DIGITAL

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