Two submenu keys provide automatic parameter detection. They are Auto Detect Parameter and Detect Parameter Once. The functions of these submenu keys may vary depending upon the Measurement Mode and the Measurements setting.

Auto Detect Parameter is useful only when used in Continuous measurement mode. This automatic parameter detection function can be used in RF Measurements (Signal Power and Spectrum Monitor) and Modulation Analysis measurements. The Auto Detect Parameter feature does not perform the detection, but it triggers the Auto Reference Level function (available in the Amplitude menu) or the Detect Parameter Once function, or both, when the need arises.

In Figure: Measurement Setup and Selection Menus, the Meas Mode is set to Continuous. The Meas Setup and Advanced Settings menus in this figure apply only to RF Measurements and Modulation Analysis measurements, not to BER measurements.

Auto Detect Parameter and Detect Parameter Once are not available for BER measurements.

In RF Measurements measurement mode, the Auto Detect Parameter feature is seeking power level. The Auto Detect Parameter feature triggers the Auto Reference Level function (available in the Amplitude menu) when the need arises. If attempts to achieve optimal reference levels fail twice, then the Auto Detect Parameter feature is automatically turned off. Otherwise, the Auto Detect Parameter feature remains On and triggers the Auto Reference Level feature only when needed.

In Modulation Analysis measurement mode, the Auto Detect Parameter feature is seeking Mode, GI, Modulation, Hierarchy parameters, and Reference Level in multiple sweeps. If none of these parameters are detected, then the search ends, and the Auto Detect Parameter feature is automatically turned off. The Auto Detect Parameter feature automatically changes instrument settings for these parameters and triggers the Auto Reference Level feature (available in the Amplitude menu) or the Detect Parameter Once function, or both, when the need arises. If all of the parameter settings cannot be determined, or if parameter detection fails twice, or if attempts to achieve optimal reference levels fail twice, then the Auto Detect Parameter feature is automatically turned Off.

If Auto Detect Parameter is Off, then you can press the Detect Parameter Once submenu key to detect the same measurement parameters that would be detected by the Auto Detect Parameter feature if it were On.

While the Auto Detect Parameter function is seeking the correct signal parameters, it changes the settings. If unsuccessful, it tries again. If not successful after 2 tries, it is automatically turned Off. When the Auto Detect Parameter function fails and is automatically turned off, any of the parameter settings may then be different from their settings before using the Auto Detect Parameter function.

The Auto Detect Parameter feature also applies to Carrier MER measurements.

The Auto Detect Parameter and Detect Parameter Once functions detect and set the FFT Start position only if the FFT Start Detection submenu key is set to On. The instrument searches for the best possible FFT Start position, which yields the highest MER result. Measurement begins after FFT Start is detected. This function is not valid when the FFT Start is set to a fixed position. Refer to FFT Start.

When the FFT Start Detection submenu key is set to Off, the detect parameter operation does not search for FFT Start, but it does search for the other parameters. If you do not have a need to determine the FFT Start position manually, then the use of FFT Start Detection is recommended because it saves significant time.