849
Federal Aviation Administration, DOT
§ 171.311
T
ABLE
1b—C
HANNELS
—Continued
Channel pairing
DME parameters
DME No.
VHF freq.
MHz
MLS angle
freq. MHz
MLS Ch.
No.
Interrogation
Reply
Freq.
MHz
Pulse codes
Freq.
MHz
Pulse codes
µ
s
DME/N
µ
s
DME/P Mode
IA
µ
s FA
µ
s
118Z ..................
....................
5090.1 697
1142
..............
21 27
1079
12
119X ..................
117.20 ....................
..............
1143
12 ..............
..............
1206
12
119Y ..................
117.25 5090.4 698
1143 36 36 42
1080
30
119Z ..................
....................
5090.7 699
1143
..............
21 27
1080
15
120X ..................
117.30 ....................
..............
1144
12 ..............
..............
1207
12
120Y ..................
117.35 ....................
..............
1144
36 ..............
..............
1081
30
121X ..................
117.40 ....................
..............
1145
12 ..............
..............
1208
12
121Y ..................
117.45 ....................
..............
1145
36 ..............
..............
1082
30
122X ..................
117.50 ....................
..............
1146
12 ..............
..............
1209
12
122Y ..................
117.55 ....................
..............
1146
36 ..............
..............
1083
30
123X ..................
117.60 ....................
..............
1147
12 ..............
..............
1210
12
123Y ..................
117.65 ....................
..............
1147
36 ..............
..............
1084
30
124X ..................
117.70 ....................
..............
1148
12 ..............
..............
1211
12
** 124Y ..............
117.75 ....................
..............
1148
36 ..............
..............
1085
30
125X ..................
117.80 ....................
..............
1149
12 ..............
..............
1212
12
** 125Y ..............
117.85 ....................
..............
1149
36 ..............
..............
1086
30
126X ..................
117.90 ....................
..............
1150
12 ..............
..............
1213
12
** 126Y ..............
117.95 ....................
..............
1150
36 ..............
..............
1087
30
Notes:
* These channels are reserved exclusively for national allotments.
** These channels may be used for national allotment on a secondary basis. The primary reason for reserving these channels
is to provide protection for the secondary Surveillance Radar (SSR) system.
S
108.0 MHz is not scheduled for assignment to ILS service. The associated DME operating channel No. 17X may be as-
signed to the emergency service.
(b)
Polarization.
(1) The radio fre-
quency emissions from all ground
equipment must be nominally
vertically polarized. Any horizontally
polarized radio frequency emission
component from the ground equipment
must not have incorrectly coded angle
information such that the limits speci-
fied in paragraphs (b) (2) and (3) of this
section are exceeded.
(2) Rotation of the receiving antenna
thirty degrees from the vertically po-
larized position must not cause the
path following error to exceed the al-
lowed error at that location.
(c)
Modulation requirements.
Each
function transmitter must be capable
of DPSK and continuous wave (CW)
modulations of the RF carrier which
have the following characteristics.
(1) DPSK. The DPSK signal must
have the following characteristics:
bit rate ..............................
15.625 KHz
bit length ...........................
64 microseconds
logic ‘‘0’’ ............................
no phase transition
logic ‘‘1’’ ............................
phase transition
phase transition ................
less than 10 microseconds
phase tolerance ................
±
10 degrees
The phase shall advance (or retard)
monotonically throughout the transi-
tion region. Amplitude modulation
during the phase transition period
shall not be used.
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