PK-88 OPERATING MANUAL
COMMAND SUMMARY
5 - 41
PK-88 - 116
If some, but not all, of the outstanding packets are acknowledged, a smaller number may be
transmitted the next time, or new frames may be included in the retransmission, so that the total
number of unacknowledged packet frames does not exceed
n
.
The 'best' value of MAXFRAME depends on your local channel conditions. In most cases of key-
board-to-keyboard direct or local operation (links that don't require going through digipeaters),
you can use the default value MAXFRAME 4.
NOTE:
The FRACK counter begins counting from the first ' flag of each frame. If MAX-
FRAME is set to 7 and PACLEN is set to maximum (0), FRACK should be lengthened
to prevent the distant station's ACK from colliding with a possibly-prematureretry.
When the amount of packet traffic, the path in use, the digipeaters involved – or other variables
not under your control – make packet operation difficult (as shown by lots of retries!), you can im-
prove your throughput by reducing MAXFRAME.
Experimental evidence indicates that MAXFRAME 1 or 2 can sometimes produce best throughput,
especially on HF radio, when operating in conditions of multipath propagation and numerous colli-
sions.
⇒
If packet traffic is heavy or the path is poor, reduce MAXFRAME to 3, 2 or 1.
⇒
If the radio link is good, an optimal relationship exists between the parameters set by these
commands. The maximum number of data characters outstanding should not exceed the re-
ceive buffer space of the TNC receiving the data.
MBELL
ON|OFF
Mnemonic:
MBE
Default: OFF
Parameters:
ON
Ring the terminal when packets appear from call signs listed in MFROM or
MTO.
OFF
Don't ring the terminal when packets appear from call signs listed in MFROM
or MTO.
MBELL permits the terminal operator to be alerted when packet frames from a selected station or
group of stations appears on the monitored radio link.
When MBELL is set to OFF, packet frames are monitored normally according to the MFROM and
MTO callsign lists.
When MBELL is set to ON, packet frames are monitored FROM and TO all. If call signs in the moni-
tored headers match the MFROM or MTO lists, the PK-88 sends three BELL characters <CTRL-G>
to the terminal.
Use MBELL ON to alert you to the presence of a specific station on the radio channel. Examples of
typical applications are:
To detect when station WX1AAA is present, set:
MBELL ON
MONITOR 4
MFROM YES WA1XXX
MTO NONE
