TB 9-4920-358-24
16. MODE 4 System Accept/Reject
a. Performance Check
(1) Connect equipment as shown in figure 8 except move oscilloscope CH1
connection from U2TP8 to U3TP9 (fig. 2) on TI and connect oscilloscope CH2 to radar test
set IFF VIDEO OUT FIRST REPLY.
(2) Initialize radar test set by selecting FUNCTION and ENTER. Set radar test set
INTERROGATOR menus as listed below:
(a) Menu 2 - M4: WORD C, S1 through S4 to ON, S5 to OFF.
(b) Menu 3 - REPLY SIGNAL to MODE 4-3, M1 through MC OFF, RANGE
DELAY 10 S, CHAL SOURCE to INTERNAL, F2 to OFF.
(c) Menu 4 - REPLY SIGNAL to MODE 4-3, 2ND REPLY DELAY to 0 sec.
(d) Menu 16 - SOURCE to LOW PWR, RF to - 0.
(3) Observe ACCEPT indication on the TI.
(4) Measure pulse width of GTC gate on CH1. Pulse width will be between 71 and
86 sec.
(5) Observe three-pulse reply on oscilloscope CH2. On radar test set Menu 3,
increase and decrease RANGE DELAY as necessary to shift CH2 three-pulse reply out of
range of the GTC gate pulse on CH1. Observe that TI REJECT lamp goes ON when the
three-pulse display on CH2 moves beyond the end of the CH1 pulse waveform.
b. Adjustments. No adjustments can be made.
17. MODE 4 SLS Pulse
NOTE
If special MODE 4 cable is not available, refer to table 5 and
figure 7 for connection of suitable coaxial test leads.
a. Performance Check
(1) Connect equipment as shown in figure 9.