Bernd shared a white paper this morning, "Analysis of an Ultrasound-Based Physical Tracking System " by Cunche and Cardoso (https://hal.inria.fr/hal-01798091/document) which goes over how they rever engineered an ultrasound-based in-store tracking application. They wrote an app that generates it’s own ultrasonic sounds to jam such applications. Souce code is available (alegedly, their GitLab instance was having an issue when I looked at it.) The site does have samples of ultrasonic applications caught in the lab and in the wild (http://sonicontrol.fhstp.ac.at/) which you could use for you experiments.
Article Link: https://isc.sans.edu/diary/rss/23707