I read, on this forum, that the altitude can be adjusted +- 500 feet. How is that done? I cannot find it anywhere in the documentation. Also, I understand that by adjusting this, it will also feed the encoder the adjusted altitude. If that is not true, then how can the encoder be adjusted?
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Altitude Calibration
- Thread starter N64KR
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In the EFIS menu, under SETUP, press MORE until you see the button labeled ALTADJ. Press this button to enter a menu where you can adjust the altimeter up or down. This is for making minor adjustments to the altimeter and does affect the altitude reported by the encoder. There is no independent encoder output adjustment.
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The encoder always outputs the altitude reported by the EFIS, unadjusted for baro. So if you set your baro to 29.92, the altitude you see on the screen is what is being reported via the encoder. Changing baro does not change what's output by the encoder.
Sorry, I am a bit confused. In your previous post, you stated "This is for making minor adjustments to the altimeter and does affect the altitude reported by the encoder. There is no independent encoder output adjustment. "
So if I set my baro to 29.92, and adjust to get the right altitude at my airport, will this not adjust what is being sent by the encoder, since the encoder sends what the D10a sends to it?
I have just installed my XPDR and the encoder. Now I have to get it certified, and I am sure that the technician will not know how to work with a Dynon, so if there is a way to adjust what comes out of the encoder, by adjusting what goes into the encoder, then I am sure that I will have to tell him how to do it.
So if I set my baro to 29.92, and adjust to get the right altitude at my airport, will this not adjust what is being sent by the encoder, since the encoder sends what the D10a sends to it?
I have just installed my XPDR and the encoder. Now I have to get it certified, and I am sure that the technician will not know how to work with a Dynon, so if there is a way to adjust what comes out of the encoder, by adjusting what goes into the encoder, then I am sure that I will have to tell him how to do it.
The encoder always outputs the altitude reported by the EFIS, unadjusted for baro. So if you set your baro to 29.92, the altitude you see on the screen is what is being reported via the encoder. Changing baro does not change what's output by the encoder.
We get that. But what if the the encoder is reporting the wrong altitude (when checked at the Bi-Annual certification)?
Most encoders have a "low adjust" and a "high adjust" that can be adjusted in the field. Is there any adjustment for the encoder or can it only be adjusted at the factory?
PilotKris
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We calibrate across the full range of altitudes that we measure, but if the single point adjustment doesn't bring the altimeter in line with table one in FAR 43 appendix E as required, we'd need to take a look at it. Note that the altimeter tolerances are tight at sea level, but looser at altitude. We'd expect that in most cases, after doing the adjust so you're on at sea level, that everything else will fall into place.
Now, keep in mind that that test applies to the altimeter itself. The part that pertains to encoder states:
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(c) Automatic Pressure Altitude Reporting Equipment and ATC Transponder System Integration Test. ..... The difference between the automatic reporting output and the altitude displayed at the altimeter shall not exceed 125 feet.
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Now remember, our altimeter IS our encoding device. At 29.92 (pressure altitude, which is where the tests are done), they differ by 0 feet, all the time. The pressure altitude being measured by the EFIS is ALWAYS reported out the serial port.
Now, keep in mind that that test applies to the altimeter itself. The part that pertains to encoder states:
----
(c) Automatic Pressure Altitude Reporting Equipment and ATC Transponder System Integration Test. ..... The difference between the automatic reporting output and the altitude displayed at the altimeter shall not exceed 125 feet.
---
Now remember, our altimeter IS our encoding device. At 29.92 (pressure altitude, which is where the tests are done), they differ by 0 feet, all the time. The pressure altitude being measured by the EFIS is ALWAYS reported out the serial port.
Now remember, our altimeter IS our encoding device. At 29.92 (pressure altitude, which is where the tests are done), they differ by 0 feet, all the time. The pressure altitude being measured by the EFIS is ALWAYS reported out the serial port.
OK, Now I'm officially confused...
You said in your 1st reply that the ALTADJ will adjust what the altimeter reads but not the encoder.
You now say that the encoder ALWAYS reports the same as the altimeter (if set to 29.92).
Which is it?
PilotKris
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The first reply stated "This is for making minor adjustments to the altimeter and does affect the altitude reported by the encoder. There is no independent encoder output adjustment."
This is the same as saying that the encoder output always reports what the EFIS altimeter displays if the baro is set to 29.92.
Think of it this way:
Changing ALTADJ does modify the encoder output.
Changing BARO does not modify the encoder output.
This is the same as saying that the encoder output always reports what the EFIS altimeter displays if the baro is set to 29.92.
Think of it this way:
Changing ALTADJ does modify the encoder output.
Changing BARO does not modify the encoder output.