Timewave PK-232MBX, Руководство по эксплуатации

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PK-232 MBX – OPERATING MANUAL PACKET-RADIO
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0 A B C D E F G 0 0 H I J K L M 0 N O P Q R S T 0 0 u v w x Y Z
If we label the 7 standard right-justified callsign bytes 1-6 and SSID, here is how we de-
rive the first group of address-bits A-M:
ABCDE = (byte 1 XOR byte 4) AND $1F
FGHI = (byte 2 XOR byte 5) AND $0F
JKLM = (byte 3 XOR byte 6 XOR SSID) AND $0F
Timewave firmware derives the second group of bits N-Z the same way. Other implemen-
tations are free to select any combination of 26 bits when setting up the short address in
either the initial SABM frame or its UA response.
4.11 Packet Meteor Scatter Extension
A new packet protocol extension has been added for meteor scatter work that allows a Mas-
ter/Slave Packet connection to be established. This is done to reduce the possibility of simul-
taneous transmissions by both sides of a Packet connection over a long meteor scatter path.
This experimental protocol is activated by turning User SIT 18 ON (UBIT 18 ON). When
UBIT 18 is ON (default OFF) the Packet station that initiates a Packet connect will become
the Master station and the station that acknowledges the connect becomes the Slave.
After a Meteor Scatter connection has been established, the Master station will continually
send either information frames (I-frames) or polling frames and await an acknowledgment
from the slave. The Master station therefore sends packets constantly, even if all its I-frames
have been acknowledged. The slave station sends nothing, not even I-frames, until it re-
ceives a polling frame from the master. The Slave station may only send an I-frame to the
Master after a poll frame has been received.
The Packet timing of the Master station is critical for proper Meteor Scatter operation. In a
normal AX.25 Packet connect, the FRACK timer counts down until it reaches zero and then a
Retry of a poll frame is sent. The FRACK timer counts in units of seconds however and a fi-
ner timing resolution is desirable for Meteor Scatter work. A new timer called FRICK has
been added which times in 10 msec increments. The FRICK timer can be set from 0 (dis-
abled) to 250 which corresponds to a time of up to 2.5 Seconds. See the Command Sum-
mary for a complete description of the FRICK timer.
The following settings are recommended for this method of Meteor Scatter work. Both Pack-
et stations should use these same settings.
UBIT IS ON
RETRY 0
AX25L2V2 ON (default)
MAXFRAME 1
(CHECK doesn't matter)
FRICK n, where n is large enough to allow the other station time to send the start of an ac-
knowledgment frame
Note: Do not operate the unit with multiple Packet connections while FRICK is active (1-
250). In contrast to FRACK, which provides one retry timer per multi-connect chan-
nel, there is only one FRICK timer in the PK-232. Each logical channel will try to use
the same FRICK timer, causing interference to the operation of the other channels.
Digipeaters should not be used when in the Meteor Scatter mode. The FRICK timer (unlike
FRACK) does not allow any extra time when digipeater stations are specified.