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Old Jan 22, 2013, 06:39 PM
Michael
United States, ME, Wells
Joined May 2008
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Disconnected Gain and Initial Pots Setting?

If you read between the lines, your strategy can work with a couple of caveats: (1) if the speed range of the plane is fairly small; i.e., not a wide multiplier between WOT and slow flight and (2) if the POTs are set too high, that there is time for the Guardian to tone down the gain to reduce the oscillations.

As John explained, while that second option is there, it is a safety net, but the unit will take a few seconds to respond and I can tell you that it does get the juices flowing when you see it happening.

My personal habit, now (I own six of the units), if I do not have a gain channel, is to set the POTs to about mid-point unless the speed range is small, then I might set the POTs to about 60% or even 70% depending upon how comfortable I am with the plane.

Just my $0.02, but with six units installed ranging from a biplane (narrow speed range) to a Habu 32 EDF (wide speed range), I am comfortable with the rough SWAG indicated above.

For the Habu, I do have a gain channel, and on any plane where I have a gain channel, I make a note of the maximum gain setting vis-a-vis POT settings, across a wide speed envelope, when relevant, and that is how I came up with the SWAG I use. And, yes, I know the difference between a SWAG and a WAG; with the observations I have made this past flying season, I am comfortable with adding the initial "S". :-)

Michael
Quote:
Originally Posted by TheBum View Post
These two are telling me that, if I have the gain input permanently disconnected, I should just crank the pots all the way up from the get-go. If that's really the case, it would be nice to say something to that effect in the manual.
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Old Jan 22, 2013, 07:01 PM
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Originally Posted by Snowflake6515 View Post
If you read between the lines, your strategy can work with a couple of caveats: (1) if the speed range of the plane is fairly small; i.e., not a wide multiplier between WOT and slow flight and (2) if the POTs are set too high, that there is time for the Guardian to tone down the gain to reduce the oscillations.

As John explained, while that second option is there, it is a safety net, but the unit will take a few seconds to respond and I can tell you that it does get the juices flowing when you see it happening.

My personal habit, now (I own six of the units), if I do not have a gain channel, is to set the POTs to about mid-point unless the speed range is small, then I might set the POTs to about 60% or even 70% depending upon how comfortable I am with the plane.

Just my $0.02, but with six units installed ranging from a biplane (narrow speed range) to a Habu 32 EDF (wide speed range), I am comfortable with the rough SWAG indicated above.

For the Habu, I do have a gain channel, and on any plane where I have a gain channel, I make a note of the maximum gain setting vis-a-vis POT settings, across a wide speed envelope, when relevant, and that is how I came up with the SWAG I use. And, yes, I know the difference between a SWAG and a WAG; with the observations I have made this past flying season, I am comfortable with adding the initial "S". :-)

Michael
Michael,

I have six of them too and none use master gain simply because I am out of radio channels. Most are set at 50% on the pots. Work fine. My concern is if you assume the Master Gain is simply a master control that has to be set full on to have the same pot gains with Master Gain installed you will have a big surprise.
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Old Jan 22, 2013, 07:35 PM
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Originally Posted by Prof100 View Post
Michael,

I have six of them too and none use master gain simply because I am out of radio channels. Most are set at 50% on the pots. Work fine. My concern is if you assume the Master Gain is simply a master control that has to be set full on to have the same pot gains with Master Gain installed you will have a big surprise.

Hi Prof,
Should the last line not read "without Master Gain installed ...", rather than "with Master Gain installed..."?
Or am I still not getting it?
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Old Jan 22, 2013, 08:05 PM
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Originally Posted by Galand View Post
Hi Prof,
Should the last line not read "without Master Gain installed ...", rather than "with Master Gain installed..."?
Or am I still not getting it?

I guess I am not communicating. According to the latest explanation of how gains are interpreted by the Guardian with and without Master Gain you can have a problem if you set up with no Master Gain and the pots give you ideal flying performance.

NO MASTER GAIN connected yields 80% of the pot setting. You don't know this because you don't have the Master Gain operating. You just know the setting works. However when you connect the Master Gain is now operating with a different set of rules. It can be adjusted from 0% (off) to 200%. Mid point on the dial or slider while half way through dial or slider range gives you more pot gain that you are used to flying with when you had no MASTER GAIN connected. If you turn the dial full on then you could have problem flying because you have roughly twice the gain.
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Old Jan 22, 2013, 08:26 PM
Michael
United States, ME, Wells
Joined May 2008
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My Typical Gain Setting

I checked my notes of my typical Master Gain settings on the range of models that I fly and the values, on a scale of -100 to +100, fall between -12 and -19.

