Chinese 4+4 is a multi-carrier transmission mode. It consists of 8 carriers. They are 300 Hz apart, execpt the 4th and 5th carriers, which are 450 Hz apart from each other.
|
Parameter |
Value |
|
Frequency Range |
HF |
|
Operation modes |
Multi-carrier PSK |
|
Modulation |
DQPSK |
|
Symbol rate |
75 Bd |
|
Shift |
300 Hz between each carrier, 450 Hz between the two carriers in the middle |
|
Receiver settings |
LSB or USB |
|
Input format(s) |
AF, IF |
Every carrier is DQPSK modulated with a symbol rate of 75 baud.
Wavecom Chinese 4+4 decoder uses Hadamard soft-decision decoding. During decoding the paramater Confidence shows the error correction quality. A values above 95% means almost all errors are corrected. However, this is just a qualitative measure.
The decoder can correct a center frequency error of up to +/- 30 Hz automatically. The user needs to place the frequency cursor in this range. The user has to specify the polarity of the signal, i.e., NOR(mal) or INV(erse).