Section III. SYSTEM APPLICATION

Figure 5. Mounting MT-2100/APX-44.

(1) An interconnecting cable for con-

pin connectors for the control unit

n e c t i n g the receiver-transmitter

a n d the receiver-transmitter.

to the control unit, the power

(2) A 52-ohm coaxial cable, terminated

s o u r c e , and the aircraft's elec -

at both ends with Plug, Connector

tronic system. This cable consists

UG-573A/U, for connecting the re-

ceiver-transmitter to the antenna.

of 28 shielded wires within multi-

Section Ill. SYSTEM APPLICATION

14. General

(4) Identification of position.

( 5 ) Emergency.

a. Interrogator signals, consisting of

p a i r s of pulses with their spacing gov-

15. Interrogations and Replies

e r n e d by the interrogation mode (para

15 a) are transmitted to the transponder

a . I n t e r r o g a t i o n s . T h r e e independent

s e t in the aircraft by the challenging

interrogation modes are presently in use

b y military operations: mode 1, mode 2 ,

ground-based IFF radar interrogator

and mode .3. All three modes consist of

station. The transponder set decodes the

t w o identical pulses. The difference be-

interrogation signal pulses and transmits

a coded reply to the ground-based IFF

tween each of these modes is established

by pulse separation. The interrogation

r a d a r interrogator station. Replies from

the transponder set permit positive iden-

pulses have specific characteristics which

tification of the aircraft and its position.

permit the transponder set to distinguish

b e t w e e n interrogations and other pulse

b. C o d e d t r a n s p o n d e r r e p l i e s a r e

groups that may be received from radars

formed in five operational categories (para

o r jamming devices. Transmitted inter-

16) or types as follows:

(1) Normal.

r o g a t i o n pulses consist of bursts of a

(2) Modified (also referred to as sif).

radiofrequency (rf) carrier similar to

(3) civil.

c o n t i n u o u s - w a v e ( C W) code transmissions