Altitude Out; Tc978 Connections; Figure 31: Fdl-Db - FreeFlight ADS-B FDL-DB Dual Band Series Installation Information

2.7.4 Altitude Out

The TC978 outputs pressure altitude data on this RS-232 serial output pin (ALT_OUT) at 9600
baud using the "Icarus" format (Refer to 2.8 for more details). The pressure altitude data output
depends on the Altitude input configuration. If an external Altitude/Air Data Input is configured to
a FDL-DB-XVR ARINC or Serial port, then the pressure altitude data output from the TC978 will
pass through data from that sensor.
If an Altitude/Air Data Input is not configured, then the pressure output defaults to the TC978
built-in altitude encoder. If used, this output must feed the aircraft transponder, so they share
the same altitude source.

2.7.5 TC978 Connections

PIN
J1-24
J1-2
J1-44
J1-26
J1-27
FFS Copyright © 2020 All rights reserved.
DB-62
SIGNAL PIN
Vcp 8
GND 1,6,9
REM ON 7
TRxD3+ 2
TRxD3- 3
ADS-B FDL-DB Dual Band Series
Installation Manual
Document No. 88552 Rev A
TC978 (DB-9)
SIGNAL
POWER
GND
REM ON
TMAPA
TMAPB
2-31