weather anymore !

cheers







.
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Old Jan 02, 2010, 11:19 AM
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Elmhurst, NY (Queens in NYC)
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Quote:
Originally Posted by Wobby View Post
FIRST OFF,
[snip]
BEST BIT IS...........since getting into fpv driving, I'm not as obsessed with the wind and weather anymore !

cheers
.
I'm sure if it where me my main concern with the weather would be waiting to see how it goes on snow and ice!

When I learned to drive finding an empty parking lot on a snowy day was a fantastic treat, and if I was the first one at work on a snowy day the second person would usually find the most peculiar imaginable tire tracks all over the parking lot.

Up in Vermont racing cars on frozen lakes is a winter sport. A little too far for a weekend drive for me, but I would love to go up and see that at least once.

Pete
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Old Jan 02, 2010, 03:31 PM
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there already is a fpv ground thread

you can find it here:
http://www.rcgroups.com/forums/showthread.php?t=788665

Its over two years old now.
lots of fun stuff!
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Old Jan 03, 2010, 05:32 AM
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Hi Steve,

I am Simon Dale from FirstPrsonView.co.uk (and Chairman of the British First Person View Model Flying Association...now I sound like a complete knob!!)

I'm very interested in your project and I'm happy to help any way I can. In the UK, in addition to the 10mW 2.4GHz and 25mW 5.8GHz which are allowed from the air, there is a single frequency that is allowed for licence free transmission of video from the ground - and up to 500mW too.

This is 1394MHz. The problem with 1394MHz is that it's peculiar to the UK - unlike most of the other radio rules which are Europe-wide and often very similar to the US. What this means is that there isn't much equipment available and what there is tends to be big and heavy (by our standards) and very expensive (it seems mostly to be aimed at film crews).

However we have recently manufactured some small, light, relatively cheap 1394MHz gear for the purpose. We're still testing it now but it may offer a good solution for you.

You should have my email address (if not just reply to your order confirmation emails) if you want to discuss further (I'm not always on this forum).

All the best

Simon
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Old Jan 03, 2010, 02:55 PM
Technician Steve
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Rochester
Joined Jan 2010
98 Posts
Rubbish FPV Nitro Havoc

Hi all.
Thanks for all the replies, very helpful.

And Simon, it looks like we might have to do business....

Here's an update.
All new equipment has arrived, ive built a new mounting plate and placed tx arial as high as possible. Protected the tx with a JD tobacco tin. Poked the arial through the top??

Im new bits i'm using:
CAMCORDER DOWNLINK (2.4GHZ TX & PSU WITH RCA INPUT & RECEIVER)
from:
http://www.firstpersonview.co.uk/tra...input-receiver

plus a 8DBI PANEL ANTENNA for the new receiver.
Im powering the Cam and TX from 1, or 2, 9volt disposable batteries??!!
Have I gone seriously astray with my choice of battery?

Everything else is the same as before.

Here's some pics:







Heres the new receiver with patch antenna, held together by my little metal bracket made from fencing reinforcements.



Here you can see the transmitter with psu from FirstPersonView:


The Whole Shebang:


---------

You know what i'm gonna say now....
Unfortunately i'm still getting the same, bad signal.
Most of the time no signal at all.

I took the Car out this morning, and made two quite poor videos on the iphone but you will see the problem im having and see the car in action!:

Vid One
FPV Havoc (1 min 5 sec)


Vid Two
FPV havoc (1 min 42 sec)



Basically I know that I am going to have to move over to a 1.3GHz system to get the most out of FPV Driving, so I will plan to do this in the near future. And yes ill go for battery power as well.
But in the mean time I would like to find out why i am getting such poor results from what should be a good quality system. Even if it is designed for ground to air.

Thanks for reading.

Steve, UK
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Old Jan 03, 2010, 04:01 PM
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Montreal,Canada
Joined Feb 2002
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The main problem is you do not have enough tx power output, you need a "real" 500mw tx (1.2 or 1.3 ghz, not 2.4ghz). Also your car have a lot of metalic part, this is the worst scenario for fpv setup. I would install the tx away from meatllic part on your car.

You have tried 800mw tx you said previously, some cheap chineese product said it 800mw output, but in fact it's the electrical consumption at the input...

