Boonton 4540 Peak Power Meter User Manual - Manual (Page 16)

Boonton 4540 Series RF Power Meter
General Information 1-2
1.2 Description
The 4540 Series RF Power Meter is the latest generation of BOONTON RF Peak Power Meters and
Analyzers, including Models 4400, 4500, 4400A, 4500A, 4500B and 4530. The 4540 Series, when
operated with Boonton peak and CW power sensors, provides one of the most versatile power measuring
systems available, with capability to make over 20 different power related measurements on captured
signals. The 4540 is available as the single-channel Model 4541 or the dual-channel Model 4542.
The 4540 is really several instruments in one, and can function as a CW Power Meter, a Peak Power Meter,
a Statistical Power Analyzer, and an RF Voltmeter. It accepts the full series of Boonton RF power and
voltage sensors, which includes coaxial dual-diode sensors and thermal sensors.
The 4540 Series instruments provide three basic measurement modes - pulse power, modulated power, and
statistical power. Each mode is targeted towards a specific type of measurement.
The Pulse Mode is used with peak power sensors. The instrument functions as an enhanced peak power
analyzer and provides the functionality of a random repetitive sampling oscilloscope for viewing and
analyzing the RF power envelope of signals up to 40 GHz. The RF frequency range and detection
bandwidth are sensor model dependent. Accuracy approaches that of average-only power meters, but with
the ability to capture wide bandwidth power-versus-time data. With the requirement of an internal or
external trigger event it can automatically measure up to 15 characteristics of the RF power envelope.
These are peak power, pulse power, average power, pulse width, risetime, falltime, overshoot, pulse period,
pulse repetition rate, duty cycle, top amplitude, bottom amplitude, offtime, edge delay and the delay
between two RF pulses. In addition to these automatic measurements, the 4540 offers a powerful set of
marker measurements, which includes the ability to make marker measurements at full accuracy,
independent of vertical scale or offset. This is possible because of the use of non-linear signal processing
techniques, and high-resolution analog to digital converters that provide rangeless operation. In addition,
the markers can be used to define regions of the waveform for analysis. This analysis includes average
power of a portion of the waveform, minimum power, and maximum power.
The Modulated Mode is designed for continuous, true average power measurements of complex modulated
signals. When used with Boonton Peak Power sensors, Modulated Mode is similar to the operation of a
conventional CW power meter, but does not suffer the measurement inaccuracies that occur when some
diode sensors are used to measure modulated signals. For applications that require very wide dynamic
range, Boonton CW power sensors can be used for CW signals or low-level modulated signals up to 110
GHz. A scrolling graphical trace or multi-reading text presentation is available.
The Statistical Mode of the 4540 Series is used for advanced analysis of non-periodic modulated signals.
This mode does not require a trigger event to make measurements and is useful for signals that are noise-
like such as CDMA, OFDM, or QAM. In Statistical Mode, the RF signal is sampled continuously at high
speed, without discarding or losing any data. The acquired sample population is processed statistically in
real time to determine peak power, average power, minimum power, peak to average power ratio, and
dynamic range, while reporting the sampling time and total number of samples captured.
Rangeless operation ensures that a representative power sample population can be acquired and analyzed in
minimum time. By analyzing the probability of occurrence of power levels approaching the absolute peak
power, it is possible to characterize the occasional power peaks that result in amplifier compression and
data errors. Because of the random and very infrequent nature of these events, they are next to impossible
to spot with the conventional techniques used in other power meters. In addition, the instrument’s
extremely wide video bandwidth ensures that even the fastest peaks will be accurately measured.
The statistical analysis of the current sample population is displayed using a familiar, normalized CCDF
presentation. The CCDF expresses the probability of occurrence of a range of peak-to-average power ratio
on a log-log scale, and a cursor allows reading of CCDF point. As with all other graphical displays, the
trace can be easily scaled and zoomed, or the statistical data may be presented in a tabular format.