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Oct 24, 2016, 04:42 AM
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Thread OP
Question

rx servo output jitter


Hi,

I'm using an Eagle Tree Vector as an autopilot. The 'Return To Home' function on the Vector is triggered with a switch on my transmitter (mz-24).
Fail-safe on the rx (gr-24 pro) is programmed in such way that when fail-safe is activated, the RTH swich is also triggered.

This setup works as expected. When I flip the switch manually, or when I power off my transmitter (forcing fail-safe), the Vector goes in RTH mode.

When flying far out (almost 2km), signal quality drops and packet loss ramps up (as expected). The receiver never went into fail-safe, but the rx output started to show serious jitter. This is logged by the Vector. This jitter confuses the Vector. The Vector unit thinks I'm flipping swithes and moving my sticks, thus aborting the RTH mode.

I can solve this by powering down my transmitter, thereby forcing the rx to go into fail-save.

Is this observed jitter normal? Can I make fail-save more sensitive and kick in faster?

Kind regards,
Joris
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Oct 24, 2016, 07:41 AM
Registered User
Hi Joris,

I don`t know if your bec is producing this kind of jitter. Did you read the log-file your transmitter writes to the sd-card?
If it`s a voltage problem then i would try a storage capacitor like this capacitor 4700F/10Volt, Graupner # 7082.1
Oct 24, 2016, 08:09 AM
Registered User
Thread OP
Thanks for the reply, but the mz-24 log shows no voltage drops. The receiver voltage never drops below 5V.

The jitter is produced only when flying far out. At that point the logs show a significant amount of packet loss.
Oct 24, 2016, 09:07 AM
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TheBum's Avatar

rx servo output jitter


If you're losing that many packets, it's no wonder the servos are jittering. What mode is the receiver in (SAME, SUMO, SUMD)?
Oct 24, 2016, 01:21 PM
Registered User
Thread OP
Well, I would like fail-safe to kick-in before the jitter starts. The receiver is not in SUMO or SUMD, so I suppose it's in SAME (each output on it's own wire).
Oct 24, 2016, 04:02 PM
No bounce, No play.
davidmc36's Avatar
Quote:
Originally Posted by Joris05
...a significant amount of packet loss.
How much exactly?
Oct 24, 2016, 04:42 PM
Registered User
TheBum's Avatar
I was looking for something else in the MZ-24 Pro manual and came across a setting in the receiver. There is a DELAY value that determines how long after loss of signal the receiver will go into failsafe. Try reducing that time.
Oct 24, 2016, 05:22 PM
No bounce, No play.
davidmc36's Avatar
Quote:
Originally Posted by TheBum
..reducing..
Increase to prevent oscillating? ?
Oct 24, 2016, 05:38 PM
Registered User
TheBum's Avatar
Quote:
Originally Posted by davidmc36
Increase to prevent oscillating? ?
No, reduce to induce failsafe mode earlier. That seemed to be the OP's complaint.
Oct 24, 2016, 05:48 PM
No bounce, No play.
davidmc36's Avatar
(scratches head) I got the feeling going in and out was causing the jitters.
Oct 24, 2016, 05:59 PM
Registered User
TheBum's Avatar
Quote:
Originally Posted by davidmc36
(scratches head) I got the feeling going in and out was causing the jitters.
This is what I was going by:
Quote:
Originally Posted by Joris05
Well, I would like fail-safe to kick-in before the jitter starts. The receiver is not in SUMO or SUMD, so I suppose it's in SAME (each output on it's own wire).
Oct 24, 2016, 06:24 PM
No bounce, No play.
davidmc36's Avatar
I'm confused by the symptoms.

Wondering again, what is the Packet Loss number?

Do you have a log from the Tx?
Oct 25, 2016, 01:46 AM
Registered User
Thread OP
Hi all,

Thanks for the reply's/Suggestions. Attached is a tx logfile. The observed rx ouput wobble starts at 2:35.

The RXSQ drops to 0 briefly and packet loss is around 80%.

I'll look at the fail-safe delay setting.

Best,
Joris
Oct 25, 2016, 01:47 AM
Registered User
Thread OP
Looks like the attachment was missing
Oct 25, 2016, 06:51 AM
No bounce, No play.
davidmc36's Avatar
How long did the jitter last?


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