Microair Avionics
T2000UAV-L
Install and User Manual
T2000UAV-L Installation and User Manual 01R1.doc
Page 9 of 24
28
th
July 2009
3.4.1
STANDBY (S=T)
To bring the T2000UAV-L to the standby condition, the “s” parameter is set to value “t”. Then the transponder
can then be powered down. When the T2000UAV-L is restarted, it will return in standby
The transponder should be commanded to the standby condition, when the vehicle is on the ground. The
transponder is typically set to mode 3A or mode 3A/C operation once airborne.
3.4.2
MODE 3A (S=A)
The T2000UAV-L transponder will respond to all mode A interrogations with the identity code set by the “c”
parameter. The transponder will also reply to all mode C interrogations with just the framing pulse (no altitude
data). This ensures visibility to TCAS operators, while the transponder is operating in mode A.
3.4.3
MODE C (S=C)
The T2000UAV-L will respond to all mode A interrogations with the identity code set by the “c” parameter, and
all mode C interrogations with the encoder’s altitude data, as defined by the “a” parameter. The transponder will
reply to both SSR and TCAS interrogations.
3.4.4
IDENT (I=S)
The ident function is performed at the request of ATC to “squawk ident”. To initiate the ident function the “i”
parameter is set to s. The T2000UAV-L will switch to ident mode, which will add an additional data bit to the
outgoing replies. The additional data bit makes the transponder return on the ATC display flash to assist the
controller with identification. The transponder will remain in ident mode for 18 seconds, and then return to the
previous mode of operation.
3.4.5
ALTITUDE (A=?)
The T2000UAV-L will reply with the current mode C value.
If the T2000UAV-L is configured to operate with an altitude encoder the T2000UAV-L will reply with the
current barometric altitude from the encoder.
If the T2000UAV-L is configured to operate with a serial altitude data source, the T2000UAV-L will reply with
the last received altitude data value.
3.4.6
ALTITUDE SOURCE (D=?)
The T2000UAV-L can accept altitude data for the mode C response either from a Gillham (d=g for 10 line
parallel) source or from a serial (d=s for RS232) source.
When d=g is selected the T2000UAV-L will look to the 10 line Gillham input for data from an altitude encoder.
When d=s is selected the T2000UAV-L will look for altitude data to be passed via the “a” command on the
RS232 serial data link. The altitude data source shall send the a=<altitude value> where the altitude value is
between -1000 and 62000 feet, in increments of 100 feet. The altitude data source should issue this data report to
the T2000UAV-L no slower than 1Hz.
Where the altitude data cannot be detected from the assigned source or the data cannot be encoded, no altitude
data will be outputted. The mode C response will be framing pulses only. The T2000UAV-L will question the
altitude data with a=?, via the RS232 serial interface.
