Which Squitter selection to use?

[BigFlapper]

I recently had my Skyview transponder checked out and the tech. had me to change the Squitter setting to NONE from AUTO, is this the correct setting?

 

[dynonsupport]

This option was removed in the 5.0 firmware, released over a year ago.  So you should probably update your firmware.

Back in the pre-5.0 install guides, it says:

TRANSMIT TEST SQUITTERS: Because of limitations in the ATC radar computer systems, in US airspace the FAA require ADS-B equipped aircraft to periodically transmit their Mode A squawk code in an ADS-B squitter message. This allows the computer system to reconcile conventional radar traces with ADS-B information in a mixed surveillance environment. Because the Mode A code does not form part of the base ADS-B message set, the code is sent in a “TEST” message. Because different regulatory authorities have not agreed on the behavior of the TEST message, the installer must select the local preferred behavior. For aircraft registered in the USA, the TEST message should always be transmitted. For other airworthiness approval authorities, the preferred behavior is to apply a geographical filter so that these messages are only sent when the aircraft is visible to US radar systems. Because it has a GPS position input, the transponder already knows the geographic position of the aircraft, and therefore in this case, the recommended option setting for these messages is “AUTO”.

So basically, it should always be "AUTO." In the USA, having it to OFF is actually a non-compliant Mode-S install. Outside the USA, OFF is acceptable but not required.

Ultimately, we removed this option because AUTO is right for everyone, so that is the forced setting in software versions 5 and newer.

 

[BigFlapper]

I have checked my firmware and it's ver. 7.01, the transponder firmware is SW02.04. when I go into setup menu -> transponder setup -> Auto Alt/Gnd. I get the choices:
None
Squat switch low on ground
Squat switch low in air
Auto

When it was set to auto the transponder tech said that I was not outputting any signal but when I switched it to none he got a signal.
So, do I have a firmware problem or what??

Thanks
Tom

 

[Dynon]

Regardless of the setting there, you can always manually over-ride it with the transponder menu buttons, and the transponder status area of the screen will always tell you what mode the transponder thinks it is in. So to really answer your question, we'd need to know what mode the transponder was in when you were working with your transponder tech. Did you happen to record exactly what the transponder status area was showing?

 

[BigFlapper]

The status area showed "alt" after I changed the setup to none.

 

[dynonsupport]

Was your tech using a Mode-S or a Mode-C test set? Mode-S transponders must be tested with a Mode-S test set, which should show the state accurately as being ON GROUND when the system is in AUTO mode. A Mode-C set will show it as non-responsive, and the only way to get it to respond is to force it into ALT mode by turning off the squat switch.

If they were using a Mode-S test set, then we're confused as well.

 

[BigFlapper]

It was mode C, guess that explains it. So now do I return the selection to auto?

Thanks
Tom

 

[Dynon]

Yes, after you've done the test, you can return the squat setting to auto.