Radar Basics - Peak- and average power
If a RADAR transmitter sent out a 10 kilowatt pulse 1 microsecond long every millisecond, its peak power output would be 10 kilowatts, and its. As we know, the ideal Gauss pulse is distributed in an infinite time domain, so the average power is zero for an ideal Gauss pulse. However, for Gauss pulse. A summary or overview of the different types power level measurements that can be made - average power, pulse power, peak envelope power, PEP.
Events RF Power Measurements: Different signals have different waveforms and factors like average power, peak power, peak envelope power,- PEP and the like have a major impact on the type of power sensor needed.
Each power sensor, or power meter will state the type of waveforms that it can measure. Some are able to measure carrier waveforms that are steady, whereas others are able measure peak, RMS, peak envelope and pulsed waveforms. These typically require much faster levels of response and often the ability to compute the value within the power meter.
Basics of Power Measurement — Average or Peak
In view of the options available for measuring different formats for the power, it is important to select the correct power meter or test instrument and its sensor or sensors if applicable. RF average power The most obvious way to measure power is to look at the average power. This is defined as the energy transfer rate average over many periods of the RF waveform.
The simplest waveform to measure is a continuous wave CW. As the signal is a single frequency steady state waveform, the average power is obvious. For other waveforms the averaging parameters may be of greater importance.
Take the example of an amplitude modulated waveform. This varies in amplitude over many RF cycles, and the RF power must be averaged over many periods of the modulating waveform to achieve a meaningful result. To achieve the required results, the averaging period for RF power meters may range from several hundredths of a second up to several seconds. In this way the RF or microwave power meter is able to cater for the majority of waveforms encountered.
RF pulse power or peak power In a number of applications, it is necessary to measure the power of a pulse of energy. Capturing instantaneous power requires instrumentation that can react fast enough to capture the rapid changes in the signal. Envelope power, Pe tis the amplitude change due to modulation, or sometimes distortion, and is another measurement as a function of time.
Root mean square
Envelope power is not a re-creation of the waveform itself, but a representation of the average power over the sensor aperture interval at any point in time see Figure 2 for another example of the relationship between envelope power and instantaneous power.
The peak envelope power, PEP, is the highest single power measurement from within the envelope power readings. Note that power meters often provide crest factor or peak-to-average power ratios PAPR. In this case, the peak power is actually PEP, rather than instantaneous, peak power. More on video bandwidth and crest factor later, though.
The burst average power, PBAvg, simply is the average power from within just the burst.Average Value & RMS Value - Problem 1 - AC Circuits - Basic Electrical Engineering - First Year Engg
Another Example of Instantaneous vs. Average Powers The last value in our list is the average power, Pavg represented by the purple line in Figure 1which is the average power taken over a specified period of time. In our example, it is during the period from the beginning of one burst to the next also known as the pulse repetition interval, or PRI.
These particular diode-based sensors are sometimes referred to as true-RMS sensors, because they are designed to keep the measured signal within the square-law region of the diode — where the DC output of the sensor circuit has a strong linear relationship to the square of the applied RF voltage. This allows them to accurately measure the average power of most signals, including modulated, multi-tone, or pulsed signals.
- Your Answer
- RF pulse power or peak power
- RF average power
For unmodulated signals i. Note that, although the average sensor cannot measure the peak power of the modulation, in some cases you can still use it to determine certain characteristics of the burst.
For instance, in the pulse signal example used in the diagram, the burst average power can be determined, as long as you know the duty cycle of your signal. In this case, the PBAvg is equal to Pavg divided by the duty cycle, where the duty cycle is the pulse width divided by the pulse repetition interval.