SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Aug 15, 2012, 06:20 PM
Registered User
United States, AZ, Tucson
Joined Mar 2008
2,195 Posts
Discussion
I almost lost my DJI F450 FPV rig today from losing the video, just wanted to share.

I have a 500mw 900Mhz system with a inverted Vee from Range Video that I'm having some issues with reception.
It seems that no matter which way I have the open end of the Vee it gives the same results.
I had the opened end facing forward and facing the rear.
when I am about 1000ft away I have clear video then turn around and lose the signal.

Today I wasn't paying attention and didn't mean to go that far again and realized I passed 1,000ft and turned around and got a blue screen in my Vuxiz 920 glasses.
I faced away again and tried to come home backwards but the signal was too week to see. I climbed and still couldn't see.
I've only had a few FPV flights so I'm very inexperienced, I was in a very open area at work though.

I got disorientated and panicked and hit the fail safe. About 20 seconds later the video came back in and I could see that the fail safe was working.
I took off the glasses and just stared in the sky. a few minutes later I saw the quad. I was still shaking but cancelled fail safe at about 15ft and manually landed.
What a nerve racking experience.

I have a GPS tracker and the quad just would have landed or crashed in the desert BUT I was on my lunch break and I use my work cell phone SIM card for the tracker so I had no tracker and on that last flight I wasn't recording from the RX so I couldn't have seen the last recorded coordinates.

I really need to get my signal issue resolved. The RX just has the cheap whip antenna. I'm thinking about getting a patch antenna to see if the range improves.
IBCrazy is sending me his Vee antenna, hopefully I'll get better results from that.

Just wanted to share my first FPV scary experience.
jasper7821 is offline Find More Posts by jasper7821
Reply With Quote
Sign up now
to remove ads between posts
Old Aug 15, 2012, 06:44 PM
Multi rotors=No Paycheck left
SDSURFnGLIDE's Avatar
United States, CA, San Diego
Joined Apr 2011
3,452 Posts
man that sounds like a scary moment for you there!! but hey...here is the positive...thankfully you had the RTH on the Naza and it was successful in a real life situation!!!

im dreading the moment this happens to me....as im sure most everyone in FPV has experienced something like this...my FPV ship doesnt even have a RTH....i havent gotten my Naza back yet from sending it in for warranty work...so im flying a KK V2 which is actually pretty stable... but i prefer the safety of the Naza...
SDSURFnGLIDE is offline Find More Posts by SDSURFnGLIDE
Reply With Quote
Old Aug 15, 2012, 06:50 PM
Registered User
United States, NJ, Trenton
Joined Sep 2006
292 Posts
Set the Naza to "go home and land". This way whenever you lose signal, it will come back automatically; or with a flip of a switch. I had reception problems with the antenna being blocked by the battery. Now it's the highest point of my quad.

joop1987 is offline Find More Posts by joop1987
Reply With Quote
Old Aug 15, 2012, 07:00 PM
Registered User
United States, AZ, Tucson
Joined Mar 2008
2,195 Posts
Quote:
Originally Posted by SDSURFnGLIDE View Post
man that sounds like a scary moment for you there!! but hey...here is the positive...thankfully you had the RTH on the Naza and it was successful in a real life situation!!!

im dreading the moment this happens to me....as im sure most everyone in FPV has experienced something like this...my FPV ship doesnt even have a RTH....i havent gotten my Naza back yet from sending it in for warranty work...so im flying a KK V2 which is actually pretty stable... but i prefer the safety of the Naza...
Thanks, I was also nervous because my battery was getting low and I wanted to fly it home faster than the RTH would take since climbing to 60ft and waiting 10 seconds. But it landed with 3.6v per cell unloaded so it was just barely ok.
I'm really glad I have the GPS now otherwise it just would have been an autoland in the middle of the desert and probably hours and hours of searching for it in the 110 degree temp in dress shoes, slacks, and dress shirt. That would've sucked.
jasper7821 is offline Find More Posts by jasper7821
Reply With Quote
Old Aug 15, 2012, 07:48 PM
Project Tormentor is flying!
United States, WA, White Salmon
Joined Nov 2005
2,066 Posts
You should really look into CP antennas. way WAY better image/reception. Plus, your goggles shouldn't blue screen...I would look into a different set of goggles that are known not to blue screen (Fatsharks, AIO, RVG920s,etc).
philthyy is offline Find More Posts by philthyy
Reply With Quote
Old Aug 16, 2012, 01:18 AM
Registered User
United States, AZ, Tucson
Joined Mar 2008
2,195 Posts
Quote:
Originally Posted by philthyy View Post
You should really look into CP antennas. way WAY better image/reception. Plus, your goggles shouldn't blue screen...I would look into a different set of goggles that are known not to blue screen (Fatsharks, AIO, RVG920s,etc).
Thanks, I was told 900Mhz CP antennas are too huge. I've never seen one in person.

I would like a 2nd pair of glasses for my friends to fly with me.
I need 900Mhz so I may have to get another pair of Vixux's
jasper7821 is offline Find More Posts by jasper7821
Reply With Quote
Old Aug 16, 2012, 02:10 AM
Registered User
joemi's Avatar
United States, WA, Kent
Joined Sep 2001
718 Posts
I know exactly how you feel. I thought I was going to lose my quad. Video cutting out and lost my orientation and didn't have RTH. I got VERY lucky and made it back with barely enough battery. After reviewing my GoPro video, I saw that I was inches from hitting some trees while my video was out!