I also checked the POTs and they range from about 40% to almost 100% with ailerons definitely running on the lower side.

I guess that is why I am comfortable flying with no gain channel on some of my channel-limited birds.

During my setup flights, I do tend to crank up the gain so that I can adjust the POTs and like to know where the oscillation limits are. I also like to fly with lower and higher gain settings (below oscillation issues, obviously) just to get a feel for how the unit is working.

Even in high crosswinds, I rarely find the need to crank up the master gain. I find that the Guardian does its job even if slightly slower than a higher overall gain would achieve. I find, being older than dirt, that even a "slow" Guardian is faster at correcting / compensating than this pilot. :-)

Michael
Quote:
Originally Posted by Prof100 View Post
Michael,

I have six of them too and none use master gain simply because I am out of radio channels. Most are set at 50% on the pots. Work fine. My concern is if you assume the Master Gain is simply a master control that has to be set full on to have the same pot gains with Master Gain installed you will have a big surprise.
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Old Jan 22, 2013, 08:39 PM
Rick
United States, CA, Santa Clara
Joined Mar 2011
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Quote:
Originally Posted by John.T View Post
Regarding the use of percentages, let's try different units: On a standard servo, the PWM pulse width of the signal is roughly 1.1ms for -100% deflection, 1.5ms for centered and 1.9ms for +100% deflection.
The average RC flyer doesn't know much about pulse widths and doesn't want to. It shouldn't be implied that he must learn about them to use the Guardian. A couple of people have commented already that they are avoiding Guardian because it's too complicated. They will buy someone else's system with a manual they can understand.

Quote:
Originally Posted by John.T View Post
Thanks for your feedback on the Master Gain's disconnected behavior. The intention here was to allow the Guardian to operate in as many applications as possible. Having a default Master Gain value of 80% allows for a beginning user to push their starting gains without the possibility of going wildly out of range and introducing oscillations.
Although percentages seem pretty simple we have already seen how much confusion can be caused by references to negative percentages and 200%. For instance, the disconnected default isn't really 80% is it? It's actually 80% on a 200% scale or 40% of the maximum available

The manual description should avoid pulse widths and percentages as much as possible, both are unnecessary to setting up a plane. I like your analogy of the mixer slider. Here follows a shot at a simpler description:

--------------------------

Guardian Master Gain

The individual gain pots on the unit work in concert with a master gain optionally controlled by the transmitter much the same way an audio mixer board uses individual sliders for each input and a master for overall volume. Ideally the gain wire from the Guardian will be plugged into a channel controlled by a knob or slider on the transmitter. Other setups are possible and some will be mentioned later.

With all the axis pots on the Guardian and the master on the transmitter at maximum the greatest overall gain is achieved. Caution: Too high a gain setting can result in oscillation, see {oscillation reference} for more information on this. Turning the master knob to the opposite extreme will lower the overall gain to zero while positions in between will yield proportional gain. Lowering the individual pot gains on the Guardian will lower the gain for that axis only and allow fine tuning. This might be desirable if, for instance, oscillation is encountered on one axis but not the others.

One possible strategy for setting gains would be to set all three axis pots to max and the master to zero. While flying the plane with the Guardian engaged, slowly turn up the master gain and watch for signs of oscillation. If oscillation is encountered, back down the master until it ceases. With the plane on the ground, reduce the setting on the pot for the axis for which oscillation was observed. Repeat until the plane can be flown with the master at maximum without oscillation. If you have a plane with a wide speed range, such as a hovering 3D aircraft, conducting this procedure using only mid range on the master will allow you later to turn the gain even higher when hovering as oscillation is seldom a problem under these conditions.

If you do not have a channel available for the gain wire that can be controlled by a knob or slider you may use a two or three position switch to provide low/high or low/mid/high gains by adjusting the travel limits in your transmitter. If you have no available channel for the gain wire, you may leave it disconnected. In this case the gain range of the on-board pots is reduced to approximately half of the maximum possible gain to reduce the possibility of encountering oscillation. Note that if oscillation is experienced with no master gain available, switch the Guardian off immediately with the mode switch or reduce the airspeed. On the ground, reduce tho pot gain on the oscillating axis as described above.

Note that, as with all transmitter controls, it may be necessary to reverse the gain (or mode) channel direction in the transmitter so the operating direction of the control suits your preference.

-------------------------

This explains how the gains work and how to set them (currently missing from the manual), and what to do if you don't have a knob (also missing currently), in language that most flyers can understand without any potentially confusing references to pulse width, multiplier, negative percentages, etc. It might be useful for ET to maintain a technical info sheet downloadable for those who want more detail.

