When information is "born analog," it arises from the characteristics of the physical world. Such information becomes accessible electronically when it impinges on a sensor such as a camera, microphone, or other engineered device. When data are born analog, they are likely to contain more information than the minimum necessary for their immediate purpose, and for valid reasons. One reason is for robustness of the desired "signal" in the presence of variable "noise." Another is technological convergence, the increasing use of standardized components (e.g., cell‐phone cameras) in new products (e.g., home alarm systems capable of responding to gesture).
Today, cell phones routinely contain not only cameras, microphones, and radios but also analog sensors for magnetic fields (3-D compass) and motion (acceleration). Other kinds of sensors include those for thermal infrared radiation; air quality, including the identification of chemical pollutants; barometric pressure (and altitude); low‐level gamma radiation; and many other phenomena.
Examples of born‐analog data providing personal information and in use today include:
- the voice and/or video content of a phone call — born analog but immediately converted to digital by the phone's microphone and camera
- personal health data such as heartbeat, respiration, and gait, as sensed by special‐purpose devices (Fitbit has been a leading provider61) or cell‐phone apps
- cameras/sensors in televisions and video games that interpret gestures by the user
- video from security surveillance cameras, mobile phones, or overhead drones
- imaging infrared video that can see in what people perceive as total darkness (and also see evanescent traces of past events, so‐called heat scars)
- microphone networks in cities, used to detect and locate gunshots and for public safety
- cameras/microphones in classrooms and other meeting rooms
- ultrasonic motion detectors
- medical imaging, CT, and MRI scans, ultrasonic imaging
- opportunistically collected chemical or biological samples, notably trace DNA (today requiring slow, offline analysis, but foreseeably more nimble)
- synthetic aperture radar (SAR), which can image through clouds and, under some conditions, see inside of non‐metallic structures, and
- unintended radiofrequency emissions from electrical and electronic devices.
- "Overview" section: Big Data and Privacy: A Technological Perspective, at x, 21-22, 23.