Fortifying Your Position

Using omnipresent RF signals, LSOP locates when GPS fails

50 Ratings

Imagine you are part of a Special Operations team tasked with locating downed and injured pilots in enemy territory. A helicopter extraction is required at a precise location, but your GPS is being jammed. Oceanit's LSOP (Localization using Signals of Opportunity) provides a backup to GPS using existing wireless transmissions to establish position.


An infantry squad is on a night patrol in hostile country. The lead fire team has been ambushed and the squad leader reaches for his radio to call for artillery support. When asked for his position he realizes that his GPS is being jammed by the enemy and the darkness prevents him from taking visual bearings of nearby landmarks. What could have been the beginning of a disaster is no longer an issue as LSOP (Localization using Signals of Opportunity) quickly locks on to half a dozen Signals of Opportunity (SoOPs), including nearby radio and cell towers, local TV transmissions and even the GPS jammer itself. Using the SoOPs in concert with the squad's radio communications network, LSOP computes his position. Fire support is soon on the way.


The heavy reliance on GPS in all aspects of military operations is an Achilles' Heel. Current military conflicts take place in GPS-degraded environments like urban settings, or areas with dense foliage, mountains, and canyons. In addition, GPS is susceptible to denial by both unintentional interference or by deliberate jamming by hostile forces. Without a positioning backup such as LSOP, losing GPS would undermine the efficacy of our military, crippling capabilities in navigation, situational awareness, tactics, munition guidance, search and rescue, logistics, and more. The principal challenge in using SoOPs for positioning is the lack of timing information at the transmitters. A conventional solution synchronizes receivers so that the time-difference-of-arrival of the transmitted SoOPs may be measured and a multilateration solution calculated. But it is very difficult to maintain receiver synchronization without using beacon-disciplined clocks or expensive miniaturized atomic clocks at each receiver. LSOP was created to surpass these conventional methods by positioning receiver nodes without synchronization.


Oceanit works in microwave engineering, signal processing, biomedical engineering, materials science, nanotechnology, astronomy, lasers, software, ocean engineering, and more. This diverse expertise allows ample opportunity for interdisciplinary cross-pollination of innovative ideas. LSOP was conceived while researching a method to coherently aggregate RF power using a network of physically separated phased arrays. Oceanit developed a stigmergic architecture to coordinate efficient distribution of clock information throughout the network. During research it was found that if certain data were shared by network members, positioning could be realized without synchronization -- LSOP was born.

"LSOP provides precise positioning in a GPS-denied environment. LSOP does not require additional hardware to be implemented on software defined radios, enabling rapid and universal implementation." — Chris Sullivan


Oceanit's network-based, asynchronous LSOP algorithm is a novel localization technique utilizing Signals of Opportunity from radio frequency (RF) transmitters such as radio, TV and cellular transmissions. It provides an alternative to conventional GPS when this is unavailable due to terrain blocking or deliberate jamming of satellite signals. The technique derives the locations of a number of handheld receiver nodes by exploiting the signal from multiple existing transmitters in known locations. By allowing the nodes to share data in a cooperative network, the technique eliminates the need to synchronize transmitters or receivers. In addition, since LSOP is network based, every member of the network can receive position updates from all other users. Another benefit of LSOP is that it requires no additional hardware, resulting in virtually no increase to existing warfighters' size, weight, and power (SWAP) demands. It can be implemented as a simple software upgrade to current and future fielded military software defined radios (SDR). This allows LSOP to be transparent to the user. Existing navigation hardware and displays can be utilized, preserving the look and feel of familiar systems and eliminating the learning-curve associated with adopting new systems.


Precise positioning is an essential component of modern military tactics. The real-time position of friendly and hostile forces enables effective attack and defense; this ensures precise placement of munitions minimizing collateral damage and friendly fire. The US military is highly dependent on GPS to provide this positioning. Consequently, the absence or degradation of GPS severely reduces our military's capability. Oceanit's LSOP provides backup positioning capability in this eventuality.

Oceanit Laboratories, Inc.

Honolulu, HI

Oceanit, established in 1985, is one of Hawai`i's largest and most diverse science and engineering companies. Oceanit's staff of over 150 occupies offices and laboratories throughout Hawai`i and parts of the mainland, including San Francisco, Houston, and Arlington, Virginia.

Donald Harbin Donald Harbin

Donald Harbin

Senior R&D Engineer

Erin Horner Erin Horner

Erin Horner

Senior R&D Engineer/Program Manager

Ryan Miyamoto Ryan Miyamoto

Ryan Miyamoto

Director of Electronic Systems


GPS-Denied Positioning Using Networked Communications





For more exciting Air Force launch stories, visit



Strong Security


Measuring The Atmosphere