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Old Feb 01, 2011, 04:54 PM
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Yippee!
Futaba R617 LostPacket display for OSD Pro

We all know where the (analog) RSSI Pins are, this thread list them all. But as described at rcexplorer we'd rather want to know whether the receiver had to dump bad packets. That "strong signal" a RSSI pin might indicate could easily be the interference source that is about to crash our heli.

But the pin at the red (bad packet) LED of the R617 constitutes a digital signal, jumping for 2ms(?) to 1.7V to indicate a bad packet, then it goes back to zero.
That's why the guys at rcexplorer use a low pass filter circuit to smoothen out things.

That circuit would work with our digital output IF it would switch between Vcc and high impedance. The Futaba however has a totem pole output so it'll drain the small amount of charge a single bad packet pulse might have fed into the capacitor immediately after the blip.
I was worried that such a small lost packet blip might be overlooked on the OSD or even not sampled at all.

So I added a diode (schematic see first pic) to make sure the R617 only charges the capacitor, and a 220Ohm resistor to limit the charging current to app. 4mA.
Discharging that capacitor is done by EagleTrees OSD, which internally has a 5kOhm resistor to ground.

For a single bad packet the voltage at the capacitor will rise quickly to max. (1.7V - 0.6V)/(5220Ohm)*5000kOhm = 1.05V and fall back slowly to 0V. So the higher the voltage at the capacitor the worse the signal is (many lost packets). This means you have to calibrate the RSSI function using the OSD onscreen menu (which means you need to setup those AUX1 and AUX2 inputs ).

But the beauty is EagleTree OSD can be calibrated to 1V reading "bad" and 0V indicating "fine" hence we can actually label the field RSI (with "100" meaning swell) very well done guys !

I've found that "in the lab" the servos respond well till down to RSSI of 30, that would be na indicator to head back home again in real flight.

As usual the electrical design and calculations are simple compared to mechanical realization: I syphon the ground signal from some servo extension wire (the one needed to power the eLogger ), the output is the futaba style connector with the solitary white wire in the center pin.
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Old Feb 08, 2011, 11:14 PM
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WOW, cool!
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Old May 28, 2011, 09:52 AM
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Futaba R6008HS

Hello
I tested this setup on a r6008 and I could not make it work on the eloggerV4.

I took the bad packet of this forum because the red LED on the receiver does not share the ground with the receiver and i have no readings from here


Until I discovered that the ground of the temp1 (top pin) in not shared with the receiver ground and connect this ground with the central pin + of the temp1 through a 1uf capacitor as it says here:
The readings in the eagletree are quite acceptable, with a little noise but I think that is solved by changing the values ​​of resistor and capacitor.

Is this correct?
might affect the operation of eagletree?

Thanks
Daniel
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Old Jun 26, 2011, 06:33 PM
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So i've been playing with RSSI output of 617FS receiver (using the above-mentioned method) and have found a strange (or normal?) occurrence...

It works perfectly (1 = no signal and 100 = full signal) when my TX is the only one used at the time... however, when there's at least one more TX turned on (probably 30-40 ft away) the RSSI indicator does not go to 1 (meaning no signal) but stays at ~60...

Anyone else has experienced similar behavior? If so, how do I monitor the signal between my TX and RX and not signal of nearby (foreign) receivers?

Thanks in advance for any help!
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Old Jul 26, 2011, 04:41 AM
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Quote:
Originally Posted by igorek82 View Post
So i've been playing with RSSI output of 617FS receiver (using the above-mentioned method) and have found a strange (or normal?) occurrence...

It works perfectly (1 = no signal and 100 = full signal) when my TX is the only one used at the time... however, when there's at least one more TX turned on (probably 30-40 ft away) the RSSI indicator does not go to 1 (meaning no signal) but stays at ~60...

Anyone else has experienced similar behavior? If so, how do I monitor the signal between my TX and RX and not signal of nearby (foreign) receivers?
You don't want to do that!

Your RSSI indicator shows perfectly that some packets were corrupted.
That was to be expected, with mutiple frequency hopping TX operating.
Switch on a third FASST transmitter, and that value should be even lower.

The only thing to question is, whether the setup weighs failed packets too heavily:
a system that turns 1 bad packet into 1 second of "RSSI=1" would be way to sensitive,
showing "no RSSI", while the communication still allows for perfect control of the model.

In my system the "bad packet LED" charges the capacitor via 220 Ohm and the Eagle Tree OSD discarges it via 5000 Ohm. E.g. the charge current is twenty times the discharge current (of course depending on current voltage on the capacitor) so I'm on the cautions side. I just wanted to know about even slight singal quality problems. Could be I might see unnecessary bad RSSI when a second TX is running, but didn't test for that, yet.
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Old Jul 26, 2011, 08:08 AM
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Hi, i understand what you're saying but...

The LED we're connecting to is supposed to show BAD packets... why is it showing 60% positive packets, when in fact, there are none? If it was a small number, then perhaps it would not be a problem... but the way it works right now it most likely won't be a reliable meter in areas with more than one RC TX....


