Remote Spectrum Monitor™ MS27201A User Guide : 5GNR Measurements : 5GNR Constellation
5GNR Constellation
5GNR constellation measurement displays the demodulated symbol point location of a selected SSB beam on an IQ coordinate plot, which illustrates the constellation of a particular modulation format. Remote Spectrum Monitor displays QPSK constellation with a PCI summary and power tabular data. An example 5GNR constellation display and measurement is shown in Figure: 5GNR Constellation Measurement.
5GNR Constellation Measurement
1. 5GNR Analyzer Status Panel: Each measurement features a unique status panel that displays settings and information relevant to the current measurement and view settings. This panel provides quick access to the measurement frequency, subcarrier spacing, channel bandwidth, and band configuration. See Status Panel (5GNR Constellation).
2. PCI Summary: This area shows the physical cell ID summary data, including the sector ID, cell group number, frequency error, time offset, and sync status. Sync status can indicate if there is a PSS, SSS, or Beam Index failure, Full Sync, or an Unknown condition. Also noted is the instrument’s reference clock accuracy of Internal, External, or GPS high accuracy (requires GPS).
3. Constellation: This area displays the demodulated symbol point location on an IQ coordinate plot. Points are drawn in colors that are associated with the symbol point density. Warmer colors (red/orange) indicate a higher symbol density where cooler colors (cyan/blue) indicate lower symbol density. The ideal symbol reference point location overlay can be toggled on or off via the SETUP menu.
4. Channel Summary: For the currently selected beam, shows the RMS error vector magnitude (EVM), peak EVM (@ subcarrier/symbol) and received power in dBm for each block measurement:
PBCH-DMRS: In 5GNR measurements, the PBCH decoding relies on a demodulation reference signal (DMRS, which is a physical layer reference signal used for decoding) rather than a cell specific reference signal (CRC).
PSS: The primary synchronization signal provides the primary frame boundary
(i.e., the position of the first symbol in the frame).
SSS: Similar to PSS, the secondary synchronization signal provides the secondary sub-frame boundary.
5. SETUP Menu: The constellation measurement settings are configured in the SETUP menu. See SETUP Menu (5GNR Constellation).
SETUP Menu (5GNR Constellation)
The control channel SETUP menu is available in MEASURE > MEASUREMENT > Constellation > SETUP.
SETUP Menu (5GNR Constellation)
Selects the modulation format (only QPSK is available).
Selects the data format (only Physical Broadcast Channel (PBCH) is available).
BEAM SELECT: Selects the 5GNR SSB beam for the demodulation and display.
Toggles the ideal reference point locations on or off.
Presets the SETUP menu to default settings.
Status Panel (5GNR Constellation)
The status panels illustrated in this section are unique to the current analyzer and to the particular measurement and view that is selected.
Figure: Status Panel (5GNR Constellation) shows the 5GNR status panel that covers the 5GNR constellation measurement.
Status Panel (5GNR Constellation) 
SWEEP: Toggles the current sweep setting between continuously or sweep once.
When sweep is set to single sweep, SWEEP ONCE updates the measurement display. Data continues to be captured in the background.
Select MANUAL, Global All or one of the predefined bands. Selecting MANUAL disables ARFCN and GSCN settings.
ARFCN is the Absolute Radio Frequency Channel Number. The ARFCN is a unique identification number assigned to each radio channel within a communications spectrum. The ARFCN can be used to calculate the center frequency of the radio channel. The available input range is dependent on the selected band. ARFCN is activated when the BAND is set to a predefined band or Global All.
Sets the measurement channel bandwidth. The available bandwidth settings depend on the selected band and bandwidth option installed in the instrument. Refer to Options Settings.
GSCN is the Global Synchronization Raster Channel. The GSCN identifies the mapping of the synchronous signal block (SSB). The available input range is dependent on the selected band. GSCN is activated when the BAND is set to a predefined band or Global All.
Sets the subcarrier spacing. The available input range is dependent on the selected band.
When the band is set to MANUAL, sets the center frequency of the measurement channel. Changing the center frequency sets the band to MANUAL.
SSB is the Synchronous Signal Block. The SSB Offset sets the frequency offset between the SSB and the overall resource block.
Indicates the current frequency reference source of Internal, External, or GPS Hi Accuracy (requires GPS). The instrument automatically selects the frequency reference in the following order of priority: external, GPS, then the internal time base.