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Last updated: 2014-11-28
Spectrum Emission Mask Measurement Description
Spectrum Emission Mask Measurement Parameters
Spectrum Emission Mask Measurement Results
Spectrum Emission Mask (SEM), as defined in 3GPP TS 34.122, is a relative measurement of the out-of-channel emissions to the in-channel power. The SEM measurement is used to measure the excess emissions that would interfere to other channels or to other systems.
In-channel power: The in-channel power is measured on the RF input signal which is filtered with a Root-Raised Cosine (RRC) filter with a rolloff of alpha = 0.22. The measurement interval for the in-channel power is 1 timeslot (666.7 us).
Out-of-channel emissions: The out-of-channel emissions in frequencies between 0.8 and 4.0 MHz away from the center channel frequency are determined in three symmetrical bands on each side of the carrier (see Spectrum Emission Mask in the Test Set). The emissions are measured with either a 30 kHz or 1 MHz bandwidth Gaussian measurement filter. The spectrum emission mask measurement's pass/fail limits for the 30 kHz bandwidth filter and 1 MHz bandwidth filter can be set from the front panel.
Spectrum Emission Mask in the Test Set
|
|
Frequency Offset from carrier |
Measurement Bandwidth |
|
Range 1 |
0.8-1.8 |
30 kHz |
|
Range 2 |
1.8-2.4 |
30 kHz |
|
Range 3 |
2.4 – 4.0 |
1 MHz |
This measurement requires the calibration data of the measurement receiver path gain, which are part of the results of the measurement calibration, see Calibrate Measurements.
Multi-Measurement Count: see Multi-Measurement Count
Limit 30 KHz Bandwidth: +-0.8 MHz
Limit 30 KHz Bandwidth: +-1.8 MHz
Limit 30 KHz Bandwidth: +-2.4 MHz
Limit 1 MHz Bandwidth: +-2.4 MHz
Limit 1 MHz Bandwidth: +-4.0 MHz
Trigger Arm: see Trigger Arm
Trigger Source: see Trigger Source
Trigger Delay: see Trigger Delay
Time Slot to Measure: see Time Slot to Measure
Manual Power Range Offset: see Manual Power Range Offset
Measurement Timeout: see Measurement Timeout
Integrity Indicator: see Integrity Indicator
In-Channel Power: see In-channel power
Pass/Fail for the overall spectrum emission mask: If any out-of-channel frequency range does not comply with the limit you set, the entire mask fails.
Results for each frequency range:
Level Result relative to in-channel power: Average results for each offset. This can also be used to calculate the Mask Margin in the range.
Frequency Offset: Specifies in which the Mask Margin was calculated.
Mask Margin: Mask Margin = Mask Limit – Result/Average, and the minimum Mask Margin found in the range is displayed.
Pass/Fail: The mask for the range fails if the Level Result exceeds the mask.
Measurement results can be displayed in either numeric or graphic form.
When the graphic display is used, the result trace of the measurement is displayed. The green line is the spectrum emission mask for each frequency band range. There are four markers in the screen: the three red markers are always on and used to marker the largest mask error of the three frequency ranges; You can also turn on the white marker to see the corresponding frequency offset, relative power level and the margin on the top of screen. The lower part in this screen has six columns, which represents the index, the frequency range, the Pass/Fail result, the frequency Offset, the average result level and the Mask Margin of the frequency bands respectively.
When the numeric display is used, the Level column displays the average leakage power values measured at each offset, the Margin column displays the Mask Margin value and P/F column shows the Pass/Fail values for each offset.
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The measured signal level is expected to be within 9 dB of the expected power.
The level into the test set's RF IN/OUT connector must be in the range of +5 dBm to +28 dBm, in a 1.28 MHz bandwidth.
For Non-HSDPA channel type, the frequency of the measured signal should be within 20KHz from the expected receiver frequency; For HSDPA channel type, the frequency of the measured signal should be within 2KHz from the expected receiver frequency.
GPIB Commands: SETup:TSEMask, FETCh:TSEMask