2026-04-18
Added a live global shipping map powered by the Automatic Identification System (AIS), one of the most critical radio systems in the world. AIS operates on two dedicated VHF maritime channels: 161.975 MHz (Ch.87B) and 162.025 MHz (Ch.88B). Every large vessel — cargo ships, tankers, container ships, cruise liners, and naval vessels — is required by international law (IMO SOLAS) to continuously broadcast its position, course, speed, heading, and identity using a self-organizing TDMA (Time Division Multiple Access) protocol. Ships transmit every 2–10 seconds while underway, and every 3 minutes while at anchor. The system was developed in the 1990s by a Swedish inventor and adopted internationally in 2004. Shore-based AIS receivers along coastlines pick up these VHF transmissions and relay them to tracking networks, while satellite AIS receivers extend coverage to the open ocean. The result is a real-time picture of virtually every commercial vessel on Earth. AIS is a prime example of how VHF radio enables global infrastructure — the same frequency band used by FM broadcasting, aviation, and emergency services. Our embedded map centers on the Strait of Hormuz, the world's most strategically important maritime chokepoint, through which 20% of the world's oil supply transits daily. Visit dxtra.com/ships to see live vessel positions worldwide.
2026-04-13
Added a real-time FM-specific tropospheric ducting forecast map covering the entire continental United States. Tropospheric ducting (tropo) is a weather-driven phenomenon where temperature inversions in the lower atmosphere create an invisible waveguide that bends FM radio signals beyond the horizon. During a tropo opening, stations that are normally limited to 40–60 miles of coverage can suddenly be received at 100, 200, even 500+ miles — with full stereo audio and station identification. For FM DX enthusiasts, hunting tropo openings is the ultimate radio sport: point a directional Yagi antenna toward the coast, monitor signal levels, and wait for the atmosphere to deliver stations from hundreds of miles away. Our forecast uses NOAA GFS atmospheric model data processed through the ITU-R P.453 radio refractivity formula, filtered specifically for the FM band (88–108 MHz). Unlike generic VHF/UHF forecasts, we only show duct layers thick enough (>50m) to trap FM wavelengths. The forecast map updates every 6 hours and includes regional zoom buttons for East Coast, Gulf Coast, Great Lakes, Pacific Coast, and Florida — all prime tropo territory. Combined with our live automated scanner (8-element Yagi, Airspy HF+ SDR, GNU Radio RDS), dxtra.com is the only site that provides both forecast AND live measurement of FM tropospheric ducting. Our first confirmed catch: WGBZ Ocean City, MD at 186 miles with full RDS decode. Visit dxtra.com/tropo to see the live forecast, signal analysis, and confirmed tropo events.
2026-04-12
Launched an automated tropospheric ducting detection system for FM radio DX. Tropospheric ducting (tropo) occurs when a temperature inversion in the lower atmosphere bends VHF radio signals beyond the horizon, allowing FM stations to be received at distances of 100 to 500+ miles — far beyond their normal 40–60 mile groundwave range. Our system uses an 8-element Innova Yagi FM antenna at 40 feet feeding an Airspy HF+ software-defined radio (SDR) with a GNU Radio RDS decoding engine. The scanner sweeps the entire FM band (87.9–107.9 MHz) every 27 minutes, measuring signal strength in dBuV, decoding RDS station identification, and computing distance to each transmitter. Statistical analysis uses robust z-scores (Median Absolute Deviation) to detect anomalous signal enhancement — when a station reads 2 or more standard deviations above its baseline, it indicates atmospheric propagation enhancement. Multiple anomalous stations simultaneously confirms a tropospheric duct. Our first confirmed detection: WAYV 95.1 MHz Atlantic City, NJ received at 103.9 miles with +8.3 dB enhancement above baseline. Tropo DXing is most productive along coastlines during late spring and summer, when warm air masses move over cooler ocean water. The U.S. East Coast, Gulf Coast, and Great Lakes regions are prime territory. A directional antenna (Yagi) is essential for serious FM DX work — it focuses reception in the direction of the duct and rejects interference from other directions. Visit dxtra.com/tropo to see live scan results, signal baselines, z-score analysis, and confirmed tropo events in real time.
2026-03-29
Added terrain-aware coverage maps for all 1,035 NOAA Weather Radio transmitters across the US. NWR broadcasts emergency weather alerts on 162.400–162.550 MHz — when cell towers and internet fail, these are your lifeline. Three coverage scenarios computed with Longley-Rice: Handheld (weather radio or HT with rubber duck, 50 mi), Portable Yagi (foldable directional for backpackers, 7 dBi, 75 mi), and Fixed Yagi (EOC or home station, 10 dBi, 100 mi). The difference is dramatic in mountainous terrain — a handheld in a valley may lose NWR entirely while a Yagi on a ridge reaches stations 60+ miles away. Links directly to our IPAWS live alert monitoring. Try it at dxtra.com/nwr.
