Instruction manual

MFJ-1289 Multicom User's Manual Page 46
During any binary file transfer, the transmitting station can keep a record of the
elapsed time, speed, baud rate, and effective baud rate throughput This display
appears in the upper left window while the binary file is being transmitted. After
the completion of the file transfer, a new line will appear in the bottom window
which will display the final computation of the "effective baud rate" Remember,
this "effective" baud rate considers only the data that was actually saved to disk,
otherwise known as the "usable data."
If some of the figures you encounter seem small compared with other data
transfer modes or systems, remember that in packet radio, AX.25 HDLC uses a
simplex mode of operation; each station in a connected stream will have to stop
while each packet of information is acknowledged by the distant, connected
station.
Also, consider that each packet contains the destination callsign, the origination
callsign, the path information (digipeaters and nodes), and the Frame Check
Sequence (FCS) This data is not part of the usable data, and it presents each
packet of information with an "overhead" that may seem larger than with other
systems. However, this overhead is necessary since it is responsible for seeing
that each packet arrives intact at the correct destination.
With a tool of this kind built into the terminal software, you can test many
different combinations of TNCs, radios, computers or the throughput of different
packet frequencies to determine the best links or paths to use for binary transfers.
<F9> This is a "hotkey" to the MFJPIC digitizer software. From
MFJPIC, you may press <Alt> +X to return to the terminal
screen.
<F10> "PMPX" Packet Multi-Plex. This is a very special feature of
MULTICOM that enables you to send a one-line message to the
connected station during a binary file transfer. This one-line
message will, in no way, become part of the file being