New transponder mode S vs. mode C

Marc Ramsey wrote:
Why would you want a Mode S transponder to be fed by a GPS? The
Extended Squitter variation of ADS-B does layer on top of the Mode S
downlink protocol, but simply feeding GPS data to a Mode S transponder
will not make it ADS-B compliant. An entirely new box will be needed.

The only reason to use a Mode S transponder in the US (outside of the
categories of aircraft for which it is mandated) is to take advantage of
the uplinked traffic and weather information, which needs an expensive
and power hungry multi-function display. Since some of those services
are now being shut down in anticipation of ADS-B deployment, even that
reason is slowly being rendered meaningless. Also, do not forget that
it costs roughly twice as much to recertify a Mode S transponder, and
you may have to go farther to find a shop that has the right test equipment.

In response to the original poster, if you spend extra money to install
and maintain a Mode S (instead of C) transponder in a glider operating
in the US, you're simply wasting money...

Marc

Gary Emerson wrote:
AH, but the real question is... would a 302 or other GPS be capable of
generating the data that could be fed to a Mode S transponder? Yeah,
yeah all the illegal stuff and your insurance would never pay if you
ground looped..., but would it work or are the certified GPS units
sending out a different data protocol?

hans wrote:
Hi Tom!

your 302 does not qualify as a certified GPS for the mode S transponder.

Best Regards


Hans


Tom N. schrieb:

I live in San Antonio, Texas, USA. We fly out of a field 15 nautical
miles away from San Antonio International airport and are basically on
final approach for a lot of jet traffic. There are also two Air Force
bases in the immediate area. There is no requirement in the U.S. to
have mode S as there will be in Europe. However, if there is less
power consumption due to fewer interrogations or if there is more
accuracy on TCAS, I would be willing to go with it. I use a Cambridge
302 for GPS.
Stefan wrote:

Tom N. schrieb:

Any opinions? I plan to install a new Becker transponder in my
ASW-28.
Should I go with the old mode C unit or pay extra for the new mode S
unit? Thanks.

Tor answer this question, it would be extremely helpful to know in
which
part of the world you intend to fly.



Hi Marc - I purchased mode S simply because there doesn't seem
to be a material cost difference with the current available equipment.
In Europe and other parts of the world, Mode S is becoming required,
so as I may take my toy and fly in other countries it seems prudent !
I haven't checked if there's any difference in recertification cost
with the local shops.

Hope that helps,
Best Regards, Dave