As soon as my hands stopped shaking enough to type, I ordered a Naza GPS. Got it today and it couldn't wait to try RTH. It worked great and I don't think I will ever fly again without a RTH feature.
joemi is offline Find More Posts by joemi
Reply With Quote
Old Aug 16, 2012, 02:47 AM
Registered User
BushmanLA's Avatar
Joined Dec 2005
1,820 Posts
Yeah 900mz CP are gonna be big, unless there is another style other than the cloverleaf types we commonly see.

Get a better whip for your Rx or a patch and keep it low to the ground. I gave up on 900mhz because I couldn't find CP antennas for it.
BushmanLA is offline Find More Posts by BushmanLA
Reply With Quote
Old Aug 16, 2012, 03:08 AM
fly by night
BCSaltchucker's Avatar
Joined Sep 2011
5,852 Posts
1000ft? why bother with 900 if that is all it is getting. I run 5.8 with CP and it works fine farther than that. But even with a 5000mah battery that I run, I dare not go out much further than 1000ft. Beauty of the Naza quad - it can run in very tight and interesting spaces. I take a plane to go out for miles. A Sim card cell device will not work in precisely the places I need it most, so i have dismissed that idea. Might add the DJI GPS anyways, but haven't needed it yet.

Bluescreen goggles? Chalk it up as a lesson learned and set them aside for passengers only.
BCSaltchucker is offline Find More Posts by BCSaltchucker
Reply With Quote
Old Aug 16, 2012, 06:30 AM
On a holiday?
boopidoo's Avatar
Uppsala, Sweden
Joined Sep 2008
3,638 Posts
It shouldn't matter that much which way you face the antenna so Alex's antenna won't solve your problem. The antenna was probably blocked by something on your aircraft. Make sure that you install it so that isn't blocked either by mounting it high above everything else or maybe better below.

Also if your goggles go to blue/black screen instead or showing static you should definitely not get another pair of the same goggles.
boopidoo is online now Find More Posts by boopidoo
Reply With Quote
Old Aug 26, 2012, 01:28 AM
Registered User
United States, AZ, Tucson
Joined Mar 2008
2,195 Posts
I flew again today at work and used the stock whip antenna and for some reason it worked great today.
I actually flew out 2,600ft ft at about 100ft high. It was really awesome to be able to go that far in the middle of the desert.

I then came home and tried to FPV down the street and I only got about 25ft away and got interference.

In the mail was my LC filter from ReadyMadeRC and I'm totally amazed on how clear my picture is now through the goggles.
That's why I never flew low close to objects, the depth perception looked funny and the picture was not that great anyways.

I'll test at the park tomorrow and with the clear picture I have now flying FPV should be much easier.

I have my TX mounted on the bottom of my F450 and the Vee antenna was just hanging below. Now with the stock whip antenna again, I just hover then pull the whip down and put on the goggles and go.

I use 900Mhz because I already had the equipment from several years ago.
I think I'll try the 8db patch antenna next.

It seems that at work in the desert my system works awesome but at home in the neighborhood is works like crap.

As far as my Vuzix's having a blue screen after a few seconds of lost transmission. I do want another pair so someone else can enjoy the ride with me. I'll look around to see what goggles won't blue screen that I can use on my 900Mhz system.
jasper7821 is offline Find More Posts by jasper7821
Last edited by jasper7821; Aug 26, 2012 at 01:57 AM.
Reply With Quote
Old Aug 26, 2012, 08:58 AM
Registered User
neato4u's Avatar
Malaysia
Joined Feb 2012
336 Posts
Hi Jasper,

I have the same problem as you did, but I am using a 900Mhz 200mw vtx vrx combo bought from Hobbyking. Upon getting the unit, I straight ditched the dipole and used an inverted vee instead to the vtx. The vrx's still using the stock dipole. I thought I was getting good video but the colors were pale and range wise was not that good.

Then I switched over to the stock dipole on both and video were better (good colors) and I was able to go further. Until one day I lost video signal within 500m far and around 100m height probably.. unfortunate that my quad does not have RTH and being an inexperienced FPV pilot, I descended more rather than throttling up.. ended with my quad flip and crashed to the ground (was able to find it after 15 minutes or so).

I initially bought the 900Mhz because it should gives me more range and better penetration. But when I flew my quad between trees along with my friend 5.8Ghz vtx, I get a lot of video interference and black-outs while my 5.8Ghz friend flew without a glitch.

He was using a bluebeam set of antennas though.. while I used the stock dipole. And yes I agree that CL for 900Mhz is too big..

So possibly my next vtx going to be a 5.8Ghz and I probably get a bluebeam set together. I don't know why but I don't trust 900Mhz that much these days. Maybe the freq is too polluted than before? I don't know...
neato4u is offline Find More Posts by neato4u
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Yippee! Just wanted to share an Awesome video! TMAC4123 3D Flying 10 Sep 08, 2012 11:20 PM
Discussion Downsized from my DJI S800 to a DJI F450, here it is all finished with the FPV gear, jasper7821 Multirotor Talk 84 Aug 14, 2012 08:25 AM
Discussion Just lost my FPV/AP ship - please recommend me a new replacement TheNiceGuy Multirotor Talk 3 Aug 11, 2012 09:17 PM