But even with a high quality, high output power tx, you will still have break in the video transmission. r/c car is harder than r/c plane, you have less space and your car is very close to ground.
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Old Jan 03, 2010, 05:26 PM
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I'd steer away (no pun intended) from the cheapy low power video transmitters (with the 9V battery setup) and actually splash out on a PROPER unit that you can purchase off a handful of FPV specialists - dpcav.com or rangevideo.com being highly recommended. These Video Tx/Rx's will be powered by a LiPo battery instead, as used on the planes.

Also dont see any real advantage in using a Patch Antenna on your Video Receiver? You should get decent results with omni-directional Antennas (ie: 3db rubber duck on the car) and a standard omni-directional on your Receiver, which could still potentially see a couple of KM range!

Its not like you will be driving the R/C Car miles away (as you could fly a Plane), so you will probably get better results with an omni setup. Also, with the nature of the cars, whizzing all over the place , you can drive it in any direction around you, while maintaining decent video reception (and not having to worry about aiming a patch antenna!).

You will probably disregard these points, but from reading your project, which is great by the way , I just think you will get a more solid video feed and enjoyment, with the setup I describe.

All the best!
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Old Jan 04, 2010, 12:51 AM
Technician Steve
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Rochester
Joined Jan 2010
98 Posts
Cheers again all,

Jetstreaming, your comments match your fellow experts, so it all gone "on-board"
(pun intended), so give me a few weeks to start from scratch, a third time, and hopefully ill be able to show you mark three.

I imagine it will look something like this:


Ill let you you know what im planning on the way so maybe i can avoid another noob blunder.

Some other comments suggested the metal clad look of my Havoc is also pretty much the exact opposite of ideal for its purpose but i quite like the industrial look so until I can afford an appropriate electric truck it'll have to do..

Also another question you might be able to answer is..
The camera im using on my car is a reversing camera and the image is automatically mirrored, my 7inch monitor has a mirror function so not a problem..
However if i were to purchase some video goggles would I have this option or would a new camera be required?
Yet another example of me jumping in at the deep end..

P.S. is anybody looking to buy a 2.4GHz wireless AV transmitter + receiver, never worked and only dropped once....

Cheers all.

Steve, UK
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Old Jan 04, 2010, 06:09 AM
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Quote:
Originally Posted by Stylish187 View Post
Cheers again all,

Jetstreaming, your comments match your fellow experts, so it all gone "on-board"
(pun intended), so give me a few weeks to start from scratch, a third time, and hopefully ill be able to show you mark three.

Steve, UK
Your welcome, by the way, I love your Nitro Car !!
I was seriously looking into getting one like that not so long ago...

However, I used the budget on my existing FPV Plane, enhancing it with more components, to hopefully give me a more reliable setup!

Defo keep us updated, more pics and vids will be great, as and when.
With a more powerful Video Tx/Rx combo, you should be very pleased with the results.

Another point, attempt to keep your Video electronics on the car as far away as possible from the radio gear, to reduce interference, helping maintain decent range.

Also it appears when your Screen detects a degraded video signal, it switches to a Blue screen!
You might be interested to experiment with different displays, as it might be better to see static (and not go Blue), at least you get a more consistent picture that way, and dont lose all video, when reception is lost temporarily - its actually a common issue, quite simply rectified.

Great FPV platform , all the best.
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Old Jan 04, 2010, 06:21 AM
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With the weight of the battery and VTX not being much of a problem on an RC car, wouldn't going with a 2 watt plus VTX be worth a try? I wonder if it would be worth it to work out an antenna panning system that could keep a patch antenna on the car pointed at the receiver? Agian with weight not being an issue there are a lot more options.
I am going to give this a go, the weather in NY has been horrible..
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Old Jan 04, 2010, 07:06 AM
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Charles Town, WV
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Wobby has driven his car further then anyone. I would closely examine his setup.
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Old Jan 04, 2010, 08:25 PM
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United States, IL, Champaign
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Hey Wobby, great advice! do you happen to have any links to those quality low cost 1.3 gHz units from HK?

Also, 1.3gHz over 900mHz? I thought I read somewhere 900 mHz was a good option as well on the ground.
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