To send out an ADS-B out with my TRT 800 Transponder F.U.N.K.E.(or Funkwerk or Filser) i need a Serial Interface (RS232) with the following Data:

NMEA-Format, data format RMC is expected 4800 Baud rate,
or:
AR-NAV: Bendix King KLN 89B, KLN 94: “Standard RS232 Sentence”, KMD 150: “Sentence Type 1” Garmin 400 Series: “Sentence Type 1” (with and without altitude data) 9600 Baud rate
or
Freefligt GPS/WAAS Sensor 1201 NexNav NNL 3101, 19200 Baud rate

Setting for all described GPS-systems: 1 ... 2 position messages per 2 sec.

This is only for Europe: Using serial interface a GPS receiver can be connected to broadcast own position via ADS-B Out position message. Position could be received by other appropriately equipped aircrafts and processed for
collision avoidance ADS-B Out functionality. Connecting a GPS source will not comply to FAA certification requirements with regard to ADS-B.

Since i have 3 GPS Sources at the Moment (Aera 660 wired to the 3500S, AFS GPS PUK (Garmin) wired to the 3500S, and an 3. one to the Powerflarm) i dont whant a 4. one.

Is there a chance that one of the serial Ports can provide this Data?

Markus