Quote:
Originally Posted by reely340 View Post
You don't want to do that!

Your RSSI indicator shows perfectly that some packets were corrupted.
That was to be expected, with mutiple frequency hopping TX operating.
Switch on a third FASST transmitter, and that value should be even lower.

The only thing to question is, whether the setup weighs failed packets too heavily:
a system that turns 1 bad packet into 1 second of "RSSI=1" would be way to sensitive,
showing "no RSSI", while the communication still allows for perfect control of the model.

In my system the "bad packet LED" charges the capacitor via 220 Ohm and the Eagle Tree OSD discarges it via 5000 Ohm. E.g. the charge current is twenty times the discharge current (of course depending on current voltage on the capacitor) so I'm on the cautions side. I just wanted to know about even slight singal quality problems. Could be I might see unnecessary bad RSSI when a second TX is running, but didn't test for that, yet.
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Old Jul 28, 2011, 04:34 AM
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Quote:
Originally Posted by igorek82 View Post
Hi, i understand what you're saying but...

The LED we're connecting to is supposed to show BAD packets... why is it showing 60% positive packets, when in fact, there are none? If it was a small number, then perhaps it would not be a problem... but the way it works right now it most likely won't be a reliable meter in areas with more than one RC TX....
It's a question of number of packets per second and duration of bad packet LED signal.

Both values are unknown to me, but somewhere on the net I have read that FASST is sending out 200 packets per second.

If the LED would light up 5ms per bad packet you'd have a perfect correspondence between % bad packets and % LED illumination.

BUT as people might not see a 5ms blip on that LED, futaba might have decided to light the LED for 1/10th of a second (=100ms) for each bad packet, so people do notice the light.

Thus if the above were true, then an environment, where every 20th received packet (of the 200pkts/sec) is bad (~5% bad packets), would result in a constantly lit LED (100% on)!

If someone knows for sure the packet rate of FASST and the minimum bad packet LED on-time, we could calculate which bad packet rate could be deduced correctly from monitoring that LED.


edit:
That source even claims FASST is hopping 500 times per second. I assume it sends off a whole 14-channel data packet per visited frequency. Or does it transmitt "throttle" on frequency X, 2ms later "aileron" on frequency Y, another 2ms later the rudder channel on frequency Z and so on?

Towerhobbies, too, claims 500 FASST jumps per second.

Futaba themselves only speak of "hundreds of times per second", w/o saying if that means it is sending all the TX channels' values in one "packet".
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Old Jul 29, 2011, 06:30 PM
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Thanks for a detailed response, it all makes perfect sense.

I'm moving away from 2.4Ghz to UHF for my FPV gear so won't be playing with R617FS anymore ;-)

Quote:
Originally Posted by reely340 View Post
It's a question of number of packets per second and duration of bad packet LED signal.
...

Futaba themselves only speak of "hundreds of times per second", w/o saying if that means it is sending all the TX channels' values in one "packet".
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Old Jul 30, 2011, 06:49 AM
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Quote:
Originally Posted by igorek82 View Post
Thanks for a detailed response, it all makes perfect sense.
You're welcome.

Quote:
Originally Posted by igorek82 View Post
I'm moving away from 2.4Ghz to UHF for my FPV gear so won't be playing with R617FS anymore ;-)
Interesting! What was the farthest you could safely go with 2.4GHz, what brand was that?

And regarding UHF: What system did you opt for, what device combo?
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Old Aug 04, 2011, 09:22 PM
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Originally Posted by reely340 View Post
You're welcome.

Interesting! What was the farthest you could safely go with 2.4GHz, what brand was that?

And regarding UHF: What system did you opt for, what device combo?
I've been out 2000ft or so at 398ft altitude... i have futaba 8fg w/r6117fs and i have a feeling that i could have done more ;-) but the video signal started to degrade... i probably need better antennas for vrx/vtx ;-)

i did buy DL because a) shipped from US b) 24 hour shipping c) excellent reviews...
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Old Aug 05, 2011, 06:26 AM
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Hi,
I wrote this thread http://www.fpv-community.de/comm/for...d.php?tid=2353

I made it work well. Even though the percentage drops very sudden, you have enough time to recognize you are leaving the range. One could react in standing up of the chair and return. I use a Futaba T10 2,4GHz with a R6008. Last week I reached 2000m at ~250m height. Then RC had around 20% --> time to return home.

The article above is written in german. but the parts I used are universal. Is there a need to translate the article?

Cheers, Richard
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Old Aug 05, 2011, 10:35 AM
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good article, google translate does a good job (link)
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Old Aug 05, 2011, 01:53 PM
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great stuff
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Old Aug 20, 2011, 01:23 AM
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Hello!
Can I get this mod on futaba 6014HS?
How?
Who can help me?
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Old Aug 20, 2011, 06:25 AM
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Hi,
I think the same way...
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