Originally Posted by Wintr

Did you look at the mode channel? It needs to have clear spacing between the positions, but not go too close to the limits on either end.

I'm using a Spectrum rx, and tx so I assume that Eagle Tree has programmed the correct spacing into the G.

The question is whether you have programmed the correct spacing into your radio.

This may well turn out not to be the problem but wouldn't it be easier and faster to just check your radio rather than waste time and effort arguing with people who are trying to help you?

From the manual: "If you have problems getting this to work, you can test the switch temporarily by connecting a servo to the channel on your receiver that is controlled by it. Then, move the switch. If it has 2 positions, you should see the servo move from one extent to the other. If it has 3 positions, you should see the servo move from one extent, to center, and to the other extent."
If the servo moves, but not a lot, the problem is in the settings for that switch/channel in your transmitter.

Originally Posted by Wintr

From the manual: "If you have problems getting this to work, you can test the switch temporarily by connecting a servo to the channel on your receiver that is controlled by it. Then, move the switch. If it has 2 positions, you should see the servo move from one extent to the other. If it has 3 positions, you should see the servo move from one extent, to center, and to the other extent."
If the servo moves, but not a lot, the problem is in the settings for that switch/channel in your transmitter.

Thanks, I'll try that.

Originally Posted by Wintr

From the manual: "If you have problems getting this to work, you can test the switch temporarily by connecting a servo to the channel on your receiver that is controlled by it. Then, move the switch. If it has 2 positions, you should see the servo move from one extent to the other. If it has 3 positions, you should see the servo move from one extent, to center, and to the other extent."
If the servo moves, but not a lot, the problem is in the settings for that switch/channel in your transmitter.

I just checked the Mode switch channel on my TX monitor.
It's showing -100 (2D) 0 (OFF) +100 (3D).

Originally Posted by clearprop88

I just checked the Mode switch channel on my TX monitor.
It's showing -100 (2D) 0 (OFF) +100 (3D).

I had issues with mine on one end, and had to change to +/- 90. Seems the pulse went beyond what the G recognized (I have a Futaba system).

I've read comments to that effect, needed to reduce the travel slightly on the mode channel, usually regarding FrSky which has a wider default travel. I experimented with that once but wasn't able to duplicate the problem with my FrSky. It shouldn't hurt to reduce to 90% so maybe it's worth a try.

Otherwise; I had another thought but it didn't pan out when I tested it on one of my planes, so ... All I can think of is a random glitch in the Guardian, your hand, or the radio link.

Originally Posted by choochoo22

I've read comments to that effect, needed to reduce the travel slightly on the mode channel, usually regarding FrSky which has a wider default travel. I experimented with that once but wasn't able to duplicate the problem with my FrSky. It shouldn't hurt to reduce to 90% so maybe it's worth a try.

, , ,

Spektrum 1% = 4uS
Neutral = 1500uS
130% = 1500 + 130x4 = 2020uS
-130% = 1500 - 130x4 = 980uS

OpenTX, 1% = 5.12uS
130% = 5.12x130 +1500 = 2165.6uS
-130% = 5.12x130 +1500 = 834.4uS

Credit to jj604. Thanks.
Don

There are differences in the definitions of 100% between brands. That isn't really the issue in question.

The Guardian defines some range around 1500µs as the center switch position. If the mode signal received is above this range it is interpreted as mode switch high, below the range as mode switch low. The default ±100% range for Spektrum and FrSky are different but both are far enough outside the center to be properly interpreted as low-center-high by the Guardian.

The proposition is that some fliers assert that if the signal is too far outside the range, near the limits of the data above for example, that the Guardian sensing breaks down and a high or low position may be sensed by the G as center. Further, the assertion is that the FrSky range (also Jeti and probably others, by the way) is by default far enough from center to trigger this problem. To counter this alleged problem, it is suggested that users of these brands reduce travel on the range channel to 80% to match the Spektrum/Futaba range.

Personally, I used Spektrum for years with the mode channel at 100% without issue. For the last two years I've used FrSky (FrOS) with the mode channel at 100% and not encountered the issue even though it is a wider range than Spektrum. When I first switched to FrSky I tested the issue and found that the G properly interpreted the mode channel even if the travel was pushed to the limits.

So, as stated, I've not been able to verify that this alleged problem exists at all but if it concerns you it won't hurt to reduce the travel a little. I haven't tested this limit but clearly some point is too narrow and operation will be compromised. I would consider it thin ice below ±300µs, which would translate to 75% on Spektrum/Futaba or 60% on FrSky/Jeti. So Winter's suggestion of 90% on Spektrum is probably unnecessary but should be OK.

I have a Futaba 7C radio, and have used a Guardian since April or May of '14. The firmware has probably changed in this regard since then, but I have my end point settings at +75/-74 with a subtrim of -30, because with the first one I had, it wouldn't change modes reliably at the default +100/-100 and 0. I just copy those values to any new model, so it hasn't changed for 5 years. I'll have to fire up a receiver to measure the actual pulse widths, but it is clearly less than the 1120-1520-1920 that is default full range for Futaba.

