Spectrum Monitor Description

How is the spectrum monitor (SMON) used?

The Spectrum Monitor (SMON) can be used to locate, identify and measure transmitted signals from a device under test. The Spectrum Monitor can be used while a call is in progress.

The Spectrum Monitor is intended to be used for indication only. The Spectrum Monitor does not have the same level accuracy specifications as other measurements provided by the test set, and should therefore not be used when parametric accuracy is required (for example, calibration of a mobile). It is recommended that you use the other wireless format-specific measurements when you require accurate parametric measurements.

The Spectrum Monitor has the following two modes of operation:

• Swept mode, in which the X axis represents frequency , and the Y axis represents absolute amplitude.
• Zero span mode, in which the X axis represents time and the Y axis represents absolute amplitude.

You can use the markers on the Spectrum Monitor's graphical display to set the expected frequency and power levels that are used by the test or lab application for parametric measurements.

The center frequency used by the Spectrum Monitor is initially set at the expected frequency maintained by the test set's base station emulator. The expected frequency range is 292.5 MHz to 2700 MHz.

The range of frequencies which the spectrum monitor is calibrated to measure is determined by the range of traffic band frequencies supported by the specific test or lab application that is currently running. For example, if you are using the GSM Test Application, any of the frequencies used by the GSM traffic bands are available for you to monitor accurately. You can view signals which fall outside of any of the frequencies used by GSM, but the Spectrum Monitor will not be calibrated.

From the test set's front panel, the Spectrum Monitor can be accessed by pressing the Instrument Selection key, then selecting Spectrum Monitor . If you require more details on manual operation of the Spectrum Monitor, see How Do I Use the Spectrum Monitor? .

Single or Multi-Measurements

The Spectrum Monitor can return either single or averaged results.

• If you set the averaging state OFF then the trace represents a single measurement sweep.

• If you set the averaging state ON, and the averaging count number to a value greater than one, then the trace represents the rolling average of the specified number of sweeps.

Input Signal Requirements

The Spectrum Monitor will complete and meet its accuracy specifications under the following input signal conditions.

• The signal is within 40 dB of the reference level.
• The measurement frequency is within the traffic band frequencies supported by the specific lab or test application that is currently running, and the expected frequency is tuned to the carrier.

Trigger Source

Triggering choices available for the Spectrum Monitor are Auto, Immediate, Protocol, RF Rise, and External.

When Auto triggering is selected, the test set chooses Protocol triggering if a protocol trigger is available. Otherwise, RF Rise triggering is selected.

For more information on measurement triggering, refer to Triggering of Measurements .

Related Topics

Programming the Spectrum Monitor

Test Adherence to Standards

Spectrum Monitor Troubleshooting