PK-232 OPERATING MANUAL
PACKET RADIO
Transmission of data:
7C F0 B0 65 10 F0 Test <CR>
3E38 shifted 5832 shifted [I, P; 0, 0]
short dest. short source CTRL PID text
WAIABC sends data to WB2XYZ in Packet Lite format. The address field
consists of the short address from WB2XYZ's UA frame, reversed and
left-shifted. The added bits come from AX.25 version 2.0's command and
response bits, and the end-of-address bit.
Acknowledgment of data:
BO 64 7C Fl 31
5832 shifted 3E38 shifted (RR,F;l)
short dest. short source CTRL
WB2XYZ acknowledges the data from WALABC. The address field is
reversed. This is the shortest length frame possible in Packet Lite. 4
address bytes + 1 CTRL byte + 2 flags + 2 CRC bytes = 9 bytes.
Every 10 minutes the stations must identify using both long and short
addresses:
W B 2 X Y Z -0 W A 1 A B C -0 [RR,P;0] 0l 3E 38 58 32
destination source CTRL PID short address
W A 1 A B C -0 W B 2 X Y Z –0 (RR,F;1) 01 58 32 3E 38
destination source CTRL PID short address
Either station may initiate the ID exchange.
Disconnect:
W B 2 X Y Z -0 W A I A B C -0 DISC 01 3E 38 58 32
destination source CTRL PID short address
Disconnect acknowledgment:
W A 1 A B C -0 W B 2 X Y Z -0 UA 01 58 32 3E 38
destination source CTRL PID short address
At the end of the connection, the two stations must once again identify
using both long and short addresses.
Timewave firmware supporting Packet Lite also contains code that
permits monitoring of Packet Lite and extended AX.25 frames.
Packet Lite Shortened Address Technical Details
The Packet Lite address field consists of 26 bits distributed over 4
bytes (or 'octets', as the AX.25 Spec calls them). These bits are
considered to be two groups of 13 bits each, roughly equivalent to a
destination and a source ID. If we label the bits A-Z and show their
use in the address field of a Lite frame, the bits are distributed as
follows:
A B C D E F G 0 x H I J K L M 0 N 0 P Q R S T 0 y U V W X Y Z 1
2 /93 4-30
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