Remote Spectrum Monitor™ MS27201A User Guide : LTE Measurements : LTE Channel Spectrum
 
LTE Channel Spectrum
Channel spectrum (occupied bandwidth) is a common measurement performed on radio transmitters. This measurement calculates the bandwidth containing the total integrated power occupied in a given signal bandwidth. There are two different methods of calculation depending upon the technique used to modulate the carrier.
% Integrated Power Method: The occupied frequency bandwidth is calculated as the bandwidth containing the specified percentage of the transmitted power.
X dB Method: The occupied frequency bandwidth is defined as the bandwidth between the upper and lower frequency points at which the signal level is a desired number of dB below the peak carrier level.
An occupied bandwidth measurement using the % integrated power is shown in Figure: LTE Channel Spectrum (Occupied Bandwidth) Measurement. The occupied bandwidth here is the bandwidth containing 99% of the total channel power. This is calculated from 0.5 % of the total mean power below the lower frequency limit and 0.5% above its upper frequency limit of the signal. Alternatively, the measurement can be set up to use the X dB method where the occupied bandwidth is determined from the upper and lower bandwidth edges that are X dB down from the total mean power of the signal.
LTE Channel Spectrum (Occupied Bandwidth) Measurement

1. LTE Channel Spectrum 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 and band configuration. See Status Panel (LTE Channel Spectrum).
2. Occupied Bandwidth: Occupied bandwidth is integrated over the shaded region where the dashed green lines indicate the upper and lower frequency thresholds. The analyzer will determine and track the occupied bandwidth of the signal within the current span.
3. SETUP Menu: The occupied bandwidth settings are configured in the SETUP menu. See SETUP Menu (LTE Channel Spectrum).
4. OBW Summary: This area shows the occupied bandwidth measurement summary data and pass/fail test results, when enabled:
The occupied bandwidth value and the test limit are expressed in frequency units with a pass/fail result.
The total power is integrated over the measured bandwidth and is expressed in dBm.
The received signal power is expressed in dBm.
The transmit signal frequency error is expressed in frequency units (Hz).
Tapping this summary area opens the OBW SETUP menu.
 
SETUP Menu (LTE Channel Spectrum)
The Occupied Bandwidth SETUP menu is available in MEASURE > MEASUREMENT > Channel Spectrum > SETUP. Once the channel spectrum measurement is selected, the SETUP menu can be quickly accessed by tapping on the summary display area below the spectrum display.
LTE SETUP Menu (Channel Spectrum)
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% OBW POWER
Sets the percentage of the total power that is measured within the occupied bandwidth for the current measurement. The resulting occupied bandwidth and total power values are displayed in the measurements results table.
X DB
Sets the x dB value used for the "x dB bandwidth" measurement. The occupied bandwidth is the frequency range between two points on the signal that are x dB down from the highest signal point within the OBW span.
OBW LIMIT
Enables limit checking at the specified frequency. The limit test results show as a green PASS or a red FAIL in the measurement table.
METHOD
Select the measurement method to be PERCENT (%) or X (dB).
PRESET SETUP
Presets the SETUP menu to default settings.
 
Status Panel (LTE Channel Spectrum)
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 (LTE Channel Spectrum Measurement) shows the LTE status panel that covers the LTE Channel Spectrum measurements.
Status Panel (LTE Channel Spectrum Measurement) 
 
MIMO ANTENNAS: Toggles the current MIMO antenna setting between AUTO or to select one of the available antennas. When a single antenna is selected, a blue underscore will appear below the antenna icon. The antenna icon is highlighted green when receiving a signal.
SWEEP: Toggles the current sweep setting between continuously or sweep once.
SWEEP ONCE
When sweep is set to single sweep, SWEEP ONCE updates the measurement display. Data continues to be captured in the background.
CHANNEL BW
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.
TRACES: Displays the current status of up to six traces in a quick-view summary. The summary information includes the trace number, type, mode, and detector type. The active trace or cursor will show a highlighted background with the mode and detector type restated under the table. Clicking a trace in the summary panel opens the TRACE menu. It allows you to select and set up an individual trace as desired.
FREQ REFERENCE
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.