The factor you are missing is that approved Aviation GPS have an error
detection system, and send a message (which is included in the 1090ES data
out) to confirm the information is reliable. Low cost GPS doesn't.

In Europe, as I understand it, you can egally connect a low cost GPS to a
TT21 and it will be broadcast in the DS-B out, but including a 'do not rely
on this information' message. That's regardless of WAAS (or EGNOS over
here).



At 15:36 02 November 2012, Grider Pirate wrote:
I cannot help cringing at the requirement for WAAS. If WAAS reduced
positional error to ZERO, that is still less than a 50 foot (15 meter)
improvement over non-differentially corrected GPS. If 50 feet is a
factor, they're screwing up.... big time. Does requiring a WAAS
capable GPS make sense to anyone? (aside from the FAA!)



On Oct 26, 8:05=A0pm, son_of_flubber wrote:
On Friday, October 26, 2012 6:39:14 PM UTC-4, Paul Remde wrote:
The bummer is that even though it is possible to connect a GPS up to
th=
e
Trig TT21 or TT22 an send ADS-B data out, the FAA says that is
illegal.
They say you must use an approved GPS costing $3000+.

A quick list of the approved GPS position sensors and prices

Freeflight 1201 WAAS/GPS Sensor $2,919.00
Freeflight 1204 WAAS/GPS Sensor $6,889.00

Could not find prices for the NexNav sensors:
NexNav MINI WAAS/GPS Sensor
NexNav MAX WAAS/GPS Sensor

Is NexNav shipping these products?

Maybe the price will come down when more than one vendor is shipping
appr=
oved products.