Epson MFJ-1278B manual Connect, SPEEDup/SPEEDdown

MFJ-1278B MULTI-MODE BASIC OPERATION

To prevent Uncontrolled Disconnects, we are unable to listen to all kinds of third party Pactor transmissions for (WAIT x Cycle_Time) seconds after receiving the other side's last disconnect. This includes all unproto and connected packets, along with connect requests. The actual cycle time is 1.25 or 1.4 seconds.

CONNECT

[Connect] message: The MFJ-1278B monitors connect attempts received from other station's with a message containing the called station's callsign when idle. To successfully monitor a connect attempt to someone else, the called callsign must be at least 4 characters in length, and the signal be of sufficient quality that the 200 baud area be error-free when received. Unfortunately, the callsign in the connect-attempt packet (unlike all other monitored data) is subject to corruption; the Pactor protocol did not provide for error- free connect packets. Therefore, you may at times see a garbled callsign in a [Connect] message, but it should be rare. Remember, this "garbling" affects only monitored connect-attempt packets. It does NOT affect ARQ or FEC data packets because they are error-protected by a sophisticated CRC checking scheme.

SPEEDup/SPEEDdown

Speedup and speeddown: When the MFJ-1278B is the receiving station or IRS, and after four consecutive failures to receive a 200 baud packet the TNC requests a SPEEDDOWN to 100 baud. A SPEEDUP occurs when the MFJ-1278B receives 10 error free 100 baud packets. If NO200 is set to ON all SPEEDUP requests are inhibited

Bad band conditions: During poor band conditions links will be quicker by avoiding use of the 200 baud mode. Setting NO200 to ON instructs the MFJ-1278B to avoid 200 baud operation in a compatible way.

AUTOMATIC ON-LINE COMPRESSION

Huffman coding: Huffman coding offers somewhere between 2:1 and 4:1 compression on lower case German and English plain text. In receiving modes, conversion to 8 bit data is automatic.

On transmit, the MFJ-1278B packetizes outgoing data and transparently selects the mode. Huffman coding will be used if a) all data are 7 bit ASCII characters, and b) Huffman coding is at least as efficient as straight 8-bit coding.

FLOW CONTROL

Flow control: Hardware flow control is always on. Software flow control defaults to on using the XON and XOFF parameters. Unlike TNC operations, the same characters are used for receive flow control as for transmit flow control. Type-in flow control is only effective while entering commands at the "p_cmd:" prompt.