AOA tone generator

[cheeselion]

Full disclosure: iEFIS admirer at this point, I have a bunch of the Vega/Blaze singles in my RV-4 but haven't had the guts to truly tear my panel apart yet.

I've been following the ONSPEED project closely and love what they're doing with a primarily audio-only AOA indication that lets you easily determine if you are "on speed", or flying with maximum thrust and turn performance available. In other words AOA becomes as much about aircraft performance as it is about stall protection.

I'm wondering if there's any desire to implement something similar in the iEFIS AOA tone generator logic, maybe as a second mode for the AOA tones? From reading the documentation and playing with the simulator it seems to be pretty close already, almost like it would "just" be (easy for me to say, I'm not the one writing the code) some changes to the logic around when to play the tones and for how long.

[rainier]

Had a brief scan though that link.
It seems you can do that right now - the table you can create for a custom AOA tone sequence sets for every angle the pitch, beep pattern and durations...

[cheeselion]

Hmm, I don't see anything in the docs about that level of customisation, just the "AOA Tone if [yellow,>50% green,>70% green]". Sounds like it would be just the ticket if it exists though. Can you point me in the direction of the right documentation?

[rainier]

Sure, just create a small file using a basic text editor such as notepad with the name AOATABLE.txt

Then copy the below text and edit as you like. Copy this file into your EFIS "Other" folder. It will be loaded on startup and replace the built in default table.

;User AOA tone sequence table

;Minimum indicated airspeed to activate AOA tone followed by maximum airspeed. Speed in MPH.

30,90

;Each line consists of 5 numbers in the following order:
;Frequency
;Tone duration in milliseconds
;Pause between tones in milliseconds (if tone repeat > 0)
;Repeat count (set to a value of 10 or greater for continuous), Tone parameters will be updated at a rate of 8 Hz in EFIS.
;Volume Attenuator 0,1,2,3 (0=High volume -> 3=low volume, each step is 6db)
;
;This table must have exactly 38 lines. This covers the AOA range from 0 to 18 degrees in 1/2 degree steps.

0,0,0,0,0 ;0
0,0,0,0,0 ;0.5
0,0,0,0,0 ;1
0,0,0,0,0 ;1.5
0,0,0,0,0 ;2
0,0,0,0,0 ;2.5
0,0,0,0,0 ;3
0,0,0,0,0 ;3.5
0,0,0,0,0 ;4
0,0,0,0,0 ;4.5
0,0,0,0,0 ;5
0,0,0,0,0 ;5.5
400,1000,0,0,3 ;6
400,1000,0,0,3 ;6.5
400,1000,0,0,3 ;7
400,1000,0,0,3 ;7.5
600,1000,0,0,2 ;8
600,1000,0,0,2 ;8.5
1000,1000,0,0,2 ;9
1000,1000,0,0,2 ;9.5
1500,1000,0,0,1 ;10
1600,1000,0,0,1 ;10.5
1700,1000,0,0,1;11
1800,1000,0,0,1;11.5
1800,100,100,10,1 ;12
1800,100,100,10,1 ;12.5
1800,100,100,10,1 ;13
1800,100,100,10,1 ;13.5
1800,100,100,10,1 ;14
1800,100,100,10,1 ;15.5
1800,100,100,10,1 ;15
1800,100,100,10,1 ;15.5
1800,100,100,10,1 ;16
1800,100,100,10,1 ;16.5
1800,100,100,10,1 ;17
1800,100,100,10,1 ;17.5
1800,100,100,10,1 ;18
1800,100,100,10,1 ;18.5

[cheeselion]

Ha! This is exactly what I needed. I can't believe this is built in already -- great job Rainier.

Follow-up question, is it possible to get AOA angle on the screen (for calibration purposes)? I had a poke around the designer in the sim and I can get various representations of the AOA (coloured status light, some number like "142" which isn't an angle... unless it's the angle without the decimal), but not the angle itself. It seemed like it should be available under the "special text" label type, but there's nothing in there.

For interest, I'm planning to install a CYA-100 vane-type AOA probe (which uses electrical signals, not pressure signals) and connect it to an analogue input on the system. That the iEFIS supports all this hackery out of the box just blows me away. What a tinkerer's dream!

EDIT: just googled "AOATABLE.txt" and found the reference in the MX1 manual. Didn't think to look there as I wasn't considering an MX1. Great that it's out there.

