There are four key things any ham needs to run Digital Modes.
In order to run Digital Modes, you need a Radio capable of preforming some key functions. The Radio must first be able to operate at a high duty cycle (transmitting for up to three minutes at a time). This often means reducing power, or adding external fans to keep your rig cool. In addition, you must make sure your radio has a fairly clean audio output, so make sure to turn off the Speech Processor (if you have one), any sort of Microphone DSP and any ALC or Microphone Gain. Otherwise, your signal will be noisy and will interfere with others on the band. If you are not sure of your signal, ask others on the band, many will send you a picture of your waterfall, or will tell you if your signal is improving as you tune it.
Digital Modes rely on having a computer to generate the audio signals. Most computers will do nicely (even old ones). The computer needs to be able to run any Digital Software you plan on running, as well as Logbook Software. In addition, it must have either a built-in soundcard, or the ports for your radio interface.
The most essential part of any radio rig is the Digital Interface. The interface preforms a few key functions.
The most important is that it takes the sound data produced by the digital software and pipes it to the audio input of your rig, and takes the audio from the rig and pipes it to the computer’s line-in or microphone ports. Most operators use the computers soundcard to connect to the radio, although check with the manufacturer of your radio for their recommendations. Some rigs do not require a soundcard at all, whereas others need a different type of Soundcard than the one in your computer.
Secondary to this is PTT. Although you can manually press the PTT button every time you wish to send a digital signal, it becomes very tedious. One simple solution is to turn on the VOX operation in your radio, so whenever the computer sends digital information, the radio transmits. Many radios offer controller boards or control cables, which allow you to control the PTT via a cable to the computer or a wire connected to the microphone port of the Radio,
One unnecessary, but useful piece of equipment is a rig controller. This are made specific for your rig and allow for control of the Radio by the computer. This is useful as it allows you to easily jump to packet spots with the computer and allows the computer to automatically log the radio’s frequency.
There are many free and paid options for Digital Modes on the Market, each specific to the types of modes they can use. I recommend Digital Master (a part of Ham Radio Deluxe), as it integrates well with the HRD Logbook, and offers a more robust receiver and transmitting window than other programs. In addition, there are many softwares that are specific to one mode. JT65HF and AMTOR are both programs specific to one mode, and although less robust, are the only programs that can be used by that mode and are therefor essential.