5 Using E9300 E-Series Power Sensors
192 Keysight N1911A/1912A User’s Guide
Measuring Spread Spectrum and Multitone Signals
To achieve high data transfer rates within a given bandwidth, many transmission
schemes are based around phase and amplitude (I and Q) modulation. These
include CDMA, W-CDMA and digital television. The signals are characterized by
their appearance on a spectrum analyzer display — a high amplitude noise-like
signal of bandwidths up to 20 MHz. An 8 MHz bandwidth digital television signal
is shown in Figure 5-4.
Figure 5-4 Spread spectrum signal
The diode pair/attenuator/diode pair architecture of the E9300 E-Series power
sensors is ideally suited to the average power measurement of these signals. The
sensors have wide dynamic range (80 dB max, sensor dependent) and are
bandwidth independent.
Some signal modulation formats such as orthogonal-frequency-division
multiplexing (OFDM) and CDMA have large crest factors. The E-Series E9300/1/
4A power sensors can measure +20 dBm average power even in the presence of
+13 dB peaks but the peak pulse duration must be less than 10 microseconds. For
high power applications, such as base-station testing, the E9300/1B and E9300/
1H are recommended.
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