Radiotele­type (RTTY — often pro­nounced “Rit­ty” ) is a ven­er­a­ble data com­mu­ni­ca­tion mode that remains in wide use today among radio ama­teurs. While RTTY does not sup­port the fea­tures of new­er com­put­er-based data modes, it is well suit­ed for key­board to-key­board chats with oth­er sta­tions. It is also the most pop­u­lar mode for world­wide dig­i­tal con­tests and remains in com­mon use among DXers and DXpe­di­tions. RTTY was orig­i­nal­ly designed for use with mechan­i­cal teleprint­ers, pre­dat­ing per­son­al com­put­ers by sev­er­al decades. Today, Ama­teur Radio RTTY uses sound­card-equipped com­put­ers and ded­i­cat­ed RTTY soft­ware.

An HF dig­i­tal mode for gen­er­al domes­tic and DX con­tacts is PSK31. This mode is par­tic­u­lar­ly effec­tive for low-pow­er (QRP) com­mu­ni­ca­tion. It’s easy to trans­mit and receive PSK31 using a PC and soft­ware — typ­i­cal­ly free — that oper­ates via a PC sound­card. Quite a few dif­fer­ent dig­i­tal modes use the same basic PC and sound­card set­up, and new ones are devel­oped on a reg­u­lar basis.

Anoth­er dig­i­tal mode, pack­et radio, is much less pop­u­lar in today’s ham radio world than it was in the 1990s. Packet’s most impor­tant appli­ca­tions include net­work­ing and unat­tend­ed oper­a­tion. The most com­mon uses are the world­wide DX Clus­ter net­work, the Auto­mat­ic Packet/Position Report­ing Sys­tem (APRS) and region­al or local gen­er­al pur­pose net­works. Would you like to see what 20 meter sta­tions in Asia have been worked or heard recent­ly by sta­tions in your area? Log onto your local DX Clus­ter node and find out. Is your friend out of range of your 2 meter pack­et radio? Send your mes­sage through the pack­et net­work.

APRS Devel­oped by Bob Bruninga, WB4APR, APRS or the Auto­mat­ic Packet/Position Report­ing Sys­tem (aprs.org) is used for track­ing sta­tions or objects in motion or in fixed posi­tions and for exchang­ing data. It uses the uncon­nect­ed pack­et radio mode to graph­i­cal­ly indi­cate objects on maps dis­played on a com­put­er mon­i­tor. Uncon­nect­ed pack­ets per­mit all sta­tions to receive each trans­mit­ted APRS pack­et on a one-to-all basis rather than the one to-one basis required by con­nect­ed pack­ets.

As with oth­er pack­et trans­mis­sions, APRS data are relayed through sta­tions called digi­peaters (dig­i­tal repeaters). Unlike stan­dard pack­et radio, APRS sta­tions use gener­ic digi­peater paths, so no pri­or knowl­edge of the net­work is need­ed. In addi­tion, the Inter­net is an inte­gral part of the sys­tem that is used for col­lect­ing and dis­sem­i­nat­ing cur­rent APRS data in real time.

Vir­tu­al­ly all VHF APRS activ­i­ty occurs on 2 meters, specif­i­cal­ly on 144.39 MHz, the rec­og­nized APRS oper­at­ing chan­nel in the US and Cana­da. On UHF, you’ll find APRS activ­i­ty on 445.925 MHz. Many groups and indi­vid­u­als that par­tic­i­pate in pub­lic ser­vice and dis­as­ter com­mu­ni­ca­tions find APRS a use­ful tool. Oth­ers use it to view real-time weath­er reports


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