Need some ideas on best way to troubleshoot some EzUHF link issues - losing control

[londonguy]

I've got some symptoms with my EzUHF. These are not new, I believe they've been there since I got it. I've had a couple of occasions at home during setup where I've had strange issues with my link, like motor spinning up servos behaving strange.

My flight yesterday:

1. I started TX up, throttle at bottom, placed 1 meter away from plane. Powered plane up and left it there whilst I went to arrange my goggles. A minute later the motor starts pulsing as if there is some throttle, I check the throttle its off, I lift plane and the motor pulses a couple of times then settles down, I check TX is still bound and inputs are working fine.. OK I think it must be ghosts....

2. I start flying and within a few minutes I get a lock out, link quality blips to 0. Seems fairly consistent in terms of how long the blip lasts for and the link quality shows 100 all other times. My RSSI never goes above 60.

I carried on staying high up, never more than 700 meters away and again I had two more serious occasions when I got a lock out before I emergency landed.

No idea where to start looking for these ghosts. is there any chance it's my RC transmitter? If I'm getting 100 link quality and under 60 rssi but sudden drops to 0? My UHF TX is mounted behind my 2.4ghz TX and the antenna sits there to the side next to the UHF. Is that an issue?

[ssassen]

When was your EzUHF Rx/Tx bought?

[londonguy]

When was your EzUHF Rx/Tx bought?

Feb 20 2012, 14:16 PM - From the estore rotterdam

[ssassen]

Feb 20 2012, 14:16 PM - From the estore rotterdam

Got some video I can look at showing the problem perhaps?

[londonguy]

Got some video I can look at showing the problem perhaps?

I will attempt to reproduce it at home with my capture card running.

One very strange occasion I had at home was when I went to check inputs on my TX the servos were moving, but not in a coordinated fashion, that is, the servos would twitch and move erratically but only when I was moving my sticks, as if it were getting scrambled inputs from my TX. This TX has been perfect for me as a 2.4 radio with no glitches but it's possible it's output is dodgy? That only happened once.

[Mictronics]

I will attempt to reproduce it at home with my capture card running.

One very strange occasion I had at home was when I went to check inputs on my TX the servos were moving, but not in a coordinated fashion, that is, the servos would twitch and move erratically but only when I was moving my sticks, as if it were getting scrambled inputs from my TX. This TX has been perfect for me as a 2.4 radio with no glitches but it's possible it's output is dodgy? That only happened once.

You are saying the servos move not smooth but in a more stepping way?

I see this behavior frequently under a special circumstance:

When I switch on the TX in low power mode with antenna connected standing next to the plane, then power on the plane my servos not moving smooth and proportional to the controls but just stepping in more or less uncontrolled way.

I found that the RX seems not to hit the exact frequency or hopping sequence when powered on this way. It seems the RX gets overdriven by the TX standing close by. To avoid this I usually take the TX antenna off while powering the plane. When ESC beeps for a good signal then I connect the antenna back on. Works all the time.

Sander, this happens especially with the LNA fitted receiver you sent me.

[ssassen]

Can you give me brief run down of what equipment you use and how it is all connected?

[londonguy]

Below is an image of the layout.

WDR600 camera, with 5 twisted turns through a toroid at camera side.
HobbyWing 5A BEC powering UHF RX, with toroid at the RX side.

[Mictronics]

It's not a problem of the setup so far. My guess is that the RX is overdriven by the strong RF signal and settles to the first strong frequency it finds during bind process which is not exactly the one where the TX is transmitting.

Once the bind process is fine my setup works flawlessly. I was out already to 5km on low power with RSSI around 70 and link quality 100%. And there is still a big margin for longer range.

[londonguy]

Here is a quick video of what is happening...

Link drops off, alarm shows, I regain control after half a second. Seems random as to when it occurs, sometimes it happens a few times in succession and I have more serious control problems.

This happens on high and low power on my TX. I have tried the upper and lower bands of frequency, I will reprogram my set for the two remaining bands to see if that makes any difference, but I'm never more than 1km out and this is the sort of issue I'm getting, even within 200-300 meters. RSSI tends to hover around 50-60 generally within these ranges.


View this video on YouTube