Measurement Of Noise Power Within A Transmission Channel - Rohde & Schwarz R&S FSP Series Operating Manual

R&S FSP
2.4.2

Measurement of Noise Power within a Transmission Channel

Noise in any bandwidth can be measured with the channel power measurement
functions. Thus the noise power in a communication channel can be determined, for
example. If the noise spectrum within the channel bandwidth is flat, the noise marker
from the previous example can be used to determine the noise power in the channel
by considering the channel bandwidth. If, however, phase noise and noise that nor-
mally increases towards the carrier is dominant in the channel to be measured, or if
there are discrete spurious signals in the channel, the channel power measurement
method must be used to obtain correct measurement results.
2.4.2.1 Measurement Example – Measuring the intrinsic noise of the R&S FSP at 1
GHz in a 1.23 MHz channel bandwidth with the channel power function
Test setup:
The RF input of the R&S FSP remains open-circuited or is terminated with 50 Ω.
Measurement with the R&S FSP:
1. Set the R&S FSP to its default state.
2. Set the center frequency to 1 GHz and the span to 2 MHz.
3. To obtain maximum sensitivity, set RF attenuation on the R&S FSP to 0 dB.
4. Switch on and configure the channel power measurement.
Operating Manual 1164.4556.12 - 06
Press the PRESET key.
The R&S FSP is in its default state.
Press the FREQ key and enter 1 GHz.
Press the SPAN key and enter 2 MHz.
Press the AMPT key.
Press the RF ATTEN MANUAL softkey and enter 0 dB.
Press the MEAS key.
Press the CHAN PWR ACP softkey.
The R&S FSP activates the channel or adjacent channel power measurement
according to the currently set configuration.
Press the CP/ACP CONFIG ! softkey.
The R&S FSP enters the submenu for configuring the channel.
Press the CHANNEL BANDWIDTH softkey and enter 1.23 MHz.
The R&S FSP displays the 1.23 MHz channel as two vertical lines which are
symmetrical to the center frequency.
Press the PREV key.
The R&S FSP returns to the main menu for channel and adjacent channel
power measurement.
Press the ADJUST SETTINGS softkey.
The settings for the frequency span, the bandwidth (RBW and VBW) and the
detector are automatically set to the optimum values required for the
measurement.
Getting Started
Noise Measurements
2.17