The parts cost of say a GTX330 is c. $200… no point in saving a little bit of money on that.
CS-STAN Issue 3 has a concession that you can use a non-WAAS/EGNOS GPS as the position source.
Where is this concession applicable? It does say the transponder manufacturer needs to support it. It would seem to me that most certified ADS-B OUT products will simply not work with this.
Does it mean that if you use e.g. a GNS430 or a KLN94 as the position source, you get SIL=3 data coming out and thus you will be visible on certified ADS-B IN displays?
Peter wrote:
Does it mean that if you use e.g. a GNS430 or a KLN94 as the position source, you get SIL=3 data coming out and thus you will be visible on certified ADS-B IN displays?
The Standard Change does say that in this case the installation should set SIL=3.
Peter wrote:
Does it mean that if you use e.g. a GNS430 or a KLN94 as the position source, you get SIL=3 data coming out and thus you will be visible on certified ADS-B IN displays?
Peter,
SIL = 0 is not displayed on certified ADS-B displays, but any non zero SIL is allowed. SIL = 3 and SDA = 2 iplus a bunch of other requirements are needed in the US for access to ADS-B Out rule airspace. SIL and SDA are not involved with a portable ADS-B In system.
2Airborne_Again wrote:
The Standard Change does say that in this case the installation should set SIL=3
This is incorrect. With an un-approved GPS source, the SIL must be set to zero:
This SC addresses three cases:
Note: The aircraft identified in the applicability/eligibility section of this SC do not need to comply with Commission Implementing Regulation (EU) No 1207/2011 or its later amendments. Consequently, they do not need to satisfy the requirements set by CS-ACNS Subpart D Section 4 ‘1090 MHz Extended Squitter ADS-B Out’.
The likelihood of erroneous data being transmitted to ADS-B ground stations and to other aircraft is defined by quality indicators.
The Standard Change does say that in this case the installation should set SIL=3.
That’s really interesting. Which transponder manufacturers are supporting this?
The end result could be obtained by building a protocol converter which converts a non WAAS GPS data stream into a WAAS one. Such a product would be illegal to install, however 
And you would have to reverse engineer the Garmin WAAS data stream…
Just seen wigglyamp’s post above…
With an un-approved GPS source
Is that simply non-WAAS?
For some reason I can’t get a part of the CS to post when i cut and paste. it should include this line:
Configuration 3: an ADS-B OUT system with a GNSS position source that is not approved[ fixed, I think… I removed some strange characters and added blank lines and bullet points ]
Peter wrote:
Is that simply non-WAAS?
This is a GPS that doesn’t meet TSO C199 (a TABS device) or TSO C146 such as a GNS-W, GTN or IFD (all of which are WAAS).
wigglyamp wrote:
This is incorrect. With an un-approved GPS source, the SIL must be set to zero:This SC addresses three cases:
Configuration 1: an ADS-B OUT system that conforms to AMC 20-244;
Peter wasn’t referring to unapproved GPS sources but certified non-SBAS IFR GPS sources such as the GNS430.
As I understand AMC 20-24, ETSO C-129A or TSO C-129(A) GPS sources can be used for “configuration 1”. The GNS430 conforms to TSO C-129A.
