Boonton 4500B Peak Power Meter Bedienungsanleitung PDF herunterladen (Seite 329)

Boonton 4500B RF Peak Power Analyzer

Application Notes

6-19

Sensor Temperature Coefficient. This term is the e

        

 for drift exceeding ±4C on

non-temperature compensated peak sensors. For these sensors, the typical temperature effect 4 degrees from the

AutoCal temperature is shown as a graph versus level on the sensor datasheet.

Temperature compensated peak sensors have a much smaller temperature coefficient, and a much larger temperature

deviation, ±30C is permitted before a warning is issued. For these sensors, the maximum uncertainty due to

temperature drift from the autocal temperature is:

Temperature Error = ± 0.04dB (0.93%) + 0.003dB (0.069%) /degreeC

Note that the first term of this equation is constant, while the second term (0.069%) must be multiplied by the

number of degrees that the sensor temperature has drifted from the AutoCal temperature.

Sensor Noise. The noise contribution to pulse measurements depends on the number of samples averaged to



sensors in modulated mode, it depends on the integ

setting. In general, increasing filtering or averaging reduces measurement noise. Sensor noise is typically expressed

as an absolute power level. The uncertainty due to noise depends upon the ratio of the noise to the signal power

being measured. The following expression is used to calculate uncertainty due to noise:

Noise Error = ± Sensor Noise (in watts) / Signal Power (in watts) × 100 %

The noise rating of a particular power sensor may be found on the sensor datasheet, or the Boonton Electronics

Power Sensor Manual. It may be necessary to adjust the sensor noise for more or less filtering or averaging,

depending upon the application. As a general rule (within a decade of the datasheet point), noise is inversely

proportional to the filter time or averaging used. Noise error is usually insignificant when measuring at high levels



Sensor Zero Drift. Zero drift is the long-term change in the zero-power reading that is not a random, noise

component. Increasing filter or averaging will not reduce zero drift. For low-level measurements, this can be

controlled by zeroing the meter just before performing the measurement. Zero drift is typically expressed as an

absolute power level, and its error contribution may be calculated with the following formula:

Zero Drift Error = ± Sensor Zero Drift (in watts) / Signal Power (in watts) × 100 %

The zero drift rating of a particular power sensor may be found on the sensor datasheet, or the Boonton Electronics

Power Sensor Manual. Zero drift error is usually insignificant when measuring at high levels (25dB or more above

ates a time interval such as one hour. If

the time since performing a sensor Zero or AutoCal is very short, the zero drift is greatly reduced.

Sensor Calibration Factor Uncertainty.  for

sensor frequency response deviations. These calfactors are characterized during factory calibration of each sensor

by measuring its output at a series of test frequencies spanning its full operating range, and storing the ratio of the

actual applied power to the measured power at each frequency. This ratio is called a calfactor. During measurement

operation, the power reading is multiplied by the calfactor for the current measurement frequency to correct the

reading for a flat response.

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Boonton 4500B Peak Power Meter Bedienungsanleitung Seite 329