TSO Qualifications | Page 2 | SkyGuardTWX Systems | Discussion Forum

Tim:
I am aware of the FAA guy calling all ADS-B Transmitter customers and telling
then there is something wrong with their unit. This is not correct and this guy
does not know what he is doing or he is mis-informed by his management,
at least as far as the SkyGuardTWX units are concerned.
As I understand it, he has a list of 900 names and is working his way thru the phone
calls. Obviously we have not sold anywhere near 900 units, so he must be calling everyone
who has any possible (key word is Possible!) issue flagged with the FAA ADS-B compliance report.
The FAA has an ADS-B compliance report that many have requested the FAA run on their ADS-B Transmitter.
This report is comparing the transmitter output message results against the "requirements for
a certified transmitter". As you know, our units are not yet certified, so there will be some areas
that show up in RED highlighting the specific discrepancy. In our case, the 3 primary RED areas are:

- reporting GPS altitude rather than pressure altitude
- SDA set to 0
- SIL set to 0

Our original models transmit GPS altitude because in the ADS-B equipment specification (DO-282B), it clearly
states that the transmitter may transmit either GPS altitude, Pressure Altitude, or Both.
Since our units are currently "Portables", there was no FAA authorization to physically connect them
to a Mode C Transponder or a pressure altitude sensor. The FAA would not allow us to do this.
Therefore had no way to collect the Pressure Altitude value and had to report only the GPS altitude.
Once we achieve the TSO certification, these units can connect to a Mode C Transponder to get the pressure altitude.
Also, we recently introduced a new model that has the ability to wirelessly listen to a Mode C Transponder and acquire
the pressure altitude that way. Either way, the DO-282B specification for ADS-B equipment functionality states
that either can be used.

As far as SDA and SIL values, I will address them below:

FAA management is well aware of our Transceivers and has never told us they cannot be used.
The head guy in Washington for the FAA who is responsible for ADS-B equipment implementation
Is named Don Walker. I speak with him often and he knows the configuration of our units.
He also knows we are in process of completing the TSO certification. Per his direction,
As long as we set certain bits in the ADS-B transmitted message stating that our units are
Not yet certified, we are OK. These bits tell ATC not to rely on our transmitted signal
For aircraft separation. These bits are the SDA and SIL bits and we have to set both of these
To ‘0’ which is used by ATC to know that the transmitted message comes from an uncertified
ADS-B Transmitter. Once we achieve certification, we will change these bits to values that
Will indicate the unit is TSO’d.

Also, our Transceivers have been authorized by the FCC and we have a license that clearly
States we can turn them on and broadcast over the US airwaves. It does not matter whether
You have the SkyGuardTWX unit in your car, airplane, or sitting on your back porch, you have
The right to turn it on and begin broadcasting. As long as you treat the unit as a “portable”,
There is nothing the FAA can do to keep you from using it.

Thanks
Don Houtz
SkyGuardTWX