Attendees at sensor reporting workshops and panels often ask, “What can be sensed?” Unfortunately, that is a simple question with a complex answer. There are a number of sources available to introduce journalists to sensing possibilities. For electronic prototyping, lists of sensors can be found on parts retailers including DIY stores Adafruit and Sparkfun, or online stores like Mouser. Wikipedia also has a “list of sensors” page. The electronics retailers divide their catalogue, into categories to guide buyers. Examples include motion, sound, scanners, touch, and biometric. Wikipedia’s categories, on the other hand, mix technologies with applications; one “type” is chemical, another is automotive. In any case, browsing those sources can help readers start to see what physical sensor parts they can buy is theoretically possible. However, note two points when it comes to the question of “what can be sensed.” First, lists of sensors are long and defy consistent organization. Second, logic and imagination have as much to do with answering that question as do the technologies. In the case study to come about the Sun Sentinel’s Pulitzer Prize-winning investigation, sensors on tollgates registered times and radio frequencies emitted by tags on cars driven by police passing through known locations—from which the journalists derived identities, their speeds and concluded ’criminality.’ This is all to say that while no one suggests that the journalists used a criminality type of sensor, or that Wikipedia should include a ’criminality’ section on its sensor page, but sensors still helped prove that Florida cops were breaking the law.
Likewise, a Washington Post story based on ShotSpotter data—gunshots sensed via sound—relied on the fact that explosions in a gun barrel cause air-pressure changes (also known as sound waves); these were converted into digital signals by arrays of microphones and pattern-matched by computers to produce records of the gunshot locations throughout Washington, D.C. The point here is that rather common sensors can feed data into processes that apply various computations of complicated physics and produce higher-level applications. Journalists have conducted further logical analysis and combined other reporting processes to derive some insight into the world. At each of the steps—between physics, application, and insight—engineers and journalists make decisions that affect what can be measured, derived and the analysis that can be made. So, the question of ’what can be sensed’ has different answers depending on which step in the process you are discussing. The answer can also change as journalists apply effort and immagination.