A dF/dT trigger system and method includes instantaneously triggering on a frequency deviation of a data signal, which can be associated with an SSC signal. After receiving a signal at an input terminal of a test and measurement instrument, the signal is low-pass filtered and transmitted to trigger circuitry. When a frequency deviation rate in the filtered signal exceeds or crosses one or more thresholds, a trigger event is produced. Also disclosed is a test and measurement instrument including an input terminal to receive the signal, input circuitry to receive and process the signal, and dF/dT trigger circuitry configured to receive the signal and produce a trigger event when a frequency deviation in the signal exceeds or crosses one or more thresholds.