[PaulSS]

Oooo, I hope this works. I still haven't managed to successfully get audio piped from my iEFIS Lite to my Trig radio Aux input (volume way too low) but I can get the AoA vario-type 'warble' (very, very faintly even with Aux volume at max). I really don't like the 'warble' because I'm not searching for thermal lift in a glider but I do like the 'on speed' audio and hope I'm able to incorporate it into my system.

[technerdian]

Ha! This is exactly what I needed. I can't believe this is built in already -- great job Rainier.

...

EDIT: just googled "AOATABLE.txt" and found the reference in the MX1 manual. Didn't think to look there as I wasn't considering an MX1. Great that it's out there.

Hey Cheese,

I have similarly just found onspeed.org. Cecil (Tron), one of the developers, is an MGL fan too. I have come up with a DRAFT UNTESTED aoatable.txt that implements onspeed for the iEFIS. My plane is not flying yet, so you may get this working before I do!

Key thing to test (at altitude) is once the AOA calibration is completed in the iEFIS does this pattern of tones match where onspeed actually is for the aircraft and does the stall warning tone (1600Hz solid tone) sound at the correct AoA. I'll post feedback here once I get to that stage.

Gareth.

;DRAFT UNTESTED User AOA tone sequence table. See ONSPEED (flyonspeed.org)
;Minimum indicated airspeed to activate AOA tone followed by maximum airspeed. Speed in MPH.
30,80
;Each line consists of 5 numbers in the following order:
;Frequency
;Tone duration in milliseconds
;Pause between tones in milliseconds (if tone repeat > 0)
;Repeat count (set to a value of 10 or greater for continous), Tone parameters will be updated at a rate of 8 Hz in EFIS.
;Volume Attenuator 0,1,2,3 (0=High volume -> 3=low volume, each step is 6db)
;
;This table must have exactly 38 lines. This covers the AOA range from 0 to 18 degrees in 1/2 degree steps.
0,0,0,0,0 ;0
0,0,0,0,0 ;0.5
0,0,0,0,0 ;1
0,0,0,0,0 ;1.5
0,0,0,0,0 ;2
0,0,0,0,0 ;2.5
0,0,0,0,0 ;3
400,100,900,5,3 ;3.5
400,100,567,5,3 ;4
400,100,195,5,3 ;4.5
400,100,138,5,3 ;5
400,100,110,5,3 ;5.5
400,100,92,5,3 ;6
400,100,79,5,3 ;6.5
400,100,70,5,3 ;7
400,100,62,5,3 ;7.5
400,100,56,5,3 ;8
400,100,51,5,3 ;8.5
400,1000,0,10,3 ;9
400,1000,0,10,3 ;9.5
400,1000,0,10,2 ;10
400,1000,0,10,2 ;10.5
1600,100,567,5,1 ;11
1600,100,195,5,1 ;11.5
1600,100,138,5,1 ;12
1600,100,110,5,1 ;12.5
1600,50,50,5,1 ;13
1600,25,25,5,1 ;13.5
1600,1000,0,5,1 ;14
1600,1000,0,5,1 ;14.5
1600,1000,0,5,1 ;15
1600,1000,0,5,1 ;15.5
1600,1000,0,5,1 ;16
1600,1000,0,5,1 ;16.5
1600,1000,0,5,1 ;17
1600,1000,0,5,1 ;17.5
1600,1000,0,5,1 ;18
1600,1000,0,5,1 ;18.5

[cheeselion]

Fantastic! And glad to hear that an onspeed insider is an MGL fan. I wonder if Cecil is willing to test this table (if he has the equipment)? I don't yet have an actual iEFIS in my airplane so I'm playing with the simulator.

Unfortunately the simulator barfs on both your AOA table and Rainier's example one, it gives "AOA Table error in line x", where x is the final line of the table. I'm playing around trying to get it to work.

[rainier]

Make sure the last line is terminated with a carriage return / line feed - the system will complain if the file just ends there even if there is an end of file marker - it wants to see a proper terminated line.
Add a blank line or comment line at the end to make sure - just in case your text editor wants to play smart...

[cheeselion]

Thanks Rainier, a blank line at the end of the file did it.

The simulator isn't playing the AOA tones. Sound is working in general (I get GPS AVAILABLE when I start it up). This happens with either the custom AOATABLE or the defaults. I've got the sim in a high AOA state (it's giving me the red triangle indicator), so it seems like it should be playing something. Are the tones maybe not fully implemented in the sim?