820
14 CFR Ch. I (1–1–19 Edition)
§ 171.113
(b)
Power output.
The normal carrier
power output must be of a value which
will provide coverage requirements of
§ 171.109(a)(6) when reduced by 3 dB to
the monitor RF power reduction alarm
point specified in § 171.111(j)(3).
(c)
VSWR.
(1) The VSWR of carrier
and sideband feedlines must be a nomi-
nal value of 1/1 and must not exceed 1.2/
1.
(2) The sponsor will also provide addi-
tional manufacturer’s ground stand-
ards and tolerances for all VSWR pa-
rameters peculiar to the equipment
which can effect performance of the fa-
cility in meeting the requirements
specified in §§ 171.109 and 171.111.
(d)
Insulation resistance.
The insula-
tion 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
°
or 12
°
.
The course sector must be maintained
with
±
17 percent of the standard.
(g)
Course alignment.
Course align-
ment must be as specified in
§ 171.109(a)(8).
(h)
Back course alignment and width.
If
a back course is provided, standards
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 § 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 de-
scribed 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 radi-
ation 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 mon-
itor 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 radi-
ation 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 re-
moved, within 10 seconds after a fault
is detected by the monitor, and no at-
tempt must be made to resume radi-
ation for a period of at least 20 seconds.
If an automatic recycle device is used,
not more than three successive recy-
cles may be permitted before a com-
plete 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]
§ 171.113
Installation requirements.
(a) The facility must be installed ac-
cording to accepted good engineering
practices, applicable electric and safe-
ty codes, and FCC requirements.
(b) The SDF facility must have the
following basic components:
(1) VHF SDF equipment and associ-
ated monitor system;
(2) Remote control, and indicator
equipment (remote monitor) when re-
quired by the FAA;
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