Here are some measurements. The methodology was:

• Program a Guardian to 2D-OFF-3D so the LED would indicate mode changes
• Create a transmitter memory for testing and bind to a rx
• Assign a knob to control two channels
• Set the travel limits of the two channels to the max ±125%
• Connect the G mode input to one of the channels
• Connect the other channel to a logic analyzer to measure pulse width
• Starting in the center, verify OFF
• Reduce the knob position until 2D is indicated, note pulse width
• Reduce the knob to min, verify 2D still indicated, note pulse width
• Starting from center again, increase knob until 3D is indicated and note pulse width
• Increase knob to max, verify 3D still indicated, note knob position
• Note pulse width at other points of interest

There was some observable flickering in the LED near the boundary points indicating ambiguity of the mode selected. The boundary values listed were the first values that seemed solidly selected. Once these boundaries were exceeded there was no further ambiguity and 2D/3D remained solidly selected all the way to the maximum limits. From these observations one may conclude:

• The Guardian identifies the center switch position as approx 1500µS ±200µS
• As long as transmitter settings are at least ±300µS there should be a comfortable margin for solid mode selection. This would include the default 100% settings on all modern transmitters
• There is no point at which the signal is "too far" for proper mode selection, at least not between 900-2100µS
• There should be no need to reduce the default mode travel on any transmitter but doing so should do no harm as long as it remains at least ±300µS

EDIT: Guardian firmware V1.29

I guess we established that my G didn't jump out of 2D mode in the knife edge.
Assuming it was still in 2D mode during the knife edge what else would have caused it to suddenly turn left.

Originally Posted by clearprop88

I guess we established that my G didn't jump out of 2D mode in the knife edge.
Assuming it was still in 2D mode during the knife edge what else would have caused it to suddenly turn left.

The maximum roll angle in 2D is ~80 degrees; while you can easily exceed this, depending on the gain and other settings, the G doesn't like it, and as I understand it, won't hold a knife edge, even if you hold the stick hard over. But, if you did achieve the 90 degree angle, it would be unstable, and could easily command a roll that is unexpected, especially if it goes over 90 degrees. The 3D mode is meant for knife edges, since it isn't trying to return to level or limit your roll angle.

I had that thought as well. A few days ago I tried putting one of my planes in knife edge (in my hand) and holding it there for a while. It held the knife edge for longer than would ever be likely in flight so I ruled out that possibility. I've never tried flying a knife edge in 2D but it certainly is within the range of possibility. The auto-turn-coordination works to oppose the up rudder so that would need to be off, which it is by default. It might be necessary to have heading-hold off as well as that could get confused. I didn't test that and it was off in my test plane as I generally don't use it. Clearprop, did you happen to have HH on?

There's no way to determine with certainty that it didn't lose the 2D mode but the reasons we have postulated so far seem unlikely. There are always various gremlins present like signal interruption or brownout that are equally hard to determine conclusively. At this point I can only write it off as a random glitch of unknown origin.

Winter, did you do any testing on the mode selection range. I would be interested in whatever you found. The tests I did support my earlier, less detailed, observations but this is an issue that has come up from time to time over the years from different people. It could be just a self perpetuating rumor, or it may have had some basis in earlier firmware, or perhaps my tests missed something.

Originally Posted by Wintr

The maximum roll angle in 2D is ~80 degrees; while you can easily exceed this, depending on the gain and other settings, the G doesn't like it, and as I understand it, won't hold a knife edge, even if you hold the stick hard over. But, if you did achieve the 90 degree angle, it would be unstable, and could easily command a roll that is unexpected, especially if it goes over 90 degrees. The 3D mode is meant for knife edges, since it isn't trying to return to level or limit your roll angle.

Originally Posted by choochoo22

I had that thought as well. A few days ago I tried putting one of my planes in knife edge (in my hand) and holding it there for a while. It held the knife edge for longer than would ever be likely in flight so I ruled out that possibility. I've never tried flying a knife edge in 2D but it certainly is within the range of possibility. The auto-turn-coordination works to oppose the up rudder so that would need to be off, which it is by default. It might be necessary to have heading-hold off as well as that could get confused. I didn't test that and it was off in my test plane as I generally don't use it. Clearprop, did you happen to have HH on?

There's no way to determine with certainty that it didn't lose the 2D mode but the reasons we have postulated so far seem unlikely. There are always various gremlins present like signal interruption or brownout that are equally hard to determine conclusively. At this point I can only write it off as a random glitch of unknown origin.

Winter, did you do any testing on the mode selection range. I would be interested in whatever you found. The tests I did support my earlier, less detailed, observations but this is an issue that has come up from time to time over the years from different people. It could be just a self perpetuating rumor, or it may have had some basis in earlier firmware, or perhaps my tests missed something.

Thanks guys.
I don't normally use 2D HH on my planes.
I think it was just a glitch since it only happened one time.
The reason I use 2D for knife edge is because I do it close to the ground, and I don't trust myself in 3D close to the ground.
I agree Wintr knife edges should be done in 3D.