Tx Spurious Emissions Measurement Description

Last updated: October 29, 2004

How is a Tx Spurious Emissions measurement made?

TX Spurious Emissions is a measure of the mobile station's transmission at frequencies outside its assigned channel. This measurement is made while the mobile station is a loopback call connection at full data rate transmission (see Operating Considerations ).

The test set's TX Spurious Emissions measurement is made by first making a channel power measurement centered on the assigned channel, to determine carrier power. The test set then measures the power at four frequencies offset from the center of the assigned channel. The test set measures the average power present at each frequency offset, over a power control group, within a 30 kHz filter centered on the offset frequency. The test set then reports the power of each frequency offset relative to the carrier power (the result is given in dBc). A graphical view or a numeric view can be displayed.

The four frequency offsets at which power is measured depends upon the mobile station's band class:

Frequency offsets for band classes 0,2,3,5,6,7,9,10,11 and 12:
- ± 885 kHz (lower and upper adjacent channels)
- ± 1.98 MHz (lower and upper alternate channels)
Frequency offsets for band classes 1,4,8,13,14,15,16 and 17:
- ± 1.25 MHz (lower and upper adjacent channels)
- ± 1.98 MHz (lower and upper alternate channels)

Tx Spurious Emissions measurements are triggered by a 20 ms clock derived from signaling protocol.

Operating Considerations

See Tx Spurious Emissions Measurement Troubleshooting .

TX Spurious Emissions Measurement Parameters

Mask Control: When set to auto, the pass/fail limits for the spurious emissions at the adjacent and alternate channels are set as specified by TIA/EIA-98-E 4.5.1. When set to manual, you can set the pass/fail limits for the measurement. Separate pass/fail limits are provided for the adjacent and alternate channel measurements.
Adjacent Limit (in dBc): Sets the pass/fail limit for the adjacent channel measurement (range is -65 to -10 dBc).
Alternate Limit (in dBc): Sets the pass/fail limit for the alternate channel measurement (range is -65 to -10 dBc).
Multi-Measurement Count - When ON, this enables averaging of the TX spurious emissions results. (See Statistical Measurement Results ).
Trigger Arm - (see Trigger Arm (Single or Continuous) Description ).
Timeout Time/State - (see Timeouts ).

TX Spurious Emissions Measurement Results

Integrity Indicator - (see Integrity Indicator ).
Pass/Fail Result: An overall pass/fail indicator is displayed on the measurement screen and is available via GPIB commands (see FETCh:CTXSpurious:MASK[:FAIL]? ). The pass/fail result indicates whether the spurious emissions for all adjacent and alternate channels are within limits.
Spurious Emissions for Adjacent and Alternate Channels: The test set returns the spurious emissions levels for all adjacent and alternate channels. These spurious emissions levels are available from the measurement screen marker and via GPIB commands (see FETCh:CTXSpurious[:ALL]? ).

The TX Spurious Emissions Measurement Screen

The TX Spurious Emissions measurement screen can display numeric results or a graphical display.

The y-axis on the graphical display is fixed at -80 dBc/30 kHz to 0 dBc/30 kHz.
The x-axis on the graphical display is fixed at -2.5 MHz to 2.5 MHz relative to the carrier frequency.
Pass/fail limit lines are shown in green on the graphical display. These lines are set based on Mask Control and Adjacent/Alternate Limit (see TX Spurious Emissions Measurement Parameters ). If spurious emissions at any adjacent or alternate channel exceed a limit line, the word Fail appears on the display.
The carrier is displayed in the center of the display as a solid yellow bar. The spurious emissions power at the four frequency offsets is displayed as yellow bars.
The marker can be positioned on each of the four frequency offsets. The spurious emissions for that frequency offset is then displayed.

Input Signal Requirements

The Tx Spurious Emissions measurement meets or exceeds specifications when the following requirements are met:

The frequency of the signal being measured must be in the range of 411 MHz to 484 MHz, 804 MHz to 934 MHz, 1.75 GHz to 1.78 GHz, or 1.85 GHz to 1.98 GHz, and be within 100 kHz of the expected frequency.
The signal level into the test set's RF IN/OUT connector must be in the range of 0 dBm to +30 dBm. The test set can autorange to a signal that is within +/- 9 dB of the expected input level (see RFANalyzer:AUTO:POWer[:SELected]? ).

Key TIA/EIA-98-E Tests Using the Tx Spurious Emissions Measurement

Testing 4.5.1 Conducted Spurious Emissions

Calibrating the Tx Spurious Emissions Measurement

The Tx Spurious Emissions measurement is automatically calibrated during a channel power calibration. Follow the channel power calibration schedule and the Tx Spurious Emissions measurement will be properly calibrated. Refer to Calibrating the Test Set for a description of channel power calibration.