APRS Digipeatersoftware DIGI_NED
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KISS use

When using KISS there are some special things you'll need to know. We will elaborate on this in this section .

Before you start AX25_MAC the TNC has to be switched on should have been set to KISS mode. AX25_MAC does not offer the option of putting the TNC into KISS mode. To set the TNC to KISS mode you can use an the external program like SETKISS (which can be in the TFPCX driver package for example).

AX25_MAC supports the KISS-enhancements SMACK (Version 1.0) and RMNC-CRC-KISS, which both improve the reliability of transfers between the TNC and the PC. SMACK or RMNC-CRC-KISS will be activated automatically if the connected TNC supports it. SMACK or RMNC-CRC-KISS is only activated when least 1 Frame has been sent and received.

With KISS, the Send-/Receive indicator does not show the send/receive status on the radio channel, but the send/receive status on the serial port to the TNC or to a connected other PC.

To couple two PCs together (e.g. one running a digipeater and another running a mailbox) you need a null-Modem-Cable. When using this setup AX25_MAC always works in duplex mode (the command @D is meaningless). The parameters should be setup accordingly. The following descriptions are mainly important for normal use with a TNC (no direct cable connection).

In KISS-Mode, AX25_MAC has no direct control over the radio channel, because the TNC is in between. AX25_MAC has no possibility to detect whether or not the frequency is free and when the frames to be sent are actually transferred, which may lead to unwanted transmissions. This may lead to two transmitters to come on air at the same time, despite the use of the '-L' flag. Since this will only be for a short duration when this happens, this is most likely not a big problem. If it is really an issue then do not use KISS or use a hardware interlock on the transmitters also.

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