Rohde & Schwarz SME02 - Broadband Noise; Residual FM

Test Procedure SME
1038.6002.02 5.14 E-13
5.2.8 Broadband Noise
Test equipment Broadband noise is measured using the test setup of 5.2.7 (SSB
Phase Noise).
Test principle Calibration is effected in the same way as in Section 5.2.7, SSB Phase
Noise. For measurement, the signal generators are detuned until the
difference frequency falls into the stop band of the lowpass filter (> 10
MHz). A 1-MHz section of the sum of the broadband noise powers of
both signal generators is to be measured at the spectrum analyzer
then, which corresponds to the carrier frequency offset from the
difference frequency up to the difference frequency minus 1MHz. Due
to the mirror inversion of the spectrum at the zero line, the power
measured must be halved.
Measurement
À Calibration see Section 5.2.7.
À Increase the detuning to the measurement offset frequency
(
≥
10MHz, recommended offset frequency 10MHz).
À Set the preamplifier to 40dB and read the noise voltage at the
analyzer at a center frequency of approx. 100kHz, normalized to a
bandwidth of 1Hz (noise level).
Evaluation
À Subtract from the reference level and add 43dB for the
amplification switchover and the mirror image. The measured value
is the sum of the noise powers of both signal generators. If the
signal-to-noise ratio of the second signal generator is not better
than the one of the test object by at least 10dB, the noise
component of the reference transmitter must be determined and
subtracted as well. In the case of two identical transmitters, the
correction is further 3dB.
Corrected measured value ................................................
≤
-140 dBc
Recommended test
frequencies
see table 5-2.
5.2.9 Residual FM
Note: The measurement of SSB phase noise usually makes a measurement of unwanted deviation
superfluous as it is more sensitive.
Test equipment
Test system 5.1.1.1
Measurement
À Settings at the SME
- 1GHz, unmodulated,
- Level 8.1dBm.
À Settings at the analyzer
-FM, RMS value
Unwanted deviation in the case of CCITT filtering 1Hz and with
a measuring bandwidth of 30Hz to 23kHz .........................≤ 4 Hz