PSK Reporter

Lore & Background

PSK Reporter takes its name from the popular amateur radio digital mode PSK31. The platform supports numerous digital modes, but the vast majority of digital reports recorded by the service are FT8 traffic. Most traffic recorded on PSK Reporter is in the HF amateur radio bands, but the platform also supports MF, VHF, and UHF bands. As of 2021, PSK Reporter had collected over 20 billion reception reports.

The website works by collecting digital signal reports from software clients such as WSJT and FLDIGI, then mapping them to show which stations are being heard by other clients. This allows operators to see where their radio signals are being received in near real time.

Reporting networks such as PSK Reporter allow researchers in near real time to evaluate space weather conditions, particularly changes in the earth's ionosphere. Observations made during the 2017 eclipse included over 5,000 amateur radio operators' reception reports, which helped researchers document the eclipse's effect on HF communications.

Reader's Guide

PSK Reporter's significance lies in its dual role as both a practical tool for amateur radio operators and a valuable resource for scientific research. For operators, it provides immediate feedback on where their signals are being heard, enabling them to assess propagation conditions and antenna performance. For researchers, the platform's massive dataset—over 20 billion reception reports as of 2021—offers a near-real-time window into space weather and ionospheric changes. The platform has been used to study the effects of the 2017 eclipse on HF communications, drawing on over 5,000 amateur radio operators' reports. Additionally, PSK Reporter data has been applied to research in UHF and VHF radio propagation, to improve machine learning algorithms that predict HF propagation, and to evaluate and test the performance of installed antennas. Its support for multiple bands (MF, HF, VHF, UHF) and digital modes, though now dominated by FT8 traffic, makes it a versatile tool for understanding radio wave behavior across the spectrum.

Did You Know?

• PSK Reporter was started by Philip Gladstone in 2014.
• As of 2021, the platform had collected over 20 billion reception reports.

Origins and the Open-Source Transition

Joe Taylor, known by his call sign K1JT, first released WSJT in 2001 as a tool for weak-signal amateur radio communication. The program went through several major revisions over the years, with communication modes being added and removed as the software evolved. A pivotal shift occurred in 2005 when the software was re-licensed under the GNU General Public License, making it open source. This transition demanded substantial rewrites that consumed several months of work. While Taylor remains the project's maintainer, a small team of programmers now collaborates on development. The latest WSJT version is written in Python and C, with certain utilities implemented in Fortran. The software's evolution also brought dramatic structural changes: WSJT7 (versions up through 7.06 r1933) bundled sixteen different modes, while WSJT8 (version 8.0 onward) completely overhauled the mode set to just five—JTMS, ISCAT, JT64A, JT8, and Echo—none of which were back-compatible with earlier releases. By May 2018, the project had reached WSJT10.

Fast Modes and Meteor Scatter Communication

WSJT's fast modes—character-by-character transmissions without error correction—include FSK441, JT6M, JTMS, and ISCAT. FSK441, the very first mode shipped with WSJT in 2001, was purpose-built for meteor scatter communication, exploiting brief radio-reflecting trails left by meteors. These signal bursts, colloquially called pings, can last as little as one-tenth of a second yet carry enough data to complete at least one stage of a contact. The mode uses four-tone multi-frequency shift keying at 441 baud and is self-synchronizing, relying on a space character in the message as a syncword rather than a dedicated synchronization tone. Operators typically deploy FSK441 on the 2-meter and 70-centimeter bands, reaching distances up to 1,400 miles at nearly any time of year, with no active meteor shower required. JT6M, added in late 2002, targets similar ionospheric scattering but is especially optimized for the 6-meter band, employing 44 tones—one for sync, 43 for data—at a symbol rate of 21.53 baud. Both modes were eventually removed from WSJT-X as of version 2.1.2.

Slow Modes, FEC, and the Moonbounce Revolution

The slow modes in WSJT prioritize minimal high-power usage, optimizing for extremely weak signals. JT65, developed and released in late 2003, stands as the flagship example, designed for troposcatter and Earth-Moon-Earth (EME, or moonbounce) paths. Its defining technical achievement is the ability to decode signals many decibels below the noise floor within a 2,500 Hz band, enabling amateurs to exchange contact information even when the signal is inaudible to human ears. Messages are compressed, then encoded with Reed-Solomon forward error correction, which adds redundancy so that an entire message can be recovered even if some bits are lost. This produces a binary outcome: the message decodes correctly or it does not, with very high probability. Transmission uses 65-tone MFSK. Beyond its original EME purpose, operators adopted JT65 for HF-band contacts using QRP, a use the software did not originally anticipate. Its popularity prompted the addition of several new features to WSJT specifically to facilitate HF operation.

Spotting Networks, Propagation Testing, and Ecosystem Reach

WSJT and its successor WSJT-X are not merely standalone decoding tools; they are embedded within a broader amateur radio ecosystem. One key integration is the ability to transmit signal reports to spotting networks such as PSK Reporter, allowing operators to share weak-signal contacts with the wider community in real time. This reporting capability transforms individual QSOs into collective knowledge about propagation conditions. The software also includes dedicated modes for propagation measurement and testing: WSPR and Echo, the latter specifically designed for testing moon-bounce echo. The project's open-source nature, maintained by a small collaborative team under the GPL, means improvements propagate quickly across the global amateur community. The split between WSJT (now at version 10) and WSJT-X (the experimental successor that introduced JT9, FT8, and QRA64) reflects ongoing evolution where new modes are trialed before stabilization. The digital signal processing techniques at the core of these programs have made exotic propagation modes—high-speed meteor scatter, moonbounce, and beyond—substantially more accessible to everyday amateur operators.