Packet

At present, MultiMode decodes 300 and 1200 baud packet. It can also transmit Unnumbered Information (UI) packets. It is designed to show all packets that are received, and does not attempt to organize them, as a TNC would, into the correct stream of data. All packets, including supervisory, are shown. 

By selecting the DEBUG mode, even packets with bad checksums are displayed. 

By selecting the INFO mode, only information packets are displayed. Supervisory packets are not displayed.

Below is an example of some packet transmissions copied off of HF (300 baud) on 14099 kHz:
 
[   RR ] [ AJ0O  7 ][ W6OAV ? ]   
[    I ] [ W6OAV ? ][ AJ0O  7 ]   DX de lu6hdf:    14260.0  AY0N/X             
[   UI ] [ BEACON0 ][ AJ0O  0 ][ W0TX  0 ]   
[   RR ] [ EA8DW 2 ][ EA3RKD2 ]   
[    I ] [ W0TX  7 ][ W9UW  0 ]   SP W6OAV
[    I ] [ W6OAV ? ][ AJ0O  7 ]   DX de wa6yfd:    14217.3  RN6BY        
[    I ] [ W0TX  7 ][ W9UW  0 ]   Hello Bill...hope that all is we
[    I ] [ W0TX  7 ][ W9UW  0 ]   ll with you.  We had a very nice
[    I ] [ W0TX  7 ][ W9UW  0 ]    day here today.Sun and the high

The format is as follows:

[ type]  [ dest ] [ source ] [ digipeaters]    Message

Packet Types:
DISC       Disconnect Request
DM

Disconnected Mode
I             Information
FRMR     Frame Reject
REJ

Reject
RNR

Receive Not Ready
RR

 
Receive Ready
SABM
   Connect Request
UA          Unnumbered Acknowledge
UI

  Unnumbered Information

To transmit, enter transmit mode (from the menu, or command-T). Type a string, and then press enter, the string is sent. The destination callsign is "CQ", and your callsign (from preferences) is used. If you have enabled one of the serial ports to serve as the PTT line, that handshake line will be used. Right now, the delays between turning on PTT and transmitting, and after transmitting and before turning off PTT are around 400 milliseconds, fixed.

MultiMode uses the following standard tone pairs:

HF (300 baud):        2110 / 2310 Hz
VHF (1200 baud):   1200 / 2200 Hz

For VHF this isn't a problem. For HF, you need to make sure your receiver is properly tuned. The FFT mode is handy for checking the tuning.