Signal Hopping Jammers on HF Frequecnies
Signal Jamming on HF Bands 0-30MHZ - A Research Project
Research in to HF Signal Jamming, frequency hopping jamming on military bands. Who is doing it and what is the effect
Signal jammers are commonly associated with GPS and GSM bands used by criminals and in conflict but HF is a different challenge because its much lower frequencies and the large transmitters and antennas required make effective HF jamming a far more resource-intensive activity. Because HF signals propagate via the ionosphere and groundwave, transmissions (and therefore hostile interference) can travel extremely long distances; a jammer located in Russia, for example, could potentially disrupt maritime operations in the Atlantic.
HF matters because it provides long-range links that other bands cannot. Aviation and maritime long-distance communications, weather broadcasts, search-and-rescue at sea, and many other long range missions routinely rely on HF radio so disruption in these bands can directly degrade safety-critical communications and essential services.
Every day HF jamming is audible across Europe. The signal characteristics, such as signal strength, bandwidth and consistent fade patterns and timing that match daily ionospheric propagation indicate a long-range source. Using a rotatable antenna array makes it possible to determine the jamming signals source of direction, this is done by tracking the direction of maximum signal strength over time and using different receiving stations.
What is HF Long Range Signal Jamming
HF (high frequency, ~3–30 MHz) is the long-range radio band militaries use for beyond-line-of-sight command and control. Frequency-hopping (FH) on HF means radios rapidly switch carrier frequencies according to a shared pseudo-random sequence so individual frequencies are only used briefly, which raises the cost and complexity for any jammer trying to deny communications.
Who’s doing HF jamming: state actors and capable regional militaries are the primary users of long-range HF jammers, while frontline forces, proxies and even some non-state groups deploy smaller, software-defined and portable systems; in modern conflicts both large strategic jammers and distributed tactical jammers have been used to shape or deny HF comms.
How HF jamming against FH nets is done: adversaries employ a mix of techniques from high-power broadband/barrage jamming to raise the noise floor across many hops, partial-band or sweep jamming to deny likely hop regions, reactive/follower jammers that detect and attempt to follow active channels, and intelligent SDR-based jammers that prioritize frequencies based on signal analysis with each approach trading off power, range and sophistication.
Why is HF Jamming Different to Typically known GPS and GSM Jamming
HF matters because it provides long-range links that other bands cannot. Aviation and maritime long-distance communications, weather broadcasts, search-and-rescue at sea, and many other long-range missions routinely rely on HF radio so disruption in these bands can directly degrade safety-critical communications and essential services.
Why HF is different: HF propagation depends on ionospheric and groundwave conditions that vary by time, season and space, so effective HF jamming requires adapting power, antenna direction and timing, long-range denial typically needs larger antennas or distributed nodes, and multipath, Doppler and propagation delays make rapid follower jamming on HF technically harder than at VHF/UHF.
Observed effects on military HF FH nets: jamming causes dropped or delayed messages, repeated retransmissions, reduced throughput and fractured command-and-control, forcing units into emission control, scheduled or burst communications and alternate methods; smart jammers can selectively deny high-value nets while barrage jammers create broad “no-go” spectral zones that disrupt many users.
Subject: Call for Interest — DIGITPOL RF Team: HF Jamming Detection & Forensics (Expert Collaboration)
DIGITPOL’s RF Team invites qualified RF/signal analysis experts to express interest in a collaborative research project on HF jamming detection, investigation and forensics. Our goal is to produce a practical, scientific paper for law enforcement agencies (LEA) that documents detection methods, attribution approaches, measurement best practices, and mitigation recommendations. If you have expertise in HF propagation, signal processing, spectrum monitoring, direction finding, measurement validation, or criminal/evidentiary procedures, please submit a brief expression of interest to our email info @ digitpol.com