TM 1-1510-225-10
3C-40
Table 3C-3 lists the VHF NAV frequencies and
corresponding DME channels. The frequency is listed
across the top and down the left side of the table. This
frequency matrix is used to determine the DME
channel. For example, ILS-LOC frequency 108.30
MHz is DME channel 20, VOR frequency 114.70 MHz
channel 94, etc. DME channels 1 through 126 listed in
the table are the DME X channels. The DME Y
channels can be determined from the table by adding
0.05 MHz to each of the 0. 1-MHz columns. For
example, ILS-LOC frequency 108.35 MHz is DME
channel 20Y, VOR frequency E 114.75 MHz is DME
channel 94Y, etc. The 126X channels and 126Y
channels total the 252 DME channels available.
Table 3C-3. VHF Frequencies Versus DME X Channels
0.1 MHz
VHF
NAV
(CTL-32)
.0
.1
.2
.3
.4
.5
.6
.7
.8
.9
134
---
---
---
---
1
2
3
5
6
135
7
8
9
10
11
12
13
15
16
Unpaired channels
108
17
18
19
20
21
22
23
24
25
26
109
27
28
29
30
31
32
33
34
35
36
110
37
38
39
40
41
42
43
44
45
46
111
47
48
49
50
51
52
53
54
55
56
112
57
58
59
---
---
---
---
---
---
---
Even-numbered channels paired with ILS localizer
Odd-numbered channels paired with VOR
133
---
---
---
60
61
62
63
64
65
66
134
67
68
69
---
---
---
---
---
---
---
Unpaired channels
112
---
---
---
70
71
72
73
74
75
76
113
77
78
79
80
81
82
83
84
85
86
114
87
88
89
90
91
92
93
94
95
96
115
97
98
99
100
101
102
103
104
105
106
116
107
108
109
110
111
112
113
114
115
116
117
117
118
119
120
121
122
123
124
125
126
Channels paired with VOR.
NOTE: The unpaired channels (1-16 and 60-69) cannot be received.
(3) Channel Selection. After the three VHF
NAV frequencies are tuned, DME information from any
of the three can be displayed on the IND-42A by
sequentially pressing the CH button to call up T, 2, or
3. If one of the three channels has invalid data,
dashes will be displayed.
When DME data is valid, sequentially pressing
the CH button on the IND-42A will display the NM and
ID for each of the three channels.
(4) Normal Operation.
(a) Select
the
three
desired
NAV
frequencies as previously described. Use the CH
button on the IND-42A to select the desired channel
for display (1, 2, or 3). The numeric display will show
the slant range distance from 0 to 300 nm. The
distance is accurate to 0.1 nm and the display will
show tenths of a mile from 0 to 199.9 nm, and 1-mile
increments from 200 to 300 nm. The NM and ID
annunciators will be illuminated and the alphanumeric
display will show the station identifier. A 10 to
14 second memory in the DME-42 prevents dashes
from being displayed if the received – signal is
temporarily lost or weak.
NOTE
The maximum range of the DME-42 is
300 nm. The range capability of a DME is
limited by aircraft altitude, obstructions
such as hills or mountains, and the
curvature of the earth.
DME
slant
range
is
the
straight-line
distance from the aircraft to the ground
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