MFJ-1270C/1274C MANUAL BASIC OPERATION
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Here the user mis-typed the first three characters of the call sign and rubbed
them out. The MFJ TNC displayed "\" for each character rubbed out. The user
then retyped the characters correctly and redisplayed the line. He finished typing
the call sign on the new line. The redisplay-line character can be changed to any
ASCII character by the command REDISPLA.
If the MFJ TNC displays information faster than you can read it before it scrolls
off the screen, you can halt the display by typing <CTRL-S>. To resume
output from the MFJ TNC to your computer, enter <CTRL-Q>. These
characters can be changed to any ASCII character by the commands STOP and
START, respectively.
You may occasionally want to include one of the special input characters in a
packet. For example, to send several lines at once in the same packet, you would
have to include <CR> in the packet at the end of each line, bypassing its "send-
packet" function except at the actual end of the packet. You can include any
character in a packet including all special characters by prefixing it with the pass
character, <CTRL-V>. For example,
I wasn't at the meeting.<CTRL-V><CR>
What happened?
Ordinarily, this message would be sent as two packets. By prefixing the first
<CR> with <CTRL-V>, the operator sends it all at once, but maintains the <CR>
in the text. The pass character can be changed to any ASCII character by the
command PASS.
We will discuss operation of packet in more detail in the next chapter. For now
let us discuss the operation of HF packet with the MFJ TNC.
HF Packet Basic Operation
The requirements for optimum performance with a typical HF or OSCAR 10
path are very different compared to local VHF FM environment. Lower signal to
noise ratios require lower baud rates, noise spikes and fades require shorter
packet lengths, and a higher rate of false carrier detects lowers the total usable
dynamic range in the audio input. The MFJ TNC hardware and software are
configured to improve throughput in these environments. The MFJ TNC s
settings of MAXFRAME and PACLEN provide the possibility of several
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