2026-04-09
Launched a comprehensive TV station database with 2,158 FCC-licensed DTV transmitters across all 50 states, DC, Puerto Rico, Virgin Islands, and Guam. Every station has terrain-aware Longley-Rice coverage maps with city-grade and DX contours plus full signal strength heatmaps — the first site to offer this since TV Fool went offline. Search by callsign, channel number, zip code, city, state, or network (ABC, NBC, CBS, FOX, PBS, CW). Coverage data includes 1,750 full-power DTV stations, 399 Class A, and 9 digital translators. FCC OET-69 Grade B thresholds: VHF-Lo 47 dBuV/m, VHF-Hi 56 dBuV/m, UHF 64 dBuV/m. Try it at dxtra.com/tv.
2026-03-28
Launched a comprehensive amateur radio repeater directory with 12,621 repeaters across all 50 states. Data sourced from the Amateur Repeater Directory (ARD) and RadioID.net, cross-referenced with EchoLink node data. Includes FM analog, DMR digital, and EchoLink-enabled repeaters with ARES/RACES/Skywarn emergency designations. Every repeater has three Longley-Rice terrain-aware coverage maps: HT (5W handheld with rubber duck, 15 mi), Mobile (50W with mag-mount, 40 mi), and Base with Yagi (50W with 13 dBi directional, 60 mi). 37,491 coverage contours computed in 13 minutes on our compute cluster. Search by zip code, city, or callsign with radius filtering. Try it at dxtra.com/repeaters.
2026-03-27
Added the pre-conflict IRIB (Voice of the Islamic Republic of Iran) English shortwave schedule to the About page. Nine frequencies from the Sirjan and Kamalabad transmitter sites targeting Europe, North America, and South Asia. Our shortwave database also includes 124 IRIB entries across all languages, plus broadcasts into Iran from BBC Persian, Voice of America/Radio Farda, and clandestine opposition stations broadcasting from relay sites in Armenia, France, Bulgaria, and Uzbekistan. Historical reference preserved as transmitter sites may be damaged or off the air following the 2026 conflict. See dxtra.com/about.
2026-03-26
Built a full Longley-Rice terrain-aware simulation of a FEMA emergency communications deployment in the mountains around Asheville, North Carolina following Hurricane Helene (September 2024). Models 8 deployable assets — FirstNet COWs, VHF/UHF repeaters, MERS mobile command, ARES amateur radio, SatCOLT, and an AT&T Flying COW tethered drone at 100m AGL. Each asset's coverage is computed over real SRTM 30m elevation data at 125-meter resolution, showing terrain shadows in Blue Ridge Mountain hollows and valleys. Click anywhere on the map to probe signal strength from all deployed assets. Toggle individual assets and coverage gap overlays to visualize deployment effectiveness. Explore at dxtra.com/disaster/asheville.
2026-03-26
Added live FEMA IPAWS emergency alert monitoring with interactive map, severity filtering, and a new location-based audio alert system. Set your location and enable Audio Alerts to receive audible notifications when new emergency alerts intersect your position — point-in-polygon intersection against alert boundaries or proximity check for centroid-only alerts. Extreme/Severe alerts trigger an EAS-style urgent tone; Moderate/Minor alerts produce a gentler chime. Data sourced from the National Weather Service API, updated every 5 minutes. Try it at dxtra.com ALERTS.
2026-03-21
New AM band quick-access buttons for FEMA Primary Entry Point (PEP) stations and AM Clear Channel stations. PEP stations are ~77 high-power AM stations designated by FEMA as the backbone of the Emergency Alert System (EAS), equipped with hardened facilities and backup generators to remain on-air during catastrophic events. Clear Channel stations are the legendary Class I-A and I-B stations allocated under the 1941 NARBA treaty — including international allocations to Mexico (XEW, XEG, XEB) and Canada (CJBC, CBW, CBR). Both features include educational info panels with links to FEMA IPAWS, FCC, and Ready.gov. Try them at dxtra.com AM.
2026-03-21
We ported the VOACAP (Voice of America Coverage Analysis Program) ionospheric propagation engine to run on NVIDIA GPUs using CUDA and CuPy. VOACAP is the gold standard for HF (shortwave) propagation prediction, used by broadcasters, amateur radio operators, and military planners since the 1980s. The original Fortran code processes one frequency/site/hour grid at a time on a single CPU core. Our GPU implementation runs the full VOACAP electromagnetic model — including ionospheric layer MUF/LUF calculations, D-layer absorption, E/F-layer multi-hop ray tracing, antenna gain patterns, and statistical reliability estimation — as massively parallel CUDA kernels on an NVIDIA RTX A5000 (24 GB VRAM). A single CPU core computes one propagation grid (the entire world at 2.5° resolution) in ~6-7 minutes. Our GPU engine computes the same grid in ~2.7 seconds — a ~150x speedup. This allowed us to compute the full shortwave coverage matrix of 3,657 HF transmitter/frequency combinations across all 24 hours (87,768 grids total) in approximately 3 days, a task that would have taken over a year on a single CPU core. The results power the LIVE shortwave view, showing real-time receivability predictions for every shortwave station on the planet. Technical details: float16 reliability and SNR grids stored as compressed NumPy .npz files; live solar flux index (SSN/SFI) from NOAA SWPC; ITU Gaussian curtain array TX model (18 dBi peak at 30°); dipole RX model at 30 ft with frequency-dependent height factor. Try it: dxtra.com/sw LIVE view.
