GW-PSK is used by Globe Wireless on the Maritime Data Network of the company. The network works with several digital modes in an adaptive system. GW-FSK is always used for opening a connection. Depending on propagation conditions, it may switch to GW-PSK or other digital modes.
|
Parameter |
Value |
|
Frequency range |
HF |
|
Operation modes |
Simplex ARQ |
|
Modulation |
DQPSK, D8PSK |
|
Symbol rate |
200 Bd |
|
Bandwidth |
400 Hz |
|
Receiver settings |
DATA, CW, LSB or USB |
|
Input format(s) |
AF, IF |
|
Additional Info |
ASCII |
GW-PSK is DQPSK and D8PSK modulated with a bandwidth of 400 Hz. The bit rate is 400 bits/s or 600 bits/s with a fixed symbol rate of 200 Baud.
A GW-PSK frame consists of 288 or 432 bits. Each frame contains 25 characters or data bytes. For error detection a 16 bit CRC-checksum is required. For smaller packets, a filler ‘U’ for traffic or ‘<’ for last packets is used.
A GW-PSK signal is tuned in the same way as a PACTOR-II signal. The precision of the center frequency is very important and influences directly the performance of the decoding.
Most of the traffic is compressed. From time to time uncompressed GPS position data in NMEA format is transmitted on ship frequencies. GW-PSK stations can be found on all maritime bands and also in the fixed service bands. More Information is available on http://www.globewireless.com.