Federal Aviation Administration, DOT

Section 171.311

TABLE 7c - AUXILIARY DATA FUNCTION TIMING - 
(ALPHANUMERIC) - Continued
Event time slot
begins at:
Event

15.615
kHz clock
pulse
(number)

End guard time; (end function ground)

................

Time
(milliseconds)
5.900

(i) Preamble. Must be in accordance
with requirements of Section 171.311(i)(1).
(ii) Data transmissions. Basic data
must be transmitted using DPSK modulation. The content and repetition
rate of each basic data word must be in
accordance with Table 8a. For data
containing digital information, binary
number 1 must represent the lower
range limit with increments in binary
steps to the upper range limit shown in
Table 8a. Data containing digital information shall be transmitted with the
least significant bit first.

(j) Basic Data word requirements. Basic
Data shall consist of the items specified in Table 8a. Basic Data word contents shall be defined as follows:
(1) Approach azimuth to threshold distance shall represent the minimum distance between the Approach Azimuth
antenna phase center and the vertical
plane perpendicular to the centerline
which contains the landing threshold.
(2) Approach azimuth proportional coverage limit shall represent the limit of
the sector in which proportional approach azimuth guidance is transmitted.
(3) Clearance signal type shall represent the type of clearance when used.
Pulse clearance is that which is in accordance with Section 171.311 (i) (2) (iv). Scanning Beam (SB) clearance indicates
that the proportional guidance sector
is limited by the proportional coverage
limits set in basic data.

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