HP 5988-8522EN free download

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Agilent EPM-P Series Power Meters Used in Radar and Pulse Applications Application Note 1438 Introduction The focus of this product note is the alternative ways that pulse and peak power meas- urements are made. The note looks at the measurement capability of the EPM-P series power meters and E9320 peak and average sensors for pulse measurements, along with the pulse analysis feature provided by the EPM-P Analyzer Software. Pulse Power Pulse power was traditionally determined by measuring the average power of the pulse and then dividing the measurement result by the pulse duty cycle value to obtain the pulse power reading, as shown: Pp = Pavg / Duty Cycle Power B (pulse repetition interval) Duty cycle = A B Measured average power A (pulse width) Time Figure 1: Pulse power measurement The measurement result is a mathematical representation of the pulse power rather than an actual measurement and assumes constant peak power. The pulse power averages out any aberrations in the pulse, such as overshoot or ringing. For this reason it is called pulse power and not peak power or peak pulse power as is done in many radar references. In order to ensure accurate pulse power readings, the input signal must be a repetitive rectangular pulse of constant, known duty cycle. Other pulse shapes (such as triangle or Gaussian) will cause erroneous results. This technique is also not applicable for digital modulation systems, where the duty cycle is not constant, and when the pulse amplitude or shape is variable. There are some advantages with using duty cycle to calculate the pulse power. The duty cycle technique provides the lowest cost solution, with average power meters and sensors being less expensive than peak and average power meters and sensors. They also have the ability to measure over a wide power and frequency range. Agilent 8480 and E9300 average power sensors have a power range