HF Marine DSC vs HF
Land-Mobile selcall
- The bits are inverted in Land-mobile
vs Marine.
- Marine and Land-Mobile tone pair
separation is the same ie. 170Hz.
- Marine and Land-Mobile is the same
baud rate ie 100 baud.
- Marine never generates a revertive
tone, Marine generates a revertive DSC call if an ACK (117)
is required.
- Land-Mobile
generates a revertive tone for selcall and
beacon. Phone, Txt Msg, GPS location,
Status etc are
more complex and may produce a revertive selcall.
- Marine countdown starts at 111,
Land-Mobile at 109.
- Marine
has a 9 digit MMSI (using 5 x 2 digit bytes, and the very last digit is
always 0) which is functionally equivalent to a Land-Mobile selcall
number.
- Land-Mobile has a 4 or 6 digit selcall
number (either 2 or 3 bytes respectivly).
- Marine
DSC frequency quoted is halfway between the FSK tones so the real radio
Dial freq is 1785hz below quoted. (for USB ). ie. Marine DSC freq is not Dial freq.
- Marine voice frequency quoted is
always Dial….. This is confusing.
- Land-mobile frequency quoted is always
Dial, both voice & selcall, both for USB and LSB.
- The minimum length Land-Mobile selcall
is 30 bytes for a 4 digit selcall/beacon call.
- Minimum Marine DSC is 62
bytes.
- Marine DSC contains pad character(s)
126 if the position or freq bytes are not used.
- Marine DSC always has a checksum (from
XORing the payload data), Land-Mobile beacon & selcall does
not.
- Marine DSC can specify a geographical
area (as distinct from position) rather than a target MMSI.
- Marine
DSC can send (drive) the rx radio to another freq for non-selcall voice
(or TTY CW etc ) contact. Whilst maintaining dual watch on DSC channels.
- Marine DSC provides for automated
distress DSC retransmission relay.
The following selcall decodes were captured with a Skippy MkIV
in Logging
mode.
Standard 4 digit Land-Mobile selcall 2346 calls 1234
1 125
2 109
3 125
4 108
5 125
6 107
7 125
8 106
9 125
10 105
11 125
12 104
13 120
14 120
15 12
16 120
17 34
18 120
19 100
20 12
21 23
22 34
23 46
24 100
25 117
26 23
27 117
28 46
29 117
30 117
SYMB 120 012 034 100 023 046 117
Rx 1234 Tx 2346
Standard 4 digit Land-Mobile Beacon Call 2346 calls 1234
1 125
2 109
3 125
4 108
5 125
6 107
7 125
8 106
9 125
10 105
11 125
12 104
13 123
14 123
15 12
16 123
17 34
18 123
19 100
20 12
21 23
22 34
23 46
24 100
25 117
26 23
27 117
28 46
29 117
30 117
SYMB 123 012 034 100 023 046 117
Rx 1234 Tx 2346
4 digit Codan NGT telcall 2346 calls 1234.
A 10 digit phone number 0403895555
1 125
2 109
3 125
4 108
5 125
6 107
7 125
8 106
9 128
10 105
11 128
12 104
13 120
14 128
15 12
16 120
17 34
18 120
19 100
20 128
21 23
22 128
23 46
24 100
25 100
26 23
27 10 ===> 10 digits
28 46
29 4
30 100
31 3
32 10 ===> 10 digits
33 89
34 4
35 55
36 3
37 55
38 89
39 117
40 55
41 117
SYMB 120 012 034 100 023 046 100 010 004 003 089 055 055
Rx 1234 Tx 2346
100403895555
4 digit Codan NGT message call 2346 calls 1234.
1 125
2 109
3 125
4 108
5 125
6 107
7 125
8 106
9 125
10 105
11 125
12 104
13 123
14 123
15 12
16 123
17 34
18 123
19 100
20 12
21 23
22 34
23 46
24 100
25 102
26 23
27 100
28 46
29 63 Z
30 102
31 58 U
32 100
33 49 L
34 63 Z
35 58 U
36 58 U
37 5
38 49 L
39 60 W
40 58 U
41 38 A
42 5
43 56 S
44 60 W
45 5
46 38 A
47 45 H
48 56 S
49 42 E
50 5
51 55 R
52 45 H
53 42 E
54 42 E
55 117
56 55 R
57 61 X ===>codan checksum
58 42 E
59 23 2 ===>codan checksum
60 117
61 117
62 61 X ===>codan checksum
63 117
64 23 2 ===>codan checksum
SYMB 123 012 034 100 023 046 102 100 063 058 049 058 005 060
038 056 005 045 042 055 042 117 061 023
Rx 1234 Tx 2346
ZULU WAS HERE