Wavecom W61PC V7.5.0 - Manual (Page 200)

190  Transmission Modes WAVECOM Decoder W61PC/LAN Manual V7.5
The data field can contain up to 256 characters. All characters and character combinations are permitted
since transmission is transparent. A checksum is sent in the FCS field.
The status field contains three fields with connection status information in addition to the call-signs:
Frame types are indicated by I, S or U.
S-frame status messages, e.g. Receiver Ready (RR), Receiver Not Ready (RNR) or Reject (REJ) are dis-
played.
In the third field the transmit and receive sequence numbers are displayed. This number ranges from r0 to
r7 or s0 to s7. The sequence number indicates to the opposite station which packets have been received
free of errors.
The large volume of available radio amateur literature is recommended for further study of the packet ra-
dio system.
PACKET-300
PACKET-300 is mainly used by radio amateurs. Very seldom 600 Baud test transmissions may be heard.
On HF SSB modulation (LSB or USB) is standard.
Parameter Value
Frequency range HF
Operation modes Duplex FEC TDMA
Modulation FSK
Symbol rate 300 and 600 Bd, variable 30-650 Bd
Receiver settings DATA, CW, LSB or USB
Input format(s) AF, IF
Additional Info ITA-5 with block coding, amateur AX.25 System
The packet radio protocol is a derivative of the X.25 and HDLC computer network protocols. Packet radio
is a synchronous system in which data is transmitted in ASCII character packets.
At the start and end of each block a control character or flag (01111110) is sent. The address can consist
of up to 80 characters, but 16 or 24 character addressing is common when using direct connections or a
single repeater.
The packet protocol distinguishes between three frame types: I (Information), S (Supervisory) and U (Un-
numbered). Payload data transfer uses I frames or very rarely U frames. S and U frames are used for
transmission control.
The data field can contain up to 256 characters. All characters and character combinations are permitted
since transmission is transparent. A checksum is sent in the FCS field.
The status field contains three fields with connection status information in addition to the call-signs:
 Frame types are indicated by I, S or U.
 S-frame status messages, e.g. Receiver Ready (RR), Receiver Not Ready (RNR) or Reject (REJ)
are displayed.
 In the third field, the transmit and receive sequence numbers are displayed. This number ranges
from r0 to r7 or s0 to s7. The sequence number indicates to the opposite station which packets
have been received free of errors.
The large volume of available radio amateur literature is recommended for further study of the packet ra-
dio system.