In amateur radio , QRP operation refers to transmitting at reduced power while attempting to maximize one's effective range. QRP operation is a specialized pursuit within the hobby that was first popularized in the early s. Reliable two-way communication at such low power levels can be challenging due to changing radio propagation and the difficulty of receiving the relatively weak transmitted signals. QRP enthusiasts may employ optimized antenna systems, enhanced operating skills, and a variety of special modes, in order to maximize their ability to make and maintain radio contact. Since the late s, commercial transceivers specially designed for QRP operation have evolved from vacuum tube to solid state technology. A number of organizations dedicated to QRP operation exist, and aficionados participate in various contests designed to test their skill in making long-distance contacts at low power levels.

Amateur radio has a lot of different sub-disciplines, ranging from volunteering for public service gigs to contesting, the closest thing the hobby has to a full-contact sport. With QRP you can literally talk with someone across the planet on less power than it takes to run a night-light using a radio you built in an Altoids tin. QRP takes its name from the Q-codes developed as shorthand by early Morse operators. Generally, any radio capable of transmitting at 5 watts or less would be considered a QRP rig, although some argue for anything below 10 watts.

PSK31 is a highly-efficient data mode that lets you work long distances, even when you can barely hear the signal. Unlike RTTY radio teletype the characters are formed by changing the phase of the sound wave, not by using different tones. It works very well with low power levels and for this reason it has become a firm favourite for QRP and stealth antenna operators. The mode was enthusiastically received and has since quickly spread into worldwide use.