2026-03-20
Added ~1,000 FM and ~190 AM Argentine radio stations from WorldRadioMap across 11 cities. Covers Buenos Aires, Córdoba, Rosario, Mendoza, Salta, Tucumán, Santa Fe, La Plata, Mar del Plata, Bahía Blanca, and Ushuaia. Interactive map with coverage maps. Browse at dxtra.com/ar.
2026-03-20
New personalized feature: click the star icon on any AM or FM station to add it to your My Radio page. Your favorites are saved in your browser and sync across visits. Build your own custom station list, see coverage maps at a glance, and get a personalized RSS feed of your saved stations. Try it at dxtra.com My Radio.
2026-03-20
Added 1,106 FM and 10 AM South African radio stations from the ICASA Terrestrial Broadcasting Frequency Plan. Includes Public (SABC), Commercial, and Community stations across all nine provinces. Full Longley-Rice terrain-aware coverage maps computed for all stations. Browse at dxtra.com/za.
2026-03-20
Added 1,641 FM and 140 AM Chilean radio stations from SUBTEL (Subsecretaría de Telecomunicaciones). Covers all 15 regions from Arica y Parinacota to Magallanes. Full Longley-Rice terrain-aware coverage maps with SRTM elevation data for the Andes and Chilean coast. Browse at dxtra.com/cl.
2026-03-17
Added 2,864 FM and 380 AM Australian radio stations from the ACMA Register of Radiocommunications Licences (RRL). Data includes National (ABC/SBS), Commercial, Community, and Retransmission services across all states and territories. Coverage maps and Longley-Rice propagation contours are being computed for all stations. Browse at dxtra.com/au.
2026-03-16
New elevation profile panel on FM coverage map pages. When you set your location, a Google Earth-style terrain cross-section appears showing the path between you and the transmitter. Includes line-of-sight analysis with 4/3 earth curvature correction, 1st Fresnel zone clearance, transmitter tower height, and your antenna height (adjustable: indoor 3m, car 1.5m, DX 10m). Toggle via the checkbox in the map legend.
2026-03-17
Completed Longley-Rice ITM propagation contours for all 46,852 FM stations across US, Europe, UK, Brazil, and Australia. Computed on a Dxtra in-house multi-CPU cluster running Linux at 9.7 stations/second with zero errors. Both 60 dBu (city-grade) and 40 dBu (DX) contours are available on every station's map page.
2026-03-16
Loaded Brazilian radio stations from ANATEL's open data portal. Includes FM and AM (Onda Media) stations across all 27 states. Coverage maps with Longley-Rice terrain-aware propagation. Browse at dxtra.com/br.
2026-03-14
Added 22,000+ European FM stations from BNetzA data covering 32 countries. Each station has terrain-aware Longley-Rice coverage maps and directional antenna patterns. Browse at dxtra.com/eu.
2026-03-13
Loaded UK radio stations from Ofcom's TxParams data. Includes FM (VHF) and AM (MW) services with full transmitter site details, ERP, antenna heights, RDS PS/PI codes, and OS Grid Reference coordinates. Longley-Rice coverage maps for all stations. Browse at dxtra.com/uk.
2026-03-12
Replaced simple HAAT-based coverage circles with full Longley-Rice Irregular Terrain Model (ITM) propagation. Coverage maps now account for actual SRTM terrain elevation data along each radial, atmospheric refractivity, ground conductivity, and frequency-dependent path loss. Computed at 1-degree angular resolution with 0.3 km terrain sampling.
2026-03-10
New shortwave band with 5,440 transmitters and 12,903 schedules. LIVE view shows all receivable stations ranked by VOACAP ionospheric propagation reliability. Full VOACAP computation across 3,657 HF frequency/site combinations over 24 hours on a Dxtra in-house multi-CPU cluster running Linux. Try it at dxtra.com/?band=sw.
2026-03-09
Added full-coverage PNG heatmap overlays for FM stations. These show signal strength across the entire coverage area as a color-coded overlay on the map, computed from 360 Longley-Rice radials at 1-degree resolution. Available on every FM station's map page.
2026-03-05
Search FM stations by format: Country, Rock, Christian, News/Talk, Classical, Jazz, Hip-Hop, and more. ~9,600 stations indexed across ~15 major categories with location-aware results.
2026-03-04
Built in-memory indexes for city autocomplete, station lists, and FM format search. City lookups, station searches, and format browsing now complete in microseconds from in-memory caches.
2026-03-01
Launched dxtra.com with comprehensive US AM and FM radio station databases. 4,700+ AM stations with groundwave contours (M3 conductivity model) and ITU-R P.1147 skywave propagation. 12,000+ FM stations with coverage maps. Interactive search by call sign, frequency, city, state, or owner.