TM106601_(7/01) 2-
18
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C
O M M A N D
S
Y S T E M S
D
I V I S I O N
Note
+
The RT-1601 Receiver Transmitter has a
special feature. In SRI or SR2 mode, at 2 NM
range or less, a 500-foot-wide red band will
appear, with the outer edge at the 500-foot
point in the display.
(13) Set the mode to BCN and the range to 20. Observe that the characters "BCN" appear in the
mode field on the MFD display. The fault field should be off and the display should be free of
all noise and ground clutter. If a beacon station of 9310 MHz is within range, a beacon reply
may be observed on the screen.
(14) Proceed as follows to check the DO-172 6-pulse beacon format.
(a) With the indicator in the BCN mode, press and release the BCN button until the word A1
appears on the display. This selects the 6-pulse beacon format.
(b) Press the PUSH CODE button and observe that the beacon code displayed in the lower
left corner changes sequentially from A1 to A15, then changes to A1, and then repeats
the sequence.
(c) Observe the display for any 6-pulse beacon replies. The 6-pulse beacon transponder
reply will be displayed by two frame marks with either 1,2,3, or 4 other closely spaced
marks between the two frame marks.
Note
+
The marks between the frame marks represent
the beacon code number in 4-bit binary format,
with each mark a logic 1 and the closest mark
to the origin being the least significant bit.
(d) If a beacon reply is observed, repeatedly press the PUSH CODE button until a beacon
code (e.g. A12) appears in the display between the frame marks.
Note
+
The selected range must be set for 2,5,10,20, or
40 miles to identify the DO-172 beacon reply.
(e) Observe the beacon code number selected and the beacon code number displayed by the
beacon marks are the same number.
(f) Press the BCN button until the beacon-selected character changes from A to B. Only the
two-pulse beacon replies will now be identified.
