The U.S. Navy, like other military organizations within the United States and around the world, maintains sites at which it stores bombs and other types of ordnance that are detonated by what is known as an electro-explosive device (EED), or an electrically initiated device (EID). An EED or EID is an explosive or pyrotechnic component activated by the application of electrical energy.
Electromagnetic radiation (EMR) produced by RFID tags and readers, as well as other automatic identification technology (AIT) equipment, may have the potential to inadvertently actuate or disable EIDs contained in ordnance. This unintended actuation could result in safety (premature firing) or reliability (dudding) consequences. The inadvertent actuation or disablement of electrically initiated ordnance by EMR is known as Hazards of Electromagnetic Radiation to Ordnance (HERO).
Visible Assets, a manufacturer of 134 kHz tags and readers based on the RuBee (IEEE 1902.1) standard, has announced this week that its tags, portable handheld readers and base-station wireless technology are the first to be certified by the U.S. Department of the Navy with a zero Safe Separation Distance (SSD) for ordnance. Other wireless RF-based technologies (EPC passive RFID, Wi-Fi, ZigBee, Bluetooth and UWB) have tags under the HERO test program that may be safely applied to ordnance, according to John K. Stevens, Visible Assets’ CEO and chairman, but the readers of those tags typically have SSDs ranging from 3 feet to 12 feet. Therefore, Stevens says, reading those tags may constitute a risk near HERO Unsafe ordnance, while his company’s hardware can be safely operated.
In November 2011, at the request of Visible Assets, the Naval Surface Warfare Center, Dahlgren Division (NSWCDD), located in Dahlgren, Virginia, conducted a HERO safety evaluation test of Visible Assets’ fixed readers and antennas, handheld reader and battery-powered tags. Based on the testing results, the Naval Surface Warfare Center concluded that the firm’s equipment can be used safely with electrically initiated ordnance purpose of test at a zero SSD, including munitions deemed to be HERO Unsafe/Unreliable.
The U.S. Department of Defense (DOD) defines a HERO Safe ordnance item as one that is percussion-initiated, sufficiently shielded or otherwise protected so that all EEDs contained by that object are immune to adverse effects (safety or reliability) when the item is employed within its expected radio frequency environments. A HERO Unsafe ordnance, on the other hand, consists of ordnance items containing EEDs that have not been classified through testing as HERO Safe or HERO Susceptible, while HERO Unreliable ordinance is any object whose performance is degraded due to exposure to an RF environment.The Naval Surface Warfare Center’s tests involved Visible Assets’ Sidewinder (SW-121) and Blaster (Base-110) base stations, in conjunction with its Ranger reader antenna (RP-A351), handheld pRap reader (PRP-100) and 1T tag (TID-100-W-1T-S). “The 1T tag is our longest-range and most powerful active tag,” says Stevens, who notes that the tag is currently available on the company’s Web site, as model TAS-112-B-107-B.
According to a report issued by the Naval Surface Warfare Center, the RuBee base stations tested are capable of operating from power level 1 to power level 7. The highest power level was evaluated first, after which the power was decreased until a level was identified as achieving the goal of having a zero SSD from HERO Unsafe or Unreliable ordnance. Therefore, only power levels 7, 6 and 5 were evaluated.
Based on the HERO safety-evaluation test results, the report indicates, NSWCDD concludes that at power level 5, RuBee base stations with a Ranger antenna can operate safely at a zero SSD to HERO Unsafe or Unreliable ordnance, but the antenna terminals must not come in direct contact with ordnance. In addition, the pRap reader has a zero SSD from HERO Unsafe or Unreliable ordnance, and the 1T tags have no HERO restrictions. As such, NSWCDD recommends that the RuBee base stations be designed to have maximum power output at level 5. In the case of the operational use of multiple RuBee base stations with as many as two Ranger antennas, the report recommends that a minimum distance of 8 feet be maintained between two transmitting Ranger antennas in free space, as well as in confined electrically reflective spaces.
“All our products use the tested base station, Version 409, and as long as we lock down power 5, we meet HERO Zero specification,” Stevens says. “This HERO Zero certification means we can be safely used in all of these SI [sensitive item] stores. We have a number of existing working installations in the U.S., at DOE, Australian Defense, and Special Forces in Abu Dhabi, UAE, but none have been HERO Zero-certified. We are starting our first HERO Zero installs as we speak, in both the Mid-East Gulf and Asia.”