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Using E9300 E-Series Power Sensors 5
N1911A/1912A P-Series Power Meters User’s Guide 157
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- 116 .
Figure 5-116 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 m20 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.