Brought to you by Cisco
Tech Q&A: Pam Reilly of DRS Tactical Systems
PoliceOne this month is focusing on an array of issues related to communications, from the proposals put forth for a shared mobile broadband network to the computer hardware and peripherals that would connect to it. We recently had an interaction with Pam Reilly, Fleet and Public Safety Business Development Manager for DRS Tactical Systems, a manufacturer of rugged notebook computers — the sort that mount inside squad cars and reside in the hands of other mobile workers.
The universe of rugged computer manufacturers is not huge, but it is populated with some big names — Panasonic Toughbook, General Dynamics Itronix, and Dell Rugged are the principal players with whom DRS competes. In fact, prior to joining DRS Tactical Systems, Pam served as a Vice President at General Dynamics Itronix. Based in Melbourne, Florida, DRS counts among its customers the U.S. Army, Marine Corps, and Air Force. Among its products, DRS Technologies makes ARMOR rugged mobile computers such as the C12 convertible notebook and the X10 tablet PC. The company points to its quarter century of experience developing military computer systems as the reason it has come to offer computers for police that “survive in the harshest environments.” We asked Pam a few questions to help better understand this notion of “fully rugged mobile computers.”
PoliceOne: Put yourself in the shoes of the procurement officer at a mid-sized police department. What do you need to think about when looking at mobile computers?
Pam Reilly: Today, people who perform normal job functions in demanding environments use rugged mobile computers that guard against water and dust, operate in high and low temperatures, and protect against shock and vibration. However, meeting these standards is not a "yes/no" or "pass/fail" proposition. Computers are designed with different tolerances. Understanding the working environment and how computers handle these conditions is a key part of selecting the correct unit.
For example, dust and water are two of a computer's worst enemies. Non-organic matter can clog connections. Organic matter such as mud can lead to fungal growth or the retention of moisture, leading to corrosion that could take months before intermittent operation occurs. Water, in the smallest amounts, turns to vapor upon operation of electronic equipment and thereby migrates throughout the entire unit. In order to prevent or minimize dust and water ingression, a computer's external housing must be designed and manufactured to very tight tolerances, and all gaps must be carefully sealed.
P1: It’s our understanding that rugged computers are ranked for protection against the penetration of against water and dust into the computer. Can you explain the so-called IP ratings — the two numbers indicating the levels of protection? The first digit in this set addresses solids and the second speaks to protection against liquids, correct?
Reilly: Within the category of rugged computers, the highest levels of dust protection — a five or a six — are desired; a water protection level of 6 is considered to be water resistant. For example, with the first digit, addressing dust and solid objects, a zero indicates no protection, one shows protection against solid objects up to 50mm, a three shows protection against solid objects over 2.5mm such as tools and wires, and six is totally protected against dust.
For the second digit — water — a zero once again says, “no protection,” one indicates protection against drops of water such as condensation, a rating of five provides protection direct sprays of water from all directions, a computer rated at seven is protected against effects of immersion in up to one meter of water for as much as 30 minutes, and an eight can tolerate long periods of immersion under pressure.
P1: Police officers operate in every weather condition imaginable—from the coldest winter nights in the North Dakota to hot August afternoons in Alabama. Consequently, their gear is subjected to a much broader range of temperatures than the notebooks you see in the hands of business travelers at the airport. How do manufacturers address this range of environments?
Reilly: Sound thermal design practices not only address electronic components, but also the liquid crystal display (LCD), battery, and spinning storage media.
Designs that use fans to remove heat run the risk of single point failures, may become clogged, or are difficult to clean and/or decontaminate. A computer designed for use in harsh environments uses mechanical design to transfer heat away from internal components, such as chip sets, to the housing where heat is dissipated into the ambient air. This "heat pipe" approach has proven superior to an internal fan.
The liquid crystal chemistry of LCDs is also affected by temperature. At low temperatures, the viscosity of the liquid increases, and if inappropriate vendor specification and/or design techniques are used, the display updates are slow, leading to "ghosting" of images. At high temperatures, the viscosity decreases to almost that of water, resulting in "brownout” of the screen.
A battery that is fully charged provides its stated capacity at room temperature. However, this capacity will decrease as temperatures rise or fall to extreme operational limits. Rugged designs leverage trades between weight and total available battery capacity, selection of battery chemistries, thermal design, and power management to optimize user performance over broad temperature ranges.
P1: It would be wonderful if every high-speed pursuit was run on freshly laid pavement, but officers in this nation’s squad cars rarely have that luxury. They tend to experience levels of shock and vibration that no ordinary vehicle mounted computer would have to contend with. What are some design considerations that address this issue?
Reilly: Let’s back up a little before I address the vehicles, because mobile devices are subjected to a broad range of intentional and non-intentional usage environments not present with office equipment. Non-intentional shock includes dropping and sliding off surfaces, while intentional shocks occur through operations such as a vehicle backing up to a loading dock, a rail car engaging, or a tow truck winch operating. Vibration, on the other hand, is specific to the vehicle or stationary equipment on which the device is mounted.
Careful attention to material properties such as malleability — too malleable leads to wear and fragility such as glass shatter are required. All components, boards, brackets, and cables need to have rigid mounting. Spinning media are isolated so the drive head does not crash. For shock, materials that deform and then relax at a slow rate are used. For vibration, materials that absorb the vibration energy and dissipate as heat are used.
The growing market for rugged computers is characterized by a degree of confusion about the meaning of the term rugged. There are categories like "semi-rugged," rugged" and "fully rugged" that are often used, but are not easily defined. But there are some specific ratings, such as ingress protection that may be used to gauge specific performance criteria. Thus, users must evaluate levels of protection in light of the specific environment in which the computer will be deployed.