General Information
CHN 4+4 is a mode assumedly used by the Chinese
military.
It is based on two groups, with a
450 Hz gap, of 4 tones with 300 Hz spacing.
Usage:
§ Transfer of textual information over HF.
Mode Details
|
|
Item |
Value |
|
Standard |
Modulation |
QPSK |
|
|
Tones |
2 x 4 |
|
|
Channel distance (Hz) |
300 / 450 |
|
|
Bandwidth |
3000 |
|
|
Symbol rate (Bd) |
75 |
|
|
Data rate (bit/s) |
1200 |
|
|
Modulation |
QPSK |
|
Demodulator Settings |
Demodulator |
MPSK 2,4,8 A/B |
|
|
Symbol rate (Bd) |
75 |
|
|
SR tolerance (Bd) |
1 |
|
|
Modulation order |
4 |
|
|
Version |
B |
|
|
Number of channels |
8 |
|
Features |
Demodulation |
yes |
|
|
Recognition |
yes |
|
|
Decoding |
no |
|
|
Automatic Polarity Adjustment |
no |
|
|
Combination with other modems (modem list) |
yes |
|
Tuning |
The tuning frequency is the center between channels 4 and 5 | |
Table 6: CHN 4plus4
Figure 8: CHN 4plus4 Spectrogram
Modem Version History
|
Release |
Date |
History |
|
2.0.0 |
2013-01-10 |
Modem added |