Spectrum Measurements
R&S
®
ESRP
415
User Manual 1175.7445.02 ─ 08
room temperature (-174 dBm (1Hz)) and the measured noise power P
noise
the noise fig-
ure (NF) is obtained as follows:
NF = P
noise
+ 174 – g,
where g = gain of DUT in dB
Example:
The measured internal noise power of the R&S
ESRP at an attenuation of 0 dB is
found to be -143 dBm/1 Hz. The noise figure of the R&S
ESRP is obtained as follows
NF = -143 + 174 = 31 dB
If noise power is measured at the output of an amplifier, for example, the sum of the
internal noise power and the noise power at the output of the DUT is measured. The
noise power of the DUT can be obtained by subtracting the internal noise power from
the total power (subtraction of linear noise powers). By means of the following diagram,
the noise level of the DUT can be estimated from the level difference between the total
and the internal noise level.
Figure 6-29: Correction factor for measured noise power as a function of the ratio of total power to
the intrinsic noise power of the signal analyzer
6.4.5.2
Measurement of Noise Power within a Transmission Channel
Noise in any bandwidth can be measured with the channel power measurement func-
tions. Thus the noise power in a communication channel can be determined, for exam-
ple. 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 con-
sidering the channel bandwidth. If, however, phase noise and noise that normally
increases towards the carrier is dominant in the channel to be measured, or if there are
Advanced Measurement Examples