By the way, I think it would be better to have the gain default to maximum when the wire is disconnected. Defaulting to a lower value may prevent oscillation or, as someone pointed out could actually cause it, but it will certainly reduce the gain available to the pilot and some see this as a liability contributing to the opinion that an advanced transmitter is needed with Guardian.
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Old Jan 22, 2013, 08:50 PM
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I don't think it can be explained any better^^^. That is very understandable.
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Old Jan 22, 2013, 08:53 PM
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Canton, Michigan USA
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Quote:
Originally Posted by choochoo22 View Post
The average RC flyer doesn't know much about pulse widths and doesn't want to. It shouldn't be implied that he must learn about them to use the Guardian. A couple of people have commented already that they are avoiding Guardian because it's too complicated. They will buy someone else's system with a manual they can understand.



Although percentages seem pretty simple we have already seen how much confusion can be caused by references to negative percentages and 200%. For instance, the disconnected default isn't really 80% is it? It's actually 80% on a 200% scale or 40% of the maximum available

The manual description should avoid pulse widths and percentages as much as possible, both are unnecessary to setting up a plane. I like your analogy of the mixer slider. Here follows a shot at a simpler description:

YES, AVOID PULSE WIDTH REFERENCES

--------------------------

Guardian Master Gain

The individual gain pots on the unit work in concert with a master gain optionally controlled by the transmitter much the same way an audio mixer board uses individual sliders for each input and a master for overall volume.
NOT REALLY ACCORDING TO THE LAST EXPLANATION FROM OUR GUARDIAN rep's post. If you crank up the slider on your radio to full with a MASTER GAIN attached you will have twice the gain on your Guardian with NO MASTER GAIN connected.


Ideally the gain wire from the Guardian will be plugged into a channel controlled by a knob or slider on the transmitter. Other setups are possible and some will be mentioned later.

With all the axis pots on the Guardian and the master on the transmitter at maximum the greatest overall gain is achieved. Caution: Too high a gain setting can result in oscillation, see {oscillation reference} for more information on this. Turning the master knob to the opposite extreme will lower the overall gain to zero while positions in between will yield proportional gain. Lowering the individual pot gains on the Guardian will lower the gain for that axis only and allow fine tuning. This might be desirable if, for instance, oscillation is encountered on one axis but not the others.

One possible strategy for setting gains would be to set all three axis pots to max and the master to zero. While flying the plane with the Guardian engaged, slowly turn up the master gain and watch for signs of oscillation. If oscillation is encountered, back down the master until it ceases. With the plane on the ground, reduce the setting on the pot for the axis for which oscillation was observed. Repeat until the plane can be flown with the master at maximum without oscillation. If you have a plane with a wide speed range, such as a hovering 3D aircraft, conducting this procedure using only mid range on the master will allow you later to turn the gain even higher when hovering as oscillation is seldom a problem under these conditions.

If you do not have a channel available for the gain wire that can be controlled by a knob or slider you may use a two or three position switch to provide low/high or low/mid/high gains by adjusting the travel limits in your transmitter. If you have no available channel for the gain wire, you may leave it disconnected. In this case the gain range of the on-board pots is reduced to approximately half of the maximum possible gain to reduce the possibility of encountering oscillation. Note that if oscillation is experienced with no master gain available, switch the Guardian off immediately with the mode switch or reduce the airspeed. On the ground, reduce tho pot gain on the oscillating axis as described above.

Note that, as with all transmitter controls, it may be necessary to reverse the gain (or mode) channel direction in the transmitter so the operating direction of the control suits your preference.

-------------------------

This explains how the gains work and how to use them (currently missing from the manual) in language that most flyers can understand without any potentially confusing references to pulse width, multiplier, negative percentages, etc. It might be useful for ET to maintain a technical info sheet downloadable for those who want more detail.

By the way, I think it would be better to have the gain default to maximum when the wire is disconnected. Defaulting to a lower value may prevent oscillation or, as someone pointed out could actually cause it, but it will certainly reduce the gain available to the pilot and some see this as a liability contributing to the opinion that an advanced transmitter is needed with Guardian.
See comments in blue.
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Old Jan 22, 2013, 09:22 PM
Rick
United States, CA, Santa Clara
Joined Mar 2011
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Quote:
Originally Posted by Prof100 View Post

Guardian Master Gain

The individual gain pots on the unit work in concert with a master gain optionally controlled by the transmitter much the same way an audio mixer board uses individual sliders for each input and a master for overall volume.
NOT REALLY ACCORDING TO THE LAST EXPLANATION FROM OUR GUARDIAN rep's post. If you crank up the slider on your radio to full with a MASTER GAIN attached you will have twice the gain on your Guardian with NO MASTER GAIN connected.

