Tektronix NetTek YBT250, User Manual

Page: 234 / 338

Taking Measurements
3- 132
YBT250 Field Transmitter & Interference Tester User Manual
Measuring cdmaOne, cdma2000, or 1xEV-DO
Adjacent Channel Power Ratio (ACPR)
Requires Option CR1
The Adjacent Channel Power Ratio (ACPR) measures the relative
amount of CDMA signal power leaking into nearby narrowband
channels. ACPR is the ratio of the mean power in the selected
channel (1.23 MHz bandwidth) to the mean power detected in an
adjacent channel of 30 kHz bandwidth.
Four adjacent channels are measured (two above and two below the
selected channel), and an ACPR value result is calculated for each.
The ACPR value is computed as the difference between the
corresponding adjacent channel power and the center channel power.
This measurement provides a simplified test to detect excessive
out-of-band emissions from a CDMA transmitter.
To measure ACPR:
1. Select a cdmaOne, cdma2000, or 1xEV-DO signal standard.
2. Select a channel.
3. Tap the Measurement button.
4. Tap Select Measurement... .
5. Tap ACPR .
The window displays the four ACPR measurements for the
Lower and Upper adjacent channels, as well as the channel power
for the selected channel and the adjacent channels. Larger
negative values of ACPR indicate better suppression of signal
leakage. See Figure 3--66.