Hardware for Digital Modes

Most digital modes can be run with "sound card" software (below) which requires an interface (3 cables) to connect your radio to your computer's sound card. Interfaces can be homebrewed, made from a kit, or purchased. See club member Ralph NM5RM's (formerly KC2RLM) web site for information about these options: http://www.soundcardpacket.org/

Although NM5RM's site describes an interface suitable for 2 meter packet and the AGWPE packet program, the interfaces described will work for all digital sound card modes.

One advantage of pre-built interfaces or kits is that they will usually be designed to work for the radio you specify and you won't need to worry about "pin-outs", the connection points (MIC jack, data port) on your radio for received and transmitted audio and PTT control. If you homebrew an interface, you will need to determine the pin-outs.  Your radio's user manual should provide this or it may be on the internet. Club members can also help you sort it out.

A few modes, such as RTTY and packet, can be run with a special radio modem (a hardware device) that is designed for that mode. Some net participants may be using these hardware devices, instead of using a sound card program.

Software for Digital Modes

Net participants should have RTTY and PSK31 software, since these two modes are the most popular net modes. You should be able to find a club member willing to help you test out the software before you get on the net. There is a chart below which has information about download sites for these and other digital mode software programs.

If the net experiments with other modes they will probably be modes designed specifically for keyboard-to-keyboard/ "live" conversations (rather than transmissions of previously composed copy or files). These 'conversation' modes (such as RTTY, PSK31, MFSK16 and Hellschreiber) work well for 'round table' nets since everyone can 'listen in' to the transmitting station, and transmission rates are not slowed by protocols that check to make sure each station received perfect copy. In fact, it is a given that when using conversation modes, you will not receive perfect copy. Even if the transmitting station typed perfectly (rare!), other factors such as noise can produce errors. So please understand that what you receive is not necessarily exactly what was sent. Still, you can usually make out the meaning of the sender's message.

Other modes such as packet, PACTOR, and AMTOR were designed primarily for error-free transmissions. These 'error checking' modes are generally used in one-to-one situations where it is important to verify that the receiving station has received all data perfectly from the sending station. These modes are generally not used in 'roundtable' nets, since error-checking protocols are difficult to use where there are many receiving stations. (Note: Packet does have a special 'roundtable' mode called 'unconnected' or 'UI' mode).

Most sound card modes  were developed for use on HF frequencies. The wide variety of modes stems from the objective of achieving the ideal mode for various situations. Each of the modes has advantages and disadvantages in the areas of bandwidth, speed, accuracy, and resistance to the noise, fading and distortion that is common on HF frequencies.