VLF/LF Sensing

VLF/LF Sensing

QFS has designed and built high performance and SWaP optimized sensing devices for the VLF (very low frequency) and LF frequency bands. Our technology is the best in class for performance in compact form factors, and its solid state nature enables robust configurations that can be deployed in various modalities, such as hidden under structures or buried. The technology can perform for various applications, so feel free to contact us to discuss yours.

GPS-Denied Navigation

Working under DARPA's S-BUG program, QFS built a number of VLF receivers optimized for positioning underground. The concept involved building a network to acquire lightning signals, which would then be triangulated to establish their position. Receivers underground capable of acquiring the lightning strikes' signals could use the established positions of those strikes to locate themselves. QFS's technology is capable of acquiring the low frequency components of lightning strike signals from 100s of miles away even when the sensors are functioning underground, and we have also developed a sophisticated clock system to ensure consistent timing between receivers in a network.


There is considerable interest in using VLF waves for communication in challenging situations. Although VLF waves can't transmit as much data as conventional radio waves, they travel further without signal degradation and can travel through media such as earth and water much more easily than the higher frequency waves generally used for communication transmissions. QFS has been involved in investigations into the feasibility of using VLF frequencies for communications underground, for example in mines and other underground facilities, and underwater. Please contact us to discuss how our world-class receiver technology can add value to your communications project.

Atmospheric Science

VLF/LF sensing offers some unique capabilities to the study of atmospheric phenomena such as lightning. Because lower frequency waves can travel great distances before they decay, detection networks covering large areas can be set up with only a few sensing devices. In addition, the lower frequency components of strikes contain information about peak current and charge transfer that can be used for fire prediction and damage assessment. Low frequency sensing also has capabilities for detection of Transient Luminous Events (commonly known as sprites), lightning-ionosphere interaction studies, and general meteorology investigations. QFS is pursuing applications in this area; please contact us to find out how we can benefit your work.