Security researchers say they have developed a new technique to detect modern cell-site simulators. Cell site simulators, known as “stingrays,” impersonate cell towers and can capture information about any phone in its range — including in some cases calls, messages and data. Police secretly deploy stingrays hundreds of times a year across the United States, often capturing the data on innocent bystanders in the process. Little is known about stingrays, because they are deliberately shrouded in secrecy.