FAQs from Rohde & Schwarz

How to Measure Noise Power in a Transmission Channel


How can I measure noise power in a transmission channel, e.g. 1 MHz

bandwidth at 1 GHz RF frequency?


There are two solutions for measuring noise power in a transmission channel.

One solution is the Noise Marker function at the RF with bandwidth correction.

The bandwidth correction factor must be calculated as follows:

Correction factor = 10x log (bandwidth / 1 Hz)

But: If the noise in the channel is not flat, the result is not correct!!

A better solution is the Channel Power function. Please proceed as follows:

Set the analyzer center frequency to the DUT’s RF and SPAN > transmission

channel bandwidth.

Go to the MEAS menu where you will find the softkey for channel power measurement

(CHAN PWR ACP) and open the configuration menu (CP/ACP CONFIG).

Set Channel Bandwidth and press Adjust Settings to get optimum settings for resolution

bandwidth, video bandwidth und detector.

The result is displayed on the analyzer. To normalize the noise power to 1Hz (= noise

power density), press also the CHAN PWR / HZ softkey.