General Information
This SelCal standard is based on a CCITT-Recommendation (now ITU) for tone-based selective calling.
Usage:
§ Narrowband FM SelCal system in the VHF/UHF frequency range.
Mode Details
|
|
Item |
Value |
|
Standard |
Modulation |
Multitone |
|
|
Number of tones |
15 |
|
|
Coding |
Character coding |
|
Demodulator Settings |
Demodulator |
Analogue SelCal |
|
|
Tone duration (ms) |
100 |
|
|
TD tolerance (ms) |
5 |
|
|
No. of tones |
11 |
|
|
SELCAL type |
Euro |
|
|
Min. burst length (s) |
0.400 |
|
|
Max. burst length (s) |
1.000 |
|
|
Min. pause length (s) |
0.100 |
|
|
3 | |
|
Features |
Demodulation |
yes |
|
|
Recognition |
yes |
|
|
Decoding |
yes |
|
|
Automatic Polarity Adjustment |
no |
|
|
Combination with other modems (modem list) |
yes |
|
Tuning |
The tuning frequency is the center of the signal’s frequency range | |
Table 4: CCITT
Figure 4: CCITT Spectrogram