pinger

noun

1. A device that emits a short, high-pitched sound burst, such as in sonar or other echo location systems.“We couldn't take the boat into the shallows near the reef because our sonar pinger was broken.”
2. A device that periodically emits a signal that can be monitored to permit movement tracking.“The scientist attached a pinger to the carapace of the sea turtle to track its migration.”
3. A computer program that sends a ping message over a network.“Some people like fancy pingers with extra features, but I always use the default ping application.”
4. A user of a ping program; one who pings.“Every time we replace the main page, we get flooded with pingers making sure our web site is still there.”