Air Force 1st Lt. Julian Martinez, an Air Force Research Laboratory (AFRL) electrical engineer, was part of the winning team of the 2015 AFRL Commanders Challenge that asked groups of junior personnel to design systems to detect and thwart internal base threats. In June, four teams tested their systems in real time with a SWAT team and fellow servicemembers acting out an active shooter scenario. Some of the winning team's systems already are being put to use, and four types of portable door locks they created are in testing for release on the market.

Q. Tell us about your approach.

A. It's a little bit of everything in one. From the beginning of an active shooter incident, right before the shooting happens, there's a detection piece. We created a mobile app to report [suspicious people] immediately to people within their surrounding area.

Once the first shot was fired, we came up with a gunshot detector using acoustic sensing and some signal processing. We tied in those sensors into a building map to a web page, where we could pull up the indoor map and we could see where those shots were fired. … In many [military or school] buildings, you may or may not be able to hear a shot, depending on where that shot was fired.

We also came up with an indoor tracking system using ultra-wideband for the first responders. It's kind of like GPS. Right now, you'll sometimes be in a building where you don't have a network or GPS signal just because of the way buildings are set up. We came up with our own sensors using indoor tracking technology. Once a first responder came in, they would have a little tracker … and we could see them moving in live time.

Mechanical devices that could be quickly be removed and inserted into doorframes further protect the door from being knocked down by an active shooter trying to get into the room.

Q. How does the ultra wideband system help first responders?

A. Something we realized during an active shooter incident is that most incident commanders, most police officers, they will not send in multiple teams at once. They'll send in the first team, but because of fratricide issues and whatnot, they are hesitant about sending in multiple teams through different entrances because they don't know where their people are. With our indoor tracking technology, we have this display system where you can see the entire floor plan of a building and see where all your people [are] coming into the building. That way you could send in multiple teams at one time. If a team was getting too close to another, you could just over the radio tell them, “Hey, watch out on your left, about 100 feet to your left the Bravo team is going to be next to you.”

Q. How did the judges react to your solution?

A. We had a SWAT team there who has been working maybe 20 years. They said they had never seen anything like this indoor tracking solution before … something that would update itself so fast and could within a meter tell you where your person was.

Another application we're trying to pursue is for firefighters. Sometimes firefighters have to enter a burning building. Especially if one of them gets injured or hurt, you don't really know where they are.

Q. Who else was on your team?

A. I was on a seven-member team. Each of us had a different background. We had an experimental psychologist. We had a couple of mechanical engineers, an industrial engineer, and two electrical engineers. From that, coming together as a team over the course of six months was really fantastic.

Q. What did you enjoy most working on this challenge?

A. I enjoyed most working on the mobile app. I'm the electrical engineer, but I'm not really a fan of software design. I have a smartphone and I use a ton of apps, but I've never truly appreciated how much work goes into making those apps. When I started this app, I learned how to program an Android from scratch. Going through the whole process of learning and iterative design to create an application that could not just communicate with other phones but could also communicate with our internal server we had created was a challenge, but it was a ton of fun.

Q. What was competition day like?

A. We were in the middle of nowhere in Indiana at an Army National Guard base testing out our system, and adrenaline was pretty high. You have the judges there evaluating you all week. On top of that, you have all the other teams there that you haven't seen for six months, and you see their systems live and running.

We were all given the same problem statement, but we all chose to solve it differently. Another team utilized IT phones that people already have at their office desk to essentially create some kind of heat map. … When an emergency is declared, all the phones on a base or in a building, they all turn on passively, and depending on whether people are screaming or whatnot, someone at a control desk or at the security office can see where the loudest noises are coming from.

The most interesting thing for me was how different teams came to different solutions given the same problem.