SBE-1/S.Bus/AQ? major issue - confirmed

Info and discussion about the original AQ v6 flight controller

Re: SBE-1/S.Bus/AQ? major issue - confirmed

Postby Teletubbie » Sat Oct 06, 2012 8:43 am

I did a search on Google and imo Futaba is not sending RSSI. There are several blogs how to take the RSSI signal form the receiver CPU. I like to hear if there are others using Futaba SBUS and don't see RSSI.

Yes, I am using the Spectrum port.

Well the radio is set to 14 channels (Multi in Futaba), but I can only see 8 in the Groundstation, so 14 channels are sending.

Yes the receiver is on ;) , groundstation RSSI '0'
If I turn of the radio the RTH kicks in, so I am not affright for the zero rssi.

I made the converter myself: http://autoquad.org/wp-content/uploads/ ... verter.png

But I am not powering the receiver by 3v3, I use a spare channel on the receiver to feed it with 5V. I do this because 3v3 is on the limit of the receive and if there is a power dip I am loosing it.

Oke, will log it and look back.


Let me know if I need to do something else.

//Frank
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Re: SBE-1/S.Bus/AQ? major issue - confirmed

Postby Teletubbie » Sat Oct 06, 2012 8:48 am

PS:

You can set the Futaba receivers in to two Failsafe modes.

1) Radio lost, the channels will go to the predefine Failsafe position

2) radio lost, no output puls from the receiver. They made this for the multirotors because most of the boards can act on lost signal. So I use this mode.
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Re: SBE-1/S.Bus/AQ? major issue - confirmed

Postby Max » Sat Oct 06, 2012 8:57 am

Thanks Frank.

Right, the SBus isn't really sending RSSI as such. There is just a bit which is set high in the last byte of the protocol if signal is lost and/or failsafe is engaged. Actually there are 2 bits with slightly different meanings (one for signal loss and another for when failsafe is engaged). But the AQ code makes use of the relevant bit and sets RADIO_QUALITY based on that. Or it should, anyway. :)

What might be confusing is that even though in QGC they call it "rssi," it is not really. Since AQ has no RSSI input, the RADIO_QUALITY is derived by other means and is then viewable as "rssi" in QGC. But it's not the "traditional" RSSI that is commonly discussed.

-Max
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Re: SBE-1/S.Bus/AQ? major issue - confirmed

Postby Teletubbie » Sat Oct 06, 2012 9:09 am

I wonder why the RSSI is zero, oke later:

Here the graph from the FrSky, and yes there are little drops but are they big enough to trigger something?

Next the Futaba.
Attachments
qual.png
Radio quality, FrySky
Ch8Qa.png
!!! SPAM !!! 8 and Radio quality, FrySky
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Re: SBE-1/S.Bus/AQ? major issue - confirmed

Postby Teletubbie » Sat Oct 06, 2012 9:23 am

Now the Futaba SBUS receiver R6208SB, a solid 100% line !
(I gonna replace my FrySky now !!)
Attachments
FutabasbusQch8.png
FutabaSbusQ.png
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Re: SBE-1/S.Bus/AQ? major issue - confirmed

Postby Teletubbie » Sat Oct 06, 2012 9:28 am

Now Futaba, 1st graph and Frysky receiver showing Quality and all channels.
Attachments
All chanelsFut.png
allchanelsFrySky.png
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Re: SBE-1/S.Bus/AQ? major issue - confirmed

Postby Teletubbie » Sat Oct 06, 2012 9:39 am

Radio quality graph on futaba sbus 6208SB when switching radio on and off.
Still vague why RSSI is showing 0%.
Attachments
radio_on_off_futaba.png
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Re: SBE-1/S.Bus/AQ? major issue - confirmed

Postby Max » Sat Oct 06, 2012 9:54 am

Awesome, thanks!

Those dips on FrSky Rx are very minor... but they shouldn't be there at all, I think. Do they get worse if you move the radio sticks around slowly? The Futaba Rx certainly seems much better.

Looking at your graphs, I see your end-points are set ~ 700 on most channels. My throws were larger when I was using the SBE-1. Hmm... makes me want to go back and check it with lower end-points now. Not that it should matter with the SBus serial protocol. But makes me wonder.

Are you looking at the RSSI in that guage widget in your screenshot? I've actually never used that... I usually find/open the MAVLink Message Inspector widget/window, then expand the RC_CHANNELS_RAW tree, and the last line in there is RSSI. There is also a "Data Stream Rates" widget somewhere in there and I bump up the value for "RC Chan" to something like 5 or above so the feedback is more real-time.

Thanks again,
-Max
Attachments
qgc-sidebar.png
qgc-sidebar.png (17.53 KiB) Viewed 12467 times
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Re: SBE-1/S.Bus/AQ? major issue - confirmed

Postby Kisssys » Sat Oct 06, 2012 2:40 pm

Is that really RSSI or frames lost. If that's frames lost it would not be as confusing if it was titled as such in QGC. In theory you could have a RSSI of 5 and have never lost a frame. I've always thought RSSI meant Receiver Signal Strength Indicator. Doesn't seem practical to try and get that value from the few receivers that provide it so it would be best to label it what it is IMHO.
Steve
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Re: SBE-1/S.Bus/AQ? major issue - confirmed

Postby GoFaster » Sat Oct 06, 2012 2:51 pm

I agree. In the case of the PPM module, the displayed RSSI value denotes how long the AQ did not get a valid frame. It's not a true signal strength value. Or note that in the wiki that it's a pseudo value.
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