We present TeSSLa, a specification language based on stream run-time verification, designed for monitoring a specific class of real-time signals. Our monitors can observe concurrent systems with a shared clock, but where each component reports observations as signals that arrive to the monitor at different speeds and with different and varying latencies. The signals and streams that TeSSLa supports (including inputs and final verdicts) are not restricted to be Booleans but can be data from richer domains, includin…