Keysight 81150A - Page 388

Appendix
388
Frequency-Shift Keying Modulation (FSK) Commands
Introduction
You can configure the instrument to “shift” its output frequency between
two preset values using FSK modulation. The rate at which the output shifts
between the two frequencies (called the “carrier frequency” and the “hop
frequency”) is determined by the internal rate generator or the signal level
on the rear-panel Modulation - In connector.