Kantronics MT1200, Руководство пользователя

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Linesub mode
LINESUB Protocol Description
The LSUB mode of operation provides a method of transmitting-and receiving raw
ASCII data via a radio. Data is sent and received in a totally transparent fashion,
allowing all ASCII characters to be utilized (hex 00 through hex FF). There is no
addressing, error-detection or automatic retransmission of the data. When the receiving
modem detects the proper Start-of-Data sequence generated by the transmitting
modem, it will output the data that follows to its; serial port. At the end of the received
data there is an End-of-Data sequence that permits the receiving modem to recognize
the end of the data and quit translating the receiver audio. This allows the modems to
operate with open squelch audio from the radios. Since the protocol constitutes a very
small portion of the transmission, the effective data throughput is very nearly that of the
radio baud rate (1200).
Commands Used
TXDELAY - The TXDELAY (TXD) command determines how long the modem must key
the Push-to-Talk line of the radio before sending data. This time will have to be
determined experimentally since it will vary from radio to radio. If the TXD is set too
short, the data transmitted will be garbled and not received by other units in the system.
Setting TXD too long will reduce channel capacity.
PACTIME - The PACTIME parameter determines how long the modem will wait after
receiving data to be transmitted from the DTE before beginning the radio key-up
sequence. Normally, this parameter should be set to AFTER 1 (100 ms.) in order to
minimize "dead-air" time on the system.
PERSIST and SLOTTIME - These parameters determine how aggressively the modem
will attempt to access a multi-user channel based on carrier detect. See KPC-series
manual for a full explanation of these parameters.
Entering LSUB Mode
When you have made any desired changes from the default settings for the above
parameters, use the INTFACE command to begin LSUB operation. Set the INTFACE
command to LINESUB:
cmd:INTFACE LINESUB <cr>
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