Folks - the VOR OBS needle is very abrupt as a radial (or ILS localizer) is approached.

Is there a way to increase the OBS sensitivity so it isn't as abrupt and late in moving the needle? 

Thanks - Pete

I'm not a real life pilot, but I would imagine the sims are realistic in that the closer you are to the VOR the more sensitive it will become. Waiting to hear what people with more expertise say.

Edited November 10, 20241 yr by WestEnd

It's been decades since I did RW flying, but the VOR response seems appropriate.  Again, it's been a long time so I can't say for certain.

Also, be aware that there is quite a difference btwn the response to a VOR radial and a Localizer.  When intersecting a localizer the path is quite narrow and the needle will be sensitive.  VORs can be picked up at a much greater distance and the radial width is wider and will respond slower unless you are very near the station.

When approaching a VOR station (within a mile or so) we would always hold our course, because when you are very close to the station the needle will swing from one side to the other and trying to follow it would just jerk the aircraft around.  We would hold the current bearing and the needle would begin to move off center.

As we passed over the station the needle would pick up speed in its transit, then quickly flip to the other side as we transitioned to FROM the station.  Again, we would hold our original bearing and the needle would slowly return to center.  After we were a couple miles past, we would make any necessary adjustments to keep the needle centered.

 

Guys - I am a real-life GA pilot and am aware of the VOR distance/ILS localizer differences. 

What I am wondering is if MSFS has the ability to adjust the needle's sensitivity.

Pete

12 minutes ago, Ramberga said:

Guys - I am a real-life GA pilot and am aware of the VOR distance/ILS localizer differences. 

What I am wondering is if MSFS has the ability to adjust the needle's sensitivity.

Pete

Are you using a mouse to turn OBS knob? Did you use scroll wheel?

6 minutes ago, sd_flyer said:

Are you using a mouse to turn OBS knob? Did you use scroll wheel?

I am using rotary encoders tied to an Arduino board to control the OBS dial - programmed using "control options" in MSFS.

The dial responds correctly and the needle moves fine. It is simply too harsh and not a fine enough control. The needle starts its movement toward the radial (or localizer) and it is too abrupt. The plane (C172) would have to do a 45 degree or more bank to follow the needle of the OBS. By the time a turn is initiated, it is too late as the needle has gone all the way to the other side of the dial.

Pete

12 minutes ago, Ramberga said:

I am using rotary encoders tied to an Arduino board to control the OBS dial - programmed using "control options" in MSFS.

The dial responds correctly and the needle moves fine. It is simply too harsh and not a fine enough control. The needle starts its movement toward the radial (or localizer) and it is too abrupt. The plane (C172) would have to do a 45 degree or more bank to follow the needle of the OBS. By the time a turn is initiated, it is too late as the needle has gone all the way to the other side of the dial.

Pete

It most likely be your on your hardware side. I'm using mouse and I don't have issue as you describe. But I remember that was MSFS bug when heading or OBS would skip 10 degrees per one  rotation. I believe it has been fixed quite while ago in one of updates

11 minutes ago, sd_flyer said:

It most likely be your on your hardware side. I'm using mouse and I don't have issue as you describe. But I remember that was MSFS bug when heading or OBS would skip 10 degrees per one  rotation. I believe it has been fixed quite while ago in one of updates

It doesn't matter what device (keyboard stroke, mouse/wheel, external encoder) is used to "spin" the OBS dial. That has nothing to do with the instrument's sensitivity. No matter what is used to move the needle, the sensitivity of the instrument is just too abrupt to catch the needle before it swings well past center.

4 minutes ago, Ramberga said:

It doesn't matter what device (keyboard stroke, mouse/wheel, external encoder) is used to "spin" the OBS dial. That has nothing to do with the instrument's sensitivity. No matter what is used to move the needle, the sensitivity of the instrument is just too abrupt to catch the needle before it swings well past center.

Then I'm not sure I don't have this problem. Perhaps some add on conflict?

2 minutes ago, sd_flyer said:

Then I'm not sure I don't have this problem. Perhaps some add on conflict?

Will keep working on it - thanks for your time, SD.

2 minutes ago, Ramberga said:

Will keep working on it - thanks for your time, SD.

Another thing. Make sure that your simulator rate is 1X. If by any change something trigger it for example 2x, it might feel like what you describe. It  happened to me once by accident until I discovered a problem. 

6 hours ago, Ramberga said:

Folks - the VOR OBS needle is very abrupt as a radial (or ILS localizer) is approached.

