Frequency Counter And Pulse Generator Measure Time-Varying Signals

Jan. 16, 2007

PULSE COUNTERS ARE usually used just for measuring pulses. When combined with a microwave frequency counter's inhibit input and a pulse generator, however, time-varying signals can be accurately characterized. Such characterization is the focus of a four-page white paper from Phase Matrix, Inc. (San Jose, CA) titled, "Measuring Time Varying Microwave Signals."

This paper focuses on the company's 1230A/1231A VXI microwave pulse/CW counters. The inhibit input can be used to define the time interval in which a frequency measurement is to be made. The frequency versus time characteristics of the repetitive time-varying signals can then be measured. Examples include the output of voltage-controlled oscillators (VCOs), chirped radars, or the pulling of microwave signals due to pulse modulation.

In addition to detailing the setup for making the profile measurement, the note provides a setup diagram. Though simple, this setup vows to fully characterize time-varying microwave frequencies both quickly and accurately. The application note also offers tips. When setting the pulse width to the desired sample width, for example, as wide a window as possible should be used.

The pulse generator should be set to trigger externally. It is best to set the delay to the minimum value. To move the measurement window to the next desired position, the delay setting of the 1911A is increased after the measurement at minimum delay is taken. The measurement window is actually generated by the 1911A pulse generator. To measure frequency versus time, it can be moved through the signal under test.

Phase Matrix, Inc., 109 Bonaventura Dr., San Jose, CA 95134; (408) 428-1000, FAX: (408) 428-1500, Internet: www.phasematrix.com

About the Author

Nancy Friedrich | RF Product Marketing Manager for Aerospace Defense, Keysight Technologies

Nancy Friedrich is RF Product Marketing Manager for Aerospace Defense at Keysight Technologies. Nancy Friedrich started a career in engineering media about two decades ago with a stint editing copy and writing news for Electronic Design. A few years later, she began writing full time as technology editor at Wireless Systems Design. In 2005, Nancy was named editor-in-chief of Microwaves & RF, a position she held (along with other positions as group content head) until 2018. Nancy then moved to a position at UBM, where she was editor-in-chief of Design News and content director for tradeshows including DesignCon, ESC, and the Smart Manufacturing shows.