[Code of Federal Regulations]
[Title 14, Volume 3]
[Revised as of January 1, 2006]
From the U.S. Government Printing Office via GPO Access
[CITE: 14CFR171.111]
[Page 230-231]
TITLE 14--AERONAUTICS AND SPACE
CHAPTER I--FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION
(CONTINUED)
PART 171_NON-FEDERAL NAVIGATION FACILITIES--Table of Contents
Subpart F_Simplified Directional Facility (SDF)
Sec. 171.111 Ground standards and tolerances.
Compliance with this section must be shown as a condition to
approval and must be maintained during operation of the SDF.
(a) Frequency. (1) The SDF must operate on odd tenths or odd tenths
plus a twentieth MHz within the frequency band 108.1 MHz to 111.95 MHz.
The frequency tolerance of the radio frequency carrier must not exceed
plus or minus 0.002 percent.
(2) The modulating tones must be 90 Hz and 150 Hz within 2.5 percent.
(3) The identification signal must be 1020 Hz within 50 Hz.
(4) The total harmonic content of the 90 Hz tone must not exceed 10
percent.
(5) The total harmonic content of the 150 Hz tone must not exceed 10
percent.
(b) Power output. The normal carrier power output must be of a value
which will provide coverage requirements of Sec. 171.109(a)(6) when
reduced by 3 dB to the monitor RF power reduction alarm point specified
in Sec. 171.111(j)(3).
(c) VSWR. (1) The VSWR of carrier and sideband feedlines must be a
nominal value of 1/1 and must not exceed 1.2/1.
(2) The sponsor will also provide additional manufacturer's ground
standards and tolerances for all VSWR parameters peculiar to the
equipment which can effect performance of the facility in meeting the
requirements specified in Sec. Sec. 171.109 and 171.111.
(d) Insulation resistance. The insulation resistance of all coaxial
feedlines must be greater than 20 megohms.
(e) Depth of modulation. (1) The depth of modulation of the radio
frequency carrier due to each of the 90 Hz and 150 Hz tones must be 20
percent 2 percent along the course line.
(2) The depth of modulation of the radio frequency carrier due to
the 1020 Hz identification signal must be within 5 percent to 15
percent.
(f) Course sector width. The standard course sector width must be
6[deg] or 12[deg]. The course sector must be maintained with 17 percent of the standard.
(g) Course alignment. Course alignment must be as specified in Sec.
171.109(a)(8).
(h) Back course alignment and width. If a back course is provided,
standards
[[Page 231]]
and tolerances for back course sector width and alignment must be the
same as course sector width and course alignment specified in paragraphs
(f) and (g) of this section.
(i) Clearance. Clearance must be as specified in Sec.
171.109(a)(10).
(j) Monitor standards and tolerances. (1) The monitor system must
provide a warning to the designated control point(s) when any of the
conditions described in this paragraph occur, within the time periods
specified in paragraph (j)(6) of this section.
(2) Course shift alarm: The monitor must alarm and cause radiation
to cease, or identification and navigation signals must be removed, if
the course alignment deviates from standard alignment by 10 percent or
more of the standard course sector width.
(3) RF power reduction alarm: The monitor must alarm and cause
radiation to cease, or identification and navigation signals must be
removed, if the output power is reduced by 3 db or more from normal.
(4) Modulation level alarm: The monitor must alarm and cause
radiation to cease, or identification and navigation signals must be
removed, if the 90 Hz and 150 Hz modulation levels decrease by 17
percent or more.
(5) Course sector width alarm: The monitor must alarm and cause
radiation to cease, or identification and navigation signals must be
removed, for a change in course sector width to a value differing by
17 percent or more from the standard.
(6) Monitor delay before shutdown: Radiation must cease, or
identification and navigation signals must be removed, within 10 seconds
after a fault is detected by the monitor, and no attempt must be made to
resume radiation for a period of at least 20 seconds. If an automatic
recycle device is used, not more than three successive recycles may be
permitted before a complete SDF shutdown occurs.
(k) Mean time between failures. The mean time between failures must
not be less than 800 hours. This measure is applied only to equipment
failures (monitor or transmitting equipment, including out of tolerance
conditions) which result in facility shutdown. It does not relate to the
responsiveness of the maintenance organization.
(l) Course alignment stability. Drift of the course alignment must
not exceed one-half the monitor limit in a 1-week period.
[Doc. No. 10116, 35 FR 12711, Aug. 11, 1970, as amended by Amdt. 171-9,
38 FR 28558, Oct. 15, 1973]