Is there a way to increase the OBS sensitivity so it isn't as abrupt and late in moving the needle? 

Thanks - Pete

I think to make the type of changes you are talking about you would have to adjust the NAV PID values, which are typically in the aircraft ai.cfg file. Setting PID values is not trivial, and IMO is more of an art than a science. There is a PID Primer in the MSFS SDK as indicated by the SDK excerpt below.
Very briefly, my simplistic understanding is that a PID controller is a feedback control mechanism that tries to reduce the "error" of some quantity to zero. In the case of intercepting a Localizer, the error is related to how far off the localizer the aircraft is. The NAV PID,  through the autopilot, tries to reduce this error to zero in an effective manner without overshooting the localizer, or weaving back and forth across it, etc.  The PID values determine how the controller goes about reducing the error.

Al

 PID Primer

This page is dedicated to helping you understand what PID controllers are, what they do, how to use them, and how to tune them. To start with, let's quickly define what PID actually stands for and how a controller using this system should work in very general terms:

A "Proportional–Integral–Derivative" controller is a control loop mechanism employing feedback for systems requiring continuously modulated control. A PID controller continuously calculates an error value as the difference between a desired setpoint and a measured process variable and applies a correction based on proportional, integral, and derivative terms.

So, essentially, a PID controller is a type of rudimentary artificial intelligence based on feedback loops that can control simple processes. Now that we know in general what a PID controller is, let's dive in and see how it actually works, in particular with reference to Microsoft Flight Simulator.

Edited November 10, 20241 yr by ark

I think there's some confusion as to what the issue is -- so let me first clarify.

I think what your issue is that when you're intercepting a radial, the needle on the CDI starts moving too late, so even if you start the turn the instant the needle starts moving, you end up overshooting the radial. Correct?

(If this is what you mean, then terminology may have confused people: The OBS is just the knob on the CDI that selects the desired radial.)

What you're therefore looking for is a way to make full-scale deflection of the needle correspond to a greater "distance", i.e. a greater difference in the number of radials -- this can also be looked at as making the needle less sensitive.

The thing is, though, that there's a definition for how sensitive a CDI should be: A "dot" of deflection should correspond to a difference of two degrees. Full-scale deflection is five dots and should therefore correspond to ten degrees. It may be that the CDI on the aircraft you're flying (which one?) doesn't get this right, but there's an easy way to test: On the ground (so you're not moving), tune a VOR and rotate the OBS so the needle is exactly centered. Now rotate the OBS until you just hit full-scale deflection; the difference from your original setting should be exactly ten degrees. If this isn't the case, let the addon developer know that the CDI needs to be fixed.

Edited November 10, 20241 yr by martinboehme

Full scale CDI deflection for a localizer is 2.5 degrees, or 1/2 degree per dot on an instrument with 5 dots per side.  So the CDI localizer sensitivity increases by 4 times compared to a VOR.

Al

 

10 minutes ago, martinboehme said:

I think there's some confusion as to what the issue is -- so let me first clarify.

I think what your issue is that when you're intercepting a radial, the needle on the CDI starts moving too late, so even if you start the turn the instant the needle starts moving, you end up overshooting the radial. Correct?

(If this is what you mean, then terminology may have confused people: The OBS is just the knob on the CDI that selects the desired radial.)

What you're therefore looking for is a way to make full-scale deflection of the needle correspond to a greater "distance", i.e. a greater difference in the number of radials -- this can also be looked at as making the needle less sensitive.

The thing is, though, that there's a definition for how sensitive a CDI should be: A "dot" of deflection should correspond to a difference of two degrees. Full-scale deflection is five dots and should therefore correspond to ten degrees. It may be that the CDI on the aircraft you're flying (which one?) doesn't get this right, but there's an easy way to test: On the ground (so you're not moving), tune a VOR and rotate the OBS so the needle is exactly centered. Now rotate the OBS until you just hit full-scale deflection; the difference from your original setting should be exactly ten degrees. If this isn't the case, let the addon developer know that the CDI needs to be fixed.

Martin - that is a perfect explanation. Yes, it is the CDI or course deviation indicator, that seems way off. I recall, from flying, that full scale defection is 10 degrees.

 

The aircraft is the Textron C172 that comes with the base MSFS package. It uses a G1000 glass cockpit, but I have built an analog instrument panel with 'Air Manager' that uses the data from MSFS and is used by Air Manaher.

 

As a reference, I have used the identical hardware with X-Plane12 and the CDI works appropriately.

 

I am going to see how the Reims C172 free download CDI works as a comparison.

Pete