Boonton 4540 Peak Power Meter Quick Start - Manual (Page 28)

4540 Power Meter
Quick Start Guide
PN: 98406000A © Copyright 2008 Boonton Page 28
POWER MEASUREMENTS
What you need to know
To perform accurate measurements, the following is a minimum list of things you
should know about the signal that you wish to measure.
Signal frequency
- The center frequency of the carrier must be known to allow
sensor frequency response compensation.
Modulation Bandwidth
- If the signal is modulated, know the type of modulation
and its bandwidth. Note that power sensors respond only to the amplitude
modulation
component of the modulation, and constant envelope modulation types
such as FM can be considered a CW carrier for power measurement pur-poses.
Modulation Timing
- If the modulation is periodic, know the pulse repetition rate,
frame rate, and any other relevant timing information. This is not important unless
you intend to perform synchronous (triggered) measurements in Pulse Mode.
MODULATED MODE
Modulated Mode is the best choice for signals that show repeating patterns. Since
Modulated Mode is a continuous measurement mode, it does not differentiate
between the times a pulsed or periodic signal is off, nd the times it is on. The results
If you wish to make measurements that are synchronous with a period waveform
consider Pulse Mode. Modulated Mode is the best for the following types of
measurement:
• Moderate signal level (above -40dBm for Peak sensors and -60dBm for
CW sensors)
• Signal that is continuously modulated with a modulation band width that is
less than 20 MHz.
• Signal modulation may be periodic, but only non synchronous
measurements are needed (overall average and peak power).
• Noise Like digitally modulated signals such as CDMA and OFDM when
only average measurements are needed.