It says that in the last paragraph.

Ideally the gain wire from the Guardian will be plugged into a channel controlled by a knob or slider on the transmitter. Other setups are possible and some will be mentioned later.

With all the axis pots on the Guardian and the master on the transmitter at maximum the greatest overall gain is achieved. Caution: Too high a gain setting can result in oscillation, see {oscillation reference} for more information on this. Turning the master knob to the opposite extreme will lower the overall gain to zero while positions in between will yield proportional gain. Lowering the individual pot gains on the Guardian will lower the gain for that axis only and allow fine tuning. This might be desirable if, for instance, oscillation is encountered on one axis but not the others.

One possible strategy for setting gains would be to set all three axis pots to max and the master to zero. While flying the plane with the Guardian engaged, slowly turn up the master gain and watch for signs of oscillation. If oscillation is encountered, back down the master until it ceases. With the plane on the ground, reduce the setting on the pot for the axis for which oscillation was observed. Repeat until the plane can be flown with the master at maximum without oscillation. If you have a plane with a wide speed range, such as a hovering 3D aircraft, conducting this procedure using only mid range on the master will allow you later to turn the gain even higher when hovering as oscillation is seldom a problem under these conditions.

If you do not have a channel available for the gain wire that can be controlled by a knob or slider you may use a two or three position switch to provide low/high or low/mid/high gains by adjusting the travel limits in your transmitter. If you have no available channel for the gain wire, you may leave it disconnected. In this case the gain range of the on-board pots is reduced to approximately half of the maximum possible gain to reduce the possibility of encountering oscillation. Note that if oscillation is experienced with no master gain available, switch the Guardian off immediately with the mode switch or reduce the airspeed. On the ground, reduce tho pot gain on the oscillating axis as described above.

See comments in blue.
See comment in red
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Old Jan 22, 2013, 09:36 PM
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Originally Posted by choochoo22 View Post
See comment in red
I am confused. Which last paragraph?
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Old Jan 22, 2013, 09:42 PM
Rick
United States, CA, Santa Clara
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Originally Posted by Prof100 View Post
I am confused. Which last paragraph?
"If you have no available channel for the gain wire, you may leave it disconnected. In this case the gain range of the on-board pots is reduced to approximately half of the maximum possible gain to reduce the possibility of encountering oscillation. "
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Old Jan 22, 2013, 09:43 PM
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"1.1ms: Master Gain = 0%; Stabilization disabled
1.5ms: Master Gain = 100%; recommended starting point for tuning
1.9ms: Master Gain = 200%; useful for 3D maneuvers where high stabilization is needed"

This will continue the confusion. It's counter-intuitive. 0% is off, 100% should be max, "turned up all the way".
Use "normal" nomenclature. -100% (on the tx) being "off" and +100% being "max" gain (the numeric values my tx screen shows) should be understandable. The problem arose mixing that with 200%. I don't see 1.1ms etc when I look at the tx screen, I see +/-100%.
Having a Master Gain channel active and not having one should be dealt with seperately. Intermingling them is what created much of the debate.
"Max gain available is increased with a Master Gain connected" or similar should be enough. Keep it simple.
Mention the default Master Gain percentage (no Master Gain connected) but mention it somewhere else in the manual.
My 2 cents.
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Old Jan 22, 2013, 09:50 PM
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Originally Posted by choochoo22 View Post
"If you have no available channel for the gain wire, you may leave it disconnected. In this case the gain range of the on-board pots is reduced to approximately half of the maximum possible gain to reduce the possibility of encountering oscillation. "
Yes, that's how I now understand it. The one mistake that happen is to take your plane which no MASTER GAIN connected and have it tuned to be be oscillation free then install a MASTER GAIN and mistakenly set the MASTER GAIN knob or slider to maxium. Oh boy, that's going to be a real hoot to watch in the air flying. Can you say oscillation?
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Old Jan 22, 2013, 10:04 PM
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Originally Posted by Prof100 View Post
take your plane which no MASTER GAIN connected and have it tuned to be be oscillation free then install a MASTER GAIN and mistakenly set the MASTER GAIN knob or slider to maxium.
Just say that if you add a Master Gain to a plane set up without, to start with the Master Gain at or below it's mid point.
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Old Jan 22, 2013, 10:05 PM
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Originally Posted by t.edwards View Post
Just say that if you add a Master Gain to plane set up without, to start with the Master Gain at or below it's mid point.
YES, that would be an understatement.
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