Overview

Using a station set up for sound card digital modes, text messages and e-mails are transferred by radio operators in a Keep It Simple Stupid format. It puts to work the latest in RTTY keyboard type modes with a minimum of technology and one program interface does many different modes, no knowledge of packet commands, and can pass a message with any station capable of CW, psk-31, Hellschreiber, RTTY, MFSK, or MT63. They don't have to have the same software.

Assuming you already have the interface for computer sound card to radio, you need to determine whether to run the Linux version (prefered since it will do more modes), or the Windows version. Try the EMCPup Linux live CD. Will your computer run it and does sound work...can it be made to work well without pulsing on transmit? Also, a matter of personal preference and ability...if you know Windows well and have a hard time learning another operating system, you may want to choose the Windows version. If all you have is a 2 meter FM radio and no HF, then use the Windows version, as all you will use for text on FM is PSK-125 or 250.

This is a complete operating system. For details see the help file I put on the OARS website.

NBEMS Windows program suite (vbdigi,flarq,Outlook Express)

You can download and install on your computer.

The semi-automatic e-mail handling using fldigi(or vbdigi), flarq, and e-mail (sylpheed) works well on FM mode and PSK-125 or 250 with a full-quieting signal. Relaying from station to station is easy by select, copy from receive window , and paste to transmit window. With some practice, a net can handle text traffic fairly efficiently. Text speed is in excess of 100wpm.

For SSB operations it works best without the ARQ, as one error prevents stations from connecting. Just running the fldigi/vbdigi alone allows operators to find the mode that gives the best copy by sending a test message and looking for wrong or dropped characters. In reality, we found consistent best results by using MT63-1000 which is the most robust digital mode of all the sound card modes. If you can hear the other station on voice, then MT63 should get through with perfect copy...no need for ARQ handshaking because errors are corrected by the interleaved signal. Typically, MT63 is like spread-spectrum...it gives perfect copy until it just falls apart below a certain threshold. Navy Mars has gone to preferring MT63 over Pactor. In fldigi MT63 is easy to tune...just get the signal between the lines and click. After a few seconds text will start to print.

If for some reason, stations cannot get good copy of text, there is the feldhell mode which will get it through without errors, but you have to hand-copy the text off the screen as hellschreiber copy is actually an image file rather than text, and the lines are doubled. Fading will just give fades to gray but no garbled characters.

All stations need to know specific clear channel frequencies for message transfer. An ad-hock network can use a single voice channel to negotiate who uses what digi channel, or there can be one 2Khz channel for PSK-31 beacons from each station, 100Hz apart. Beaconing stations set the PSK viewer to watch for a station located for where they wish to direct some traffic, then call and negotiate a clear channel to go and pass the traffic.

Net could also be directed by a net control station who would scan the channel assignments and direct pairs of stations to a clear channel for traffic. I have reviewed the band plans for 28 and 50 Mhz and developed a scheme for this activity. As much as possible, use 28 Mhz and above for the local traffic, with regional and long distance being handled by a limited number of stations on HF, as it is harder to find a clear frequency there. If a decent signal path can't be had or by relay for a 30 mile local contact, then use 80 or 40 meters NVIS. It is also possible perhaps to send short text messages by repeaters as long as the audio from the originating station is compatible with the repeater.