Tektronix NetTek YBT250, Руководство пользователя

Страница: 196 / 338

Taking Measurements
3- 94
YBT250 Field Transmitter & Interference Tester User Manual
If a valid external reference frequency (see page 2--25) or YBGPS1
GPS Timing Reference is connected, the instrument displays the
frequency (or timing pulse rate for the YBGPS1 Timing Reference)
of the external reference at the bottom of the screen. If the
instrument is using the internal timing reference signal, then the
external reference readout shows --- (dashes).
NOTE
. If the YBT250 indicates there is no signal when the signal
standard is set to W-CDMA, verify that the Scrambling Code setting
is correct. If it is set to Manual and the wrong value is entered for the
scrambling code, the YBT250 will not find a signal. The YBT250
does not show signals with other scrambling codes when the
scrambling code is set to Manual.
cdma2000 and 1xEV-DO measurements also display the signal PN
offset value.
Measuring Occupied Bandwidth
Requires option AR1, IR1, CR1, TR1, or WR1
One way to check the spectral response of the transmitter is to
measure the Occupied Bandwidth. The YBT250 enables you to
check the signal width of the selected signal using the Occupied
Bandwidth measurement.
The Occupied Bandwidth is the frequency range where 99% of the
power transmitted in a single channel lies. This measurement can be
properly made only if the channel being measured has no active
channels adjacent to it. If there is a signal in either channel adjacent
to the selected channel, the signal adds power to the measurement,
thus resulting in an inaccurate measurement.
To measure the occupied bandwidth:
1. Tap the Measurement button.
2. Tap Select Measurement... .