Remote Spectrum Monitor™ MS27201A User Guide : Spectrum Monitor Measurements : Spectrum Emission Mask
Spectrum Emission Mask
The spectrum emission mask (SEM) measurement is a relative measurement method to identify the power level of out-of-band spurious emissions outside of the in-channel bandwidth signal. The SEM measures the power ratio between in-band and adjacent channels. The SEM measurement then identifies the emissions that interfere with other channels. Then, the spurious signal levels of pairs of offset frequencies are identified and related to the carrier power.
The spectral emission mask measurement supports the testing for “Operating Band Unwanted Emissions” described in the 3GPP base station conformance testing document. There is support for 5GNR masks which are automatically built based on the current carrier frequency/channel and BW values. Masks with the (KR) designation in the title are built according to Korean regulator standards for FR1 signals. The instrument indicates if the signal is within the specified limits by displaying PASS or FAIL. The emission mask information is also displayed in a table format with different frequency ranges and whether the signal PASSED/FAILED in that region.
Measurement parameters are set up using the SETUP Menu (SEM). Selecting the SEM measurement does the following:
Disables all other measurements
Sets the span to the mask width
Sets the detection method to RMS
A spectrum emission mask measurement showing the 5GNR P<38 dBm mask setting is illustrated in Figure: SEM Measurement.
SEM Measurement
1. SEM Mask
2. Spectrum Emission
3. SEM Mask
Spectrum Emission Mask Measurement Basic Setup
1. Select MEASURE > MEASUREMENT > SEM from the right side menu.
2. Select SETUP and select upper or lower mask (5GNR P>38 dBm or 5GNR P<38 dBm).
3. Enter the reference channel bandwidth.
5. The SEM measurement results are displayed in a table with pass/fail results.
Selects the desired upper or lower emission mask:
5GNR(KR) P > 38 dBm
5GNR(KR) P < 38 dBm
Used to import a custom user mask.
Exports an example user mask as a comma separated value file (see Example Custom Signal Emission Mask) or exports the currently selected custom mask.
Sets the reference channel bandwidth for the measurement.
Toggles automatic max power. Some segments in the mask are dependent on the main channel power. Enabling this automatically calculates the reference channel power by measuring the channel power of the center channel bandwidth. When disabled, the reference power must be entered manually below.
Used to manually enter the reference channel power for masks that have limits dependent on main channel power.
Presets all values on the SETUP menu to default values.
Example Custom Signal Emission Mask
To create a custom SEM, use the following steps:
1. Export the existing mask as a csv file by clicking the EXPORT MASK button in the SEM SETUP menu.
2. From the FILES menu, move the exported file to a USB device and then to a computer for editing.
3. If this is the first time exporting the file, the following data should be in the file:
# Example Custom Signal Emission Mask
# Start Frequency, Stop Frequency, RBW, VBW, Is Start Amplitude Relative, Is Stop Amplitude Relative, Start Amplitude, Stop Amplitude
-3.5e6, -2.1e6, 100e6, 100e6, 0, 0, -9.5, -9.5
-2.1e6, -0.7e6, 100e6, 100e6, 0, 0, -9.5, 0.5
0.7e6, 2.1e6, 100e6, 100e6, 0, 0, 0.5, -9.5
2.1e6, 3.5e6, 100e6, 100e6, 0, 0, -9.5, -9.5
4. Change each of the values as desired. Note that the values must be entered in the listed order of the file header.
5. Save the file to a USB device and insert it into the MS2720xA.
6. Click the IMPORT MASK button in the SEM SETUP menu and select the new file from the USB drive. The file name of the imported mask file will be displayed on the EXPORT MASK button.
7. Click the SELECT MASK button and select Custom.