How to use a potentiometer to tune adf?

[birdstrike]

Hello,

 

I was wondering how i can assign a rotary potentiometer to tune an adf station?

 

I'm in the progress of interfacing this real Collins adf, and as the tuner does'nt have detends like rotary switches found on COM and NAV radios, i guess the only way is to use a potentiometer.

 

 

Thanks,

Lasse

[Pete Dowson]

I was wondering how i can assign a rotary potentiometer to tune an adf station?

 

You'd need to connect it through some sort of interface card. Normal computers can't just have potentiometers pushed into their orifices. Take a look at something like the Leo Bodnar boards. The right one will allow you to connect several potentiometers and send them to Windows via USB as normal joystick axes.

 

Regards

Pete

[birdstrike]

Thanks for the reply Pete.

I'm aware of the hardware interface using the Bodnar cards, i was thinking more of the programming part of it.

 

I have had some time thinking about how to approach this, and this particular adf unit is not straight forward! What i mean about this is that 'normally' one would work with an adf panel showing digits ie. 390.00 khz. But here, as you might imagine, i have no way of knowing wether the adf is tuned to 390.00 or 392.00.

 

So i was thinking that one way of approaching this problem would be to make the adf tune several frequencies at the same time. For instance lats say that i 'physically' tune 390.00 on the adf hardware. The frequency band would indicate .39. But the potentiometer might read 392.00 or maybe 388.05 khz.

But if the adf is programmed to tune +/- 2 khz (for 390.00 it would be 388.00, 388.05, 389.00, 389.05 etc.) it would tune - and recieve if within range of the station - the ndb that i want.

 

Would that be possible with some .ini editing?

 

Thanks a lot for any help here!

Lasse

[Pete Dowson]

But the potentiometer might read 392.00 or maybe 388.05 khz.

But if the adf is programmed to tune +/- 2 khz (for 390.00 it would be 388.00, 388.05, 389.00, 389.05 etc.) it would tune - and recieve if within range of the station - the ndb that i want.

 

I don't think you can make the potentiometer read any specific value very easily. They are simply not that accurate or predctable. Probably the easiest would be to program it for increments in one direction and decrements the other. If you want to try to map the range of values you get from the pot (which at best will be -16k to +16k, safter Windows calibration) to valid ADF frequcies in its complete range I think you might need to do it by program -- maybe a Lua plug-in.

 

Bearing in mind that the full ADF range is 200.0 to around 1750.0 in steps of 0.5, you'd need a potentiometer with at least 3100 discrete settable positions. I've never seen one better than 1024 steps, and they are expensive and the 1024 is what they tell you, but I think it's optimistic. With most good quality ones you'd be lucky to get more than 120 predictable steps. You might do better going for optical, but even then over 3000 steps is a big ask.

 

Would that be possible with some .ini editing?

 

All you can do in axis assignments in the INI is scale values by a number and add an increment.  I don't see how you'd ever be sure you could tune whatever value you wanted.

 

Regards

Pete

[birdstrike]

Bearing in mind that the full ADF range is 200.0 to around 1750.0 in steps of 0.5, you'd need a potentiometer with at least 3100 discrete settable positions.

 

This particular Collins adf operate from 190.00 to 400.00 in one band and 400.00 to 840.00 in another. I might be mistaken but are ndb's used for aviation not allways within 200 to around 535 khz? If so the pot would "only" need 400 positions in one band and 270 in the other. 

 

When i go to axis calibrating in fsuipc, i'm able to choose an axis value and assign it to set a specific adf freq. Have i understood correctly that the decimals (ie. if i want to tune 390.00) i have to convert 390.00 to binary-coded decimal?

 

/

Lasse

[Pete Dowson]

This particular Collins adf operate from 190.00 to 400.00 in one band and 400.00 to 840.00 in another. I might be mistaken but are ndb's used for aviation not allways within 200 to around 535 khz?

 

I think that's true in North America -- and I don't think they have any 0.5 increments there either, so ADF's made purely for US and Canada use often have only 3 digit adjustment and display, even if digital. Europe have a lot of 0.5 frequencies. Frequencies up to 1200 or more are found in South America for sure, maybe other places. The FS ADF can tune pretty much the whole used range.

 

When i go to axis calibrating in fsuipc, i'm able to choose an axis value and assign it to set a specific adf freq.

 

How? Do you mean in the range settings on the right? You can only do 10 settings like that.

 

Have i understood correctly that the decimals (ie. if i want to tune 390.00) i have to convert 390.00 to binary-coded decimal?

 

If you are assigning to "offset word write", for offset 034C, yes you certainly need 0x0390 for 390.0. If you don't want the 1000 digit or decimal digit you should make sure offset 0356 is zero too.

 

If you are assigning to the FS control "ADF complete set" then I think it needs to be in Hz, not kHz, but i'm not sure. Look it up in the FSX SDK.

 

Either way I think you'd need to program it, maybe via a Lua plug-in, not rely on any direct assignment. But experiment for yourself. I've advised you all I can really. You need to do your own tests so you can see what is going on.

 

Regards

Pete

[birdstrike]

Thanks a lot for your help Pete. Really appreciate it! :)

 

Regards

Lasse