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Discussion in 'Electronics' started by Dave King, May 4, 2015.
Sounds like you be the Graupner Guru now, Dave.
Now if only Graupner had that 4000 meter range it claims!
I lose signal inside 350-400 meters some times. I wonder if they accidentally put an extra 0 on the end of the spec.
Well, bear in mind that the copter is a hot-bed of radio frequency interference, all of which serve to add noise to the signal that the receiver is trying to detect. Have you done any RFI remediation on, say, the power supply to the receiver? (E.g. ferrite core?)
Right now I am making a new receiver bracket with the antennas at 90 degree angles and installing it it up higher than the top hub plate. I'm making a bracket out of a little stronger material than the QC rabbit. Those things always break on me, been through like 5 of them. I have also had a few receivers with bad antennas so I'm trying a new receiver too. Doing that tonight.
Thanks Dave, I might get up enough nerve to try turning off the transmitter...lol
BTW: the redundant Double Quadro V3 worked perfectly.
I just made my Receiver "V" holder out of a plastic laundry detergent bottle. Soft enough
to bend a bit without breaking.
Well, don't forget to check out the DC power supply to the receiver. If you have a scope have a look at what should be nice flat-line DC. It looks like Einstein's hair...
Not sure whether you can shield the receiver from RFI if there's RF "fuzz" coming to it down the power supply. There may also be noise on the "ground" line.
Well I tested last night. I have about 250 meters of good range and then it goes down hill fast. I scoped the power, signal and ground and they are all clean. Ground has only 5mv of noise. Here's how I have my receiver, I moved the left antenna up a little bit, it was pointing straight across for a 90 degree seperation when I tested.
I had a discussion with a Graupner tech guy about "signal strength", and he told me it was really the signal from, not to, the Receiver, which is not nearly as strong as the Transmitter strength (Signal Quality). I as having problems with the Rx being blocked by CF when I would Yaw. My signal strength was going very low, but my signal Quality was fine, and my dropped packets were less than 10. I ended up moving my Rx.
You can always add a 2nd Rx too?
"Signal Strength" is what the Tx is hearing on the telemetry down-link.
"Signal Quality" is what the Rx is hearing from the Tx on Control Link.
L-Pack is indicator of Lost Packets of data, the lower the better. I think Graupner said to start looking at things if it went much over 200 in a typical flight.
Hmm. The other thing that might be worth testing is the amount of RF noise emitted from all of the exposed avionics, then.
The CF certainly acts as pretty good shielding and could "shadow" the bidirectional RF signals (Tx -> Rx, and telemetry from Rx -> Tx).
I've often wondered whether moving the RX out on to the underside of a boom would improve the range...
Its interesting because many people post that Spektrum has a much better range. I also like the idea of having multiple receivers.
Yeah....diversity receivers would be a good thing....maybe one on boom 3 and one on boom 7 -- I seem to spend most of the time flying nose-out -- why make things harder when the gimbal can pan 360....
With Spektrum I had no chance to go over 200 meter with single reciever.
With Graupner (MX16-MX20 and MC 32) I loose telemetry of Mikrokopter around 200-250 meters, the data stops coming. But the control link remains stable for 600 meters (I have not tested further). On the ground I had tested it to 900-1000 meters and the control link was stable.
I made some antenna adjustments last night and it helped. Gary thanks for the tip on Signal Quality I was looking at signal strength. As Ozkan said I can get about 250-300 meters before I lose signal strength but last night I went as far as 450 meters and it was still 60% which I feel much better about. Not many times that I can recall that I need to go farther than that.
You are welcome Dave, I freaked because I was close to losing "signal", and called Graupner. They walked me through the flight log and told me that was just telemetry, and I wasn't even close to losing "quality" (control to the MK). I did move my Receiver though. They also said I could put one on front and rear, and connect them if I was concerned. Something about first one was setup as SUM IN and the other, that went to the MK was SUM OUT. You can also Bind to two on the same model, but I have no clue how that works. I know some of the guys with really big planes use it.
See also: http://forum.freeflysystems.com/index.php?threads/transmitter.910/page-2
Does this help re: binding two Rx to the same Tx?
I think there is a similar section in the MX-20 and MC-32 manuals...but don't have the page numbers to hand.
Just FYI: I switched the Wookong to Specktrum as I continued having issues. I tested the fail safe with the Wookong today.
It auto lands perfect, it even pauses for a brief section on its way down.